The APRS Radio Transmitter


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We no longer manufacture our own APRS transmitter. We recommend purchasing the StratoTrack instead. It is extremely easy to integrate into any weather balloon system and operates without the need for a separate flight computer. Click here for more details.

Track your weather balloon payload with live data anywhere in North America! The Radio Bug APRS tracker plugs into our Eagle Flight Computer's S1 Port and transmits your payload's position, altitude, speed, temperature, and pressure once every minute. Because the Eagle Flight Computer's GPS receiver works above 18,000 m (~60,000 ft), you will be able to track your payload all the way up to burst altitude. You don't even need any special equipment on the ground. The APRS system uses a network of hundreds of IGates (internet gates) distributed across North America to receive the data transmitted by our tracker. You will be able to track your weather balloon on Google Maps with any device connected to the internet, including smart phones and tablets!

Radio Bug

The Radio Bug is a state of the art APRS transmitter designed specifically for weather balloon tracking. At just under 25 grams it requires less than one cubic foot of helium to compensate for the extra weight. Just plug it into our Eagle Flight Computer and suspend it below your payload from the included 24 inch data cable and you are ready to track. No need to hassle with creating your own antenna setup, dealing with a coaxial cable, or setting up an extra power supply. The Radio Bug has a 250 mW transmitter mounted in the center of a dipole antenna. This is the most effective antenna for tracking weather balloon payloads over long distances.

Licensing and Fees

You are required to have an Amateur Radio License from the FCC to use the APRS system. It typically costs less than $20 to get your license. Studying for the test takes only a few hours. There are no fees for using the APRS system.


How do I set my callsign?

Once you pass the Amateur Radio exam, the FCC will provide you with your own unique callsign. You set your callsign by editing a file which the Eagle Flight Computer downloads onto the micro SD card when it is powered on.

What does APRS stand for?

APRS stands for Automatic Packet Radio System. The system allows amateur radio operators to share packets of information directly with each other or the internet. Our APRS Radio Transmitter will share a small packet of information once a minute over the APRS network which you will be able to view directly on Google Maps. This packet of information will include position, altitude, speed, temperature, and pressure.

Why does your APRS tracker only transmit once a minute?

The APRS network operates at a single frequency. If hundreds of devices were transmitting simultaneously over this frequency, the system would be overloaded and none of the IGates would be able to decode any of the packets. It would be like trying to understand a hundred people all shouting a different message at you at the same time. As a common courtesy to other uses on the network, we limit the transmit interval to once every minute. Theoretically it is possible that you and someone else could transmit at the same time preventing your packets from being received and decoded by surrounding IGates, but this rarely happens. A packet takes less than a second to transmit.

What range does your APRS Radio Transmitter have?

Above 60,000 ft, we've seen IGates over 300 miles away from our payload receive our signal.

Does the APRS network have any limitations?

IGates have a hard time picking up your signal when your transmitter is close to the ground. They almost always require direct line of sight. If your payload is on the ground and a hill separates it from the nearest IGate, your signal will not be picked up. For this reason you should not rely on our APRS tracker to locate your payload once it lands. You should always include a satellite tracker on your payload. Even if the satellite tracker is on the ground, it still has direct line of sight to satellites in orbit as long as it is facing up. This is also why you should never use a Styrofoam cooler as a payload enclosure. They occasionally roll upside down when they land preventing the satellite tracker from "seeing" satellites in orbit. This makes it almost impossible to find your payload.

I already have an Eagle Flight Computer. Does the firmware need to be updated before I can use your APRS Radio Tracker?

Maybe. All flight computers purchased after June 18th 2015 have the necessary firmware update. If you purchased your Eagle Flight Computer before the above date, simply mail it to the address located on the Contact Us page. Within two business days of receiving your flight computer we will service your flight computer at no charge, update its firmware, and mail it back to you along with your tracker.

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