bec515d module 3 Earth Station Testing_.pptx

Earth Station Testing module 3

1. Earth Station Testing

2. Purpose of Testing - Ensure equipment meets specifications - Prevent interference with satellites/users - Levels of testing: • Unit/Subsystem level • System level • Line-up testing

3. Unit & Subsystem Level Testing - Unit level: Done at manufacturer’s site - Subsystem level: Electrical, mechanical, environmental checks - User witnesses critical tests - Selected tests repeated after installation

4. System Level Testing - Done after integration - Acceptance tests verify: • Performance specifications • Satellite system requirements • Regulatory compliance • Baseband signal quality - Two types: Mandatory & Additional tests

5. Mandatory Tests 1. Transmit Cross-Polarization Isolation - Ensures minimal cross-polarized signal 2. Receiver Figure-of-Merit (G/T) - Methods: Spectrum analyzer, Gain & Temp, Radio stars 3. EIRP Stability - Digital services: ±0.5 dB 4. Spectral Shape - Prevents interference, monitored regularly

6. Receiver gain and system temperature method : Measurement of receiver gain

7. Receiver gain and system temperature method : Measurement of system temperature

8. In order to measure the receiver gain using the beamwidth method, the AUT measures the corrected azimuth and elevation 3dB/10dB beamwidths. Receiving gain of the antenna can then be computed from known values of the two corrected beamwidths by using formula given

9. The system noise temperature can then be computed with the help of expression given by

10. The AUT is swept over angular displacements, typically ±15◦ corrected. For antennas employing elevation over azimuth mounts, the azimuth angle needs to be corrected for the elevation angle. Corrected azimuth angle (A Z ) in terms of the azimuth angle from boresight (AZ) as measured from encoders and the elevation angle (AEL)is given by

11. Additional Tests - Antenna pattern measurements - Transmit & receive sidelobe patterns - Co-polarized & cross-polarized checks - AUT swept over ±15° angles - Corrections for elevation-over-azimuth mounts

12. Line-up Test - Performed with other Earth stations - Includes control & monitoring station - Carrier EIRP adjusted for required C/N ratio - Link cleared for traffic only after success