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DIY FPV Antenna tracker.

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The DIY Antenna Tracker

The goal of this project is to build a high spec FPV antenna tracker that is also affordable.

The tracker has been under development for a year or so now. Originally it used an FrSky telemetry receiver to transmit the information regarding the planes position back to the tracker, but as the project has evolved the ability to use an FSK Modem via an audio channel of the Video link or to use the unused parts of the video protocol itself has been incorporated.

Unfortunately the current documentation has not kept pace with the rest of the project over the last years. I hope to change that over the next few weeks.

Some of the current features are:

  • continuous rotation by using sliprings. The tracker can follow the plane continuously.
  • Several methods of sending the telemetry information, thus providing redundancy for this important data
  • As a by-product of sending telemetry via the video itself, am OSD is well on the way to being completed

See the Construction section for a guide to building the original, but I plan to replace it with a 3D printed version shortly.

You should be able to get the parts for about £100, if you look around.

See the Bill of materials for prices and sources

(Click the picture to watch the tracker in action on YouTube).

The main parts of the tracker are:

V2 was designed using the superb FreeCad.

Airborne telemetry

Originally, the telemetry is sent from the aircraft using the Frsky RC two-way telemetry system. The data was acquired from the Ardupilot Autopilot, which outputs the data using Mavlink protocol.(N.B it is also possible to use an airborne unit that is directly connected to a GPS receiver so not requiring Ardupilot. See the Main Index for a picture)

The second option for sending telemetry is using one of the Audio channels of the Video link. This option has been implemented and is in use with good results.

The third option is to use unused parts of the video picture to send data. A by-product of this is that it is relatively easy to extend this to produce a full OSD which is in progress.

airborne unit wiring diagram
Stm32f4 Discovery board

STM32F4 microcontroller

The STM32F4 is used as the microcontroller for the project. Though its a powerful microcontroller it is easy to use in this project because you use a prewired dev board the STM32F4 Discovery board. The board is available for about £12 and can be used directly in the tracker without modification.

Programming the Discovery board is simple and cheap to do. You dont need an external programmer and the programming software is free to download and use for Linux and Windows. All you need is a standard mini USB connector to plug between the Discovery board and your PC. Please see the programming section. for more details. The firmware to flash the board is available from https://github.com/kwikius/quantracker. Use main.bin to flash the board.

wiring diagram

Elevation servo

The elevation servo is a standard RC hobby servo. The one I used was the Supertec S04

Elevation servo

Azimuth Turntable

The turntable I used for Azimuth (sometimes called "pan") was from Vex robotics. The turntable is quite robust and works very well, though it would be nice at some stage to make one from scratch.

Also required is a pinion. These come in packs of 12. Ideally I would like to build a turntable from scratch, or find an alternative since the Vex turntable adds quite a bit to costs for what it is.

Vex turntable
Pololu motor with encoder

Azimuth servo motor

The azimuth servo consists of a geared motor with a quadrature encoder and a 30:1 gearbox. They are available from Polulo, but can also be purchased on Ebay, Amazon and various other places, often at a reduced price

motor connections
photo of L298 H-bridge

Also required is an H-bridge to drive the motor. The one I used is based on the L298 I.C. These can be bought quite cheaply on Ebay already on a pcb with heatsink and connector terminals.

L298 H-bridge wirong diagram

Slip rings

The slip rings enable the Tracker to rotate continuously. The video and serial port data signals are sent through the sliprings. I got my slip rings on Ebay. The ones I used have 12 wires and a body diameter of 12.5 mm. I think they are the same as the Senring SNM012A-12. Next time I might get a 24 wire version if I could get it in the same diameter.

The slip rings
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