Results and conclusions of the 60 Mbit/sec digital transmission tests

Results from breadboard models are compared with tests carried out by ground stations for OTS digital transmission. In-band impairment, interchannel interference, and noise interference were examined for their effect on bit error rate (BER). Results show good agreement between predictions and real data. Differences between given ground stations are attributed to individual demodulators responding in different ways to an impairment. Judged by the 60 Mbit/sec standard, the 40 MHz transponders of OTS perform well, although failure of the traveling wave tube amplifier in the transponder for the orthogonal polarization signal meant that investigations were limited to the uplink.