Help us with this petition for security on anti-collision systems

[sergioala...@gmail.com]

Hi,
we recently launched a petition against Flarm decision to encrypt their communication protocols.

Although Flarm have the majority of the market for anti-collision systems there are others vendors and we think that monopolies are not a good things in any market and more important security comes first.

For this reasons we invite you to subscribe our campaign.

https://www.change.org/p/mr-urs-rothacher-flarm-chairman-petition-against-flarm-decision-to-encrypt-the-communication-protocol

Thank you so much!
Sergio

[jpg...@gmail.com]

Hasn't this argument been done to death already? Flarm get to protect their intellectual property rights and gliders pilots get mutual interoperability between glider to glider collision warning units. Third party hardware makers get to include and sell Flarm capability in their own instruments. Geeks get to complain about monopoly and conspiracy. Everyone's a winner.

[Tim Newport-Peace]

At 10:30 22 May 2015, sergioala...@gmail.com wrote:
>Hi,
>we recently launched a petition against Flarm decision to encrypt their
>communication protocols.
>
>Although Flarm have the majority of the market for anti-collision systems
>there are others vendors and we think that monopolies are not a good
things
>in any market and more important security comes first.
>
>For this reasons we invite you to subscribe our campaign.
>

>https://www..communication-protocol

>
>
>Thank you so much!
>Sergio
>

Do you have any connection with DSX?

As far as I know they are the only equipment manufacturer offering a Flarm
?compatible? instrument that does not use integrated Flarm (tm) Firmware.

[sergioala...@gmail.com]

It's not a question of being a geek or having any connection with DSX.

The real issue here is that FAI rules should be that you need an anti-collision system instead of oblising the pilots in competition to use one specific brand. They should define a common protocol so anyone interested can develop its own product.

A valid example is for the flight recorders. You do not need to buy a flight recorder of a specific brand. There is a standard format (IGC) defined by the authorities.

For sure I do not like monopolies....

[Tango Whisky]

The new encryption of Flarm is a result of the OGN activity which more or less pirated the existing protocol, as well as the existing FlarmNet database without asking for permission.
OGN then put all tracked gliders with their real ID onto a public website map.

While in France people generally like that, a fair number of pilots in Germany were upset by the fact that their real-time tracks were visible on a public map without having been asked. I myself don't want this to happen.

So the choice was simple - either a new encryption, or a large number of pilots simply switching off their Flarm. I am happy with the encryption.

Now OGN people are just pissed off that they have to hack the protocol again.

[sergioala...@gmail.com]

This is a good point, however security should come first. I'm not a protocol expert at all, but it would have made more sense to hide ID.

[sergioala...@gmail.com]

In any case I think that an important organization like IGC should define a protocol, taking in consideration the privacy issue.

Exactly like the IGC file format for the loggers. Nobody contests the fact that every pilot that does competitions or records must have a certified logger. In a similar way every pilot in competition should have an anti-collision. It should not be obliged to buy a single brand like if we were in the Soviet Union

[Tim Newport-Peace]

Wrong in many ways. Earlier releases of Flarm were time-bombed long before
OGN came into being.

There has always been an opt-out.

>
>While in France people generally like that, a fair number of pilots in
>Germany were upset by the fact that their real-time tracks were visible
on
>a public map without having been asked. I myself don't want this to
happen.

The opt-out.

>
>So the choice was simple - either a new encryption, or a large number of
>pilots simply switching off their Flarm. I am happy with the encryption.

No. It was going to happen anyway.

>
>Now OGN people are just pissed off that they have to hack the protocol

Not pissed off. OGN up and running on V6.
>again.
>

[Surge]

On Friday, 22 May 2015 14:50:22 UTC+2, Tango Whisky wrote:
> The new encryption of Flarm is a result of the OGN activity which more or less pirated the existing protocol, as well as the existing FlarmNet database without asking for permission.
> OGN then put all tracked gliders with their real ID onto a public website map.

- OGN don't use the FlarmNet database any more. They use their own database now.
- OGN honour the "no-tracking" flag in the FLARM version 6 protocol.
- If you want your details to be displayed on OGN you need to opt-in.
- If you don't want your details to be displayed anymore you can opt-out but there is no auto opt-in or the copying of your ID from other sources (like the FlarmNet DB).

Plenty of detail here http://wiki.glidernet.org/opt-in-opt-out

> Now OGN people are just pissed off that they have to hack the protocol again.

Geeks like the challenge - V6 already hacked.

It's nice to see that OGN are playing nicely now for those who prefer to keeo their identities secret.

[marco....@gmail.com]

The matter with FLARM may have discussed "to death" but a few appear th have grasped the basics, so let me try to wrap it up once for ever: FLARM decided one day to make business in flight safety by manufacturing an air trafic alert device, a Version for glider pilots of a TCAS in fact. Fair enough. The device has soon spread throughout the glider pilots community and by doing so it has changed the pilot's behaviour in flight. As soon as other manufacturers showed up FLARM introduced the data encryption in the firmware of a TCAS system making the other systems invisible to them and viceversa. This modus operandi is unthinkable in the GA and commercial aviation and thanks God. We all get on planes to fly for business or leisure without realling worrying about mid air collisions in a much denser airtraffic environment. This thanks to the fact that the standards are set by an authority, the FAA generally, and not by the whim of the largest or most cunning manufacturer. The fact that the soaring world is not as heavily regulated as the general and commercial aviation by no means mean that FLARM is entitled to act as it does since 2008. The protocol transmission has to be public and I for God's sake still want to have the right to chose the system that i like the most for my glider!
Marco Maceri

[Tim Newport-Peace]

At 13:14 22 May 2015, sergioala...@gmail.com wrote:
>In any case I think that an important organization like IGC should define

>a=
> protocol, taking in consideration the privacy issue.=20

>
>Exactly like the IGC file format for the loggers. Nobody contests the
fact

>=

>that every pilot that does competitions or records must have a certified

>lo=

>gger. In a similar way every pilot in competition should have an

>anti-colli=

>sion. It should not be obliged to buy a single brand like if we were in

>the=
> Soviet Union
>
You are not.

EDIATec, LXNAV and LX Navigation all make a variety of instruments with
integrated Flarm. You have a choice.

As you are probably aware, DSX took this question to IGC many years ago
without the result they wished for.

Are you connected with DSX?

[sergioala...@gmail.com]

Tim,
I'm not. I am a DSX user and my behavior would be the same even if I had a Flarm.
I want to fly safely and I'm in favor of open market.

I like to fly in France in summer and as a matter of fact they are requesting me to throw away my DSX and install a Flarm. Do you think this is fair?

[Shaun McLaughlin]

At 13:46 22 May 2015, Tim Newport-Peace wrote:
>At 13:14 22 May 2015, sergioala...@gmail.com wrote:
>>In any case I think that an important organization like IGC should
define
>>a=
>> protocol, taking in consideration the privacy issue.=20
>>
>>Exactly like the IGC file format for the loggers. Nobody contests th

>fact
>>=
>>that every pilot that does competitions or records must have a certified
>>lo=
>>gger. In a similar way every pilot in competition should have an
>>anti-colli=
>>sion. It should not be obliged to buy a single brand like if we were in
>>the=
>> Soviet Union
>>
>You are not.
>
>EDIATec, LXNAV and LX Navigation all make a variety of instruments wit

>integrated Flarm. You have a choice.
>
>As you are probably aware, DSX took this question to IGC many years ag

>without the result they wished for.
>
>Are you connected with DSX?
>
>

Is there a report available on that IGC discussion?

Thanks,
Shaun

[sergioala...@gmail.com]

By the way, there are more than 500 glider pilots out there that are supporting us.
And we wish to thank them all for signing and the people that, reading this conversation, will sign the petition!
THANKS

[Wolf Aviator]

At 13:46 22 May 2015, Tim Newport-Peace wrote:

[Wolf Aviator]

At 11:35 22 May 2015, jpg...@gmail.com wrote:
>Hasn't this argument been done to death already? Flarm get to protect

>the=

>ir intellectual property rights and gliders pilots get mutual

>interoperabil=

>ity between glider to glider collision warning units. Third party

>hardware=

> makers get to include and sell Flarm capability in their own
instruments.

>=

>Geeks get to complain about monopoly and conspiracy. Everyone's a
winner.
>

Not really. Flarm protects their revenue by keeping their protocol closed.
Do you claim that a protocol can be pattented?

Monopoly makes things stagnant and more expensive. DSX provided better
device, for better price. Being CEO of a company you want keep competition
away, but being a consumer I don't understand why you want just one
product? What's more supporting just closed source you force others to buy
just this one only product.

Interoperability is not an issue, as long as protocol is known what DSX has
already shown.

There is no conspiracy in it. Monopoly is a simple fact.
Regards
Wolf
http://youtu.be/aQUB7erVIKw

[Wolf Aviator]

At 13:46 22 May 2015, Tim Newport-Peace wrote:

[sergioala...@gmail.com]

Well said Wolf. It's not a win-win situation. Simply said Flarm uses its dominant position to try to make more money. Business decision. What is wrong is that someone ask to have Flarm on board. They should ask an anti collision system based on a protocol certified by a third party (IGC???)

[Alexander Swagemakers]

Flarm currently does not have to ensure compatibility to its legacy code (due to mandatory updates), let alone having to respect a protocol or the ideas of other vendors. In my opinion this flexibility is one of the reasons Flarm was able to evolve so well.

Opening the protocol would mean that all stakeholders would need to agree on any change to the protocol. New ideas would need to be formally filed, debated, different interests negotiated, compromises would need to be found before a small change finally can be implemented and rolled out. Unfortunately democratic processes are not very efficient. Looking at the ADS-B discussion in another thread shows how difficult and time consuming it can be to establish a new standard.

[jpg...@gmail.com]

On Friday, May 22, 2015 at 9:33:48 PM UTC+1, sergioala...@gmail.com wrote:
> "Well said Wolf. It's not a win-win situation. Simply said Flarm uses its dominant position to try to make more money. Business decision. What is wrong is that someone ask to have Flarm on board. They should ask an anti collision system based on a protocol certified by a third party (IGC???)"

That would be fair enough - if (and its a big if) the IGC had established both a communication protocol and (crucially) a collision prediction algorithm tailored for gliders that they were prepared to continually develop and update - then it would have been perfectly logical for those to be made open to all developers. That is a route that could have been taken but it is extremely unlikely that a body such as the IGC could have had the idea, the means and the will to have done so. In the real world it was done commercially and there are 25,000 Flarm units already installed and you have simply missed the boat. Many of those will be in club gliders and many others in syndicated gliders so a very conservative estimate would be 50,000+ pilots flying using Flarm at present. 500 supporting the petition is probably about 1% of the number of users. It would be very interesting to know how many of those signing the petition are actually current Flarm users.

Your petition only mentions the communication protocols. Flarm is both the communication protocol plus the collision warning algorithm. For the rest of us who have already paid for, and are using, Flarm the prospect of competing systems has no gain and increases the possibility of incompatible warning algorithms.

John Galloway

[sergioala...@gmail.com]

Well this is an interesting point. I personally believe that the Flarm's users should also sign and the reason is easy: if they are a monopolist they can always decide to charge, as an example, a fee for using their device. If you put (always as an example) 100 EURO per year they could make 2.5 million per year on license fee. Not bad for them, not so sure for the users....

Apparently Alexander doesn't like democracy on this but we all definitely like the Internet. CISCO has the vast majority of the router but they do not own the IP protocol. This is just to make an analogy with a market a bit bigger ....

[Buddy Bob]

I'm afraid this is all a bit pointless, flarm is yesterday's company. If
I held them I'd be selling the stock, and if I could I'd be shorting it.
In 10 years you'll be saying flar...who? Why do I say this? Well as a
typical monopoly they have refused to innovate, and as usual this
works for a while, but the writing is now on the wall... The OGN
have published their tracker spec.. and if you look at it, it 'could' do
everything a flarm does... but at $30.. Now I know it doesn't right
now, but look through their code.. it's like 10 lines extra... and at a
size weight and power that would appeal to a whole host of other
users, paragliders, hanggliders, UAVS... a few glider pilots will be
irrelevant.... do you really think they won't?

I'd leave flarm to their own little bubble... you'll have exactly what
you want in a few years..

[Nick]

Why does Ebay have a monopoly when anyone could build a site and undercut them?

It's because the market for auctions is winner takes all. As a buyer you don't care which site you go to, you are just after the cheapest price.

As a seller you can only use one site per item, and you go to the one with the biggest number of users and hence the greatest number of people trying to buy. The listing costs in most cases are dwarfed by the money you make from the competition.

So with flarm, its a case that people are going to go with one system, and that's going to be determined by the number of users, or its mandated by law.

[Charlie M. (UH & 002 owner/pilot)]

I don't "own" a Flarm, but I fly sailplanes that have them.

-I think it's good for the "intended user".
-I wish it "talked" to other "users" (namely commercial/private USA pilots)
-I "believe" a large "user group" of Flarm users have a bigger impact on what Flarm does than "petition" does.

In general, the market drives the company. If the company IGNORES the users, then the company dies.
Sorta "Business 101".

While I understand this thread, I feel there is a better way to drive Flarm.
If they're resistant, then they will fail and thousands of users will "jump ship" and go another direction.

Just saying.........

PS, Flarm, are you listening?!?!?........ "Poop or get off the pot".

PPS, not saying this has to be open source, but if you want to sell more systems, it "should" cover upcoming regulations (in various countries) reg's for collision avoidance.
The superfulace (sp) stuff may be nice, but NOT regulated/mandated.

[Ian]

On 22/05/2015 12:30, sergioala...@gmail.com wrote:
> Hi,
> we recently launched a petition against Flarm decision to encrypt their communication protocols.
>
> Although Flarm have the majority of the market for anti-collision systems there are others vendors and we think that monopolies are not a good things in any market and more important security comes first.
>
> For this reasons we invite you to subscribe our campaign.
>
> https://www.change.org/p/mr-urs-rothacher-flarm-chairman-petition-against-flarm-decision-to-encrypt-the-communication-protocol
>
> Thank you so much!
> Sergio
>

There is going to be a lot of emotion around this. But from my personal
viewpoint. My club adopted Flarm back in 2004/2005. I think we were one
of the first sites outside of Europe to attempt to reach threshold usage
level required to make the system effective.

At the time Flarm was an experimental idea. Nobody knew if it would
work. As much as some US pilots have indicated reluctance to accept the
idea when first introduced to them, some of our members were also
sceptical. Yet a number of our members risked our own cash to buy the
first and 2nd batches of flarm for our private gliders (which took
nearly a year to arrive). Then we used club cash to buy units for the
club ships.

We made this risk investment on the understanding that Flarm was a
non-profit, good for glider pilots movement, empowered to a large extent
by voluntary man hours. We added to their efforts with testing and
regular feedback.

Now Flarm is commercially viable. I see it as having application in a
lot of GA aircraft as well as unmanned drones as well as gliders. It
works and I am a fan of the technology.

But I feel that encrypting the protocol goes against the spirit with
which I, and many other early adopters made risk investments.

[Bruce Hoult]

Ebay is a good example. In New Zealand they got their arses kicked by local site TradeMe.

Or Starbucks. Why is Starbucks a virtual monopoly in the USA? They also got their arses kicked in both New Zealand and Australia, where they couldn't compete with local boutique cafes (not even another chain) and have closed something like 80% of their stores.

[marco....@gmail.com]

> But I feel that encrypting the protocol goes against the spirit with
> which I, and many other early adopters made risk investments.

As a matter of fact a FLARM customer might very well receive this communication soon:

"Dear Flarm customer, as already announced four years ago the new firmware release 6.0 prevents DSX devices from exchanging position, speed and altitude data with our products operating this release. In case of a mid air collision we do not take responsibility for the DSX pilot as he/she chose to buy an incompatible device. As for that one of our customers, who will happen to be involved in accident we sincerely apologize for the inconvenience. Thanks for choosing FLARM."

[Sean Fidler]

ROTFL

[sergioala...@gmail.com]

Good point Bruce!
I would only add that in this case also the Flarm's users should care. First of all in Europe there are gliders flying with DSX. As of today Flarms can only see Flarms. So they buy an anti-collision system and they may collide with another glider only because the encryption.... Crazy isn't it?

Second, in a condition of monopoly, the incumbent may decide the commercial policy he likes the most. And this, believe me, will not be in favor of the users

[herbk...@gmail.com]

Sergio, have you heard of a little company named Apple? They seem to be the ultimate monopolist, nobody is guarding their intellectual and physical properties and trademarks as they do. Last I've seen, they are doing pretty well with that strategy - and their users seem to love them. Why don't you go whining to them? Flarm is in a much more vulnerable place and I don't begrudge them wanting to protect what they developed. To claim they are putting customers' safety at risk is the height of hypocrisy.

[jpg...@gmail.com]

DSX explicitly don't want their T-Advisor unit to function as an anti-collsion unit and they don't believe in the philosophy of a predictive algorithm for gliders - which is the absolutely defining feature of Flarm - so why would Flarm want to offer their communication protocols to DSX? In that case we Flarm users would be receiving traffic advisories of limited usefulness from DSX units instead of much more useful Flarm alerts. It would be very much better if DSX owners had bought Flarms or if DSX incorporated Flarm functionality in their products under licence - as do many other successful glider instrument companies.

See: http://www.soaringwear.com/uploadz/02/PDF/T-Advisor_07_12_19.pdf

DSX simply got it commercially wrong with the T-Advisor. At least with the SaFly they produced a sensible product that functions solely as a tracker and emergency locator.

[Kevin Neave]

So as a pilot in a Glider with Flarm I'm warned of a potential collision
risk with one of 25000 or so other Flarm equipped Gliders. If there's no
collision risk Flarm doesn't distract me.

How Many DSX equipped gliders are there in Europe?
What collision risk prediction does it do, their website suggests it does
no prediction and just tells me that there are lots of gliders flying
within 7km of me. I already know that on any day that I'm flying in the
South of England there are lots of gliders within 7km, what does DSX
provide that I don't get from looking out of the window?

[marco....@gmail.com]

I don't see much the point of your comment, but as you mention Apple, perhaps you can also tell why Samsung, LG and all the other smartphones CAN communicate with the I-Phones, and therefore be sold, in spite of the fact that Apple at first designed one and created the market for them.

[marco....@gmail.com]

Mah! This is very much an opinion of yours. In the same document there's an explaination why a prediction based method is not suited for this application. I personally agree with DSX approach.

[Tango Eight]

On Tuesday, May 26, 2015 at 1:02:45 PM UTC-4, marco....@gmail.com wrote:
> Mah! This is very much an opinion of yours. In the same document there's an explaination why a prediction based method is not suited for this application. I personally agree with DSX approach.

Only about 5 million hours of flarm experience to date showing that their predictive algorithm works very well indeed.

-T8

[Lucas]

The T-Advisor AND Flarm are NOT anticollision system.
Anticollision systems are those who tell the pilot what to do (like TCAS), in case of emergency. Neither system does this.
BOTH systems are NOT anticollision systems.

Cleared this, those who talk about the "predictive algorithm", can please explain:

1) how it works, since they must know how it works, to be in the position of saying that it works or it doesn't

2) how they know that such an algorithm has been implemented into a Flarm system: what proof do they have of this ?

3) if they have ever seen the trace of at least 10 glider flights in different conditions (competition, cross country, around-the-airfield, ridge soaring,....); whoever has seen some, not many, traces of flights, without the need to be a glider pilot, can understand that a prediction of the position of a glider in a future time beyond a fistful of seconds is impossible, exactly IMPOSSIBLE, since not even its pilot knows it, apart from some cases, like straight flying and constant turn rate thermaling. A glider pilot knows that he will be changing the trajectory of the glider to search for the best netto value, which depends on the micro air movements, which are unknown to the pilot in terms of exact location. Is there a machine capable of predicting these locations ? And even if there was, is there a machine capable of predicting what a glider pilot will do in the next 30-60-80 seconds ? Because this is what the rumored (never verified) "prediction algorithm" does. This is spectacular indeed !

4) even if they found a system to predict the position of the glider with a certain probability, would they trust as optimal a system that has (obviously) a probability to fail the prediction and miss a danger of collision ? Even if the probability was low (all but sure, since never demonstrated with objective tests and calculated data), 2, 3, 10 collisions (and deads) out of XX'XXX flights are too much. In aeronautics, this approach is wrong: this is not the way we work in professional aeronautics, that has taken us where we are in aviation


Kevin Neave, can you show in which website you read that the T-Advisor tells you "that there are lots of gliders flying within 7 km" ?
Please indicate the source of this concept. Because this is completely FALSE.
The T-Advisor does NOT USE (not that it does not calculate, a very different story) a prediction coming from an unverified, unknown algorithm (if it is at all) to give warnings to the pilot. Its approach is down to what is sure, real, objectively undeniable and at the basis of a collision: the relative approach speed of the aircraft and their distance, calculating the time to possible impact. Depending on some parameters (time to impact, approach speed, difference of altitude, etc.) the communication to the pilot is given at three different levels of warning.
No predictions based on extrapolations or assumptions of pilot's behavior, that are impossible to know beforehand.
Nevertheless, to make the Flarm systems work with the T-Advisor, it calculates the prediction in a very similar way to these systems, and transmits the data. But it does not, and will not use these hypothetical data to give warning of a possible fatal collision to a pilot.
The consistent behavior of the Flarm systems flying with the T-Advisor systems like with other Flarms has demonstrated, in some hundreds thousand hours of flight, that the prediction of position calculated by the T-Advisor is very similar to the one calculated by the Flarm. I will not say here how this is done, because it might destroy your faith (on not proved basis) in what was always told to you, but this is enough to prove that the two systems work well together, and the same could happen with other new systems around.
The reports of many pilots, during 10 years of operations and the hundreds thousand hours of flight of the T-Advisor are a clear demonstration that it is just an excuse that two different systems can't work well together.
Apart from all the above, Kevin, there is NO PILOT that can see all air traffic of gliders within a range of up to 17 km (this is the maximum range of the T-Advisor correctly installed onboard). If you are capable of that, you are the only one, and you are an outlayer when considering the behavior of the average glider pilot.


Tango Eight, your statement is lacking of a scientific base: WHAT demonstrates that the "prediction algorithm works very well" ? Not the number of hours. That is senseless, obviously.
The collisions avoided thanks to the system would demonstrate that.
So: have you got the statistics "before and after" the introduction of these systems ?
Do you know if these systems have failed anytime ? And why ? (There have been collisions between gliders equipped with Flarm).
Obviously these systems increase the awareness of the surrounding traffic, there is no doubt about that, but from this to saying that it demonstrates that the prediction algorithm is correct the step is huge, and scientifically honestly, impossible.
The technical chats without FACTS are of poor use.
If anybody wants to convince somebody else of something in aviation, and engineering in general, should do it with FACTS, not declarations without basis.
Prediction algorithm ?
Patented method from Onera implemented ? Who proved that it's implemented ? (btw: discussing with Mr. Le Tallec, the inventor of the "prediction method" rumored to be adopted in these systems, he agreed that his method doesn't work well in ridge soaring, where the only method that is sensible is the one based on the approach speed and distance).
A radio protocol copyrighted or patented ? (It is impossible, by law)
Assigned patents ? (Make a check first: you will find only one, valid just for Germany, accepted after it was refused twice - Nothing more).

This way of working has been and still is very far away from what is a sounding procedure in aeronautics.
This doesn't mean spending the money to certify a system (which, btw, with so many units around, could be spent, no ?).
- It means adopting a procedure that is sound and clear, in the design (not starting with an electronic design that is old and, i.e. without the proper radio performance: the declared range of that system was 3 km - written in the official presentation of 2005 - while the T-Advisor was reaching 15 km, with the same transmission chip and power output)
- What is used for safety has to prove its full effectiveness with facts and objective quantitative tests (marketing doesn't save lives)
- What is used for safety has to be verified by an independent party, not hidden (who hides it, is because he fears to be uncovered, usually; patents protect what can be be protected, the rest is fog and chats)
- When a firmware update is mandatory, it must be managed in a way that there isn't a situation of a part of the systems (of the same manufacturer) incompatible with the rest of the same systems, creating a situation of high risk (for example for a change of radio protocol, it can be done with three lines of code like this: if (date < XX); transmit like this; else transmit like that).

The origin of the discussion appears to be a commercial attitude of Flarm. They are perfectly right in doing what they do: they are not a charity foundation and they try to protect what they did in all ways possible.
It is then up to the sector (gliding) and customers to accept this or not.
It is then up to the authorities to make and impose the rules for the well being of the community and the continuous development.
What is sure is that what has happened until now is far from the standard practices adopted in aeronautics (and in many ways, engineering in general): it's not a matter of increasing costs (the excuse so often brought up to scare people), it is about being capable of acting according to principles established during decades of (sometimes tragic) history of aviation.
Forgetting these principles might bring something quick today (as it has happened for this topic), but it will be painful tomorrow, when a correction to the path is required. Better founding it well as soon as possible and keep on along a way that has made aviation safe.

[Kevin Neave]

Since you ask...

The first hit from Google for "dsx systems t-advisor" is

http://frank.schellenberg.nl/wp-content/uploads/2015/03/T-Advisor_07_12_19.pdf

This states..

"The Traffic Advisor, notifies the pilot the presence of all planes that
enter within the radio operating range (that for the T-Advisor is up to 7
km)"

I may be dim but I read that as "T-Advisor tells you 'that there are lots
of gliders flying within 7 km' ".

So I'll rephrase that.

It *would* tell me that there are lots of planes flying within 7km of me if
they were fitted with DSX.

The aircraft I'm interested in are the ones that are that are converging
with me. Flarm warns me of these as long as they are also Flarm equipped
Flarm is intended as an aid to lookout, generally I've seen most contacts
by the time Flarm generates a warning, occasionally I get a wake up call.
Flarm reminds me that my lookout is not as good as it could be.
(Of course I have no idea how many I'm missing and Flarm isn't picking up)

I don't see what T-Advisor would give me

A large number of the gliders flying XC in the UK (possibly a majority by
now) are using Flarm. I don't know of ANY using DSX.

So I repeat the question, how many gliders in Europe are using DSX?
Or more specifically how many in the UK are using DSX?

KN

[Tango Eight]

On Tuesday, May 26, 2015 at 7:44:07 PM UTC-4, Lucas wrote:

> Tango Eight, your statement is lacking of a scientific base: WHAT demonstrates that the "prediction algorithm works very well" ?

*Extensive* end user experience.

This might be helpful: http://en.wikipedia.org/wiki/Straw_man

best regards,
Evan Ludeman / T8

[marco....@gmail.com]

Kevin,
I honestly do not understand why you are so emotional about this topic. No one is trying to convince you that you should trash your device, nor that's the aim of the petition. But you have to take that some other may prefer a T-Advisor. I personally prefer the T-Advisor because I like better its clock and because I agree with the philosophy behind its warning algorithm. If you ask though "how many gliders in Europe are using a DSX", well, I remind you that was it only one, yet makes you Flarm's policy one of the flarm customers that may die in a mid-air collision with a DSX pilot. You have to agree this is a very unusual way of "customer caring".

[marco....@gmail.com]

Il giorno mercoledì 27 maggio 2015 12:45:08 UTC+2, Kevin Neave ha scritto:

...besides, are you really sure that all the flarms Flying around you are updated to version 6.01 and therefore that you can see them and been seen?
regards

[Andy Blackburn]

On Tuesday, May 26, 2015 at 4:44:07 PM UTC-7, Lucas wrote:
> The T-Advisor AND Flarm are NOT anticollision system.
> Anticollision systems are those who tell the pilot what to do (like TCAS), in case of emergency. Neither system does this.
> BOTH systems are NOT anticollision systems.

This is a bit of a hair-splitting argument, but to be clear - there are: 1) Traffic display systems (show traffic within a detection volume, but provide no alerts), 2) Traffic advisory systems (alert to new traffic entering a detection volume - like PCAS), 3) Collision detection systems (calculate and warn of other aircraft on a probable collision path - like FLARM), 4) Anti-collision systems (advise pilots on action to avoid a collision), 5) Automated anti-collision systems (autonomously take action to avoid collisions - I'm not aware of any of these - outside of military terrain-following autopilots).

Usefulness goes up as you move up the hierarchy. IMO FLARM, being higher that other systems is more useful.

>
> Cleared this, those who talk about the "predictive algorithm", can please explain:
>
> 1) how it works, since they must know how it works, to be in the position of saying that it works or it doesn't
>
> 2) how they know that such an algorithm has been implemented into a Flarm system: what proof do they have of this ?

Really? That's a serious question? Well, it warns me of converging traffic and when I look, there is in fact converging traffic in the direction indicated. There is no traffic converging on me for which I get no warning and warnings for traffic that is not a series factor is almost nonexistent.

>
> 3) if they have ever seen the trace of at least 10 glider flights in different conditions (competition, cross country, around-the-airfield, ridge soaring,....); whoever has seen some, not many, traces of flights, without the need to be a glider pilot, can understand that a prediction of the position of a glider in a future time beyond a fistful of seconds is impossible, exactly IMPOSSIBLE, since not even its pilot knows it, apart from some cases, like straight flying and constant turn rate thermaling. A glider pilot knows that he will be changing the trajectory of the glider to search for the best netto value, which depends on the micro air movements, which are unknown to the pilot in terms of exact location. Is there a machine capable of predicting these locations ? And even if there was, is there a machine capable of predicting what a glider pilot will do in the next 30-60-80 seconds ? Because this is what the rumored (never verified) "prediction algorithm" does. This is spectacular indeed !

Impossible? As a control-systems engineer I can tell you for a fact that a 1 second sample rate is perfectly adequate for this purpose and you only need 2-3 good data points for each aircraft to make a decent prediction. Even with dropped packets this is a reasonable task. Glider flight dynamics are not so abrupt as to make this an impossible task and pilots are not generally making so many aggressive control inputs as to flail the system. FLARM uses a probabilistic approach base on total energy to err on the side of possible control inputs that handles most situations well.

>
> 4) even if they found a system to predict the position of the glider with a certain probability, would they trust as optimal a system that has (obviously) a probability to fail the prediction and miss a danger of collision ? Even if the probability was low (all but sure, since never demonstrated with objective tests and calculated data), 2, 3, 10 collisions (and deads) out of XX'XXX flights are too much. In aeronautics, this approach is wrong: this is not the way we work in professional aeronautics, that has taken us where we are in aviation

We don't need optimal, we need better than human perception and FLARM does that very well indeed.


9B

[pcool]

What Flarm calls "prediction" I think that most likely is a simple
projection. It is quite likely calculated worst than how we calculate the
best point to turn in thermal.
I am referring to the "Beep" in Zanders, or in some flight computers .
If you want to see how a "prediction" is working, look at the thermal
Orbiter I have programmed
https://github.com/LK8000/LK8000/blob/master/Common/Source/Calc/Orbiter.cpp
which is quite similar to what Zander and SeeYou Mobile (and possibly other
software, I don't really know) do.
This is a prediction based on turning angle, estimated banking etc. and I
mention it here for a reason:
there is floating point math involved in such kind of predictions.
We use 400mhz or best ARM cpu on PNA-PDAs.
Flarm is tuned to "predict" on a 8mhz CPU by Atmel, a reduced instruction
set microcontroller that has no math coprocessor and cannot do floating
point calculations natively.

A prediction seems like something magic, and I doubt this is the case.
Each device (flarm, dsx) transmits its own position "predicted" with a
simple projection for the next second .
If your own device matches its own "predicted" position with the one
received from another one, it beeps.
That's how it works.
A projection cannot predict when you level and go straight, nevertheless as
you say it works .
It can not work "very well", as you say. But it is better than nothing.

The assumption is that the glider in thermal with you, or arriving in front
of you, has a device with the same protocol.
In the alps this is no more granted. This is what this thread is about.

greets
paolo




"Tango Eight" wrote in message
news:d4501e6b-d857-4edb...@googlegroups.com...

[Andy Blackburn]

On Wednesday, May 27, 2015 at 7:46:25 PM UTC-7, pcool wrote:

> The assumption is that the glider in thermal with you, or arriving in front
> of you, has a device with the same protocol.
> In the alps this is no more granted. This is what this thread is about.

Wow, why would people buy an incompatible device when there are multiple manufacturers of compatible devices in the market?

[Surge]

On Thursday, 28 May 2015 07:05:42 UTC+2, Andy Blackburn wrote:
> Wow, why would people buy an incompatible device when there are multiple manufacturers of compatible devices in the market?

What would happen if the relationship soured between FLARM and the manufacturer of your chosen FLARM device?
Flarm could easily issue another upgrade to the protocol and you are left with a $1000+ system which is now totally worthless and useless.

[pcool]

Who is incompatible with who? You have the freedom to choose a device
manufacturer.
The TAdvisor, and probably the OGN devices soon, are not worst than flarm to
do this job.
Anyway, as a wise guy ("Buddy Bob") here stated, shortly we may have OGN
devices acting as collision avoidance systems.
At that point Flarm will change its protocol and adopt the open one.

I fully agree with Bob, it is pointless to ask Flarm to open the protocol.
What we need is several other manufacturers selling their own devices, based
on the OGN open software for example. I have not signed the petition for
this reason.


"Andy Blackburn" wrote in message
news:c40cd3fc-fc00-406c...@googlegroups.com...

[Martin Gregorie]

On Thu, 28 May 2015 14:22:41 +0200, pcool wrote:

> I fully agree with Bob, it is pointless to ask Flarm to open the
> protocol. What we need is several other manufacturers selling their own
> devices, based on the OGN open software for example. I have not signed
> the petition for this reason.
>

IIRC the reason that FLARM encrypted the protocol was that the OGN crew
were refusing to honour the 'do not track' bit thus exposing the
whereabouts of people who didn't want to be tracked.

In view of that record, why should we trust OGN to do the right thing?

I won't sign the petition either. If DSX want to sell anti-collision kit,
let them drop their NIH attitude and join LX etc in using the de-facto
standard protocol. As long as FLARM sell licences to allow third parties
to use it they are no better or worse than, e.g. Oracle with their
proprietary attitude to Java or the companies who hold patents that
widely used wireless comms standards depend on: think WiFi.

BTW, has the DSX protocol been published? On a Creative Commons or GPL
license?


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Tim Newport-Peace]

At 12:22 28 May 2015, pcool wrote:
>Who is incompatible with who? You have the freedom to choose a device
>manufacturer.
>The TAdvisor, and probably the OGN devices soon, are not worst than flarm
>to
>do this job.
>Anyway, as a wise guy ("Buddy Bob") here stated, shortly we may have OGN
>devices acting as collision avoidance systems.

OGN Trackers work on a different frequency, so will not interface to Flarm
or DSX.

>At that point Flarm will change its protocol and adopt the open one.

Oh?

Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
The do not have the predictive algorithm that Flarm does.

The differances are too great.

>
>I fully agree with Bob, it is pointless to ask Flarm to open the protocol.

>What we need is several other manufacturers selling their own devices,
>based
>on the OGN open software for example. I have not signed the petition for

>this reason.

Are there any DSX devices in US? One might supose so judging by the number
of responses from US pilots, but I doubt it.

[Tango Eight]

On Thursday, May 28, 2015 at 9:00:06 AM UTC-4, Tim Newport-Peace wrote:

>
> Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
> The do not have the predictive algorithm that Flarm does.

That's not true (logically). One need only have open transmission of 3D location, velocity, turn rate. The predictive element of things is done on the receiving end and need not be symmetric. Better predictive capability yields fewer nuisance alarms.

Most US guys, I think, never heard of DSX until this thread. Did DSX and Flarm have an agreement or did they just hack the protocol?

[Andy Blackburn]

On Thursday, May 28, 2015 at 5:22:47 AM UTC-7, pcool wrote:

> Who is incompatible with who? You have the freedom to choose a device
> manufacturer.

Well, there is one device that is installed in >25,000 gliders worldwide and one that is installed in...how many? 500? People can decide which is the tail and which is the dog when it comes to wagging. I think if I showed up in most European countries with an electrical device requiring 110 volts I would not get agreement that the entire continent is incompatible and needs to change to 110 volts.

> The TAdvisor, and probably the OGN devices soon, are not worst than flarm to do this job.

That isn't even how they talk about themselves.

Here is what T-Advisor says about the themselves: "The functioning idea of the T-Advisor is not the one of an Anticollision or Collision Avoidance System, rather the one of the Traffic Advisor, an Early Warning System."

OGN's main purpose is tracking, not collision detection. Here is what they say about themselves: "The objective of the Open Glider Network is to create and maintain a unified tracking platform for gliders and other GA aircraft. Currently OGN focuses on tracking aircraft equipped with FLARM, FLARM-compatible devices or OGN tracker."

Hair-splitting and straw-manning are not a productive ways to advance the conversation.

9B

[Tim Newport-Peace]

At 12:47 28 May 2015, Martin Gregorie wrote:
>On Thu, 28 May 2015 14:22:41 +0200, pcool wrote:
>
>> I fully agree with Bob, it is pointless to ask Flarm to open the
>> protocol. What we need is several other manufacturers selling their own
>> devices, based on the OGN open software for example. I have not signed
>> the petition for this reason.
>>
>IIRC the reason that FLARM encrypted the protocol was that the OGN crew
>were refusing to honour the 'do not track' bit thus exposing the
>whereabouts of people who didn't want to be tracked.
>
>In view of that record, why should we trust OGN to do the right thing?

Firstly, the Easter Egg was built into the previous version of FLARM
firmware long before OGN can into being. OGN was not the cause. As I
understand it the Easter Egg was to ensure that users were on reasonably
up-to-date Firmware.

Secondly, any transmissions received by an OGN Receiver that have the
Do-Not-Track bit set are discarded at the receiver. There are never sent to
the Server.

[Andy Blackburn]

Actually, the Flarm engineers told me that the prediction is done on the transmit side for Flarm. I'm told this is helpful because it is more accurate in the event of dropped packets, which can happen for a variety of reasons. Obviously it doesn't work this way for ADS-B traffic. Collision detection and warning is done on the receive side.

There is a bit of benefit in having a consistent algorithm - for instance, in a head-to-head scenario having both systems determine that the traffic is slightly to the right wouldn't be all that great. Glider flying is dynamic and consistent dynamic behavior with humans in the control loop is important. There are other more subtle issues with respect to Stealth mode that also require a single system. Interoperability is generally better if you have a single system design rather than having to rely on adherence to standards.

9B

[Andy Blackburn]

On Thursday, May 28, 2015 at 7:04:44 AM UTC-7, Andy Blackburn wrote:

> There is a bit of benefit in having a consistent algorithm - for instance, in a head-to-head scenario having both systems determine that the traffic is slightly to the right wouldn't be all that great.

[[[[ Sorry, meant to say one says to the left and one says to the right. Dyslexia ]]]]]]

- 9B

[Tango Eight]

On Thursday, May 28, 2015 at 10:04:44 AM UTC-4, Andy Blackburn wrote:
> On Thursday, May 28, 2015 at 6:29:35 AM UTC-7, Tango Eight wrote:
> > On Thursday, May 28, 2015 at 9:00:06 AM UTC-4, Tim Newport-Peace wrote:
> >
> > >
> > > Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
> > > The do not have the predictive algorithm that Flarm does.
> >
> >
> > That's not true (logically). One need only have open transmission of 3D location, velocity, turn rate. The predictive element of things is done on the receiving end and need not be symmetric. Better predictive capability yields fewer nuisance alarms.
> >
> > Most US guys, I think, never heard of DSX until this thread. Did DSX and Flarm have an agreement or did they just hack the protocol?
> >
> >
> > regards,
> > Evan Ludeman / T8
>
> Actually, the Flarm engineers told me that the prediction is done on the transmit side for Flarm. I'm told this is helpful because it is more accurate in the event of dropped packets, which can happen for a variety of reasons. Obviously it doesn't work this way for ADS-B traffic. Collision detection and warning is done on the receive side.

Ah, I made an inference I should not have based on some other conversation. Yes of course: you need data over time to establish trends and projections. And so it absolutely has to be done on the transmission side. Limited range, spotty reception, also less processor demand (processing two dozen other gliders in a thermal might be a little intensive!). Thanks.

-Evan

[Andy Blackburn]

On Thursday, May 28, 2015 at 7:23:16 AM UTC-7, Tango Eight wrote:

...also less processor demand (processing two dozen other gliders in a thermal might be a little intensive!).

Good add - everyone responsible for their own prediction - do it only once and consistently for everyone in range. Otherwise everyone in a thermal gets a slightly different track prediction based on what data they receive - or algorithm they use. Imagine the dynamic effects as pilots react differentially based on slightly different predictions and create new tracks and predictions, all based on slightly different interpretations of where others are headed. Emergent behavior, possibly not stable, probably unpredictable to a greater extent than normal thermal flying.

9B

[Dan Daly]

Interesting podcast on FLARM.

"In this episode we talk with Gerhard Wesp, Development Manager Avionics at Flarm Technology GmbH about FLARM, a collision avoidance system for gliders and general aviation. We talk about the history of the FLARM system as well as about newer developments such as the PowerFlarm. Mostly, however, we talk about how FLARM works and how PowerFlarm integrates with Transponders and ADS-B systems."

Omegatau - omega tau covers a mix if topics from engineering and science; the selection of topics is guided by our own interest (as well as listener suggestions). Since we have German and English language episodes, the tag cloud is a mix of German and English words. Click on a tag to get to the respective episodes.


http://omegataupodcast.net/2014/03/143-collision-avoidance-with-flarm/

A look from the engineering point of view.

Dan

[drguya...@gmail.com]

I will not be signing the petition.
FLARM is a private enterprise and deserves to reap the rewards of its work.
FLARM is a optional instrument for pilots, not a mandated piece of equipment. The issue with contest pilots being required to use FLARM is an SSA matter.
I would hope that glider pilots choose to install a transponder BEFORE they add a FLARM to their aircraft.

[jpg...@gmail.com]

Out of ignorance and curiosity, what are the relative proportions of glider collisions in the US between gliders versus between gliders and CA/GA aircraft?

John Galloway

[Andy Blackburn]

From 1994 through 2013 there were 20 reported midairs involving gliders un the US - 12 were glider-glider, 3 were glider-towplane, 4 were glider-GA and one was towplane-GA (the glider was on tow). There were 16 total fatalities as a result.

These were only the ones that were serious enough to be reported to the authorities and recorded in the official record. There were probably others with minor or no damage that were not reported.

Based on the statistics FLARM is a more important investment than a transponder, though obviously that consideration includes the fact that the statistics reflect whatever deployment of transponders existed prior to introduction of Flarm and may have reduced collisions with other aircraft types over the period.

Andy
9B

[kirk.stant]

On Thursday, May 28, 2015 at 10:26:08 AM UTC-5, drguya...@gmail.com wrote:

> I would hope that glider pilots choose to install a transponder BEFORE they add a FLARM to their aircraft.

I would hope that glider pilots choose to install a PowerFLARM BEFORE they add a transponder to their aircraft, unless they routinely fly in airspace with lots of airliners (TCAS-equipped).

Why? Because with a PowerFLARM, the glider pilot can actively avoid transponder and ADS-B (mode S-ES) equipped aircraft, as well as other PF-equipped gliders that are likely to join him in a thermal. With only a transponder, your protection is entirely up to the OTHER aircraft, and in the case of most VFR traffic, will provide almost NO protection.

Of course, the best solution is to have both a transponder and PF....

Kirk

[pcool]

There is no "predictive" algorithm. See my previous post, and there are no
differences according to the people that for many years have been using both
technologies.
The assertion "do not have the predictive algorithm that Flarm does."
reminds me of old detergent advertising campaign.

The other thing you say "As I understand it the Easter Egg was to ensure

that users were on reasonably

up-to-date Firmware." makes me instead ask you : what if Bosch would have
placed a similar "easter egg" in their ABS BREAKING SYSTEM of you car?
Because this is exactly the same.

How long have you been using a Flarm, Tim?

"Tim Newport-Peace" wrote in message
news:55671155$0$6948$bed6...@gradwell.net...

At 12:22 28 May 2015, pcool wrote:
Oh?

Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
The

[pcool]

When you say "straw manning" you are talking about yourself, right?
Because In my previous post I have pointed you to a real predictive code,
and explained why there is no prediction but a simple projection in a flarm.

"Andy Blackburn" wrote in message

news:a3f65707-5f3c-4665...@googlegroups.com...

[Buddy Bob]

At 18:35 28 May 2015, pcool wrote:
>There is no "predictive" algorithm.

This does appear to be true.. The previous flarm protocol is
documented here

http://tinyurl.com/opgtogo

I haven't personally verified (all) of it, but it certainly has all the
marking that it is correct, and there really doesn't appear to be any
'prediction' there at all. A similar document for the new protocol exists
too, it shouldn't be too hard for you to find it.

I would like comments from those who said there was prediction. What
made you think there was, how does this change your thinking and
have you heard the tale of the Emperor's New Clothes?

[jpg...@gmail.com]

On Thursday, May 28, 2015 at 7:35:51 PM UTC+1, pcool wrote:
> There is no "predictive" algorithm. See my previous post, and there are no
> differences according to the people that for many years have been using both
> technologies.
> The assertion "do not have the predictive algorithm that Flarm does."
> reminds me of old detergent advertising campaign.
>
>
>

Each Flarm unit broadcasts a prediction of its own flight path over the next 20 seconds or so. It isn't a simple projection of the current instantaneous vector. It will be straight or curved or circling depending on how Flarm analyses the current mode of flight. There are also airspeed dependent vertical "buffers" e.g. a slow moving glider is unlikely to zoom up but could dive whereas a very fast moving glider can zoom up a long way. Each Flarm unit within range compares its own predictive flight path with others that it receives. Unfortunately Flarm's new website no longer holds their original Power Point presentation that, amongst other things, explains this pictorially.

The DSX T-Advisor manual (referenced again below) explains on page 3 why they do not follow the same predictive approach as Flarm and hence they confirm that they understand the difference even if pcool does not. DSX claim that "prediction of the trajectory of a glider at times 10 or 20 seconds after the present one, can be too often unreliable". The experience of 25,000 Flarm units show that this is not the general perception of pilots although everyone using Flarm needs to understand the limitations - e.g. that Flarm alerts are related to track and not heading so in a strong crosswind and flying at slow airspeed on a ridge the direction of a threat may be coming from a rather different direction to that shown on a simple Flarm LED display. The increasing use of Flarm "radar" displays helps by giving additional situational awareness of other Flarm equipped gliders

http://www.soaringwear.com/uploadz/02/PDF/T-Advisor_07_12_19.pdf

We did a study of original Swiss Flarm in 2007 in Scotland which is still generally relevant - albeit out of date as regards the hardware:

http://old.gliding.co.uk/bgainfo/safety/sguflarmreport.pdf


John Galloway

[jpg...@gmail.com]

This link concerns the radio protocol for communication between Flarms - the proprietary nature of which is what the OPs petition is about - but that is a separate issue from what Flarm units actually broadcast.

[Buddy Bob]

At 20:11 28 May 2015, jpg...@gmail.com wrote:
>This link concerns the radio protocol for communication between
Flarms -
>the proprietary nature of which is what the OPs petition is about - but
>that is a separate issue from what Flarm units actually broadcast.
>

and 5 mins before that you wrote

>Each Flarm unit broadcasts a prediction of its own flight path over

the nex=

>t 20 seconds or so. It isn't a simple projection of the current

>instantane=
>ous vector.

Please can you rationalize this in the context of the published protocol
specification?

[Andy Blackburn]

On Thursday, May 28, 2015 at 11:41:49 AM UTC-7, pcool wrote:
> When you say "straw manning" you are talking about yourself, right?

Are we in 4th grade?

I was referring mostly to Lucas' misinformed and obfuscating rant, but also to your inaccurate comments minimizing the difference between traffic advisory and path-dependent collision warning. It is quite a big difference.

9B

[Tango Eight]

Two flarm equipped gliders fly parallel to one another at 80 kts with 300' separation and -- as long as the flight paths are not convergent -- flarm gives no alarm. If the paths become convergent, alarms result very quickly. As soon as the paths become parallel or divergent, the alarms cease. The same two gliders now fly a head on approach, again at 80 kts. Flarm gives a warning at significant range... over a mile... and the warning ceases almost immediately when one glider changes his track. From this I believe it should be clear to anyone that the way flarm works is most likely just how they've said it works: by estimating what airspace any given glider is capable of occupying in the next +/-30 seconds and looking for potential conflicts.

-Evan Ludeman / T8

[Andy Blackburn]

Yes. I'm surprised this is even coming up, except as a deliberate effort to obfuscate important differences between the various technologies and why they may not be compatible.

Anyone with a rudimentary knowledge of aircraft dynamics and even a single day's flying with FLARM has to conclude that it is making path-dependent collision prediction estimates. You have to fly in a few thermals to pick up that the path prediction is curved when you are turning.

Flarm engineers have told me explicitly that the prediction is done on the transmit side and I can see why this would work better for the reasons previously raised. The specification may or may not need to specify this as a communications protocol generally needn't include a specification of the data payload or the algorithm to create or interpret it.

9B

[Martin Gregorie]

On Thu, 28 May 2015 13:58:39 +0000, Tim Newport-Peace wrote:

> Firstly, the Easter Egg was built into the previous version of FLARM
> firmware long before OGN can into being. OGN was not the cause. As I
> understand it the Easter Egg was to ensure that users were on reasonably
> up-to-date Firmware.
>

By Easter Egg, do you mean the protocol expiry date? If so its not what I
was talking about and I don't have a problem with it: given that FLARM
was designed for small, low-powered hardware, syncing protocol version
that way makes a helluva lot more sense that having to maintain backward
compatibility over the last 'n' protocol versions just because some lazy
git can't be bothered to keep his software up to date.

> Secondly, any transmissions received by an OGN Receiver that have the
> Do-Not-Track bit set are discarded at the receiver. There are never sent
> to the Server.
>

Not necessarily: you can't guarantee anything like that if the receiver
is the result of a third party reverse engineering project, which is what
I've always heard about the RPi-hosted FLARM receiver units. If the
software author decides he wants to see everybody and ignores that bit
then pop goes your invisibility cloak.

[pcool]

oh com'on, at the beginning of this thread I stated I did not sign the
petition. There is no deliberate action of any kind.
Simply you keep calling prediction what is really a projection.
If you are turning, it projects accordingly . It doesnt predict you are
turning.
"prediction" is a marketing word here. There is no computational power to
predict anything, inside the flarm.
But let it go, it does work, this is out of any question. We have been using
it since 2005.

"Andy Blackburn" wrote in message

news:3fa6d282-7857-459d...@googlegroups.com...

[pcool]

sorry andy. I wish we lived closely, to have a great discussion about this
with a beer.

"Andy Blackburn" wrote in message

news:f9688028-9463-440e...@googlegroups.com...

[Andy Blackburn]

I'll buy the beer.

Prediction, projection, position, protection. I'm not very clear on the finer points of my mother language apparently. ;-)

Here's how I look at it. FLARM calculates a projected flight path with a probabilistic "error radius" determined based on flight parameters to estimate a likely future position (assuming no change in control inputs) and then maps these paths to estimate likely conflicts and warns if it finds one. I consider that warning a prediction - if nothing changes the two aircraft will likely collide. Sure, it's an estimate but I still consider that more of a prediction than just putting airplane-shaped dots on a display and telling the pilot "you figure it out". I'd rather have a microprocessor and an algorithm than burying my head in a traffic display. I'd call that warning a prediction but maybe I'm being sloppy with the definitions.

The point is - FLARM will give you a warning only for pretty real threats. A traffic advisory system can only annoy you with constant warnings of aircraft in the vicinity whether they are a threat or not or leave it to you to find threats.by staring at a display. You need to project a flight path with some precision to strike a balance between too may false positives and leaving too many possible threats suppressed until too late. Given how we fly I think FLARM does quite well. It's also why ADS-B will struggle to operate as a collision warning system for gliders - even if someone tries to plaster a collision projection algorithm on top of some Garmin ADS-B unit. PowerFLARM throws out the ADS-B information if it detects a target with both FLARM and ADS-B Out.

9B

[pcool]

Now I understand what you meant with prediction, not referring to the
position!
yes I agree on this definition, from this point of view.
I look at it exactly as you do.

"Andy Blackburn" wrote in message

news:14d98e83-913d-450c...@googlegroups.com...

[Tim Newport-Peace]

In which case it is not an OGN receiver any longer.

"Don’t believe anything you read on the net. Except this.
Well, including this, I suppose."

DOUGLAS ADAMS (1952-2001)

[Lucas]

On Wednesday, May 27, 2015 at 12:45:08 PM UTC+2, Kevin Neave wrote:
> Since you ask...
>
> The first hit from Google for "dsx systems t-advisor" is
>
> http://frank.schellenberg.nl/wp-content/uploads/2015/03/T-Advisor_07_12_19.pdf
>
> This states..
>
> "The Traffic Advisor, notifies the pilot the presence of all planes that
> enter within the radio operating range (that for the T-Advisor is up to 7
> km)"
>
> I may be dim but I read that as "T-Advisor tells you 'that there are lots
> of gliders flying within 7 km' ".
>
> So I'll rephrase that.
>
> It *would* tell me that there are lots of planes flying within 7km of me if
> they were fitted with DSX.
>
> The aircraft I'm interested in are the ones that are that are converging
> with me. Flarm warns me of these as long as they are also Flarm equipped
> Flarm is intended as an aid to lookout, generally I've seen most contacts
> by the time Flarm generates a warning, occasionally I get a wake up call.
> Flarm reminds me that my lookout is not as good as it could be.
> (Of course I have no idea how many I'm missing and Flarm isn't picking up)
>
> I don't see what T-Advisor would give me
>
> A large number of the gliders flying XC in the UK (possibly a majority by
> now) are using Flarm. I don't know of ANY using DSX.
>
> So I repeat the question, how many gliders in Europe are using DSX?
> Or more specifically how many in the UK are using DSX?
>
> KN
>
>
>
> At 23:44 26 May 2015, Lucas wrote:
> >Kevin Neave, can you show in which website you read that the T-Advisor
> >tells you "that there are lots of gliders flying within 7 km" ?

Kevin, I understand that the sentence can be read in a way different from what was intended: the T-Advisor notifies the pilot of the NEW presence of a glider within range. It blimps once, to tell the pilot that there is a glider there, and will not continue indicating it to the pilot (how could it indicate continuously all gliders in range, on a led display ? Obviously this is impossible, beside useless).

Your comment derives from the fact that you have not had the chance of flying with a T-Advisor, otherwise you would have noticed how it works. Way differently from what you think. But you have forgotten to read the rest of the manual, where it is clearly specified that the system warns the pilot only about gliders that are going to possibly collide.

All pilots with T-Advisor, that has been developed with the input of all of them, are extremely happy to be notified when a glider enters the operating range of the system: it is very helpful to spot another glider at a quite long distance, not mainly for collision avoidance but for information. Also in competitions.

Therefore, the T-Advisor doesn't keep beeping for *any* aircraft in range, buto only for those that are close to possibly collide, warning the pilot with different levels of beeps and led flashes depending on the severity of the situation. This doesn't mean it decides which plane is more dangerous: it tells you what planes are going to hit you based on the approaching speed/distance = time to impact. The warnings are prioritized according the time to impact.
The pilot decides, ultimately.
What it doesn't is to decide which threat to display and which not, based on a "prediction", that, I reiterate, is impossible for a glider not flying with a regular trajectory (straight of stable rate of turn - it's enough to look at the glider traces of any flight to understand this).

I think that your worries are

[Lucas]

On Wednesday, May 27, 2015 at 10:35:46 PM UTC+2, Andy Blackburn wrote:
> On Tuesday, May 26, 2015 at 4:44:07 PM UTC-7, Lucas wrote:
> > The T-Advisor AND Flarm are NOT anticollision system.
> > Anticollision systems are those who tell the pilot what to do (like TCAS), in case of emergency. Neither system does this.
> > BOTH systems are NOT anticollision systems.
>
> This is a bit of a hair-splitting argument, but to be clear - there are: 1) Traffic display systems (show traffic within a detection volume, but provide no alerts), 2) Traffic advisory systems (alert to new traffic entering a detection volume - like PCAS), 3) Collision detection systems (calculate and warn of other aircraft on a probable collision path - like FLARM), 4) Anti-collision systems (advise pilots on action to avoid a collision), 5) Automated anti-collision systems (autonomously take action to avoid collisions - I'm not aware of any of these - outside of military terrain-following autopilots).
>
> Usefulness goes up as you move up the hierarchy. IMO FLARM, being higher that other systems is more useful.
>
> >
> > Cleared this, those who talk about the "predictive algorithm", can please explain:
> >
> > 1) how it works, since they must know how it works, to be in the position of saying that it works or it doesn't
> >
> > 2) how they know that such an algorithm has been implemented into a Flarm system: what proof do they have of this ?
>
> Really? That's a serious question? Well, it warns me of converging traffic and when I look, there is in fact converging traffic in the direction indicated. There is no traffic converging on me for which I get no warning and warnings for traffic that is not a series factor is almost nonexistent.
>
> >
> > 3) if they have ever seen the trace of at least 10 glider flights in different conditions (competition, cross country, around-the-airfield, ridge soaring,....); whoever has seen some, not many, traces of flights, without the need to be a glider pilot, can understand that a prediction of the position of a glider in a future time beyond a fistful of seconds is impossible, exactly IMPOSSIBLE, since not even its pilot knows it, apart from some cases, like straight flying and constant turn rate thermaling. A glider pilot knows that he will be changing the trajectory of the glider to search for the best netto value, which depends on the micro air movements, which are unknown to the pilot in terms of exact location. Is there a machine capable of predicting these locations ? And even if there was, is there a machine capable of predicting what a glider pilot will do in the next 30-60-80 seconds ? Because this is what the rumored (never verified) "prediction algorithm" does. This is spectacular indeed !
>
> Impossible? As a control-systems engineer I can tell you for a fact that a 1 second sample rate is perfectly adequate for this purpose and you only need 2-3 good data points for each aircraft to make a decent prediction. Even with dropped packets this is a reasonable task. Glider flight dynamics are not so abrupt as to make this an impossible task and pilots are not generally making so many aggressive control inputs as to flail the system. FLARM uses a probabilistic approach base on total energy to err on the side of possible control inputs that handles most situations well.
>
> >
> > 4) even if they found a system to predict the position of the glider with a certain probability, would they trust as optimal a system that has (obviously) a probability to fail the prediction and miss a danger of collision ? Even if the probability was low (all but sure, since never demonstrated with objective tests and calculated data), 2, 3, 10 collisions (and deads) out of XX'XXX flights are too much. In aeronautics, this approach is wrong: this is not the way we work in professional aeronautics, that has taken us where we are in aviation
>
> We don't need optimal, we need better than human perception and FLARM does that very well indeed.
>
>
> 9B

Andy, the T-Advisor is a
3) Collision detection system
Obviously there are different ways to detect a possible collision: to be "extreme", just to make the difference evident illustrating the two extreme positions, you can predict a collision based on approach speeds (very objective and 100% sure data) or using a crystal ball (0% objective and totally unsure data). There are ways in between, obviously.
If you possibly had the responsibility of a life, I am sure you would not go for a "probabilistic" approach, but you would base the functioning of the system only on 100% sure data.
And for a collision, the only sure data are the relative approach speeds and distance, hence time to impact. The rest are speculations about what the pilot will or will not do: you can be in a trajectory considered safe for a predictive system and suddently feel the right wing raising and deciding to turn right, where, by chance, there is another plane in your blind spot. No system can predict this.

When you write:
"it warns me of converging traffic and when I look, there is in fact converging traffic in the direction indicated. There is no traffic converging on me for which I get no warning and warnings for traffic that is not a series factor is almost nonexistent."
That is exactly the same output you get from a T-Advisor, based on the approach speed and distance of the surrounding planes.
This should show you that what you wrote doesn't demonstrate that any "prediction algorithm" is in place.
So you don't know what is implemented in Flarm because, on the contrary of the systems developed with an aeronautical procedure, it's not verified by anyone.

"Prediction": you are a control system engineer, therefore you work with deterministic systems. The glider pilot, whose actions depend on atmospheric conditions unknown a priori (i.e. vertical gusts/thermals), is not a deterministic system.
I agree with you that it is possible to say with an approximate precision where a glider will be in 2-3-4 seconds, because it's dynamic is slow compared to this time length and, in few seconds, the most abrupt control inputs from the pilot will not deviate it a lot from the existing trajectory. But it is clear to any glider pilot or person who sees a flight trace that affirming that a system can "predict" where the glider will be in 20-40 seconds anytime, is like saying that it has a real crystal ball.
It looks like discussing of the obvious: take a flight trace and place yourself in any position along it and then say if you could have told where the glider would be after 20-40 seconds. Leaving aside the straight glides and regular thermals.
This is indisputable, I think.

> We don't need optimal, we need better than human perception and FLARM does that very well indeed.
If you had to design a system to save the life of two persons, I am sure you would not take a probabilistic approach, but you would take a path based on 100% sure data. Since these are available (approach speed/distance = time to impact, although calibrated with some other parameters like relative altitude and others).
All system are improving human perception: this is not the point.
The point is which approach is safer, surer for avoiding a collision. An engineering discussion.

[Lucas]

.... I think that your worries are

Sorry: it was posted inadvertently, before completion:
I think that what worried you is clear now.
Again: pity you hadn't got the chance of flying with a T-Advisor.
Most T-Advisor pilots have been reporting their satisfaction about how the system warns them about surrounding traffic and risk of collisions.
None of them has ever said that it's annoying in thermals and has to turn down the volume. And this is another difference to the other system.
All of them reported that the function that informs them about the position of another plane entering into the range is very useful.
Many T-Advisor pilots are ex-Flarm pilots.

[sergioala...@gmail.com]

We wish to thank everybody. We have some 900 pilots (and are growing) that think that the protocol should be free and then everybody is free to buy the system he prefers!

No monopoly, especially on security. IGC should agree with this.
THANKS AGAIN

[Tango Eight]

One more time...

Did DSX and Flarm have an agreement, or did DSX reverse engineer Flarm's IP without Flarm's blessing?

I think we know the answer. I know what my response would be to a competitor that reverse engineered *my* IP.

Petitions are for losers, anyway. You want to do business, you behave like businessmen.

-Evan Ludeman / T8

[Mike Schumann]

The discussion in this thread raises a significant question as to how much "predictive" information is actually transmitted as part of the FLARM protocol. I suspect that the differences in the information transmitted by FLARM and ADS-B are relatively minor.

I don't question the sophistication of FLARM's algorithms in filtering out collision threats that are real based on the trajectories of the aircraft in a soaring environment. Much of this processing must take place in the FLARM's receiver, as the trajectories of both the receiving aircraft and the threat aircraft must be known to determine if there is a collision threat.

My problem is with the assertion that a similar system can not be implemented using ADS-B. This is patently false. Numerous low cost iPhone and/or Android apps already provide collision threat warnings today using low cost ADS-B receivers. These apps not only report collision warnings for ADS-B equipped aircraft, but also for all transponder equipped aircraft that are identified by TIS-B received from an ADS-B ground stations (Note: You need to be ADS-B OUT equipped to reliably receive TIS-B traffic).

It is unlikely that these existing apps are optimized like FLARM is to recognize the unique flight profiles that are common with glider traffic. We will have to wait and see whether or not these companies will find it worth their while to invest in more sophisticated algorithms to specifically target the glider market. However, there are glider specific apps (iGlide, etc.) that are specifically aimed at the soaring market, which would have a strong marketing advantage in including this kind of advanced ADS-B based capability.

In Europe, given the large installed FLARM base, this may be an academic discussion. In the US, FLARM will never be widely deployed outside of the competitive soaring community. Here, an economical ADS-B based solution that provided reliable warnings, not only for other gliders, but also all other GA aircraft, would be a big hit.

[kirk.stant]

Ok, so finally it all boils down to: a small group of Flarm users don't like the Flarm display setup, and want something less intrusive. So instead of DSX licencing the Flarm protocol and using their own display logic, they come up with their own system - despite the fact that there is already a huge installed base of Flarm users.

So now that Flarm decides to encrypt their protocol (due to the OGN hacking and privacy issues), suddenly DSX T-advisor users are out in the cold.

Hmm, anyone remember VHS vs BetaMax? Best system doesn't always win - but when only one system is left, it becomes the de-facto protocol!

Kirk

[John Galloway]

At 13:15 29 May 2015, Mike Schumann wrote:
>On Thursday, May 28, 2015 at 8:59:12 PM UTC-5, Andy Blackburn
wrote:

>> I'll buy the beer.=20
>>=20

>> Prediction, projection, position, protection. I'm not very clear on the

>f=

>iner points of my mother language apparently. ;-)

>>=20

>> Here's how I look at it. FLARM calculates a projected flight path with
a

>=

>probabilistic "error radius" determined based on flight parameters to

>estim=

>ate a likely future position (assuming no change in control inputs) and

>the=

>n maps these paths to estimate likely conflicts and warns if it finds
one.

>=

>I consider that warning a prediction - if nothing changes the two
aircraft

>=

>will likely collide. Sure, it's an estimate but I still consider that
more

>=

>of a prediction than just putting airplane-shaped dots on a display and

>tel=

>ling the pilot "you figure it out". I'd rather have a microprocessor and

>an=

> algorithm than burying my head in a traffic display. I'd call that

>warning=

> a prediction but maybe I'm being sloppy with the definitions.

>>=20

>> The point is - FLARM will give you a warning only for pretty real

>threats=
>.. A traffic advisory system can only annoy you with constant
warnings of
>ai=

>rcraft in the vicinity whether they are a threat or not or leave it to
you

>=

>to find threats.by staring at a display. You need to project a flight
path

>=

>with some precision to strike a balance between too may false
positives

>and=

> leaving too many possible threats suppressed until too late. Given
how we

>=

>fly I think FLARM does quite well. It's also why ADS-B will struggle to

>ope=

>rate as a collision warning system for gliders - even if someone tries
to

>p=

>laster a collision projection algorithm on top of some Garmin ADS-B
unit.

>P=

>owerFLARM throws out the ADS-B information if it detects a target
with

>both=
> FLARM and ADS-B Out.
>>=20

>> 9B
>
>The discussion in this thread raises a significant question as to how
much

>=

>"predictive" information is actually transmitted as part of the FLARM

>proto=

>col. I suspect that the differences in the information transmitted by

>FLAR=

>M and ADS-B are relatively minor.
>I don't question the sophistication of FLARM's algorithms in filtering
out

>=

>collision threats that are real based on the trajectories of the aircraft

>i=

>n a soaring environment. Much of this processing must take place in
the

>FL=

>ARM's receiver, as the trajectories of both the receiving aircraft and
the

>=

>threat aircraft must be known to determine if there is a collision
threat.
>
>My problem is with the assertion that a similar system can not be

>implement=

>ed using ADS-B. This is patently false. Numerous low cost iPhone
and/or

>A=

>ndroid apps already provide collision threat warnings today using low
cost

>=

>ADS-B receivers. These apps not only report collision warnings for
ADS-B

>e=

>quipped aircraft, but also for all transponder equipped aircraft that are

>i=

>dentified by TIS-B received from an ADS-B ground stations (Note:
You need

>=

>to be ADS-B OUT equipped to reliably receive TIS-B traffic).
>
>It is unlikely that these existing apps are optimized like FLARM is to

>reco=

>gnize the unique flight profiles that are common with glider traffic.
We

>w=

>ill have to wait and see whether or not these companies will find it
worth

>=

>their while to invest in more sophisticated algorithms to specifically

>targ=

>et the glider market. However, there are glider specific apps (iGlide,

>etc=
>..) that are specifically aimed at the soaring market, which would have
a
>st=

>rong marketing advantage in including this kind of advanced ADS-B
based

>cap=

>ability.
>
>In Europe, given the large installed FLARM base, this may be an
academic

>di=

>scussion. In the US, FLARM will never be widely deployed outside of
the

>co=

>mpetitive soaring community. Here, an economical ADS-B based
solution

>that=

> provided reliable warnings, not only for other gliders, but also all

>other=

> GA aircraft, would be a big hit.

The differences in the information transmitted by Flarm and ADS-B are
not minor. There is plenty of information included, or linked to, earlier

in this thread to explain what Flarm transmits and why.

John Galloway

[Andy Blackburn]

On Friday, May 29, 2015 at 2:13:45 AM UTC-7, Lucas wrote:
you are a control system engineer, therefore you work with deterministic systems. The glider pilot, whose actions depend on atmospheric conditions unknown a priori (i.e. vertical gusts/thermals), is not a deterministic system.

Nope - control systems engineers spend most of their time dealing with the effects of noise and non-determinist effects - no system is perfectly deterministic and you assume so at your peril. The issue is to figure out "how" deterministic a system is . Also, if you make NO assumptions about aircraft dynamics many systems are not accurately observable or controllable. Knowing what the aircraft can do dynamically makes a huge difference in knowing where it is and where it can possibly go. Assuming nothing about aircraft dynamics in your system IS making an assumption - you assume the system will keep doing exactly what it was doing when you measured it last - if it was going up it will keep going up indefinitely, if it was circling you assuming it will follow the instantaneous velocity vector and stop circling instantaneously. The simple model is worse - a lot worse. It is a disservice to the soaring community to assert that the simple model is better because the more sophisticated model is somehow "impossible" - that is bunk. It might be "impossible" to program for someone who doesn't understand aircraft dynamics, but that's not the same as claiming that it is an impossible task. Aircraft have flown on autopilots that use the same basic principles for decades - including ones that can autoland under all kinds of non-deterministic airmass dynamics.

Closure rate is an example of a simple projection model - it is the simplest you can imagine as it understands NOTHING about the dynamics of the underlying systems. Simpler is not better in this case - it is quite useful to know that gliders have energy and stall speeds and minimum turn radii to understand whether a glider getting closer to you is actually on a path to hit you or not.

As an algorithm closure rate implicitly assumes the instantaneous closure rate will continue unabated until zero distance and collision. This is NOT true - hardly ever. In only a small percentage of cases to aircraft getting closer represent a collision threat. Without a more sophisticated algorithm you either have to warn the pilot of ALL of them (hardly useful) or set a threshold on closure rate and distance that delays the warning to reduce the false warnings. You would have to set it pretty tight in terms of time to impact to get the warnings down to a tolerable level and even so you will get a lot.

Thought experiment - imagine you are on a low, flat final glide at 70 kts and a bunch of other gliders are well above you and well to either side of you at 150 knots on fast final glides. None of them represent collision risks but they will have a very high rate of closure with a very short time to impact up until they get nearly abeam of you at which point the closure rate will fall of dramatically. Maybe it would be good not to panic you unless someone actually points their glider close enough to you to be a legitimate risk.

Note: As I understand the FLARM algorithm, it is basically indistinguishable from a closure rate algorithm at close range and for high closure rates because it becomes basically mathematically impossible for the paths not to intersect given the "dynamic radius" that FLARM puts on position estimates. So in the above scenario, if one of those gliders steepend their decent and started turing towards you you would get a warning.

So to summarize - it appears based on your statements that the T-Advisor does use a collision algorithm - it's just a much more simplistic one than FLARM does. This algorithm is based on closure rate and (if I understand you) distance. Depending on the thresholds set for issuing a warning this will generate either more false negatives or (more likely given your statement about 100% probability - a very loose standard since it assumes nothing about what the airplane is physically capable of doing) it will generate a lot more false positive warnings.

I'd be interested to see a cockpit video of one of these systems in flight in a situation with, say 30 other gliders milling about in a thermal in a pre-start situation at a contest.

9B

[Andy Blackburn]

On Friday, May 29, 2015 at 7:45:05 AM UTC-7, John Galloway wrote:
>
> The differences in the information transmitted by Flarm and ADS-B are
> not minor. There is plenty of information included, or linked to, earlier
> in this thread to explain what Flarm transmits and why.
>
> John Galloway

Yep.

Has anyone actually pulled apart some of the (pre-encryption) Flarm transmissions? You would think that would settle this debate. I have not personally verified it, but have been told directly by FLARM engineers and the logic of not having to do flight path projections for every glider you are tracking individually makes sense to me when it is a relatively straightforward proposition to send out a handful of projected flight path points as part of each glider's transmission. That plus the dropped packet issue convinced me that this wasn't something the FLARM marketing people came up with just to snow people (BTW, I don't believe Flarm has any dedicated marketing people - which may explain some things).

It amazes me how much misunderstanding and misinformation is floating around out there on this. Glider pilots are generally pretty smart - though many are also dogmatic.

Andy
9B

[Ramy]

Here we go again. Mike sharing his ignorance about powerflram with the world. Mike, each and every assumption and assertion you make is wrong. Maybe someone else will be willing to correct you on every wrong assumption, I wouldn't waste my time...

[Martin Gregorie]

Indeed. Its just a bit sad that the authors of the original OGN received
got so dogmatic over their "all data must be displayed because I said so"
attitude that they forced the use of encryption to enforce the data
source's right to privacy.

IMO that makes them more akin to the most intrusive internet ad-slingers
than to normal glider pilots.

[Lucas]

One more time: have you read the previous posts ?
If yes: you know that the T-Advisor works in a different way and the hardware is more performing. What is reverse engineer for ?
If not, you can go up and read them.

Are you connected with Flarm ?
If you mention the IP, you are supposed to know them. Can you write here for everyone what IP Flarm has ?
Again, it's in the previous posts, so it is clear that you have not read them or you ignore them purposely.
To show that you know the subject, write here the IP that Flarm has.
Otherwise you make allegations without any base, which is useless for a discussion and a bad behavior.

[Lucas]

Your note doesn't solve the basic problem: you cannot "predict" where the pilot will go in 10-20-... seconds.
Therefore any "prediction" is not possible.
This is very simple: there is no way of predicting what the pilot will do in most situations.
As already wrote, it's enough to look at a flight trace.
And, pardon me, but I have been working on flight dynamics for 19 years now. I don't know about you, but the background seems quite different at this point.

[Tango Eight]

No, I am not affiliated with Flarm. I am a retail customer. See how easy that is? You ask a question, I give you a simple straight answer. It's how civilized adults interact.

There's a song I like to whistle at times like this, and it even involves a strawman.

-Evan Ludeman / T8

[Andy Blackburn]

On Friday, May 29, 2015 at 4:35:14 PM UTC-7, Lucas wrote:

> Your note doesn't solve the basic problem: you cannot "predict" where the pilot will go in 10-20-... seconds.
> Therefore any "prediction" is not possible.
> This is very simple: there is no way of predicting what the pilot will do in most situations.
> As already wrote, it's enough to look at a flight trace.
> And, pardon me, but I have been working on flight dynamics for 19 years now. I don't know about you, but the background seems quite different at this point.

Experience: NASA Ames Research Center.

It is at best an academic argument and at worst a dangerous one to say that because you can't predict with 100% certainty that the pilot won't make an aggressive control input that it is pointless or ("impossible") to project forward a flight path for 15 seconds.

If the pilot makes aggressive control inputs any prediction of future position will change, and the old prediction will no longer be accurate. However, that does not make any attempt to predict future position useless. Most control inputs over a 15 second time period when thermalling or when cruising do not so alter the trajectory as to make a path estimate irrelevant. Generally the trajectory is pretty predictable. It's actually pretty hard to make a material change in your position in a thermal and it takes a while for it to evolve. Even if there is an aggressive control input the algorithm adjusts to include the change. If you maneuver and become a collision threat FLARM generates a warning, if you don't become a collision threat it doesn't.

Works pretty well for me.

9B

[pcool]

You are the administrator of ClearNav, and you have been working WITH flarm
in the past to integrate their work into yours.
I think it is unfair to call you a simple retail customer.
I think that you are playing with no success the strawman with us.


"Tango Eight" wrote in message
news:947b89f0-19f4-47db...@googlegroups.com...

[Tango Eight]

I'm ill with the 'flu and can't fly or do much else so...

I've been on a conference call with Flarm guys exactly once, mostly concerned with their data port specification and how to use it best with our product (n.b. we're still waiting on dataport spec for v6). I bought all my flarm gear at retail price, through the retail channel. Flarm has never shared with me any information not already in the public domain.

None of that is really your business, but I'll share just for the sake of transparency.

The DSX guys have clearly behaved badly enough in a commercial sense to poison any future possibility of cooperation with Flarm. This was a *completely* predictable outcome to anyone with a shred of business savvy. That their proponents won't even acknowledge this explicitly isn't going to help (bring in "Bones" to deliver a cameo "He's [DSX] dead, Jim"). Am I happy about the Flarm monopoly? No. I would absolutely love to see a very basic, inexpensive device (which is what I understand the original Euro flarm was) made available in USA that I could get my local club guys to buy. Powerflarm is so expensive that the *only* significant US market is going to remain competition pilots. At $500, we (that is: safety advocates) could expand the user base a *lot* and I think that would be a very good thing, but I don't think Flarm will ever do this.

Complete aside (I'm just killing time waiting on this damned bug to expire):

You don't seem to know what a "Straw Man Argument" is. There are several good websites devoted to logical fallacies and we can all do well to study and avoid these common and aggravating rhetorical mistakes.

Example of Straw Man: You insist that Flarm doesn't do "prediction" because it cannot know *exactly* (i.e. to one wingspan let's say) where a glider will be in 30 seconds time. This is an absurdly high standard of "prediction" in this case, because a lower precision estimate of likely future location is in fact very useful, especially because this can be rapidly revised if the pilot changes course. What you've done in a rhetorical sense is construct a towering giant of a foe (the "Straw Man") which you proceed to knock over trivially, claiming victory, but in fact all you have done is distract. It's a favorite technique of the political class: the rubes and ideologues *always* bite. We should all try to be smarter than that.

I'm quite confident I have done no such thing on this thread.

best,
Evan Ludeman / T8

[jpg...@gmail.com]

So if a reputable avionic company assesses a technical solution from another company as being worth collaborating with that necessarily invalidates their opinion and/or objectivity? Well I guess that having been involved in systematic trial of Flarm in 2007 I am tainted too. And, of course, all those 25,000 paying customers have an axe to grind as well. I understand now - the less the knowledge or experience of, or investment in, a product that an individual has then the more valid is his opinion

[pcool]

Then we all agree on the fact that we dont want a monopoly.
I am not by any mean pushing one or another technology, I exactly want what
you write, too.
I cant subscribe a petition like the one in this thread, I think it is
worthless, to be gentle.

Concerning the strawman, it is an english term and it is not in use commonly
although the meaning is clear.
In this case it is abused, I think, and let me say it sounds offensive .
The argumentation about "where is a glider in 30 seconds" made by a 8mhz
device with no math computing power, leaves no doubts to me.
This is why I keep calling it projection, and Andy did explain what I think
better than I can do myself.

Whatever, we all agree it works.

"Tango Eight" wrote in message

news:976b3ec4-e78d-4959...@googlegroups.com...

[Andy Blackburn]

On Saturday, May 30, 2015 at 9:29:15 AM UTC-7, pcool wrote:
> Then we all agree on the fact that we dont want a monopoly.
> I am not by any mean pushing one or another technology, I exactly want what
> you write, too.
> I cant subscribe a petition like the one in this thread, I think it is
> worthless, to be gentle.
>
> Concerning the strawman, it is an english term and it is not in use commonly
> although the meaning is clear.
> In this case it is abused, I think, and let me say it sounds offensive .
> The argumentation about "where is a glider in 30 seconds" made by a 8mhz
> device with no math computing power, leaves no doubts to me.
> This is why I keep calling it projection, and Andy did explain what I think
> better than I can do myself.
>
> Whatever, we all agree it works.
>

I don't know exactly how the Flarm guys do their math to project a flight path, but I think of it as a cone with it's point at the glider and it's wide end 15 seconds ahead of the glider. The cone can be straight or curved and the cone's centerline defines the overall curvature, which can be defined by a number of factors, but for simplicity's sake lets say that it is a circle based on the last three datapoints (it could be any kind of mathematical curve). If the glider is flying straight, the circle has an infinite radius (a straight line). If the glider is thermaling the circle has a radius of a few hundred feet.

Now imagine the pilot of the glider has decided that instead of thermalling to the left he wants to thermal to the right because he thinks the core is not at the center of the left hand turn but rather at the center of the new right hand turn he wants to establish.. He puts the stick over to the right and the glider starts to roll. The bank shallows, passes through wings level and eventually settles in a steady right hand turn. From start to finish it takes around 10 seconds. What happens to the projection of his future flight path? As his circle widens the projection widens until it is straight out in front of him and then starts curving to the right until it is a cone curved to the right in a circular arc with a radius of several hundred feet (whatever his turn radius is.

It is true that because no instrument can read the pilot's mind you cannot predict that the point 15 second ahead of the glider will flip from being on a left hand circular arc to a right hand circular arc, but that projected point and any given moment is the BEST ESTIMATE of where the glider is headed and as the wide end of the cone arcs through straight ahead the edge of the cone will intersect any paths on that new circle. It won't be a 15 second warning, more like 7-10 seconds depending on how much the cone widens. There is no algorithm or system that will read the mind of the pilot before he even knows his mind, but the Flarm approach certain warns you of a glider heading your way as soon as it is in fact heading your way - that's what we want it to do.

You can be more conservative and set the warning to alert for any glider that is close enough to hit you based on the maximum possible closure rate - assuming both pilots turn aggressively to go exactly head to head. This would require a warning for any glider within a mile to a mile and a half (assuming 300 knot closure rate). Also assume the other glider is in a 25 knot thermal or 25 knots of sink and you are in the opposite to take a worst case scenario. Anyone plus or minus about 1200 feet and within a mile to a mile and a half distance should generate a warning. That is the warning volume to be 99.9999% sure that no matter what you do or the other pilot does you will be warned at least 15 seconds from possible impact. Oh, except if the higher glider has speed brakes out, then you need more like a +/- 2500 foot warning height band.

Without some assumption on projected path, collision warning turns into a traffic alert system if you want 100% certain that no matter what either pilot does you will be warned at least 15 seconds ahead of time. Getting continuous warnings on dozens of glider all the time defeat the purpose I'd like to see served in a collision warning system - that it only warns you when a collision is a real possibility, not a 0.0001% chance that I would get warned about a few seconds later anyway if the worst case circumstances in terms of pilot maneuvering actually came to pass.

If that's what this has been about, it is kind of silly and academic. You should only give warning on things that are pretty likely to happen - or like the boy who cried wolf, people will stop listening to you.

9B

[pcool]

Very interesting view, Andy!
But, can a Flarm cpu do this? My doubts come from the fact that the
calculation engine in my flight software takes about 25ms every second on a
400mhz ARM cpu. For flight path estimation, some of those calculations would
be necessary too. A very conservative estimation would be 20% of 25ms,
needed by flarm too. So let's say 5ms, but on 8mhz (50 times slower). That
means 250ms.
The available time slot is 1000ms but it cannot be used entirely, because
the data must be transmitted and received within the timeslot itself.
So using the same thumb rule, I would say 250ms out of 750ms are used for
calc, leaving 500ms for the rest.
The "rest" being dealing with the gps, receiving data from the radio,
processing data and compare for each data the collisions. outputting NMEA to
serial port if needed, recording the flight, managing the leds etc.
And we must consider that the ATmel 128 cpu has no floating point, no math,
and even a sin() and cos() function are made from scratch in C language by
the cross compiler.
This is why, although "thumb ruled", I cannot thing that a cone like yours
is in use, but something much more simpler.
Because there is no time to do things like you say, I believe.
What do you think?

"Andy Blackburn" wrote in message

news:7eeab3dd-a1e1-4aa9...@googlegroups.com...

[Martin Gregorie]

I see what you're getting at, but I know what I've done using a Parallax
BS2 STAMP that was running a 'compiled', i.e. probably P-coded, integer
BASIC to do some simple time-critical calculations while driving an RC
servo and scanning a pair of switches.

I also remember just what we managed to get a smallish mainframe to do
back in the early 70s with its 1.5 uS (666 Khz) cycle time.

I don't know the Atmel at all, but if it can use interrupts for i/o
handling rather than dimly waiting for each byte to dribble in from its
serial ports then the position might look a bit better than you seem to
think it is.

[Andy Blackburn]

I bet you could do a good enough job without a lot of trig. You need position, velocity vector and some measure of curvature. You could probably do the horizontal and vertical parts separately. The cone part is just relaxing the distance that constitutes a collision conflict progressively with each increase in projection time/distance.

Of course the proof is in how FLARM behaves so they are doing something like what I described.

How the calculations fit in processing time available is a question for the likes of Dave Nadler who understand these issues intimately.

9B