Apparatus for despreading a spread spectrum signal produced by a linear feedback shift register (LFSR)

摘要

In despreading a received spread spectrum signal, spread by means of a linear feedback shift register, the signal is demodulated and filtered and then applied to a predictor for estimating the length, connection polynominal and contents in accordance with the Berlekamp-Massey iterative algorithm. The estimates are then applied to a local LFSR to produce a despreading random signal which is mixed with the received signal to remove the spreading factor. The instantaneous total energy of the output signal is measured and when the estimations are correct, the total energy will exceed a predetermined limit and a signal is supplied to the predictor to indicate that the estimates are correct.