Analysis of DMSK Demodulators for DMSK and DPSK Reception
Abstract
This report considers some issues involved in using high data rate differential minimum shift keyed (DMSK) modulation to augment an existing satellite communication system employing differential phase shift keyed (DPSK) modulation. DMSK is preferred over DPSK for its greater spectral efficiency and robustness in nonlinear channels. Two DMSK structures are discussed, the one- and two-bit demodulators, the second of which demodulates two interleaved differential data sequences. Analytic expressions are derived giving the bit error rate performance of both types of demodulator, with either matched or Gaussian filters. It is shown that the two-bit demodulator with a Gaussian filter provides the best performance in additive white Gaussian noise. The use of DMSK demodulator to receive DPSK signals is examined. This is of interest in order to reduce the number of demodulators required, while supporting augmented and original service. It is shown that the two-bit DMSK demodulator can be used to receive DPSK signals, but the one-bit demodulator cannot. Performance with filters that provide optimized DMSK demodulation and filters modified for DPSK signals are discussed. For a very small loss in DMSK performance, performance with DPSK signals can be brought to within 2 dB of the ideal DPSK demodulator.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 16, 1990
- Accession Number
- ADA226181
Entities
People
- Bruce F. Mcguffin
Organizations
- Massachusetts Institute of Technology