High Altitude Balloon Project

I put in a request for the Interactive Classroom on Tuesday July 21st from 7pm-9pm for our next working session.

I added a link at the top of the old HAB project page to the new page with a note that the old project is inactive.

-Robert

Notes I remember are as follows:

Currently we anticipate total weight to be in the neighborhood of 1lb (not counting balloon), which gives a 60k ft burst altitude with 6m/s ascent rate, and my 32" rocket parachute can give a descent rate of 4m/s.

Nick made a good case for the Pixhawk, and since it seems like a generally better solution we’ve decided to run with it. It sounded like Nick was extraordinarily familiar with it so we should be good.

Robert (I believe) suggested aiming to land at Caddo ntl. grasslands; after looking at maps I’m not sure if we have anything better to try, although now that I think about it we might out to check that it isn’t 90% forest. Also, there were concerns that might be rather close to an air corridor. Initial runs on the predictor website suggest we will land quite a ways away (20 miles or so), which leads me to …

We discussed having multiple ground teams. With 2 teams, we can station one at the predicted landing site. With more … I can see how we might use a third to get eyes on the balloon asap, but mostly they’d be scattered in the predicted landing region
region. Although something I just thought of that we didn’t bring up is a 50 minute flight would give the launch crew a lot of time to pack and go 20 miles to retrieve.

I’m happy aprs worked after I left. I wasn’t sure how difficult that would be. I have to admit I’m leaning on y’all since I’m not very knowledgeable when it comes to ham radio.

Action items were that Nick would focus primarily on his pixhawk and other electronics, Robert would look into aprs, and I would do ground equipment gathering. We will also reach out to the FAA (maybe through Romeo) for this first (non-drone) launch and bare minimum establish a dialogue; preferably they will tell us what they need us to do. With aprs solved (in theory), Robert may need something else to do. I’m having trouble thinking of things that aren’t covered; maybe balloon detail design (what type of cable to use, how the payload will be attached, possibly a smaller icebox, icebox ventilation, etc.).

We also discussed drop testing from a drone.

I’m thinking most of what’s left is detail stuff. No major uncertainties at this point in my mind. I think if we had 4 of us working 8 hour days it’d be done by this weekend.

We set a target launch timeframe at mid/late September to give Robert time for his schedule to clear out for launch. I think that gives 3 or 4 biweekly meetings remaining if we don’t count the one Robert will miss.

I think that covers the important things.

The link I built the wiki page under (the one Nick linked) is on aero committee’s page under “projects”. I didn’t see the original one until after I made the one we’re using.

I also put in a request for the 21st for the common area yesterday while I was trying to do the one for that night. I presume someone monitors the events submissions and will catch the double entry.

Is this useful / helpful? http://forum.arduino.cc/index.php?topic=334828.0

Brian,

That looks great. I’ve seen a few similar projects, mostly based on an Atmel 328, GPS, and Radiometrix transceiver, none of them that are commercially available. I’ve just reached out to see if we can get or build one of their boards. One downside to the small integrated transceiver vs the Baofeng is lower transmit power (300mW vs 4W), but in practice, we’ll have to see how important power is. I’ve never worked with a HAB before, but I imagine having a direct LOS will negate the need for high power on our communications systems.

Chesley,

Your list looks good. One additional aspect I’d like to test with in addition to the 3DR telemetry is antenna tracking. The ground control station software that communicates with the Pixhawk already has code to drive a servo controller and move Pan/Tilt servos. I will try to interface it with a professional camera motion control system I already own (camBLOCK Adventure) If successful, we’ll be able to use high-gain directional antennas on the ground, and we also have the potential of mounting a telephoto lens or small telescope to the tracker.

When you DIY’ing a radio the FCC regs expect you to perform testing. This applies to DIY radio in the amateur bands as well. Also, remember antenna and height above ground both effect the effective radiated power of a radio.

Personally, I suggest using COTS radio like baofeng, unless the idea is to spend time developing and testing a radio as opposed to flying a package.

Hi Nick, saw your message in the Arduino forums and I figured I’d join in the fun here. I can tell you from a fair amount of experience that 300mw is more than enough power to transmit APRS from a weather balloon. I have used as low as 10mw at 100k ft without any problems what so ever. On previous flights I’ve been able to hit repeaters in Nevada from a launch in Maricopa CA.

As far as getting one of my boards I am trying to hold off giving out the source info until my kickstarter launches (sometime within the next month), but I would be more than happy to send you a demo unit. I have another round of boards and parts shipping and I expect them to arrive in about 2 weeks. Let me know if that works for you and I’ll set one aside for you.

Michael,

That would be great - yes please set aside a board for us! Our initial launch date hasn’t been set yet, but will not be for several weeks out.

My only experience with APRS to date was a simple test driving through Dallas with a Baofeng attached to an android device running APRSDroid. I was surprised that so few of my packets were picked up, even with a number of digipeaters and igates around - but I know having LOS at high altitude makes a big difference!

When do you plan to launch your Kickstarter? We’d be happy to provide feedback / data / video from our project.

Actually only antenna changes EIRP. Altitude does wonders for range, but that’s due to lack of obstructions, not an increase in radiated power.

Walter, The Tracksoar utilizes an Radiometrix HX1 module which should already be FCC certified.

Yep, sorry my mistake.

It is my understanding that the FCC doesn’t certify modules, but only systems. Which include antennas. The only transmitting modules I have seen that were certified were complete radios with antennas. Of course I could be wrong

I did a quick google and found some interesting things. First, radiometrix site has a page about UNINTENTIONAL radiators on its certification page. These items are clearly not unintentional radiators.

But I also found this link which says:

" Some transmitters come with an FCC ID on them. Does using these
devices exempt me from further testing to achieve FCC authorization?

Not entirely. While it does lower the bar from the costly 

Certification process, you are still responsible for ensuring that your
product does not emit other radio frequencies. In short, you must test
it as though it were an unintentional radiator."

Alright, will do, always glad to help out other makerspaces.

The thing to remember about APRS is there are probably a lot of other people trying to hit those same repeaters so your signal could easily be drowned out and some packets missed, it’s pretty common in a busy area like dallas. The nice thing about being up high with LOS to lots of repeaters is youre very likely to be able to get into atleast one of them.

I dont have an exact date yet, I am assembling a board this week for a test launch on saturday. If the launch goes smoothly then the kickstarter will likely pop up within the next week or two. Even if you don’t launch in time for the kickstarter some feedback / data / video would be awesome for the tracksoar site.

relevant FCC regulations:
The applicable portions of Part 97 are 97.315 and 97.317

Ҥ97.315 Certification of external RF power amplifiers.
(a) No more than 1 unit of 1 model of an external RF power
amplifier capable of operation below 144 MHz may be
constructed or modified during any calendar year by an
amateur operator for use at a station without a grant of
certification. No amplifier capable of operation below 144
MHz may be constructed or modified by a non-amateur operator
without a grant of certification from the FCC.
(b) Any external RF power amplifier or external RF power
amplifier kit (see §2.815 of the FCC Rules), manufactured,
imported or modified for use in a station or attached at any
station must be certificated for use in the amateur service
in accordance with Subpart J of Part 2 of the FCC Rules.
This requirement does not apply if one or more of the
following conditions are met:
(1) The amplifier is not capable of operation on frequencies
below 144 MHz. For the purpose of this part, an amplifier
will be deemed to be incapable of operation below 144 MHz if
it is not capable of being easily modified to increase its
amplification characteristics below 120 MHz and either:
(i) The mean output power of the amplifier decreases, as
frequency decreases from 144 MHz, to a point where 0 dB or
less gain is exhibited at 120 MHz; or
(ii) The amplifier is not capable of amplifying signals
below 120 MHz even for brief periods without sustaining
permanent damage to its amplification circuitry.
(2) The amplifier was manufactured before April 28, 1978,
and has been issued a marketing waiver by the FCC, or the
amplifier was purchased before April 28, 1978, by an amateur
operator for use at that amateur operator’s station.
(3) The amplifier was:
(i) Constructed by the licensee, not from an external RF
power amplifier kit, for use at the licensee’s station; or
(ii) Modified by the licensee for use at the licensee’s
station.
(4) The amplifier is sold by an amateur operator to another
amateur operator or to a dealer.
(5) The amplifier is purchased in used condition by an
equipment dealer from an amateur operator and the amplifier
is further sold to another amateur operator for use at that
operator’s station.
© Any external RF power amplifier appearing in the
Commission’s database as certificated for use in the amateur
service may be marketed for use in the amateur service.
§97.317 Standards for certification of external RF power
amplifiers.
(a) To receive a grant of certification, the amplifier must
satisfy the spurious emission standards of §97.307(d) or (e)
of this Part, as applicable, when the amplifier is:
(1) Operated at its full output power;
(2) Placed in the “standby” or “off” positions, but still
connected to the transmitter; and
(3) Driven with at least 50 W mean RF input power (unless
higher drive level is specified).
(b) To receive a grant of certification, the amplifier must
not be capable of operation on any frequency or frequencies
between
24 MHz and 35 MHz. The amplifier will be deemed incapable
of such operation if it:
(1) Exhibits no more than 6 dB gain between 24 MHz and 26
MHz and between 28 MHz and 35 MHz. (This gain will be
determined by the ratio of the input RF driving signal (mean
power measurement) to the mean RF output power of the
amplifier); and
(2) Exhibits no amplification (0 dB gain) between 26 MHz and
28 MHz.
© Certification may be denied when denial would prevent
the use of these amplifiers in services other than the
amateur service. The following features will result in
dismissal or denial of an application for certification:
(1) Any accessible wiring which, when altered, would permit
operation of the amplifier in a manner contrary to the FCC
Rules;
(2) Circuit boards or similar circuitry to facilitate the
addition of components to change the amplifier’s operating
characteristics in a manner contrary to the FCC Rules;
(3) Instructions for operation or modification of the
amplifier in a manner contrary to the FCC Rules;
(4) Any internal or external controls or adjustments to
facilitate operation of the amplifier in a manner contrary
to the FCC Rules;
(5) Any internal RF sensing circuitry or any external
switch, the purpose of which is to place the amplifier in
the transmit mode;
(6) The incorporation of more gain in the amplifier than is
necessary to operate in the amateur service; for purposes of
this paragraph, the amplifier must:
(i) Not be capable of achieving designed output power when
driven with less than 50 W mean RF input power;
(ii) Not be capable of amplifying the input RF driving
signal by more than 15 dB, unless the amplifier has a
designed transmitter power of less than 1.5 kW (in such a
case, gain must be reduced by the same number of dB as the
transmitter power relationship to 1.5 kW; This gain
limitation is determined by the ratio of the input RF
driving signal to the RF output power of the amplifier where
both signals are expressed in peak envelope power or mean
power);
(iii) Not exhibit more gain than permitted by paragraph
©(6)(ii) of this Section when driven by an RF input signal
of less than 50 W mean power; and
(iv) Be capable of sustained operation at its designed power
level.
(7) Any attenuation in the input of the amplifier which,
when removed or modified, would permit the amplifier to
function at its designed transmitter power when driven by an
RF frequency input signal of less than 50 W mean power; or
(8) Any other features designed to facilitate operation in a
telecommunication service other than the Amateur Radio
Services, such as the Citizens Band (CB) Radio Service.”

It is not clear to me if you believe (or how it applies) that the citation supports the idea that these components are certified by the FCC and do not require any additional testing by the licensed HAM who uses them.

When you build your own HAM transmitter you are expected to test its output to ensure that its spurious transmissions meet the standards expected. You don’t need to get a formal FCC certification for it, nor would I expect for a DIY radio on the balloon. However, I would expect that the FCC would expect such a DIY radio would have the appropriate testing conducted by the amateur responsible for it.

Anyway, best of luck with the launch and other aspects of the project.

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Ah, sorry I misunderstood your previous post.

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Your Tracksoar board just came out of the solder oven and is now being programmed. There is one minor error on the board, the FTDI TX and RX are flipped (i have corrected this on the next round of boards). So just keep that in mind when it comes time to program your call sign.

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Awesome, thanks Michael. I think we’ve all been there with swapping Tx/Rx lines.

So I found 150ft^3 of He for $105, 1 week tank rental, if we show nonprofit status. (Will I need board cooperation for showing 501c3 status? If so, how hard would it be?)

Also the tank had no stem (I think that’s what the flow shoppers are called), so it doesn’t need anything screwed in to eject gas, just open the valve and it goes. They recommended holding the balloon over the screwhole (whatever it’s called), but I don’t think that will work since we will need a load to balance against. They didn’t have any good solutions for unregulated hoses; I’m guessing it probably wouldn’t be too difficult to find the correct thread at home depot, drill a hole down the middle, and epoxy a garden hose to it or something.

That was one shop here in Arlington.

I might Google tonight and see if I can find more specifics on other people’s solutions.