OpenTracker APRS Encoder


Automatic Position Reporting System (APRS) is used to transmit location and other real-time data over amateur radio frequencies. [Scott Miller]’s OpenTracker project is designed to encode the NMEA data from a serial GPS receiver for transmission. It doesn’t have to be used for GPS telemetry though, you could hook up a weather station or any other remotely located project. Scott has boards, parts and even full kits available.

27 thoughts on “OpenTracker APRS Encoder

  1. Since we’re building things from scratch… Anyone seen a site that tells you how to build a caller id box that will display on your tv? I’ve seen where you can buy them, but not for less than $50. Seems high…

  2. ok. so I got my ham liscence. but I’m confused on the recieving end. Does this thing recieve the data and convert it back to NEMA so it can be hooked into a computer for viewing ?

    And for the transmitting/recieving, it hooks into the mic jack ? or does my radio have to support ARPS on it’s own ?

    There’s a few pictures but they don’t answer my questions. Does anybody have any experience with this project ?

  3. Hi,
    Your radio does not need to do APRS. This is a TRANSMITTING module.. NOT a receiving module.. so you hook it to your radio and hook a GPS to the module and it will transmit your location. I have one of these in my car.

  4. okay, I know this is off-topic, but I’ve got a huge question and I figured hackaday would be as good a start as any.

    At school I help the new computer teacher repair the laptops for one of my classes, many of them are having a problem with not being able to find the network’s domain, which would probably be an easy problem to fix if it weren’t for one small problem. The old admin used caspol.exe to cripple access to the control panel, caspol, registry, etc… So we have no access to hardware profiles, network settings, etc.

    Is there any way to get around the caspol blocks without administrative rights, or to just disable it without them?

    Thanks in advance :-)


  5. ryan, assuming you’re using windows, did you try ‘Policy Editor’? search the internet for poledit.exe.

    That’s how I got around all that crap in college. Network admins hated it :) On the other hand, they WERElocking us out of our own PCs.

  6. You don’t need any freaking aprs radios… aprs isn’t all that special, it’s just packet radio and aprs is just how the gps nmea data packets are formated. If you knew the format, you could hook a packet modem up to a dumb terminal and type in dummy packets to make stuff show up on people’s aprs terminals. aprs was originally just a program that ran in dos with a regular packet radio (pk12 anyone?).

    There’s probably a winaprs program out now that can decode packet radio in software from soundcard input, albeit probably only 300 and 1200 baud versions, and display the received coords on a map.

  7. Ok, I had a lot more written up on this. But yeah, it’s generally going to feed audio into a transmitter. You can do decoding with soundmodem under Linux or AGWPE in Windows using your soundcard. But as long as you’re on 144.39 (again, need a ham license) in the US, chances are an Internet gateway station will do it for you and you’ll show up at places like

  8. I updated the website with some more introductory stuff.

    As for needed a ham callsign, that’s true if you’re using ham frequencies. As I understand it, the FCC is now allowing position data on FRS (a la Garmin Rino), so you could probably get away with it there, too. But it wouldn’t be as much fun.

    Seriously, go get your ham license. It’s easy and cheap. No morse code required. And you can legally run 802.11b at obscene power levels!

  9. great to see someone else using the HC908 series microcontrollers. i really like the instruction set, going back to pic feels like trying to build a house with nothing but a rusty screwdriver. hc908 has a great range of performance and features, all the way down to a tiny 8-pin smd with integrated oscillator, it get really hard to rationalize not using a microcontroller in every project!

  10. There’s nothing that says you HAVE to transmit on 144.39 so I’m assuming picking a FRS/GMRS channel should work fine. As long as your FRS radio has a external mic/headset input your good to go.

    Also does anyone have a link to the software to decode using a soundcard ?

    – Quantis

  11. quantis – google agwpe for the decoding software. there may be limits on frs/gmrs use set by the fcc – originally you couldn’t run any data modes.

    As for 802.11b and obscene power levels, go check out the band allocations. I think they cover channels 1-6 or some such. Off the top of my head, I think there’s supposed to be a 1-watt limit for spread spectrum modes without power control, but I’m not sure if 802.11b qualifies. Otherwise the limit is a truly obscene 1500 watts.

    also, there are no gain limits as in part 15 use, so you’re free to pipe that 1 watt (or maybe 1500 watts) into a 12-foot parabolic dish if you want.

  12. which makes me wonder: *has* anyone gotten their microwave oven to modulate an 802.11 signal? they’re in the same band, and you could maybe tune the magnetron with some external magnets to get it on-channel for 802.11 …

    agree on the PIC being like being stuffed in a shoebox with a rusty paperclip.

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