"Do It Yourself" airborne proximity warning device

[Linar Yusupov]

Dear rec.aviation.soaring subscribers!

I would like to present you PDF slides of one DIY R&D project.
The slides are about open platform airborne proximity warning device.
It operates at ISM band radio but also capable to receive ADS-B reports at aviation frequency.
It is mainly targeted for our local soaring club use but can also attract pilots worldwide.

The presentation is downloadable at: https://github.com/lyusupov/Argus/raw/master/doc/Presentation_of_DIY_Airborne_Proximity_Warning_Device.pdf

If upon reading you'll find it worthwhile, feel yourself free to share this news with someone
upon your discretion.

Don't hesitate to ask any questions here. FAQ document is yet to be created.

Best regards!
Linar Yusupov.

[ahar...@gmail.com]

Beautiful!

[Dan Marotta]

Very well done!

I will be watching your progress with interest.

"Linar Yusupov" <linar.r...@gmail.com> wrote in message
news:6d078793-b609-4560...@googlegroups.com...

[Steve Koerner]

This is interesting and clever.

But it does not work with Flarm! Flarm/PowerFlarm is seeing rapid adoption. A system that competes with Flarm has only the possibility of reducing safety during the time frame that I expect to remain an active glider pilot. Though competition is usually good, it is not a good thing to have competition in this case. What makes it worse is the possibility that any pilot might consider waiting for this instead of installing Flarm/PowerFlarm right now.

Just like Flarm, this system requires that both gliders be like equipped. Having a contingent of Flarm users and a contingent of WiFi users at a contest means that we cannot get to the significant level of safety improvement that would be otherwise achievable with fully adopted Flarm or PowerFlarm.

As I read through the material I couldn't find a single element of technical superiority over PowerFlarm. It seems to me that for one technical standard to replace another established standard it needs to be distinctly better than the first. Being equivalent (if it were) is not near good enough, even if the cost is lower. Soaring is not so strongly cost driven as consumer products for example and in general having an avionic component supported by a manufacturer is a very important benefit.

Starting from where the developers are now, they are very far behind PowerFlarm. Part of the goodness of PowerFlarm is the years of evolution in the algorithms for the collision risk analysis. In a fast changing environment of side by side cruising and close thermalling, PowerFlarm makes good determinations. Even the most brilliant programmer on earth cannot just sit down and write that code. It takes years of observation and feedback to make it work really well in the real world. The electrical components are not the major part of the problem; the magic is really in the software.

And for close proximate flight, I'm led to wonder how the designers might have come to the conclusion that 2-3 second latency would be acceptable for good warnings? Having flown with PowerFlarm, I have to believe that the latency is lower than that.

On the hardware side, I think there are things the developers are not considering well. The use of a high gain (5 dBi) antenna is not advisable. It's important to use a low gain dipole pattern antenna in order to couple well with turning gliders. With a low gain antenna at both TX and RX, the link analysis will be significantly impacted and you will not have the range that has been speculated. PowerFlarm uses a simple dipole for this reason and yet has greater range than is contemplated with the high gain antennas suggested here.

Also related to the coupling matter is the choice of frequency. 2.4 GHz will be significantly more impacted by the nearby human body and other items of near wavelength dimension in the environs of the antenna. This can be overcome to a certain extent with power margin but there isn't power margin. PowerFlarm provides an auxillary receive channel to partially address this issue. An auxillary channel is needed in spades at 2.4 GHz.

There is no mention in the article as to the level of degradation that might be expected in a contest environment with say 50 gliders all within radio range. What is the duty cycle of the waveform? How much would 50 gliders be expected to further reduce functional range?

In this self assembly scenario, who does the testing? One of the things about electronics in general and avionics in particular is the need for sophisticated testing. Having a manufacturer behind an avionics product means that the items have been tested. There is the production testing of each article as it leaves the assembly area. Even more important is that all of the components that go into the design have been technically qualified as suitable. That means that they are tested for operation over a wide temperature range as well as shock and vibration and humidity and pressure. They are tested for having a suitably small degree of parameter variance over the environmental range. All of the USB consumer items that are identify for this project are items that are generally made in China and are intended only for use at room temperature in benign environments. It would be almost remarkably if they all happen to also work over aviation temperature range. I'd be particularly suspicious about the radio module power output and the radio sensitivity over temperature; especially for a device that was never actually intended for operation over temperature.

In fairness the original poster, he did not describe the system as intended to be a replacement for Flarm/PowerFlarm. Yet as described, that would be the obvious thing that many readers might be considering here. For that reason it is worthwhile to point up these considerations and limitations.

Even as I hope that it eventually works well for OP's club, I'm also hoping that no US pilots in particular might be looking at this as a suitable substitute for PowerFlarm.

[szd55...@gmail.com]

Interesting read, it has glider pilot creation written all over it. My first impression was that it looks wirey (just invented a new word). I then spent 15 minutes on the net to price the components (identical in most cases but a few exceptions). I got a total of just under $100 on Amazon and Ebay 'buy it now'. I did not include for battery or PDA.
You have 2 types of pilots, the competition guy and the week-end warrior. In most cases, the comp guy is going to have a high end ship and therefore the $1700 powerflarm is an acceptable cost, the week end warriors on the other hand can have a system for approx. 200 bucks (estimating background, take the cost and double it).
I sounds like Linar has started something and based on the above still has some bugs to sort out but Hey! Is is a start.
I will definitely keeps tabs on this thread.

mas

[Dan Marotta]

Maybe someone should develop a device like the MRX PCAS which detects
transponders and includes azimuth in addition to range and elevation. Most
of the algorithms have already been developed. There are well established
methods for very accurately locating a transponder. Look up ASDE-X, for
example (LAT/LON/ALT derived from transponder replies). Alas, I suspect
development cost would far outweigh expected return on investment.

Steve makes excellent points, especially the environmental issues with using
consumer electronics in an aviation envrionment. Having said that, I must
ask if Flarm and PowerFlarm have FAA certification, as does a certified
transponder. Steve's post implies that it is but, according to the FAC
posted at gliderpilot.org, it is not, and does not require certification.
As to Steve's question of the veracity of the system under discussion in an
environment including 50 gliders in close formation, consider that this
display has only 64 pixels and 3 of them display the own ship! That would
be a pretty busy display...

According to the NTSB accident database, since 1994 in the USA there have
been exactly 6 midair collisions involving a glider as listed below (9 if
you consider two gliders running into each other):

1999 - Gllider hit tug which was towing another glider
2003 - Piper Cub flew into aerobatic box and collided with glider using the
box
2006 - Glider and corporate jet collided at 16,000' MSL near Reno, NV
2008 - 2 gliders collide while thermalling
2012 - 2 gliders collide head on
2012 - 2 gliders collide while thermalling at the Worlds Championships

I'm going to guess that neither Flarm nor PowerFlarm were available in 2008
or earlier and, if that is the case, then this technology might have
prevented exactly two accidents in the US. I'll bet that both gliders in
the World's were so equipped and the technology failed, so I'm still waiting
for difinitive proof that it's worthwhile. In most cases, a good outside
scan would also have prevented an accident. In response to the anticipated
statement that we'll never know how many accidents were actually averted by
Flarm, I can only say that a good traffic scan is usually all that's
required, or rejecting or leaving a crowded thermal (competition excepted).

I used the keywords "midair" and "glider" in my search but there may well be
others which I missed. My point is that, considering the number of glider
flights conducted in the US, the risk of a midair is extremely low and, in
my opinion, does not warrant the expense, complexity, or distraction of a
collision warning device for most of the glider flying done in the US.
Competition flying is different, of course, as it concentrates so many
gliders in the same airspace. Europe is much more congested and has far
more glider flights than we do and I can see more of a benefit for them.

And, finally, for a good many of us glider pilots, we cannot simply lay down
for an ASG-29, full panel, and Cobra trailer. For us, the sport is somewhat
cost driven.

"Steve Koerner" <sjko...@gmail.com> wrote in message
news:cf51a15c-d5c4-46ec...@googlegroups.com...

[Linar Yusupov]

Thank you for your responses!

I've exhaused my spare time slot today for answering on e-mails.
So I'll leave my comments on this thread later on.
But for now I would like to remind you that:

- it is up to a human being to build an item himself(herself) or buy a product from reseller;
- it is responsibility of Pilot-in-Command and nobody else to carry onboard anything he(she) wants that is within w&b limitations and allowed by law;
- it is responsibility of Pilot-in-Command and nobody else to operate while in flight an electronic device or keep it switched off.

[soari...@gmail.com]

On Tuesday, December 10, 2013 10:19:07 AM UTC-8, Dan Marotta wrote:

> I used the keywords "midair" and "glider" in my search but there may well be
> others which I missed. My point is that, considering the number of glider
> flights conducted in the US, the risk of a midair is extremely low and, in
> my opinion, does not warrant the expense, complexity, or distraction of a
> collision warning device for most of the glider flying done in the US.
> Competition flying is different, of course, as it concentrates so many
> gliders in the same airspace. Europe is much more congested and has far
> more glider flights than we do and I can see more of a benefit for them.

> And, finally, for a good many of us glider pilots, we cannot simply lay down
> for an ASG-29, full panel, and Cobra trailer. For us, the sport is somewhat
> cost driven.

For some reason it is hard to get the NTSB database to cough up all the incidents. You missed several midairs I know of in the past 5 years or so including one requiring a bailout and one where one pilot tried to bailout but was unable to and thankfully was able to land without injury. That doesn't include a number of scary near misses.

I believe the data shows that midair is the second leading cause of fatality next to stall-spin/collision with terrain. Glider-glider collision is at least ten times likely as glider-GA collision and (by the data) infinitely more likely than glider-air transport collision. If we ever got one of those it would be ugly and bring the stats up to making glider-glider 100 times more likely than glider-air transport.

Yes, contests gather gliders and concentrate traffic but if you look at the some of the work that has been done to accumulate OLC traces into glider flight path "heat maps" you discover that the combination of topography, airports, airspace and (especially) lift sources puts gliders in much closer proximity to each other than you might otherwise think. Gliders tend to occupy a small, common proportion of the available airspace, even though we think we are flying just anywhere. This explains why we see more glider-to-glider collisions than any other kind of glider involved collision. It raises the question as to whether if forced to trade off transponder vs Flarm for cost reasons the most bang for the buck really might be Flarm, even for non-contest flying near terminal areas. The midair collision data suggests this might well be true since the penetration of Flarm and transponders in gliders are both low. The equation would only flip for very small numbers of gliders (<5) flying right up against a busy international airport - though there aren't many of these. I carry both Flarm and a Mode S, but I realize others feel they can't afford both, just the way some feel a parachute isn't worth the cost (I believe there also are fewer successful bailouts than glider-glider midairs - so selling one's parachute to buy a Flarm may also be a statistically superior solution - though emotionally I can't imagine anyone making the switch).

In any case, having two, incompatible, Flarm-like technologies is a terrible idea for the reasons already articulated.

9B

[Steve Koerner]

Hey Dan,

There is actually nothing in my posts that implies that PowerFlarm is FAA certified. I know that it's not and I have no concern that it's not.

Moreover, though your collision statistics are incomplete, your data would in itself drive me to an entirely different conclusion than the one that you prefer.

GW

[soari...@gmail.com]

On Tuesday, December 10, 2013 10:19:07 AM UTC-8, Dan Marotta wrote:

> Maybe someone should develop a device like the MRX PCAS which detects
> transponders and includes azimuth in addition to range and elevation. Most
> of the algorithms have already been developed. There are well established
> methods for very accurately locating a transponder. Look up ASDE-X, for
> example (LAT/LON/ALT derived from transponder replies). Alas, I suspect
> development cost would far outweigh expected return on investment.

I looked it up - ADSE-X is an active radar system that uses either a rotating or phased array antenna (apparently normally mounted on top of the control tower). It's not the sort of thing you'd find you could fit in a glider - even if it were legal. Here's a long to a schematic of the Raytheon version:

http://avstop.com/stories/asde.html

I am not aware of any system you could even adapt to put in a glider that would allow you to get accurate azimuth information off of transponder returns - even in theory.

9B

[Sarah]

Well, define "accurate", and "could put in a glider".

I've never seen one, but the rather boxy Zaon "XRX" was supposed to give azimuth information. I believe it was crude ( quadrant or octant ), and I have no information about how well it worked other than reviews. I have a Zaon "MRX", which is a small altitude-only reporting receiver, and find it useful. Too bad Zaon closed operations recently.

Review: http://www.flyingmag.com/avionics-gear/portablehandhelds/zaon%E2%80%99s-pcas-xrx-collision-avoidance-system

On Tuesday, December 10, 2013 2:34:45 PM UTC-6, soari...@gmail.com wrote:
> ...

[soari...@gmail.com]

On Tuesday, December 10, 2013 1:41:26 PM UTC-8, Sarah wrote:

> Well, define "accurate", and "could put in a glider".

Fair enough.

If you were able to put TCAS in a glider that would do it, but trying to get azimuth information off of passive monitoring of radar returns (like PCAS does) has to be a hit-or-miss proposition (pun intended) since you don't have the ability to actively interrogate other transponder-equipped aircraft to string together enough bits of information to get good direction. You are dependent on ground radar or TCAS-equipped aircraft to do the interrogating for you which is no always reliable. Some sort of directional antenna added to a PCAS might help in the way you describe (showing quadrants), but I have to believe it's not the sort of thing you could really count on and would totally suck for glider-glider scenarios.

I'd also add that the research shows that no matter how diligent the scan, see-and-avoid detects not more than half the targets that are collision threats. Non-threats are much easier to pick up because of the angular movement of non-collision targets. So, the fact that you see other aircraft when you are flying to some extent generates a false sense of security - your are much less likely to see the one that's going to actually hit you. There are scenarios in the research where successful detection in time to act is on the order of 10-20%. That gave me some pause.

9B

[kirk.stant]

On Tuesday, December 10, 2013 12:19:07 PM UTC-6, Dan Marotta wrote:
> Maybe someone should develop a device like the MRX PCAS which detects
>
> transponders and includes azimuth in addition to range and elevation.
>

Hmm, that's exactly what PowerFlarm does with ADS-B/mode S targets. Which are becoming more and more common, and includes pretty much all fast movers and advanced GA planes. Plus PF gives you the same data as an MRX (I have both - now use the MRX for towplanes and club gliders). And you get really good (as in Link-16 good) glider to glider cooperative data.

So lets see - I believe you have a transponder in your glider (about $2k) and a MRX $500 and I assume a parachute (about $2k). So you see the risk is airliners (transponder for TCAS), lightplanes (MRX), and something that will make you need to make a nylon letdown. But by your own statistics, the PowerFLARM is more useful than the parachute, replaces the MRX, and lets you see airliners BEFORE they run you down or have to maneuver around you ("Hey, FSDO, get that clown in the glider out of our approach path!"

To me it's a no-brainer. Where I fly, the transponder provides the least protection, so I haven't yet tried to squeeze one into my '6. But having experienced the SA that the PF provides in a glider-rich environment, and the SA it gives on nearby power traffic, I don't like flying without it anymore!

Of course, we all have to make decisions based on our perceived risk - but i find your dismissal of PF a bit perplexing, especially since you use the much more limited MRX and count on your xponder to keep from getting run over by a fast mover!

Oh, yeah, see and avoid. Right. How about BIG SKY theory - that's really what keeps the midairs down to a tolerable level in the US. In France they finally realized that they no longer have the luxury of a big sky, and now FLARM is mandated for all gliders.

Not so dumb, those cheese-eating surrender monkeys!

Kirk

OT, I just spent 9 months working in France. Sure was nice being in a civilized, modern country. Coming back to St Louis was like being sent off to a third world country! But hey, at least we have more cable channels!

[son_of_flubber]

This project lends "Blue Screen of Death" an entirely new dimension of meaning http://en.wikipedia.org/wiki/Blue_Screen_of_Death

I'm an enthusiastic supporter and participant in the whole Open Software/Hardware and Maker movement, but given the stakes, I have very mixed feelings about this project. A collision warning system that you cannot trust can potentially cause more harm than good. What if the system tells you to "turn right" when you should "turn left"?

A collision warning system needs to be about as reliable and trustworthy as the software and hardware that implements the ABS in your car. Implementing an ABS system properly is a whole order of difficulty beyond developing something like the very wonderful and amazing XCSoar. A defect in XCSoar is unlikely to kill you.

One thing that can in some cases make open source software and hardware more reliable and trustworthy than proprietary systems is the effect of having a large developer community scrutinizing the source code and hardware. Linar's project presently has one developer. It also helps to have a large and diverse group of users banging on the system and reporting defects.

It is an exciting time when individuals like Linar can pull together a bunch of existing building blocks and rapidly prototype a new idea. But there is an inherent fragility in any system that relies on multiple "black boxes" and a collision warning system needs to be extremely robust. Black boxes often do not do what they are advertised to do, when you use them in unanticipated ways. Just because something works when you turn it on does not mean that it is reliable.

If Linar's approach has a real potential to deliver a collision warning system at lower cost and/or higher reliability than PowerFlarm, then I hope that he obtains the funding that will allow him to pursue this project in earnest. An opensource collision avoidance system has the potential to be superior to PowerFlarm. PowerFlarm might be more reliable and better functioning if they made the software open source (but their business model does not allow that).

[kirk.stant]

Ok, lets get real here. This sounds like a nice little club project, and if the intent is to have all the club gliders equipped (as opposed to none with Flarm) then it has some value.

However, in the big scheme of things, it would have to be orders of magnitude less expensive and better performing to be able to overcome Flarm's lead (see France, Australia, etc.). And let's face it - most glider pilots are not going to cobble together a piece of kit like that - we'll pay extra for the fancy bells and whistles!

Let's take another example: I'm sure we can come up with a less expensive, better quality radio communications system to replace the old VHF system we now use for aircraft/ATC communications. But until everybody has a compatible system, you can only talk to the others who have the same system - so is your new system that much better? So we are stuck with an archaic AM radio system that you have to have, and it's good enough.

Now, what would be nice is an inexpensive ADS-B "out" box that would let gliders broadcast their position into the ADS-B "system" without needing a full up UAT/Mode S/WAAS IFR certified GPS setup. One of those, plus a PowerFLARM, would be a really nice setup.

Kirk
66

[Dan Marotta]

Excellent reply!

I tried several keywords and the midairs I found in the NTSB database were
those that I listed. I will accept your assertion that there are more - I
just couldn't find them.

While reading your response regarding Flarm being better than a transponder,
it occurred to me that, where I fly that is just not the case. Due to the
altitudes that we fly, pretty much all powered aircraft have to have
transponders (above 10,000' MSL), and there are probably less than a dozen
of us that venture far from the airport. Our airport is also very lightly
used by power traffic and the cross country pilots usually return late in
the day after all hangars are closed. Our only major concerns are the IFR
arrival and departure routes which are near the airport. So, speaking
purely from my flying situation, a transponder is a far better solution than
a Flarm.

Your situation is, of course, different.

<soari...@gmail.com> wrote in message
news:ea56acb6-6cad-4eca...@googlegroups.com...

[Dan Marotta]

Sorry, Steve.

I misinterpreted your use of the term "avionics" to mean certified. Please
see my recent post concerning those statistics and flight environment and
how they led me to my conclusion.

Dan

"Steve Koerner" <sjko...@gmail.com> wrote in message

news:ae91ba06-18c1-4d0d...@googlegroups.com...

[Dan Marotta]

Sorry, but you got incomplete information. I checked your link and the
Raytheon radar is just a part of one of the systems produced by Sensis Corp.
(now Saab-Sensis).

The rotating antenna on top of the control tower is either an FAA ASDE-3
radar or an ASDE-X (Raytheon) radar. ASDE-X and ASDE-3X (using the FAA
radar) fuse data from radar and transponders, both airborne and on the
ground, into a position/altitude. The radar is an adjunct to TDOA and FDOA
(time and frequency difference of arrival of signals) geopositioning and
aids in position accuracy, but is not required to generate a position.

My statements come from prior work as Test Director during acceptance of the
ASDE-3X system at Louisville, KY (SDF). There are 30+ of these systems
worldwide at major and second tier airports.

The company that produced ASDE-X and -3X also setup systems in Colorado and
Alaska which allowed ATC to derive aircraft positions in remote areas which
have no radar coverage.

There were additions in the concept stage when I left the company that
included in-cockpit displays of traffic detected by the system but that was
over 5 years ago and I have no idea of whether they ever came to fruition.
But, like anything aviation related, it would probably cost both arms and
legs.

<soari...@gmail.com> wrote in message
news:5fd95e32-a3bd-4c7e...@googlegroups.com...

[Dan Marotta]

You don't need directional antennae. Without getting too long winded (I
know, I know...) you monitor the arrival times and frequencies of the
interrogation signals and the replies and combining that with your known
position, you can mathematically determine the positions of all the
emitters. Multiple samples enable the system to determine velocity (a
vector of direction and speed).


<soari...@gmail.com> wrote in message
news:26e50cc1-3cd7-48a9...@googlegroups.com...

[anderson....@gmail.com]

On Wednesday, December 11, 2013 9:07:33 AM UTC-8, Dan Marotta wrote:

> But, like anything aviation related, it would probably cost both arms and
> legs.

> > Maybe someone should develop a device like the MRX PCAS which detects
> > transponders and includes azimuth in addition to range and elevation.

Thanks for the info on the ASDE-X system Dan - I think you are right that it's unlikely to make a cost-effective anti-collision system in the end.

I think Sarah's link to the Zaon XRX represents an attempt at what you are talking about that only costs one arm. It carried a retail price of $1395. Even if it were in production today I'd still rather carry a PowerFlarm for that kind of money because you'd get actual 1090ES GPS fixes plus PCAS plus glider Flarm traffic for about the same price. I think in general the idea of trying to interpret radar returns - even with a lot of calculus of variations math - is by now antiquated and far inferior to more modern GPS-based solutions. The review on the XRX seemed to confirm this - it only sometimes worked.

I looked up ABQ in the FAA's Air Traffic Activity System. On an average summer weekend soaring day it handles about 100 total airport operations during the active soaring day, which places it at #116 among airports in the US - a reasonably busy airport. Even so, I'd bet dollars to donuts that if you took all the IGC traces and all the radar traces and compared them you'd find on a typical glider flight that more than 9 out of 10 of the closest approaches to another aircraft would be another glider or towplane, not a commercial jet.

That's not to say I'm advising against a transponder - I often fly near Reno (#197 in summer weekend airport operations) and I carry one. Yes there are differences across airports in terms of how the jet approaches mix with glider flights. However - if we take it back to actual statistics, I expect ABQ is not so atypical a traffic situation to overcome the more than 10x difference in the statistics on average - that is, you are more than 10x as likely to run into another glider or local traffic at your home airport than a jet. The big jets are certainly more obvious and scarier and would make a bigger headline if you actually hit one, but the outcome for you is the same whether you smash into one of those or your soaring buddy. For that reason I consider carrying a transponder more of a public service than my primary device for personal safety - my PowerFlarm, InReach, parachute and extra drinking water all rank ahead of my transponder in terms of personal safety - more or less in that order.

9B

[Linar Yusupov]

Compatibility with other devices of similar purpose can be acheived with at least three different ways:
1) alternative device can be pluged-in into spare USB hub slot through USB<->RS232 adapter. A software converter of NMEA messages will translate PFLAU/PFLAA traffic alert messages into the input format of the device developed by topic-starter. But this is "read-only", one-way method;
2) second way is reverese-engineering of radio protocol. That was already done before (in 2008) and where published in this newsgroup followed by reaction of manufacturer.
See this thread: https://groups.google.com/forum/#!msg/rec.aviation.soaring/daOXteD5ois/KOoAiKhERhUJ
3) to purchase a license or invite a current licensee to contribute compatibility into this open project;

Any of above can be done then contributed by volunteer who wants to add the compatibility into this project.

Our club's fleet is about 40+ sailplanes and 5 tow planes. Only three of these aircrafts currently carry onboard a Flarm device. Owners are typically keep them switched off because it makes little sense to drawn battery power when majority of traffic is not equipped with Flarm.

For me, personally, I have no plans to spend my own time to develop compatibility with Flarm. ADS-B is comming soon. So any other devices will leave from market within next few years unless they will switch onto ADS-B standard.
Thus operation on ADS-B is the way where the project should go.

2-way ADS-B USB plug-in for this device is a module that worth to be developed within next couple years.

[Dan Marotta]

Thanks for the morning chuckle, Kirk. Civilization is in the eye of the
beholder, though I must agree with you about St. Louis...

I fly in a glider poor sky so Flarm is of little use to me. That's the
simple truth. Now, when a $1,500, panel mounted ADS-B system is approved
for GA aircraft, I'll drop my MRX and install one of those. I promise!


"kirk.stant" <kirk....@gmail.com> wrote in message
news:0b7aa14f-7527-4212...@googlegroups.com...

[Dan Marotta]

There seems to be a misunderstanding of the Moriarty flight environment.
We're a good 40 miles east of ABQ, on the other side of the mountains from
them, in fact.

East bound departures from ABQ generally start out north or south on the
west side of the mountains and transition to the east after 20-30 miles.
Arrivals, on the other hand, fly directly over Moriarty at about 14,000' MSL
(8,000' AGL).

Most glider flights here head north, east, or south. We do go west,
generally up to the mountains, but don't often cross. Of course we can,
it's just that we have great flying on the east side and, to the north, can
get on the range that goes up to Colorado and beyond.



<anderson....@gmail.com> wrote in message
news:92a86271-a10a-4c5e...@googlegroups.com...

[Linar Yusupov]

I've published today the parts list with price estimate:
https://rawgithub.com/lyusupov/Argus/master/doc/Parts_List_and_Price_Estimate.html

[Linar Yusupov]

I would like to express my appreciation to those subscribers of rec.aviation.soaring
who exposed the slides to honored soaring societies of Netherland and Poland
followed by a comment in native language.
Thank you very much!

[Ian]

On 12/09/2013 04:22 PM, Linar Yusupov wrote:

> I would like to present you PDF slides of one DIY R&D project.
> The slides are about open platform airborne proximity warning device.
> It operates at ISM band radio but also capable to receive ADS-B reports at aviation frequency.

I wonder how easily this device could be converted into one that can
transmit glider airspeed during a winch launch back to the winch driver?
It would require an extra hardware module with a pressure sensor to
measure pitot/static pressure, an analogue to digital converter, a USB
interface and additional software in the main radio unit.

You would need a 2nd radio device in the winch coupled with a suitable
display unit.

Dedicated devices for transmitting airspeed from glider to winch have
been made before, both on an experimental/development basis as well as
on a commercial basis. However every glider that gets winched from a
site needs the device to benefit from the technology.

The proposal describes a low cost anti collision device. If it could be
extended to provide winch launch airspeed feedback, it would provide an
additional function at an incremental cost. It might be attractive for a
club where the whole fleet is targeted for fitting of these devices, to
incorporate this additional functionality, if that club also operates a
winch.

Obviously this device is an alternative to Flarm. Adding this new
functionality might differentiate it enough from Flarm to create a niche
market.

Good luck with your project.

Ian

[darrylr]

On Tuesday, December 10, 2013 1:41:26 PM UTC-8, Sarah wrote:

> Well, define "accurate", and "could put in a glider".
>
>
>
> I've never seen one, but the rather boxy Zaon "XRX" was supposed to give azimuth information. I believe it was crude ( quadrant or octant ), and I have no information about how well it worked other than reviews. I have a Zaon "MRX", which is a small altitude-only reporting receiver, and find it useful. Too bad Zaon closed operations recently.
>
>
>
> Review: http://www.flyingmag.com/avionics-gear/portablehandhelds/zaon%E2%80%99s-pcas-xrx-collision-avoidance-system
>

And there was only one serious trial of an Zaon XRX in a glider that I am aware of and it did not do well and was removed. The upper and lower phased array antennas that TCAS II uses to get it their rough quadrant direction information is well beyond what is in a XRX type system or what you could/would want to install in a glider at all. TCAS III was supposed to provide accurate threat direction information for airliners etc., the complexity of doing that was one reason TCAS III was an abject failure and TCAS II stayed on being used.

Investing money/effort in positional transponder type systems seems a wasted effort given that FLARM exists and is already widely installed in glider fleets in many regions and that over time ADS-B will provide high resolution position report of lots of Airline, Fast jet, Military and GA traffic (eventually on-par with transponder carriage, possibly as early as a few years after 2020). But yes, even then we'll have issues with ADS-B including the dual-link silliness in the USA, problems equipping for ADS-B data-out carriage, etc.

[darrylr]

On Wednesday, December 11, 2013 9:12:45 AM UTC-8, Dan Marotta wrote:
> You don't need directional antennae. Without getting too long winded (I
>
> know, I know...) you monitor the arrival times and frequencies of the
>
> interrogation signals and the replies and combining that with your known
>
> position, you can mathematically determine the positions of all the
>
> emitters. Multiple samples enable the system to determine velocity (a
>
> vector of direction and speed).

But so what, these ground based multilateration systems have been around for years and are fairly widely used worldwide to supplement SSR radar. The way you get this traffic data to an aircraft today is via TIS-B. The position accuracy is not great (not compared to what GPS/ADS-B data-out can provide). And to receive that TIS-B traffic data your aircraft/glider needs to have ADS-B data-out, which requires an expensive IFR rated GPS, and an ADS-B data-out capable transponder or UAT (but please use a Transponder in a glider for PowerFLARM 1090ES compatibility) and a 337 field approval (for certified aircraft) that is supposed to be based on a previous STC in a similar aircraft (none of which were actually developed for gliders). So while it may be possible, good luck having that conversation with you local FSDO. And to receive that TIS-B signal requires you to be in range of the ground based ADS-B service, YMMV in some popular glider areas. And worrying about this stuff now just seems pointless given that ADS-B data-out carriage will be required in the USA in many aircraft by 2020. So you might as well just read that much higher resolution ADS-B data-out position data straight over the air now and usage will just continue to increase in future.

[Linar Yusupov]

On Thursday, December 19, 2013 1:23:08 AM UTC+4, Ian wrote:

> I wonder how easily this device could be converted into one that can
> transmit glider airspeed during a winch launch back to the winch driver?

Ian, the functionality you've mentioned about is falling into category of
"remote monitoring of an aircraft's telemetry".
There could be numerous applications of that functionality. One of the examples
is a first solo flight. Instructor, while on the ground, can prevent inadvertent low altitude stall.

Ground station device ("winch" device is your case) could be not necessarily "dedicated device".
Beacause of commonly used Wi-Fi technology, average Android tablet will likely be able to receive
and display the telemetry from an aircraft doing a close traffic pattern work.
Provided that tablet's built-in or external USB module is supported to work
in "monitor mode" ( http://wireless.kernel.org/en/users/Drivers ) .

Sensors, such as barometric, are typically low power consumption devices.
It is not necessary to feed them from USB bus. They can operate from a coin-sized battery for weeks
while submitting the measurement data troough Low Energy Bluetooth ver.4 protocol.
One known good example is the SensorTag ( http://www.ti.com/tool/cc2541dk-sensor ) USD25 device from Texas Instruments.
One can attach similar sensor to the pitot tube and submit data to Argus PM module by Bluetooth.


What I can do for now is - I can create a "Feature requests" list. And I'll put the count "1" on this particular feature.
When once upon a time the counter's value will become sufficent and there will be enough volunteers
to contribute something into this project - I will suggest them to implement this feature.

[Linar Yusupov]

To trust or not to trust in a item built by yourself?
This is a question that has no a simple answer applicable for everyone.

There are numerous RVs, Cubs, Velocities and other kitplanes flying around us.
Majority of the aircraft's structures had been built by the owners themselves.
The aircrafts have received airworthiness approval from government agencies.
A pilot of such aircraft trust his(her) life to the self-built airframe, wings and controls
which are primary, life-saving elements for 100% time of each flight.
In some countries supplemental live-saving equipment such as pilot's emergency parachutes or
a ballistic recovery system are optional, not required by air law, for this experimental
category of aircrafts.
And majority of aviators worldwide treat these facts as Ok. How EAA driven Oshkosh Airventure
and Lakeland Sun-and-Fun will look like if there would no experimental aircrafts?

Sailplane pilots operate their aircrafts under visual flight rules.
Primary and most essential instruments for maintaining situational awareness under these rules are the pilot's eyes.
Any electronic aid designed to serve this purpose is considered as supplemental.
Regulations states that you should not 100% rely on indication of a supplemental aid.
Taking this into account how it is important if the aid is a "factory built" or built by yourself?

For those who already had an experience of building an electronic device with success
my advice is: use this project as example then do your own hardware design of the device
that you personally can trust onto.

[Linar Yusupov]

A new design which is primarily considered as add-on for the Argus project has been recently released.
It is an IoT bridge between FLARM and Wi-Fi consumer devices. Codename for the design is SoftRF.

Areas of application:
---------------------
- a two-way bridge between FLARM and other traffic awareness designs ;
- alternative to Raspberry Pi based Open Glider Network (OGN) receiver ;
- wireless adapter for a smartphone or tablet to receive/transmit traffic information by iOS/Android app ;
- lightweight traffic awareness transceiver to carry onboard an UAV.

For more details, please, read these PDF slides:
http://github.com/lyusupov/SoftRF/raw/master/SoftRF.pdf

Linar Yusupov.

[Linar Yusupov]

Dear soaring community!

I've recently released development update of the open SoftRF project.

Few highlights:
- transmit power is 10 mW, so operating range is similar to the "classic" FLARM has ;
- FLARM and SoftRF can see each other ;
- is compatible with Open Glider Network (OGN) ;
- most popular gliding software (SeeYou Mobile, XCSoar, ...) just works, "out of the box" ;
- on a hardware level, it has a DIY modular design with Arduino-style "shield".

Full document in PDF format can be downloaded from:
http://github.com/lyusupov/SoftRF/raw/master/documents/SoftRF-release-2.pdf

For more information, please, visit: http://github.com/lyusupov/SoftRF

With best regards,
Linar Yusupov.

[Linar Yusupov]

With recent Fall'17 features upgrade, in addition to "Legacy" (FLARM AIR V6) radio protocol,
the SoftRF is now able to communicate using three other major ISM-band radio
collision avoidance "languages", such as:
- P3I Open (PilotAware) ;
- OGNTP (OGN tracker) ;
- FANET (Skytraxx)

Full compatibility "matrix" is availle here: https://github.com/lyusupov/SoftRF#compatibility

One more new feature is support for Garmin GDL90 datalink format, which is widely used
on North America EFB software market (ForeFlight, Naviator, WingX,...).
For details, please, read this page: https://github.com/lyusupov/SoftRF/wiki/Garmin-GDL90-compatibility

And SoftRF can now be integrated with RTL-SDR based ADS-B receivers, such as:
- airborne:
Stratux
PilotAware
- ground stations:
FlightRadar24
FlightAware
For example of integration, please, visit: https://github.com/lyusupov/SoftRF/wiki/Integration-with-RTL%E2%80%90SDR-based-ADS%E2%80%90B-receivers

[stu8...@gmail.com]

Linar,

Thanks for the interesting github pointer.

I'm not quite up to date on the state of Flarm reverse engineering and interoperability. For example, does the SoftRf understand the Flarm Frequency hopping?

The whole Flarm proprietary thing seems wrong, but on the other hand it funds a somewhat working Flarm system. Given that it exists, the most likely path to an open system seems like ADSB and/or an open software load for the existing Flarm boxes.

I wonder if ADSB is a viable path for gliders. Has anybody looked at if the broadcast ADSB state vectors are suitable for feeding a collision detection algorithm like the one in Flarm?

-Stu

[Linar Yusupov]

Stu,

> For example, does the SoftRf understand the Flarm Frequency hopping?

At first, channel hopping (CH) is more "radio signal obstruction clearance" rather than "security" feature.
Second: CH is not a factor for major FLARM's EU market ( only 2 channels are in use ), but "is"
for North (65 channels) and South America / Australia (24 channels).

"FLARM-alike" OGN CH was implemented in March'17 by Pawel Jalocha - leading developer
of OGN tracker. According to this source ( http://wiki.glidernet.org/history ), he had
relations with Flarm Technology GmbH in past.
SoftRF had adopted OGN CH algorithm.

Is OGN CH equal to FLARM CH in North America?
There were no neither positive nor negative reports from NA's SoftRF
builders till today.
So you have a chance to be the first one who will answer this question.

Regards,
Linar.

[vontresc]

Interesting project. Just out of curiosity, are you at all looking into supporting a dual band ADS-B receiver to handle both UAT and 1090 ADS-b in the states?

Peter

[SoaringXCellence]

Already exists:

Stratux.me

Build one for yourself for less than $150. parts on Amazon, have it in two days.

I've built two and might build another one pretty quick.

Mike

[Wit Wisniewski]

Folks, what we need is a system that warns of ANY aircraft that is about to come too close. The major flaw of most approaches is requiring that the other guy be properly equipped. It is not human nature for people to agree so there will always be many avoiders, contrarians, competitors, and folks too poor to comply even if they want to. Mutually inncompatible systems will proliferate and no single collaborative system will make more than a dent in the collision threat.

We as PICs should take upon ourselves the responsibility of not flying into someone and being aware of impending traffic - I mean beyond 'See and Avoid'.
A simple device that warns of impending collision would focus our attention to taking evasive action. It would not need to be very sophisticated, but some simple indication of direction would make it more effective.

Radar may be the most practical way. Detection at short distances does not require much power, nor equipment sophistication.

Some observations -

Flarm appears to be the best thought out existing system. PowerFlarm should be called Low-power Flarm because it operates as an unlicensed low power ISM band gadget. Range and reliability are limited due to lack of signal strength. IMHO, the FCC denied licensing of Flarm and refused to allocate spectrum to protect the inferior ADS-B already chosen for Nexgen.

PowerFlarm is priced out of reach for most glider operators. Clubs usually don't have it in their ships.

I live near a Class C airport. Only about 1/4 of the traffic I detect in the area is currently squittering ADS-B. Devices like Stratux don't yet show the majority of existing traffic.

IMHO, aircraft traveling too fast to see and be seen (maybe > 175 Kn) should have active radar, to avoid anything from drones on up.

The brave new world of Software Defined Radio/Cognitive Radio is a godsend for quickly developing new technology, including radar. The open source community has embraced the technology!!!

Of my many close calls, only one was a glider, half were military, and about 3/4 came from behind me. I sure hate hearing engines from within a glider!

[Darryl Ramm]

On Saturday, January 6, 2018 at 12:04:29 PM UTC-8, Wit Wisniewski wrote:

> Radar may be the most practical way. Detection at short distances does not require much power, nor equipment sophistication.
>

Can I have some of whatever you are smoking?

Radar, as in what? Actual primary radar for collision avoidance? Please describe how this would not require much equipment sophistication. You planning on mounting phased array antennas where on the glider? Transmitting on what frequencies? Do you have a estimate on the development and FCC approval costs?

[Mike Schumann]

In the US, the system you are looking for is ADS-B. Systems like Stratux show all existing ADS-B AND transponder equipped aircraft if you are within range of an ADS-B ground station and you are ADS-B OUT equipped. If you are flying within the vicinity of Class C airspace and you are not seeing the vast majority of GA traffic on your Stratux ADS-B receiver (except for gliders who are are not transponder equipped), you are either not ADS-B OUT equipped, or your system is not configured properly for the ground station TIS-B to work properly with your ADS-B IN equipment.

[Linar Yusupov]

Effective from July 13th 2018, one Chinese OEM manufacturer (LilyGO) has started to ship
a "TTGO T-Beam" board ( 'LoRaWAN GNSS assets tracker' class of equipment)
with SoftRF firmware being pre-installed by default.
More than 200 boards has already become delivered since then.

The board is available on Amazon, Ebay, AliExpress, Banggood and Alibaba stores.
Price tag for the board is around 30-40 USD, depending on the store.
SoftRF aviation firmware comes with the board, free of charge.

There are 868 MHz and 915 MHz versions of the board available, each one
is applicable for a particular world region.

Only 3 components are necessary to build a complete device :
- the T-Beam board itself ;
- one 18650 Li-Ion battery cell ;
- good 3 dBi 868 (or 915) MHz antenna (one that comes with board has low performance).

3D printable enclosure is available for free download.
The enclosure consists from only 3 plastic parts and 4 metal screws.

More information -

The board: http://github.com/lyusupov/SoftRF/wiki/Prime-Edition-MkII
Quick start: http://github.com/lyusupov/SoftRF/wiki/Prime-Edition-MkII.-Quick-start
Settings description: http://github.com/lyusupov/SoftRF/wiki/Settings
Enclosure: http://github.com/lyusupov/SoftRF/tree/master/case/v5

Home page of the SoftRF project: http://github.com/lyusupov/SoftRF

Linar.

[johs...@gmail.com]

Thanks Linar,

My TTGO is working well in Australia in ground tests. It links to my Kobo easily via the Kobo's built-in WiFi and shows traffic as well as providing a good GPS signal. I just need to sort out an enclosure and a place to put it in the glider. Well done!

John

[Mike C]

I agree. Thank you Linar!

I have the LoRa/SoftRF/Flarm device working well in New Mexico. This past Sunday our local OGN tracking system was tracking my mostly carbon LAK 17A at 43 miles from the antenna and it 'sees' other Flarm equipped sailplanes in close proximity. This system works perfectly with XCSoar.

Including my Sony Xeria Z3 phone, the total cost was $190.00 which includes a 3D printed case that was printed from your supplied .stl files.

I think this project is really a boon to the gliding community and I appreciate your selfless efforts.

Thank you again.

Mike

[johs...@gmail.com]

On Tuesday, December 10, 2013 at 1:22:31 AM UTC+11, Linar Yusupov wrote:
> Dear rec.aviation.soaring subscribers!

>
> I would like to present you PDF slides of one DIY R&D project.
> The slides are about open platform airborne proximity warning device.
> It operates at ISM band radio but also capable to receive ADS-B reports at aviation frequency.

> It is mainly targeted for our local soaring club use but can also attract pilots worldwide.
>
> The presentation is downloadable at: https://github.com/lyusupov/Argus/raw/master/doc/Presentation_of_DIY_Airborne_Proximity_Warning_Device.pdf
>
> If upon reading you'll find it worthwhile, feel yourself free to share this news with someone
> upon your discretion.
>
> Don't hesitate to ask any questions here. FAQ document is yet to be created.
>
> Best regards!
> Linar Yusupov.

Hi Linar -- can the "TTGO T-Beam" board be used as a ground-based OGN receiver?

Thanks, John

[Andy Blackburn]

Very impressive work Linar. I have some questions after looking at the GitHub info.

Do I understand correctly that FLARM AIR V6 is fully compatible with with the Flarm over-the-air interface?

How do you maintain compatibility as the Flarm over-the-air interface evolves over time. Flarm is a closed system and annual firmware updates are mandated (and may include changes that could affect compatibility). Do you have to validate and potentially rework the code for compatibility with new releases of Flarm firmware, or have you not observed the over-the-air interface to change year-to-year?

Do you fully implement the Flarm data port spec? This is a bit easier to deal with as it's public and backward compatibility to older soaring instruments is important. In the Specifications section on GitHub there is a line "Data compatibility: fraction of FLARM(TM) DATA protocol version 3". I assume this means that you didn't implement the full spec, but enough to work to some level of functionality with a decent number of soaring instruments. What are some examples of what's not included?

Since there are so many Flarm-equipped gliders and aircraft out there, maintaining interoperability is a significant concern.

Again, very impressive.

Andy Blackburn
9B

[Mark Hawkins]

Hi Andy (and others),

I got one of these units yesterday from Mike Carris. Have only done a little testing so far. However, current observations:
1. Can be seen by PowerFlarms and yes they do warn you if one of these gets too close
2. Can see other PowerFlarms
2. As Mike and others have said, it works with XCSoar
3. Have gotten it to connect via Bluetooth LE (BLE) to iSoar which seems to process the PF sentences just as it does from other devices
4. Have gotten it to connect via Bluetooth SPP to Oudie and it DEFINITELY was processing the PF sentences. "Traffic 3 O'Clock Below!!" over and over and over again. :-)
4. Can be seen by OGN receivers just fine (we have them setup here in Moriarty for tracking) with decent range.
5. Uses a decent sized rechargeable battery so it should run for quite some time on it's own.
6. Has the ubiquitous micro USB port that can both power the device and also recharges the battery.
7. Mike found a local "maker" to 3D print the cases using the provided STL files. IT was cheap ($10ish), look nice and do a great job protecting the SoftRF yet allowing access to ports, switch, lights, etc.

Only issue I've seen so far (and it's minor) is that since it's using V6 of the air protocol it doesn't output gps speed/direction of travel when using the "Legacy"/Flarm mode. So it's essentially seen as a place in space that moves periodically. Is that bad? No not really I think. Would it be better to have cse/spd? Sure. And I know it can send it out as it does via NMEA via the GPRMC sentence and if you shift it over to "OGN Tracker" mode instead it sends it. So it appears it's just a matter of the spec version not supporting it. But as you said, "Flarm is a closed system". And why is that?

I've always been confused as to why they have chosen that path. Most "specs" that I know of these days seem to work out best when they are "open" which means they are open to analysis, critique and improvement. Does that mean it sometimes take a bit longer to get updates fully approved and in place? Yup. To me, closed systems just seem to invite hacking...if for no other reason than because it's a challenge. So it would seem to make more sense to open the spec/system to allow for wide analysis providing even more confidence in the end product.

As was stated in this very long and old thread, we "believe" and "trust" (me included) the PF folks to do the right thing and produce as safe a product as possible and I believe that is the case. But there's nothing definitive that proves it, that I know of. No independent testing, etc. Should there be? Maybe...maybe not. But if not then making any claims that one system is "more accurate" or "more safe" than another, can not be fully supported.

Also, if it is desired by the soaring community at large for the concept of Flarm/PowerFlarm to be adopted as wide as possible, then it is my feeling at least that that won't occur with a "closed system". I believe allowing "others" to fully interoperate with the current Flarms/PowerFlarms is not going to make things any less safe. The more of these we can get in the air the better, from collision avoidance perspective. In fact, it could provide the opposite result. It likely will foster innovation in both the software and hardware I believe though. This SoftRF device is a good example and there are other similar initiatives out there as well. If that drives the overall price down and/or increases the overall utilization is that a bad thing?

Alot of my own feelings here I admit but thought I'd throw them out. I can't remember the last time I posted anything on RAS. However, this SoftRF device seems to be a stable and capable platform and to me seems to be the kind of innovation and creativity we should be applauding and supporting in the soaring community. As you said, it is impressive. So thanks to Linar for his work and results. I'm looking forward to seeing where it goes.

-Mark

[Eric Greenwell]

Mark Hawkins wrote on 10/4/2018 8:38 AM:
> Hi Andy (and others),
>
> I got one of these units yesterday from Mike Carris. Have only done a little testing so far. However, current observations:
> 1. Can be seen by PowerFlarms and yes they do warn you if one of these gets too close
> 2. Can see other PowerFlarms
> 2. As Mike and others have said, it works with XCSoar
> 3. Have gotten it to connect via Bluetooth LE (BLE) to iSoar which seems to process the PF sentences just as it does from other devices

..

Does this device do do collision warning, like PowerFlarm, or only proximity
warning, like the ADS-B targets on PowerFlarm?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[Mike C]

Eric,

The selections for alarm triggers in the setup menue are below. Have not tried the Vector warning yet.

Mike

................

Alarm trigger:

None - do not issue any alarms ;

Distance - issue a NMEA ($PFLAA) alarm sentence when traffic is in close
proximity ;

Vector - issue a NMEA ($PFLAA) alarm sentence when traffic is short on intersecting course.
...................

[Dave Nadler]

On Thursday, October 4, 2018 at 11:38:15 AM UTC-4, Mark Hawkins wrote:
>... "Flarm is a closed system". And why is that?

You will find a clear explanation of this policy here:
http://flarm.com/wp-content/uploads/2015/08/FLARM-System-Design-and-Compatibility.pdf

As to wide adoption, most GA aircraft (including gliders) in Europe now
have FLARM; EASA now permits panel installation in certificated AC.

I'm a firm believer in open source (and funded it heavily in my former
corporate life), but I also know well how frequently it goes off the rails.
This application would suffer from anything other than top-notch,
full-time attention. Commercially-funded open source works when there are
lots of deep pockets with common interests (see GCC, newlib, RedHat, Eclipse).
Casual open-source, for small markets, without funding, not so much.

You may not agree with this, but it has been given serious consideration
but a lot of very committed and extremely sharp folks.

Respectfully, Dave

PS: Paper above doesn't mention REQUIRED FCC certification (and analogous
foreign certifications) - expensive, and REQUIRED.

[Dan Marotta]

Mike,

Let's fly near each other soon.  Have your vector alarm enabled and
let's see how it works.

Dan

--
Dan, 5J

[Tom BravoMike]

Compatibility seems to be a big word in the article. Is FLARM actually compatible across the globe? I mean, if you take your glider from the US to Europe, South Africa, Australia for whatever reason: competition, job assignment, long vacation, retirement - will the PowerFlarm work there and be compatible with the locals?

[Andy Blackburn]

On Friday, October 5, 2018 at 9:06:01 AM UTC-5, Dave Nadler wrote:

> PS: Paper above doesn't mention REQUIRED FCC certification (and analogous
> foreign certifications) - expensive, and REQUIRED.

Not to be the turd in the swimming pool, but I have some concerns about this.

Having worked on a consumer product that used the LoRa physical layer operating in the ISM band (Flarm is an ISM band device), I can attest to what Dave says and why it's important. Without specific rules regarding power, duration and frequency hopping, for example, it is easy to end up with devices that create so much congestion that they make the band useless for everyone else. Think of this as a glider with a perpetually stuck mike on their radio. This device doesn't appear to do this in isolation, but networks rarely get congested with small numbers of devices connected, even if they are poorly behaved.

It's my understanding that the over-the-air Flarm protocol has specific (and secure) methods for congestion control through timing broadcasts versus the GPS clock and this is how it is able to accommodate reasonable numbers of aircraft in proximity without too many transmissions colliding (pun intended) and blocking each other out. It is not at all clear to me whether this device has implemented the Flarm protocol or if it simply broadcasts without any congestion control under the presumption that not too many gliders will be flying at the same time. It seems from reading the GitHub documentation like maybe it is using a hack to get around this restriction which could create congestion problems - particularly in larger numbers.

Moreover, it doesn't appear that the Chinese manufacturer of these boards has pursued any FCC licensing (I doubt it) and even if they had part of the FCC licensing requires the complete device in its physical enclosure to ensure that RF pollution doesn't flood out of the device in unpredictable ways.

Mostly I have questions and suppositions as I don't know exactly what work has been done and I'm not an RF or networking engineer, but I'd be a bit concerned if one of these devices showed up at a big OLC camp. Also, beware of ramp checks if you have unlicensed (I guess technically that means illegal) devices operating on the same frequency as licensed safety devices. The Feds might frown on that. If I showed up at the airport with home-brew ADS-B Out kit in my glider I bet I'd get at least a sternly-worded letter from the FAA.

I have a lot of respect for this effort, but there is a potential need for significant caution. Many of our fellow pilots rely on this technology to keep them safe. If that technology were inadvertently being jammed, they'd have no way to know.

There are other issues with how the data port spec is or isn't implemented, but that's a whole other kettle of fish. If you are going to bet your life on a technology it's probably good for it to work as close to 100% of the time as you can manage.

Respectfully,

Andy Blackburn
9B

[Mike C]

OK

[Wyll Surf Air]

So does this system work with Power Flarm? Mark said it does but in the documentation it does not seem to mention anything about Power Flarm, just Flarm V6 which I'm am not sure if refers to power flarm or the old Legacy flarm that is not allowed in the US. I'm wondering because if it does work with Power Flarm then I will get one for me and my partners glider since we don't have funds for a power flarm, but would like to have some sort of collision avoidance system.

[2G]

The FAA doesn't regulate the RF (electromagnetic) spectrum; that is the job of the FCC. It is HIGHLY unlikely that the FCC will show up at your local ramp with spectrum analyzers - they respond to serious complaints, and, then, with much plodding. Your fellow pilots, however, might get on your case if they figure out your equipment is interfering with theirs. The ISM band is pretty much the Wild West of the RF spectrum, and the FCC doesn't get involved.

https://en.wikipedia.org/wiki/ISM_band

Tom

[Mike C]

On Tuesday, October 9, 2018 at 5:52:57 PM UTC-6, Wyll Surf Air wrote:
> So does this system work with Power Flarm? Mark said it does but in the documentation it does not seem to mention anything about Power Flarm, just Flarm V6 which I'm am not sure if refers to power flarm or the old Legacy flarm that is not allowed in the US. I'm wondering because if it does work with Power Flarm then I will get one for me and my partners glider since we don't have funds for a power flarm, but would like to have some sort of collision avoidance system.

I can see PowerFlarm equipped sailplanes. Pretty sure the author of the documentation is using a Flarm, and not a PowerFlarm, thus his reference to "Flarm". If you decide to buy the LoRa/Flarm device, be sure to order the 915 MHz unit and an additional antenna (also 915 MHz). The antenna that comes standard has a fairly limited range. So far there have been no interference problems with PowerFlarm units that I am aware of, this includes ground tests where the LoRa unit and a portable PowerFlarm were very close to each other.

Keep looking outside.

Mike

[moshe....@gmail.com]

Alas the 915 MHz band and other ISM bands are already congested with many other uses, and (from the wikipedia page) "communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation." These bands were not intended for reliable communications use. It is a shame that we are forced into those marginal wastelands in the spectrum to do these things, while there are many hundreds of, e.g., aviation band comm frequencies available, now that they've been divided into 25 KHz channels (and 8.33 KHz in Europe and perhaps someday in the USA too). Of which gliders are officially allowed to use, what, 2 channels (dating to the 100 KHz spacing days), for air-to-air coordination?

[yellowp...@gmail.com]

PowerFLARM is not globally compatible - you need to buy a different unit for each frequency region, as I found out in both NZ and Europe. If you want to change the frequency on the unit, it's 500 Euros + VAT + shipping.

[yellowp...@gmail.com]

My reading of the implementation is that it implements the (radio) traffic control inherent in the protocol exactly the same as FLARM does. Not an expert.

[Steve Koerner]

On Thursday, October 11, 2018 at 8:41:00 AM UTC-7, moshe....@gmail.com wrote:
> Alas the 915 MHz band and other ISM bands are already congested with many other uses, and (from the wikipedia page) "communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation." These bands were not intended for reliable communications use. It is a shame that we are forced into those marginal wastelands in the spectrum to do these things, while there are many hundreds of, e.g., aviation band comm frequencies available, now that they've been divided into 25 KHz channels (and 8.33 KHz in Europe and perhaps someday in the USA too). Of which gliders are officially allowed to use, what, 2 channels (dating to the 100 KHz spacing days), for air-to-air coordination?

The ISM band is congested in an urban setting but certainly not congested where gliders do their flying. The range of influence from all those many ISM devices out there is limited because their power output is limited by regulation. So the band becomes a pretty good choice actually to take advantage of the chips, antennas etc that are available at low cost.

[Ed A]

Will this device work with iGlide on IOS?

[Linar Yusupov]

> Will this device work with iGlide on IOS?

AirConnect compatible Wi-Fi connection service is active in the firmware's source code since October 9th.
Known to work good with SkyDemon, Air Nav Pro.
You could let us know if it works with iGlide too.

[Mike C]

Mark Hawkins has it working with iGlide via WiFi.

Mike

[Ed A]

Thank you Linar. I'll try it this weekend.

[Linar Yusupov]

Mike,

> Mark Hawkins has it working with iGlide via WiFi.

Hmm. Are you sure?
He wrote earlier that:

> 3. Have gotten it to connect via Bluetooth LE (BLE) to iSoar which seems to process the PF sentences just as it does from other devices

As for iGlide, Air Avionics does not specify here: https://www.air-avionics.com/?page_id=507
that it is able to do BLE, but they do AirConnect instead.

T-Beam's are shipped with either RC4 or RC5 SoftRF firmware versions. NMEA TCP (AirConnect) option was not available at that time yet. So build of the firmware from current source code and re-flashing is necessary.

I would also appreciate if someone will confirm that ForeFlight is dong fine with SoftRF over Garmin GDL90.
I have not done it by myself yet, as well as never seen reports about that from builders worldwide.

Linar.

[Mike C]

Linar,

When I saw Ed A's post an hour or so ago, I asked Mark who uses the app and he replied exactly as I have indicated.

Mike

[Linar Yusupov]

> When I saw Ed A's post an hour or so ago, I asked Mark who uses the app and he replied exactly as I have indicated.

Ok. Good news! Thank you!

[John Wells]

Can a softrf be integrated into an existing (FLARM) setup?

I'd like to keep the flarm for its proven anti-collision warnings, and add in the ability to see all the other stuff that the Softrf provides. However the two antennae will interfere with each other (?).

[Darryl Ramm]

On Monday, November 5, 2018 at 9:04:22 AM UTC-8, John Wells wrote:
> Can a softrf be integrated into an existing (FLARM) setup?
>
> I'd like to keep the flarm for its proven anti-collision warnings, and add in the ability to see all the other stuff that the Softrf provides. However the two antennae will interfere with each other (?).

"interface" means so much asking that is pretty meaningless. What do you expect/want it to do? Work on separate displays? An integrated display? Provide what services? What FLARM do you have and what country are you in? In the USA do you have ADS-B Out?

[John Wells]

I'd like to be able to take NMEA stream from the Softrf for NON-FLARM contacts. I'm happy to write software or whip up a little micro to merge this with the NMEA output from FLARM and present them on my xcsoar radar.

But I expect the Softrf antenna will negatively impact my flarm tx/rx and vice versa.

I'm in the UK. CLASSIC Flarm. But at the high level I don't think this makes any difference. I'm happy to do a lot of the leg work myself but just wondered what was possible.

[Christophe Mutricy]

At 12:59 06 November 2018, John Wells wrote:
>I'd like to be able to take NMEA stream from the Softrf for NON-FLARM
>contacts. I'm happy to write software or whip up a little micro to merge
>this with the NMEA output from FLARM and present them on my xcsoar radar.

depending your skillset, it might be easier to review/adapt Xcsoar. I
believe XCSoar uses the data from the first device with that kind of data.
That is certainly the case for GPS.
So you might have to modify the code so that "FLARM" data is accepted from
several device. (flarm between quote because all traffic device are seen as
flarm if using the flarm protocol)

>But I expect the Softrf antenna will negatively impact my flarm tx/rx and
>vice versa.

If the SoftRF doesn't transmit and the antenna are not close there won't be
interference.

If the softRF transmit on the same or close by frequency as FLarm then we
might have provlem if they both transmit exactly at the same time.

--
Xtophe

[Linar Yusupov]

> Can a SoftRF be integrated into an existing (FLARM) setup?

If you are considering XCSoar as FMS software, you either:
1) wait until Max will release next 7.0 preview or
2) build your own XCSoar binary from current source code tree.
( make sure that this commit : https://github.com/XCSoar/XCSoar/commit/6ed282c5e158f9873ccdc9d5765fd3abf08e09e3
is in there. )

> However the two antennae will interfere with each other (?).

1) Two receivers typically do not affect each other when distance between them is more than 2X of max. antenna size. Otherwise even inactive 2nd receiver's antenna (as well almost any other metal object) will slightly alter characteristics of 1st receiver's antenna (such as RL, SWR, …) ;

2) SoftRF's transmitter is compliant with 1% duty cycle rule ;

3) in any doubts, SoftRF user can disable transmitter with "Tx Power" menu option:
https://github.com/lyusupov/SoftRF/wiki/Settings
After that, other traffic will not see you on this protocol, but you will still be able to see them all.

[John Wells]

Neat... I'm already using v7 on a custom openvario.

Is it worth transmitting ogntp if I already have a flarm?

[Ed A]

Hello Linar,

We experimented with our new Prime Mk II device last weekend. It was a non-flying day here in Colorado, so we ground tested it against a PowerFLARM in a parked Ventus. We successfully paired the device (using Wi-Fi) with XCSoar running on a Samsung Tab A tablet. Then, we tested it by walking up and down the taxiway and were pleased to see that our "glider" was clearly displayed on the Ventus FLARM display and the Ventus was displayed on our tablet. Mission accomplished, so far. Next step will be to set up an OGN receiver and do some flight testing.

It's quite amazing that a DIY product that goes together in five minutes and costs about $50 can provide this kind of capability. (One of our members made the enclosure on his 3D printer.) Thank you Linar!

Note: I was hoping to try it with iGlide on the iPhone X, but was not successful. I installed AirConnect on the iPhone but couldn't get them to link. I've never used AirConnect before and may not be configuring it correctly. Is there a secret to this? I would appreciate any helpful suggestions from anyone who has had success with iGlide. Mike, Mark ... any suggestions?

Thanks,
Ed A

[Mike C]

Ed,

I will send Mark an email asking him to contact you, I do not think he usually monitors this site. I use Android/XCSoar, so can,t help you with IGlide.

Mike

[Mike C]

On Tuesday, October 30, 2018 at 9:53:48 AM UTC-6, Linar Yusupov wrote:
> > When I saw Ed A's post an hour or so ago, I asked Mark who uses the app and he replied exactly as I have indicated.
>
> Ok. Good news! Thank you!

Just contacted Mark and there was a mistaken communication about this. Sorry.

Mike

[Linar Yusupov]

Ed, Mike, Mark

you guys should open a new ticket of a "question" type here: https://github.com/lyusupov/SoftRF/issues
and file it in accordance with the template provided. (you may use this ticket as an example: https://github.com/lyusupov/SoftRF/issues/35 )
Then I will see if I can do anything for you.

Linar.

[Linar Yusupov]

вторник, 30 октября 2018 г., 11:35:04 UTC+3 пользователь Linar Yusupov написал:

AirConnect compatible Wi-Fi connection service is a part of most recent firmware update.

Release notes:
https://github.com/lyusupov/SoftRF/releases/tag/1.0-rc6

[6PK]

I'm on the fence to add Flarm or something like this thread is all about to my glider in the upcoming off season. Any news or comment how this system is working presently would be appreciated.

[Dave Nadler]

On Monday, August 26, 2019 at 10:48:03 AM UTC-4, 6PK wrote:
> I'm on the fence to add Flarm or something like this thread is all about
> to my glider in the upcoming off season. Any news or comment
> how this system is working presently would be appreciated.

http://www.nadler.com/GliderPilotUSAflarmWeb/Flarm-Testimonials.html

[Mike C]

If you have $1.5K+ to spend, buy a PowerFlarm.

Although....

Having used the Soft RF Flarm device for a year, I can say that it does work well as a sailplane proximity device. I have as good as or better range than a commercially available Power Flarm. I see them and they see me. Last summer our OGN tracking station could see my LAK over 40 miles away and this summer a pilot told me I was visible to his powerflarm at 18 miles distance. It works.

It only sees Flarm traffic so in that regard it is not as complete as a Power Flarm that also sees transponder traffic. For a very small amount of money it is a very good safety measure. There is now a separate wifi display with voice alerts available for about $35.00 that easily connects to the SoftRF Flarm device. So, if you purchase the boards yourself and have the enclosures 3d printed you can have a Power Flarm compatible device with a daylight readable display for less than $150.00 US.

Mike

[2G]

You only need to ask these people ONE question: have you received (or even applied for) FCC approval?

If they can't answer this question affirmatively, don't walk, run from them.

Tom

[Jonathan Foster]

Tom, not trying to start an argument, but I am wondering why you have made this conclusion. I am under the assumption that Flarm uses unlicensed spectrum to transmit.

[Andy Blackburn]

I'm not an expert, but have some experience with various GPS trackers that use unlicensed spectrum. All the commercially available devices (including Flarm and PowerMouse) have had to receive FCC approval.

You can't do whatever you want in unlicensed spectrum. There are rules with regard to power output and how long you can transmit on a channel, which is one reason why many devices above a certain power output use frequency hopping. Without that the spectrum would be gummed upon and useless. I don't know what the rules are for homemade devices, but presumably if you run afoul of the FCC guidelines for frequency use and they can find you there will be a conversation.

Andy Blackburn
9B

[Darryl Ramm]

We are a nation of laws, and regulations. And they are even written down and findable with Google. https://www.law.cornell.edu/cfr/text/47/part-15

[Jonathan Foster]

Replying to any RAS topic always has this risk. Darryl, it is trite to simply say google the law, it another thing to actually interpret the law. That is exactly why I asked how Tom came to his conclusion. I would love to hear your interpretation and have a respectful conversation about it.

[Darryl Ramm]

Please read the regs. The answer to your question should be pretty obvious, and actually having read stuff will help you have a more useful informed discussion.

Major subassembly sold separately like a TTgo board qualifies as an intentional radiator under those regulations. If not that then the whole assembly will (possibly both need approval, well beyond a ras discussion). Since it's an intentional radiator you need FCC certification and not the less stringent Supplier Declaration of Conformity. Still testing can be done by a third party FCC approved lab, including many overseas/in Asia etc. The FCC has a whole web site on how to do this. https://www.fcc.gov/general/equipment-authorization-procedures.

A trap for new players is the regulations prohibit *marketing* in the USA. Not just actual sale. What pre-marketing is allowed is fairly clearly described. Yes the FCC has prosecuted for that.

My interpretation: Putting together instructions for DIY stuff and suggesting folks in the USA purchase certain components... that are not FCC approved... Well freedom of speech and all, and caveat emptor, but I'd be putting disclaimers/warnings on stuff.

And see the 47 CFR 15.23 home built carve out in the regs... but that does *not* provide an exclusion to kit manufacturers.

Actually marketing or selling a kit including an "intentional radiator" components within the USA that do not meet FCC requirements. Ah definitely not a good idea.

Lots of testing and engineering labs and consultants know this stuff backwards. Manufacturers just pick one, cough up the money, and deal with the pain of getting products thorough testing. Actual engineering requirements, like spurious radiated signal levels, in the USA can be a challenge to meet.

Not a lawyer. Never shipped an FCC certified device--would never be so crazy. Dealt with unintentional radiator, lab testing, approvals, etc. Long ago background in RF engineering/research.

[JS]

Something else to consider.
Fines for unlawful use of radios are not trivial, ten thousand dollars last I heard.
Jim

[Dan Daly]

You can download the FCC and IC testing report for the PowerFLARM CORE/Brick, pictures, etc. at https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=n9J75RqRcSKvtuXdv7XzrQ%3D%3D&fcc_id=ZKUGC625162

They are thorough.

[Darryl Ramm]

But if you do get busted, the FCC helps promote your company with a press release. :-)
https://www.fcc.gov/enforcement/orders/1839 Look at all the large digital sign manufactures they have gone after. A whole industry out of control.

I loved the $2.8M FCC proposed penalty against Horizon Hobby for their drone FPV transmitter. Now that we have your full attention... the FCC settled for $35k but Horizon accepted ongoing compliance/process improvements in the settlement. Even with potential for bad interference there I suspect there was no real incidents--there was no product recall AFAIK and the FCC mostly wanted to get Horizon's attention and get them into compliance. Seems very fair for a first violation, the FCC has a special liking for repeat violators.

[Dave Nadler]

On Tuesday, August 27, 2019 at 6:11:57 PM UTC-4, Darryl Ramm wrote:
> Never shipped an FCC certified device--would never be so crazy.

Wimp.

[Jonathan Foster]

Darryl thanks for sharing your knowledge about this to those of us that aren't as well versed. I would hope that is what the spirit of RAS is all about.

Question, does 15.103 of CFR47 provide any loophole to giving this a try? Especially the exemption concerning, "A digital device utilized exclusively in any transportation vehicle including motor vehicles and aircraft.".

PS I am just curious and I am not going to try it, (I don't have the time anyhow) opensource hardware is fascinating to me. Also, I have a powerflarm that I am super happy with.

[stu8...@gmail.com]

On Tuesday, August 27, 2019 at 5:43:55 PM UTC-5, Dan Daly wrote:
> You can download the FCC and IC testing report for the PowerFLARM CORE/Brick, pictures, etc. at https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=n9J75RqRcSKvtuXdv7XzrQ%3D%3D&fcc_id=ZKUGC625162
>
> They are thorough.

Thanks for the link. Now I know what the inside of a Flarm looks like.

I wonder why they didn't test with both antennas active. If I read the test report correctly, their radiated power (33mW) is way lower than the inteference limit (1W), so it seems like it would have passed easily.

There was another limit around 60mW for something?

[Steve Koerner]

> Question, does 15.103 of CFR47 provide any loophole to giving this a try? Especially the exemption concerning, "A digital device utilized exclusively in any transportation vehicle including motor vehicles and aircraft.".

I know there is exception for engineering development work in pursuit of product design (been there). I don't believe that extends to hobby endeavor.

That said, I think there's paranoia happening in this thread. Ultimately, a non-professional buyer of a kit to improve safety, won't be penalized for not knowing the ins and outs of FCC rules that are written in technical language to regulate business. You would no more be likely to face penalty than if your IPhone exhibited out of band leakage. FCC rules are written to manufacturers. This is distinctly different than the scenario of the FAA expectation that a pilot should know all the rules of airplane flying, for example.

[Dan Daly]

The 1W limit is designed for devices on the ground. Since your large Line of Sight range at altitude makes it much more likely that you will interfere with someone else - so they reduce the power - your reach is much greater. We 'see' PowerFLARM CORE/Bricks at about 120 km with radiated power of 0.018W on our OGN system. If you boost the power, and there are a lot of gliders/towplanes fitted (we have around 40 in my area, increasing by the day), the chances of mutual interference increases. And, the Industrial, Scientific, and Medical (ISM) 902-928 MHz band is pretty busy.

Here's the LXNAV report link https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=Aj%2FaLXySCCLWW%2F%2FLsj58HA%3D%3D&fcc_id=2ASPHLXNAVAM
Looks like it radiates 0.07W...

[Darryl Ramm]

That is not my reading of this. CFR 47 15.103 gives an exemption to "digital devices" under *this part*. Here *this part* is not the section covering intentional radiators. It's talking about digital devices (computers, controllers, etc.). Not sure of the purpose but I'll bet some manufactures lobbyists were behind that one.

The obvious sign this is all needed is that FLARM and now LXNav have spent serious time and money obtaining FCC certification for their products. To sell what? ~1k total units in the USA? Neither company is run by dummies.

[Darryl Ramm]

Oops I need more caffeine. *this part* would indeed cover everything. But the problem is the "digital devices"... that term of art is not an "intentional radiator", what we are dealing with here.

[Dan Daly]

Fines:
Installation, operation, or possession of any radio apparatus without a spectrum licence or, when used for broadcasting, without a broadcasting certificate:
Individual, first and repeat:
$25,000 $50,000
Corporations, first and repeat violations
$10M $15M

[Dan Daly]

That's Administrative Monetary Penalty in Canada. Clear why FLARM Technology and LXNAV went to the bother. They do talk about levels, and the fines are much less for "localized effects".

[Jonathan Foster]

I totally get why lxnav and flarm went through the trouble of getting certified. If I was a corporation trying to protect my assets, I would too. Reading the regulations and trying my best to interpret their meaning and spirit, I think a hobbyist could tinker with this without legal issues. Having said that I still think there are some grey issues that could throw a monkey wrench in it.

If I didn't have a powerflarm already would I give a try? Maybe, but probably not.

Side note, I found this guide to the fcc and opensource hardware that is interesting.

https://www.sparkfun.com/tutorials/398