Four-phase modems for a satellite channel: Demodulation via differential detection
Abstract
Two quarternary phase shift keying modems in which demodulation takes place according to the principle of differential detection (DQPSK-modems) were developed, for investigations concerning digital transmission via communication satellites. Both modems, one with a 4 Mbit/sec bit rate and Nyquist Shaping (NS) in the transmitter, the other a 8.448 Mbit/sec bit rate and NS in the receiver, work on a 70 MHz intermediate frequency. Bit error rate was measured in back-to-back operation, via a translator loop, and via the A2 transponder of the OTS-2 satellite. The 4 Mbit/sec modem shows a 2.5 dB degradation with respect to the ideal DQPRS curve, while the 8.448 Mbit/sec modem shows a 1.8 dB deviation at a Pe=0.0001 random error.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- May 1984
- Bibcode:
- 1984STIN...8630927M
- Keywords:
-
- Differential Pulse Code Modulation;
- European Communications Satellite;
- Modems;
- Phase Shift Keying;
- Signal Detection;
- Bit Error Rate;
- Digital Data;
- Frequency Converters;
- Nyquist Frequencies;
- Ots (Esa);
- Transponders;
- Video Data;
- Communications and Radar