A BLOCK DEMODULATOR FOR FREQUENCY DIVISION MULTIPLEXED NCFSK SIGNALS

Authors
  1. Shaw, M.D.
  2. Pearce, J.L.
  3. Wight, J.S.
Corporate Authors
Communications Research Centre, Ottawa ONT (CAN)
Abstract
A block demodulator for the noncoherent demodulation of M-ary FSK signals multiplexed in frequency has been built and tested. The various users' signals are separated and demodulated with the use of the discrete Fourier transform. The demodulator is capable of handling 16/M users. The bit error performance in the presence of system noise has been measured for M = 2-, 4-, 8-, and 16-ary FSK with a symbol period of 50 mu s. The measured implementation loss depends on the specific channel location within the demodulator's bandwidth, varying from 0.2 dB for the best channel allocations to 2.6 dB for the worst. The effects of frequency offsets and adjacent channel interference are characterized with both a rectangular and a Kaiser-Bessel (proportional to = 1.4) window. For small frequency errors the rectangular window still performs well, but for larger offsets or large differences in power levels between the users the Kaiser-Bessel window is better.
Report Number
CRC-1427 —
Date of publication
15 Jul 1987
Number of Pages
120
DSTKIM No
88-01798
CANDIS No
55029
Format(s):
Microfiche filmed at DSIS;Originator's fiche received by DSIS;Hardcopy

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