An Introduction to Rocket Tracking
Once upon a time it was a big deal for a model rocket to go out of sight, especially if it was a
relatively large one (say, the size of an Estes Big Bertha). Rockets like that would go out of
sight at maybe 1,000’, but unless your field was surrounded by trees or tall grass there was a
good chance that you would get it back because it’s not going to stray more than a few hundred
feet away from the launch pad.
With mid-power and high-power rockets, that’s a different story. To begin with, your field has
to be much larger, particularly with high-power (the rules call for a minimum size of 1500’ on
either side, or ½ the estimated altitude whichever is greater). If your rocket is flying to 6,000’,
you may have to walk at least 3,000’ to find your rocket. Even with multiple-deployment
using a flight computer (like the Eggtimer), you may find that once the rocket gets out of sight
you have no idea where it went, and the field is too large to simply walk around looking for it.
Trust us, we’ve all done this… for longer than we like to admit.
The need to be able to find “lost” rockets has created a number of electronic tracking methods.
The simplest rocket finding device is a simple “sounder”, that creates a loud audible tone. The
idea is that as you get close to the rocket, you will be able to hear it and hone in on the source
of the sound. The advantage of sounders is that they are simple and inexpensive; the primary
disadvantage is that you have to be close enough to the rocket to be able to hear the tone. If
you don’t know where the rocket landed, or if it drifted in a direction other than what you were
expecting, the sounder isn’t going to be of much help.
A more sophisticated approach is to use some sort of radio system. This is a two part system:
There must be some kind of transmitter in the rocket that sends out some kind of signal, and
there must also be some kind of receiver to pick up the signal and somehow help you find the
rocket. There are a few different ways of doing this.
The simplest radio tracking device is a “beacon”, which sends out a tone to a receiver that you
carry with you as you wander around looking for the rocket. You point the antenna of the
receiver in different directions noting the signal strength, and the direction of the greatest
signal strength is going to be where your rocket landed. These systems can be relatively
inexpensive (a few hundred dollars), or they can be very expensive (up to a thousand dollars),
depending on many factors; primarily, the range of the transmitter. Ranges for beacon systems
can be from a mile or two, up to tens of miles. Most of these beacon systems require a FCC
Technican class amateur radio license (a “ham” license), and using the signal strength to
determine position (also known as “DXing”) requires patience and practice.
In the past several years, the advent of affordable GPS location technology as made it possible
to create a rocket finding device that uses a GPS in conjunction with a radio telemetry data link
to send the location of you rocket to a ground receiver, so that it actually tells you where your
rocket landed. Early GPS-based rocketry transmitters were relatively large and heavy,
expensive, and required a FCC ham license. With recent advances in semiconductor
technology, the cost of GPS receiver chips has dropped enough so that they are now
commonplace in consumer device such as smartphones, tablets, and portable navigation
systems. Some of these same advances have also filtered down to radio-frequency devices,
such as FRS radio units and various consumer devices using the unlicensed 2.4 GHz and 900
