A FEATURE SUPPRESSED SPREAD SPECTRUM COMMUNICATION SYSTEM

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Authors
  1. McPherson, W.
  2. Wight, J.S.
Corporate Authors
Carleton Univ, Ottawa ONT (CAN) Dept of Electronics;Defence Research Establishment Ottawa, Ottawa ONT (CAN)
Abstract
The novel technique of chip-rate hopping (CRH) was devised to suppress the chip rate feature of a Direct-Sequence-Binary-Phase-Shift-Keying (DS-BPSK) communication system. Chip-rate hopping deterministically varies the chip rate through the utilization of a second Pseudonoise Sequence (PNS) in addition to the conventional PNS used to spread the transmitted data. A second enhancement, burst data transmission, was added. Spread data is transmitted on every eighth chip-rate, while a third PNS is transmitted when data is absent. A hardware implementation of a DS-BPSK transmitter is described. Experimental results demonstrate that the chip-rate feature has been suppressed when the signal is exposed to an envelope-type chip-rate-detector (CRD). In particular, the chip-rate feature was undetectable at an input signal-to-noise ratio (SNR) of -10 dB when either a swept-superheterodyne or an FFT spectrum analyser was used in a 10 minute examination of the known bandwidth. A software implementation of a matched filtering demodulation scheme was utilized to demonstrate acceptable performance is achievable at an input SNR of -15 dB.
Keywords
Chip rate hopping
Report Number
DREO-CR-96-684 — Contractor Report (Final)
Date of publication
01 Oct 1996
Number of Pages
163
DSTKIM No
96-03499
CANDIS No
500008
Format(s):
Hardcopy;Document Image stored on Optical Disk

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