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Equipment

Here’s the equipment you’ll need to make the most of APRS OTA.

  1. A ham radio license that allows you to transmit APRS messages.
  2. A way to send and receive APRS messages and position beacons
  3. A way to access this website.

If you are reading this, you’ve already got #3 sorted.

If you want to chase an op or host an op, you will need a ham radio license. In the United States, every ham radio license class allows you to transmit on the commonly used APRS frequency of 144.390 MHz. Other countries and regions use different APRS frequencies and may have different license requirements, but generally APRS is available to most licensed amateur radio operators.

You can use APRS OTA without access to the website. You can do everything by sending APRS messages and position reports, and receiving APRS messages. This means you can run an op in the field with just a handheld radio as long as it meets requirement #2 above.

The website is a bonus, not a requirement.

To host or chase, you need to be able to send a position packet with a real location in it. Certain devices send all zeros for latitude and longitude if they don’t have a GPS fix. Some devices may send position beacons that we don’t know how to parse and decode. the OTA bot will tell you if it can’t understand your position beacon. If you think you are sending a valid one, please reach out because I’d like to make sure we parse every valid position beacon.

Chasing an op

When you chase an op, you attempt to make a contact with the host of that op. You can chase even if you don’t have a ham radio. You need some way to send and receive APRS messages and position beacons. You can do this with an app on your smart phone like APRSdroid or APRS.fi. These apps can send your messages over the internet to a gateway which will transmit them on RF to the host of the op.

You can also chase an op with any of the equipment required to host an op.

Hosting an op

There are only three rules for APRS OTA. Rule #3 is relevant here: when you host an op, all your messages must originate from and be received via RF. In order for messages to reach the OTA bot, they will need to make their way to APRS-IS, which is fine, but the first leg on a transmission and the last leg on a reception must occur via radio waves.

Hosting an op therefore requires a ham radio. There are several ways you can meet the requirement.

  1. A handheld ham radio with a user-accessible KISS TNC and a smart phone app or app on your laptop. Handhelds with this capability include the VGC VR-N76 and BTECH UV-PRO. You’ll typically connect to the TNC with an app on your laptop or smart phone to send and receive messages. An external TNC such as a Mobilinkd, paired with a radio that has no TNC of its own, gets you to the same place.

  2. A ham radio that can send and receive APRS messages and beacons. There are a number of inexpensive radios that claim to have APRS support, but most of them can only beacon. The messaging support, if it exists, is usually terrible. The best handheld for this is the very expensive Kenwood TH-D75.

  3. Combine 1 or 2 with a digipeater or igate. If you go this route, not only are you complying with the letter of the “hosts must be on RF” rules, you have embraced the spirit of the event and the rules. The whole point is to encourage people to learn about and use APRS in a fun and exciting way.

Use your imagination. There are many other setups that you can put together that meet rule #3.

If your setup involves an app, one setting decides whether you meet rule #3 at all: the connection the app is using. The same app that drives your TNC will happily send everything straight to APRS-IS over your internet connection instead, and it looks identical while you use it. See point your app at your radio.