BALDOCK - Monitoring Facilities

Satellite monitoring facilities

Over recent years there has been considerable growth and UK investment in the use of satellite communication systems for voice, data and television transmission.

Facilities are available at Baldock to monitor all UK visible geostationary satellites in order to protect fixed earth stations, licensed by the Agency, from possible interference. Measurements can be taken of those satellites that have been identified as being greater than one degree from their nominal location in orbit, since these have greater potential for causing interference.

In addition to the growth in the number of geostationary satellites, there has also been a huge expansion in the use of Transportable Earth Stations, mainly by broadcasters. Checks can be made on the satellite downlinks to ensure conformity to clearance applications. The results of these investigations can then be used by the Agency to assess the potential for interference between terrestrial fixed services and TES installations, which share the same band, and thus minimise interference experienced by its customers.

In order to be able to monitor a large number of satellites, operation of the dishes has been automated by the use of specialist software. As new satellites are brought into operation, the software can be changed to include the new satellite's parameters.

12.2 metre "C" band dish

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11 metre "Ku" band dish

Major equipment

A "C Band" 12.2 metre Cassegrain fed, limited steerable antenna (100° to 260° in azimuth and 0° to 90° elevation). This currently covers the band 3.4 GHz to 4.2 GHz with a mid-band G/T of 23.9dBK.

A "Ku Band" 11 metre Cassegrain fully steerable antenna covering 10.7 GHz to 12.75 GHz with a 3dB beamwidth of 0.167 and a mid-band G/T of 34.3dBK.

The following monitoring and measurement capabilities are available:

• The measurement of emissions emanating from geostationary satellites in the C and Ku Bands between longitude 70° East and 70° West as follows:
• Occupied bandwidth and centre frequency to the accuracy as required by the Radio Regulations. These measurements are made using a microwave frequency spectrum analyser locked to a rubidium frequency standard.
• Equivalent carrier wave power to an accuracy of better than ±1dB.
• Spectrum occupancy measurements in the bands 3.4 GHz to 4.2 GHz and 10.7 GHz to 12.75 GHz.

The site also has limited capability for measurements in the "L Band" - 1 GHz to 2 GHz.