Tracking Pico Balloons Using Ham Radio [pdf] • Hacker News Board

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#21

Post by kokey » Sat, Jul 11, 2020, 6:33 PM UTC

trophyhead wrote: post #15

hanoz wrote: post #14

Earlier quoted context omitted.

But in my brief attempt to answer my own question I only found pages detailing pico balloon launches from the UK.

I'm sure people in the UK are doing launches, but it's illegal for them to transmit when flying in UK airspace. In reality, it's an almost unenforcable law to begin with. Most of the WSPR transmissions are on the order of 10mW (probably similar to the Bluetooth output of your cell phone). It's not unusual for these transmissions to be heard several thousand miles away, which is quite amazing!

If I remember right is the reason is that it’s illegal do use amateur radio bands on something that is flying, so that excludes APRS. However, using the ISM bands are fine so that’s what people in the UK tend to use, but it means no APRS and you have to have people tracking you in other ways (e.g. sending your telemetry over LoRa or RTTY)

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#22

Post by mcculley » Sat, Jul 11, 2020, 7:23 PM UTC

Can this frequency/protocol be used from sea level? I have some boats offshore that I would like to track. We currently use a combination of AIS and SPOT trackers.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#23

Post by lxe » Sat, Jul 11, 2020, 7:40 PM UTC

mcculley wrote: post #22

Can this frequency/protocol be used from sea level? I have some boats offshore that I would like to track. We currently use a combination of AIS and SPOT trackers.

I’m guessing it’s possible. I think WSPR supports a wide selection of bands so you can have over the horizon comms. APRS is usually VHF/UHF so it’s mostly line of sight. On land, there are APRS repeaters that rebroadcast your signal at higher power so I’m guessing it’s more suited for land.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#24

Post by trophyhead » Sat, Jul 11, 2020, 7:59 PM UTC

mcculley wrote: post #22

Can this frequency/protocol be used from sea level? I have some boats offshore that I would like to track. We currently use a combination of AIS and SPOT trackers.

You can, but you may not get the results you're looking for.

APRS is a line-of sight signal. In a balloon, you might be heard by transmitters 200 miles or so away. On a boat, I'd expect that range to drop to 50 or less. So if you're out at sea, it's unlikely you'd be heard when you're much outside the view of land.

WSPR has a very long range, but the density of information transmitted is very low. Each transmissison takes about 2 minutes and the tx rate is around 5 baud (not 5kb...5 baud!). The protocol was developed to test the range of ham radio antennae and it doesn't give you much more than the transmission voltage and the 'maidenhead' coordinates (which will give your location within a roughly 80 mile box depending on your latitude).

If that rough estimate of your position is good enough, WSPR may be useful to you for tracking a boat. Some balloon trackers also transmit a secondary signal under a different callsign with some more advanced telemetry information, such as altitude, speed, more granular position within a 2 or 3 mile box.

Also, you'll need an antenna of some length. My balloons transmit on the 20m bands, which means it has a 17 foot antenna both above and below the tracker constituting a half dipole (it's 36 gauge magnet wire so weights almost nothing. If your boats are big enough to cross oceans, you can likely mount them in a way where you'd be heard.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#25

Post by pugworthy » Sat, Jul 11, 2020, 8:11 PM UTC

This kind of reminds me of CubeSats. I love the simple little design with the side solar panel wings.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#26

Post by djaque » Sat, Jul 11, 2020, 10:13 PM UTC

sgt wrote: post #9

th0ma5 wrote: post #4

Earlier quoted context omitted.

Maybe they just put on a thin layer of conformal coating?

What about clear coat paint you would get from a hardware store just before launch?

I've always used clear nailpolish as a hacky version of conformal coating.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#27

Post by 0_____0 » Sat, Jul 11, 2020, 10:58 PM UTC

sgt wrote: post #9

th0ma5 wrote: post #4

Earlier quoted context omitted.

Maybe they just put on a thin layer of conformal coating?

What about clear coat paint you would get from a hardware store just before launch?

fwiw You can get urethane and silicone conformal coating in a spray can and it's not that expensive.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#28

Post by jbuzbee » Sun, Jul 12, 2020, 12:14 AM UTC

Do these balloons transmit any weather data along with their telemetry? Or at the altitude they fly, maybe there's not much weather to report?

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#29

Post by pugworthy » Sun, Jul 12, 2020, 12:55 AM UTC

themodelplumber wrote: post #3

Wow, that's amazing. 22 laps around the world over the course of one year. And HF data rx in Australia from this tiny circuit board attached to a tiny balloon over the mid-atlantic. Worth a read. Also bonus Windows XP points. Btw how are they flying a circuit board in the raw without damaging environmental effect from water? I'm new to this part of the hobby.

It amazes me that the balloon can last that long. That it's not losing it's loft over time.

Re: Tracking Pico Balloons Using Ham Radio [pdf]

#30

Post by pugworthy » Sun, Jul 12, 2020, 1:02 AM UTC

As fascinating as the electronics tech is, I'm perhaps more interested in the balloon tech.

Perhaps more reading will help me know the answer, but it doesn't seem like these are just off the shelf Mylar party balloons. Nor do they seem to be sized such that they can expand a lot as they rise.

The below linked article is kind of interesting in this area: it's about how Death Valley is littered with Mylar party balloons. According to the article...

"Mylar balloons do not go higher than about 3,000 feet to 7,000 feet before they either explode or lose their “lift.” This is because of their inability to expand to any great extent."