Required receiver for HX-1 (144.390 MHz) & NEO-6M GPS Module?

Question

Context

I'm launching a series of weather balloons as a capstone graduation project. Right now I am in the process of building the payload.

I have been going over the different components of the mission and mapping out the different parts that I am going to need to build. For tracking / storing data I'm using OLHZN's Data Logger and Radio Position tracker (OLHZN Instructions) This system uses a HX-1 Radio Transmitter (DATA) (144.390 Mhz) & a NEO-6M GPS Module (DATA).

Questions

• I understand that the HX-1 Radio Transmitter is an APRS, but how can I receive transmissions from this system? Could I track this with a RTL-SDR dongle?
• Also, with the NEO-6M GPS how do I receive these signals?. If I understand correctly the two work in tandem sending out information on telemetry and other data.
• Is there a standalone system that I would need to build to receive these signals? Or should I just rely on websites like APRS.fi? Or if I do need to build a standalone system (Antenna / Receiver) I would appreciate any guidance on how to construct one.

Answer 1

I understand that the HX-1 Radio Transmitter is an APRS, but how can I receive transmissions from this system? Could I track this with a RTL-SDR dongle?

Yes, an RTL-SDR dongle and Direwolf is one good way to receive APRS; there are many others. You can also rely on existing receivers passing data to the APRS-IS.

Also, with the NEO-6M GPS how do I receive these signals?. If I understand correctly the two work in tandem sending out information on telemetry and other data.

The GPS is a receiver, not a transmitter, you don't receive anything from it. The GPS gets your position, the APRS transmitter sends it (along with whatever telemetry you include).

Is there a standalone system that I would need to build to receive these signals? Or should I just rely on websites like APRS.fi? Or if I do need to build a standalone system (Antenna / Receiver) I would appreciate any guidance on how to construct one.

Your choice. Are you going to send out a car to chase this thing? Then you have a good reason to build a receiver for the tracking vehicle. Is your launch site far away from existing receivers? Then you have a good reason to build a receiver to track the launch phase. Otherwise, if you're just staying at home and letting it go, your receiver might not add very much to the network that's already out there.

Answer 2

One reason why APRS is perfectly suited for such an experiment is that there is a physical network of receivers set up across the world. If your balloon is high up and transmitting its location on 144.390MHz, the chances are good that as long as it is near land where there is a certain density of amateur radio enthusiasts, someone will hear it and log it to the internet, where it can be seen on aprs.fi - and possibly some other sites.

I have APRS in my car, and whenever I drive across Bangkok to go to work, I am tracked for my entire journey. If I go upcountry, then there are gaps in the logged journey until I get near a large town, but there isn’t a large number of APRS enthusiasts in Thailand. Most of Europe and the Americas are covered, though - and the densely-populated bits of most countries.

To answer your questions:

• if you need to receive the transmitted signals directly yourself, consider a portable yagi antenna and something like an APRS receiver or an SDR with an APRS decoder.
• I am not familiar with this system, and will defer to someone with more knowledge about how it works.
• See the answer to point 1 if you want to receive the signals yourself, but bear in mind that the range will be a few tens of kilometres (or miles) at the most. But you can use the APRS network to do the listening for you. Bear in mind though that if the balloon goes over a large ocean (e.g. the Atlantic or the Pacific) there won’t be anyone to receive its signals until it reaches a populated area.

There have been weather balloons that have gone all the way round the world with an APRS transmitter on board, and it was fascinating to track them as they went over populated areas - from the US over the Pacific to Asia, then all the way over through Europe to the Atlantic and back to the US. It was very interesting to follow them on aprs.fi see the routes they took!