The Trackotron automatic balloon tracking system consists of an Alfaspid antenna rotator head mounted on a tripod stand, which is usually placed somewhere high up (such as the roof of the Engineering Department) for a good view of the horizon during a balloon flight.
The aim of the system is to point a highly directional Yagi antenna at the balloon using both azimuth and elevation control, and retrieve decoded data in order to update the antenna position.
Trackotron on Baker Building tracking Apex Alpha
Antenna rotator head unit containing the two stepper motors
The antenna rotator head comprises two large stepper motors, which are powered and controlled via the control and drive unit shown below. This unit requires mains power and has two cables connecting it to the antenna rotator head. It has several modes of operation, most of which are unimportant, except that it implements a serial interface which can be used to set the desired position of the antenna.
The stepper motor control unit for the Trackotron
At present, there is a single driver board (RadioFox) which is capable of communication with a host machine in order to receive the required az/el data, parse it, and pass the data on to the Motor Driver unit. The RadioFox v1 board is also capable of transmitting uplink commands to the Badger series of flight computers via the Icom IC-7000 amateur radio set.
RadioFox v1 controlling the Trackotron
The first run of RadioFox v2 board will remove the uplink system since the current generation of flight computers are not using an uplink system. RadioFox v2 will principally be a sensor board containing at least a GPS, an accelerometer and magnetometer such that the Trackotron can orient itself and can get feedback on azimuth and elevation.
The board will be designed to be mounted to the Yagi antenna itself and must therefore be the right size to do so. The system must also work in all weather so a waterproof casing needs to be designed to keep the board dry.