With several rockets now active in the fleet that have max altitudes over 10,000 feet AGL, and with more and more expensive motors systems and electronics going into those rockets, it seemed time to start using a reliable tracking system.  Many of my friends are using various beaconing transmitters and receivers such as the Walston, but I did not want to invest in an expensive system which only provided a radio beacon.  As I was looking into various systems and weighing the advantages and disadvantages, Tony Barrett, a HAM radio expert, showed up at one of the Tripoli Idaho club meetings and introduced the Pocket Tracker APRS radio transmitter.  The device is a simple kit which, when coupled with a small GPS unit, will transmit APRS packet data to a capable receiver.  I became quite interested and decided to start building a system.  Apparently I was just in time as the Pocket Tracker is no longer available due to the discontinuance of one of the key components.  I was able to get one of the last two kits available (thanks Tony!). At this point I was ready to get started.


The Pocket Tracker is a simple to build kit which fits in an Altoid tin.  The radio is 0.5W and transmits on a single frequency, 149.390 MHz (there is a jumper option for the European frequency, 144.80 MHz). It is necessary to provide an antenna and your own GPS unit providing serial NMEA data at 4800 baud to the Pocket Tracker input port.


For testing the Pocket Tracker and GPS will do, but for flights I wanted something small, light, and cheap.  One of the options that I found that fit this description well was to use an older GPS unit designed for the Palm III PDA.  The Streetpilot GPS was an add-on GPS unit which interfaced with the palm and provided a nice 12-channel GPS at its core.  A nice web page tutorial on how to remove the GPS board and use it separately from the Palm is here.  There are also many other older GPS units with instructions on how to hack them for this use on the web.  For those who don't want to mess with that and want an out-of-the-box solution there are many inexpensive GPS receiver/antenna combination devices designed for laptops and PDAs that will work out-of-the-box with the Tracker.


Lastly, I needed a receiver that could decode the APRS packet data to be able to track the rocket.  The simplest method is to use a small handheld HAM radio connected to a soundcard input of a laptop and use some software (many freeware and shareware) that is designed to decode the APRS  packets.  In my case, I had wanted to get involved with HAM radio anyway, so I decided to just buy a handheld that has the APRS feature built in, the best radio for this is the Kenwood TH-D7AG


The System

With the three critical components together I now had the system I wanted that not only provides rocket location but also real-time telemetry including speed, altitude, and more.  Altogether, the total system price was less than $500 (Pocket Tracker and antenna, approx $100, GPS $30, Radio $350).

Big Red Bee

There has been a flurry of new, GPS-based, rocket tracking systems to hit the market recently.  One of the first, and I think one of the best, is the Beeline GPS from Big Red Bee.  This is a self-contained GPS, APRS encoder, and transmitter made specifically for high-power rocketry.  It is frequency-agile on the 70cm band and works very well with the Kenwood TH-D7 and Garmin Foretrex 101 GPS.  I simply set the packet band to the 70cm band and connect the Garmin to the Kenwood.  My callsign from the Beeline shows up as a waypoint on the Garmin GPS.  I simply set the GPS to navigate to this waypoint and I get real-time tracking on the GPS with altitude and distance.  Big Red Bee also makes a 2-meter version and other tracking systems.

Additional Transmitters

After the discontinuation of the Pocket Tracker I decided to look into building another transmitter that could take its place, and perhaps be even more compact.  The best system I have found so far uses a small Radio Shack handheld radio (ebay $50) for the transmitter and uses a GPS and another Byonics product, the Tiny Track III , to encode the GPS data into APRS packets.  I have now purchased several of the Tiny Track varieties to combine with various GPS units to construct nice transmitters for rocketry.  (Details of these are in the "radios" section of this website).