Balloon building

[Monroe]

Hey guy's
Just wanted any thoughts on balloon making.
The way we figure it we need to make our own so here we go.
My hydrogen generator gives off to much condensables in the gas so we
need to figure out how we are going to remove that. I have some Ideas
but just wanted to hear any thoughts.

We plan on using a regular natural gas flow meter to meter the gas for
the balloons.

We are going to have to experiment with sealing methods.

One more thing I dont like any of the current payload comunication
methods I can find on the internet nothing seems to be reliable. I
want full duplex at internet speeds.

Monroe

[Pete (Nebula)]

You might like to try passing the gas through a desiccant such as
silica gel beads to get rid of the water. Once saturated, the beads
can be re-used by heating them a little above 100 degC for a couple of
hours (after making sure all the hydrogen has gone).

Reliable full-duplex communication can be obtained at up to 4km line-
of-sight (using antennes without gain) with one of these or similar
modules:

http://www.rfsolutions.co.uk/acatalog/TINY_Transceiver_Module.html

I've used them before and they are very easy to set up. You could take
the range out even further if you want to use a transmitting antenna
with significant gain (check with the FCC), and/or opt for a slightly
reduced data-rate with a Forward Error Correction (FEC) technique such
as Turbo coding. I currently use RS error correction with my
telemetry, but I'm still actively looking at other techniques for
reducing bit-errors.

Best

Pete

[MisterQED]

Well, as per the previous discussion that Ham bands cannot be used for
professional purposes, you are left with a few choices.
If you then add in the budgetary requirements and weigh limitations
which seem to eliminate most of the business band items then the list
gets VERY short.
So first choose your frequency: 900MHz, 2.5GHz or visible/IR light.

In the US all are open for unlicensed use with power limitations, in
the rest of the world only the last two.
As the frequencies rise so does the atmospheric absorption, but so
does the bandwidth.
You asked for internet frequencies, so you may want to go for 2.5GHz
or lasers.

The downside is the two both have significant absorption problems and
also significant interference problems as you will be competing with
Wi-Fi, BlueTooth and Microwave ovens in the 2.5GHz range and the Sun,
Moon and streetlights in the visible or near visible ranges.
For me I am looking for a solid 1200baud modem type data rate so I am
going for 900MHz for my launch platform link, but all three are
attractive for different reasons.
My choice is based on lowest power and thus lowest weight requirement.
The wildcard in all this is the platform and thus antenna aiming
stability.
If the platform is stable then higher gain antennas could be used,
i.e. if you could point it accurately then a high power laser would
probably provide a superior datalink, but as I think and as your video
suggests, this is unlikely, at least until you get out of the jet
stream.

So my three suggestions are:
1. Near visible light, using the laser diode out of a DVD burner and a
suitable tuned receiver boosted by lenses. Possibly the cheapest of
all options and on a cloudless day should work and could give enough
bandwidth for even a live HD video broadcast.
2. Wi-Fi using high end cantenna type antennas or parabolic dish
antennas. Second cheapest as you can probably canniballize any number
of devices or buy off the shelf XBee/ZigBee devices to link to your
CPU. You can create a very high gain "cantenna" for Wi-Fi that has
been proven to work over several miles horizontally.
3. 900MHz using helical or helical/parabolic antennas, again many
devices such as cordless phones can be canniballized for this,
especially the spread spectrum 900MHz phones should be excellent donor
devices. Again I'm probably going to wimp out and buy a pair of
these:
http://www.sparkfun.com/commerce/product_info.php?products_id=9087 to
attach to my Arduino using helical antennas at least for my first
balloon launch. We'll see how it goes. But the budget will probably
force me to go with cannibalized DSS 1Watt phone later.

MisterQED
Team Daedalus


On Jun 24, 7:10 am, Monroe <monroel...@gmail.com> wrote

[Monroe]

Only the N-Prize attempt would qualify for professional use right! or
Advertizing.
We can change up for that.
We need to fly a lot of Near Space missions with bigger and bigger
payloads
I want to run a 5W 900MHZ with one dish mounted on two trucks to keep
contact at all times!
On a ham license! Do you think that will work solidly? Pete QED?
Thanks for the link Pete thats a cool modem. I am serious I see way to
many projects with broken coms.
Pete I dont know about the Turbo but that's the second time I've heard
it what is it?

Monroe

[N-prize]

Would the N-Prize be considered "professional use"?  It's a competition with a prize, but not a business as such.... How non-professional does one have to be to be counted as an amateur?

=======================

Paul H. Dear,

Chief Optimist.

The N-Prize,

PO Box 1133,

Sawston,

Cambridge CB22 3WB

England.

www.n-prize.com

The sender of this email is not responsible.

=======================

[Monroe]

I'm really not sure it is and I bet I could get the FCC to waver it
anyway.
BUT:) I dont want to argue so I'll just go along with it for now.

Monroe

[Pete (Nebula)]

Hi Monroe

If you're running 5W using a parabolic dish, you aren't going to need
two. Lets put it this way, the Mars Reconnaissance Orbiter (MRO) has a
35W Ka-band amplifier operating on an omnidirectional antenna for
emergency use in case the main parabolic dish pointing fails. 5W is
going to get you a lot further than the balloon is going to go.

Turbo codes, rather than being a single method of error correction are
actually a class of correction methodologies. They attract a great
deal of interest because their use allows the best approach so far to
Claude Shannon's theoretical limit on the amount of correction that
can be obtained for a given signal in a given noisy environment.

If you're interested, a very nice and easy-to-read paper on turbo
codes for error correction is at:

http://www.elec.york.ac.uk/comms/pdfs/20030507131153.pdf

Hope this helps

Pete

[Monroe]

Oh! thank you so much, I need that! These young fellows or so sharp
these days. I was like what? Turbo bla bla bla what? That should help.
I'm having to learn more faster now and it's taxing, softer reading is
my speed right now.
Theres only a dish on the ground on each of the two trucks is so one
can stay stationary and track while the other moves ahead. And so on.
I dont want to lose another signal I did not like that and I'm willing
to pay the penalty in weight for redundancy and overkill until we can
tune it in.

A live internet video would be the cats meow to avoid curse words.

Anyway I dont know if we can do it that way I'm trying to relearn old
stuff and new stuff.

Thanks again
Monroe

I just finished casting two motors for the QPIII my fingers are a
little burnt. Ouch! but we have two end burning I motors cooling. :)
testing a new load cell along with the new motors tommrow I hope at a
new place (Stew's place)

[Richard Hauser]

900 MHz is also a ham band, but if you are serious about keeping
contact I'd go both lower and much higher to do a two pronged attack.
Run a 2m or another "low" frequency to relay the telemetry data and
then a high ATV frequency around 10.4GHz or higher to handle the video
feed for full frame rates. If you are really paranoid you can add GSM
for recovery data unless there is a 2M repeater in the area.
I guess frequency choice is based on the frame rate you are looking to
get. Again hit up an ATV group at a ham club for expert opinions on
hardware

MisterQED
Team Daedalus

--
Sent from my mobile device

[Joseph Teichman]

The FCC rules prohibit (97.113.a.3) "Communications in which the station licensee or control operator has a pecuniary interest".  

See:

http://www.arrl.org/FandES/field/regulations/news/part97/b.html#113

[MisterQED]

Well then back to 900MHz and if you need to run legal limit power like
this guy:
http://www.natrium42.com/halo/flight2/#hardware
You can use this:
http://www.digi.com/products/wireless/xtend.jsp
it didn't work well for him, but he used stick antennas.

Or run legal limit on Wi-Fi you could get good video.

MisterQED
Team Daedalus

On Jun 24, 11:08 pm, Joseph Teichman <jtei...@gmail.com> wrote:
> The FCC rules prohibit (97.113.a.3) "Communications in which the station
> licensee or control operator has a pecuniary interest".
> See:http://www.arrl.org/FandES/field/regulations/news/part97/b.html#113
>

[Monroe]

Sure but we have to test this!
I am paranoid about LOS and yep this looks doable
Any more Ideas?

Monroe