DTIC ADA324086: Generating and Demodulating M-ary FSK-PSK Using the FFT.

by: Defense Technical Information Center

Publication date: 1997-01-01

Topics: DTIC Archive, Moose, Paul H., NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEE RING, *FAST FOURIER TRANSFORMS, *MODEMS, *DIGITAL COMMUNICATIONS, *FREQUENCY SHIFT KEYERS, FREQUENCY MODULATION, RADIO RECEIVERS, DATA RATE, FREQUENCY DIVISION MULTIPLEXING, DEMODULATION, PHASE SHIFT KEYERS, PHASE MODULATION.,

Collection: dticarchive; additional_collections

Language: English

This paper discusses a technique for modulating and demodulating M-ary FSK using an FFT based modem typical of Coded Orthogonal Frequency Division Modulation (COFDM) systems. COFDM is one of the more promising spectrally efficient, high data rate modulation techniques for line-of-sight communications between mobile platforms. This paper will show that legacy FSK radios like the AN/MRC-142 (binary FSK modulation at 144, 288, 576 kbps) used by the U.S. Marine Corps could be easily implemented in a COFDM modem originally designed for higher data rates and better spectral efficiency than the legacy radio. In addition, the performance of such an implementation is analyzed in detail and shown to result in negligible performance degradation (0.05 dB or less). Digital processing speed requirements are analyzed and shown to be similar to digital implementation of conventional FSK receivers. MATLAB code is included that simulates the modem.