Piszkéstető UHF
The Piszkéstető UHF station is a SatNOGS-capable satellite receiver station, suitable for receptions in the passband between 435 and 438 MHz. The station is based on the following components:
- SPID RAS rotator with off-the-shelf controller;
- 2x2 stacked WIMO X-Quad 70 cm UHF antennas (including the appropriate phase line);
- Aluminium tubes (40x2, 60x2);
- Cross mast clamps (for the H-shaped antenna support structure, for the counterweight) and distance mast clamps (for connecting the 60mm support tube to the bar);
- Wilkinson power combiner;
- HA7DCD LNA: triple filtered, double amplified: https://decent.org (previously: an SSB SP-70 preamplifier);
- N-N bias tee;
- N-N cables (H155, 4x 1m, exactly the same length to connect the antennas to the Wilkinson power combiner, 3m, to connect the power combiner with the LNA);
- An appropriately long N-N cable (H155, between the LNA and the bias tee);
- A shorter N-SMA cable (betweem the bias tee and the dongle);
- RTL-SDR dongle (v3);
- Lots of ferrite beads;
- PC Engines APU2 with Devuan single-board computer; and
- software stack extensions atop satnogs-client, enabling custom pre/postprocessing scripts and additional real-time packet decoding hooks.
Our infrastructure for this station infrastructure is supported by the same grants which funded the GRBAlpha mission, an 1U CubeSat for in-orbit performance tests of detectors suitable for small form-factor gamma-ray burst detections. The station also regularly receives the SMOG-1 PocketQube as well as we contribute to the data reception for the missions VZLUSAT-2, BDSat and Planetum-1. The aim of the custom extensions atop the satnogs-client is to allow the real-time decoding of GRBAlpha, VZLUSAT-2, BDSat and Planetum-1 packets and transfer the packets to the interactive ground control software with a minimal (≲ 10-20ms) latency while keeping a 100% compatible interfacing to the SatNOGS system at the same time. Our real-time packet forwarding is merged with additional stations, most prominently with the Jablonec SatNOGS station. In addition to this real-time packet forwarding, further extensions allows the proper unwinding of the antenna and rotator cabling in advance of the passes.
Gallery
The station, mounted on the guard rails of the rooftop of the RCC telescope building.
The station, a bottom view.
The dome of the 1-meter RCC telescope in the background of the antenna system. The dome blocks the horizon between 190...210 degrees of azimuth up to ~20 degs of elevation. In the sky background, one can see a SunExpress flight from Hannover to Diyarbakir.
The mast supporting the station, along with the LNA (from the back) and a meteor camera and the dome of the Schmidt telescope in the background.
A lightweight counterweight... needed to be upgraded soon.
Cable glands of the main motor + encoder cables.
A close-up photo of the motor cable holder.
The low-noise amplifier.
The phase line for one of the X-Quad antennas. In the sky background, one can see a Wizz Air flight from Bucharest to Birmingham.
The 4-way Wilkinson power combiner.
A close-up photo of the motor cable holder in order to avoid serious winding of the antenna and motor cables.
The off-the-shelf controller of the SPID RAS rotator, extended with numerous additional ferrite beads.
Power supply for the rotator, extended with a ferrite bead.
The bias tee and the RTL-SDR.
Some ethernet switches and the main PCEngines/APU control data acquisition computer.
Christmas edition.
Some Christmas lights could also be wrapped around...
... at least, the power supply is there for the Christmas lights.
An additional cavity filter has been inserted later on in the path, but only after the LNA and bias tee (it is DC-short).
The well-balanced configuration: more big rusty screws have been mounted as counterweight...
... with a bit of duct tape, just to be sure.
... and the current filter and bias tee setup.
