Objective: This series of articles presents the design of a mobile satellite ground station. The basic idea is to build a custom low-cost and mobile rotator for satellite tracking and pointing a parabolic dish for C-band communication with a satellite. Part 3 covers the elevation , dish antenna integration and tracking software link.
Recommended Prerequisite articles to read
i) Dish Antenna Rotator [part 2]: Assembly
This is the 3rd and final article in this series that covers the design and construction of a simple and low-cost antenna rotator for a mobile ground station. With the Covid-19 hiatus, the design was delayed a bit. However, I soon got things moving, literally. In part 2, the azimuth part of the rotator had been successfully completed. In this final writeup, I will present the elevation part, antenna integration and satellite tracking software link with the rotator.
Elevation Part: Attaching counterweights
A 60cm long shaft with a dimeter of 3cm was used. It was drilled on both sides with M6 holes to a depth of 2cm. These were to attach the counter-weight structure. To facilitate this attachment, the plates and shaft holders below were made.
These were attached to the shaft as shown below :
Dumbbells were chosen as the most convenient weights. More so, the structure allowed the position of these weights to be flexible enough to balance out any variations on the antenna part, such as adjusting the position of the dish. The photos below show the counterweights placement:
Elevation Part: Motor and antenna integration
Similar to azimuth rotation, the elevation uses a sprocket-chain gear system. The motor was attached to the top part of the structure as shown in the photos below:
Finally, the antenna was integrated as shown:
To facilitate smooth movement indoors, some light wheels were attached. Outdoor movement will require more robust wheels:
The overall rotator structure is as shown:
Rotator Integration to Satellite Tracking Software:
The rotator controller is based on Satnog open source firmware that incorporates the Easycomm III protocol. This is used by Hamlib’s rotctl(d) to control the azimuth and elevation movements. Gpredict was used as the satellite tracking software for the testing. On the backend, Gpredict links with Hamlib rotctl to communicate with the rotator controller that is running the Easycomm III protocol.
The image below show the current configuration of the setup:
The media below shows the rotator under operation with both azimuth and elevation control.