ITU-R REPORT SA.2190 PDF

Introduction

Earth stations for the space research service (SRS) have very sensitive receivers. To protect these (deep-space and near-Earth) SRS earth stations from interference, the ITU has published protection criteria in Recommendation ITU-R SA.1157 for the 2 GHz, 8 GHz, 13 GHz and 32 GHz bands.

For the 37-38 GHz band, Recommendation ITU-R SA.1396 gives the SRS earth station protection criterion as −217 dBW/Hz not to be exceeded more than 0.1% of the time for unmanned missions and 0.001% of the time for manned missions. This limit is applicable for both the deep-space and near-Earth SRS missions.

The analyses in § 2 show that since the range of an aircraft transmitter is much less than the range of SRS missions interference from a transmitter in the aeronautical mobile service (AMS) to an SRS earth station receiver can significantly exceed the SRS earth station protection criteria.

Recommendation ITU-R SA.1016 provided an example of a narrow-band aeronautical mobile transmitter interfering with a space research earth station (space-to-Earth) (deep space) at frequencies up to 32 GHz. Given an aircraft transmitter with maximum e.i.r.p. density of 10 W/4 kHz (equivalent to −26 dBW/Hz), antenna gain of 0 dBi, and altitude of 12 km, the results in Annex 1 (see Table 3) of this Recommendation showed that the minimum interference received by the SRS earth station would exceed the protection criteria. Therefore, the Tables of Frequency Allocations in the ITU Radio Regulations have excluded aeronautical mobile in the frequency bands 2.29-2.3 GHz, 8.4-8.5 GHz, 22.21-22.5 GHz and 31.5-31.8 GHz, where the mobile service is co-allocated with the space research service. This Recommendation did not, however, consider very low power AMS systems.

The following sections will present the results of compatibility studies for a single AMS transmitter or multiple AMS transmitters for sharing the 37-38 GHz band by SRS and AMS.