APRS Implemented At Low Cost And Small Size

Before smartphones and Internet of Things devices were widely distributed, the Automatic Packet Reporting System (APRS) was the way to send digital information out wirelessly from remote locations. In use since the 80s, it now has an almost hipster “wireless data before it was cool” vibe, complete with plenty of people who use it because it’s interesting, and plenty of others who still need the unique functionality it offers even when compared to more modern wireless data transmission methods. One of those is [Tyler] who shows us how to build an APRS system for a minimum of cost and size.

[Tyler]’s build is called Arrow and operates on the popular 2 metre ham radio band. It’s a Terminal Node Controller (TNC), a sort of ham radio modem, built around an ESP32. The ESP32 handles both the signal processing for the data and also uses its Bluetooth capability to pair to an Android app called APRSDroid. The entire module is only slightly larger than the 18650 battery that powers it, and it can be paired with a computer to send and receive any digital data that you wish using this module as a plug-and-play transceiver.

While the build is still has a few limitations that [Tyler] notes, he hopes that the project will be a way to modernize the APRS protocol using methods for radio transmission that have been improved upon since APRS was first implemented. It should be able to interface easily into any existing ham radio setup, although even small balloon-lofted radio stations can make excellent use of APRS without any extra equipment. Don’t forget that you need a license to operate these in most places, though!

17 thoughts on “APRS Implemented At Low Cost And Small Size

  1. …. he hopes that the project will be a way to modernize the APRS protocol….

    Why? There’s nothing wrong with APRS as it stands.

    The biggest problem is that almost no one has ever used the system as it was envisioned by Bob Bruninga.

    APRS was always meant to be a “tactical” communications system and not solely for tracking purposes.

    But, with Bob getting up there in years and in poor health, I’m sure APRS will stop being anything beyond a tracking system in the very near future. He’s held a pretty tight grasp on the protocol over the years.

    Add in that Kenwood discontinued the D74 and the D710GA might have also been discontinued which means there are no new radios with full APRS capabilities on the market today.

    “Shrugs shoulders and walks off while muttering about the brilliant simplicity of packet radio and how it should still be very relevant in an age where Internet connectivity shouldn’t be counted on”

    1. APRS was an excellent solution for the technology which was at hand when it was developed (FM HTs and AX.25 TNCs / BELL202 Modems)!

      Technology has marched on since then and RF Transceivers are now cheaply available which support modulations which provide much better link budgets.

      Arrow is a technology demonstrator which shows these cheap RF transceivers, with a little creativity can be backwards compatible with APRS, and still offer:
      (1) Low Cost
      (2) Support of much better solutions than AFSK.

      The objective of Arrow is to not replace APRS but show the above and be platform for the future development. There is limitations of using an FM HT that simply cannot be overcome (i.e. channel bandwidth)

      – Tyler

      1. The problem with HF as I see it is that on HV you would need a lot larger antennas for use on bands used for local communication like 160-80 and sometimes 60 and 40m. The antenna for 2m band is easier for mobile use. I recently bought a new HT for use with APRS the Anytone UV878IIplus that was suposedly to have a dedicated APRS decoder. Unfortunatly this is not able to decode all messages.

    2. I’d love to use a more modern solution with cheaper hardware than APRS seems to currently allow.

      My particular use case is exactly what Bob has described as “tactical;” I host a few endurance events in wilderness areas (no cell service) where communication would be enhanced by the tactical display of where volunteers are and what their status is. At the moment, there is APRS coverage but simple transceiver costs are relatively high. A network of similar capability but cheaper hardware would be great, but would/will take time to reach the saturation that APRS has.

  2. ” He’s held a pretty tight grasp on the protocol over the years.”

    And there is the issue!!
    APRS always was/is a solution looking for a problem.
    I’ve been on “packet” for 30 years but APRS is a waste
    of bandwidth.

    1. Yeah, in its current state APRS isn’t super useful or helpful. It has so much potential that’s been hampered by the way the protocol was written and maintained privately. On the surface it looks like a great thing to have: The ability to know what’s going on around you. But without the functionality built into an affordable radio, you wind up with projects like this being the only way to really use it.

      No offense to the creator, but I don’t want to carry my HT, an adapter dongle (which needs its own power supply), and then have to use my cellphone as an interface. It seems clunky at best.

      But, if a screen on my radio could show me which friends are nearby, which repeater they’re currently tuned to, and allow me to send them a text message with a usable interface you might really be onto something! All of this is available in the APRS standard, but no one has made a stand-alone radio that would do all these things easily, let alone affordably.

  3. What I want is a device that is equivalent to Echolink but for texting. This way I could set up a station at home to receive my texts sent from a custom packet device and once received, I could take that text and interface it anyway I wanted. The 31 concern is security which the cell companies get to use, but ham radio operators can’t. Despite the legal issues, once the backbone for echolink for texting was in place, once released to the masses, we’d see how much the FCC wanted to spend on enforcing the rules.

  4. ALOHAnet went on the air in June 1971, fifty years ago this month. In May 1978, there was the first public demonstration of amateur packet radio. There’s a direct connection, even though I never knew what the connection.

    I find this post, and the comments, a bit confusing. Packet radio existed since that May of 1978, APRS came later. The hardware was created for packet radio. Maybe no difference at this disyance, but it was back then.

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