Ground Station

To communicate with the institute's own satellite, the IRS has its own ground station. The objective of the installation of the system is to automate operations as much as possible. Thus, the usage time of the satellite is to be maximized without providing an expensive and complex 24-hour manual operation. The main tasks of this station are sending commands to the satellite (telecommanding, TC), the reception of Houskeeping data (telemetry, TM), as well as the download of the scientific payload data from the satellite (downlink payload, DDS).

HF hardware

The antenna system is capable of transmitting within the commercial space research S-band (2075 MHz - 2090 MHz) with an equivalent output power of up to 20 kW (EIRP 43 dBW) and simultaneously, also within the commercial space research S-band (2257 MHz - 2278 MHz) to receive telemetry. Both are done in the right-hand circular polarization oriented (RHCP). 

Simultaneously, the antenna system is able to receive the payload data in the left-hand circular polarization LHCP with up to 10 Mbit/s in the amateur radio S-band (2400 MHz - 2428 MHz). 

We are using a parabolic antenna with a reflector diameter of 2.5 m (max. 34 dBi gain) which is mounted on a former radar rotor. To meet the requirements of the pointing accuracy, the antenna has been equipped with new stepper motors, position sensors and new control electronics. Overall, the antenna reaches a calibrated pointing accuracy of 0.3 ° at a maximum rotation speed of 12 °/s. An overview of the antenna system can be seen in the following picture.

The location of the antenna system is on the roof of Pfaffenwaldring 31, with coordinates 48° 44' 58,19"N, 9° 06’ 13,84"E, about 442 m above N.N., QTH Locator JN48NR. This site provides good reception conditions due to its exposed location.

For personal protection, an optoacoustic warning system has been installed, which signals movements of the reflector as well as the activation of the high power amplifier. For additional monitoring of rotor movement a webcam is installed on the roof. Hence, the necessary safety equipment is installed to allow for a remote operation, which is controlled from the control room in RZBW (Pfaffenwaldring 29).

Shackroom

The high-quality LNAs, filters and power amps were purchased from SSB and Kuhne Electronic. Reception and transmission are taking place at an intermediate frequency of 70 MHz, so up and down converters towards the carrier frequencies are used. The transceiver is the commercial satellite transceiver CORTEX CRT of Zodiac Aerospace. To receive the payload data (DDS), a second channel of the base band modem is used. Furthermore, an in-house developed FPGA-based board can be used. In order to reduce costs for other radio HAMs, we are right now developing another solution based on a software-defined radio (SDR) transceiver.

As the central control software for the remote operation, the self-developed software "METEOR" is used. This has its own module for orbit prediction, is able to control all peripherals and measuring devices remotely, and regulates the other hand, the antenna pointing. It consists of a server part (CORE), which is running on a control computer in the shack room (next to the antenna on the roof), and a graphical user interface that connects via TCP/IP protocol with it. Via fiber-optic cables, this software is executed in the control center.

 IRS G/S control software