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    • 27. 发明专利
    • DE4104096A1
    • 1991-08-22
    • DE4104096
    • 1991-02-11
    • MIKOSHIBA NOBUOTSUBOCHI KAZUO
    • MIKOSHIBA NOBUOTSUBOUCHI KAZUO
    • H04B1/10H04B1/707H04B1/71H04J13/00
    • The arrangement is applicable when a wide band information signal is subjected to a narrow band disturbing signal. A first embodiment in a spread spectrum receiver has a correlator 17 in the IF stage, the correlation output passing to a mixer 6, such as a double balanced mixer, having squaring characteristics whereby frequency components of a disturbing signal are shifted to the region of DC and a region at twice the frequency of the original disturbing signal. The mixer output passes to a band pass filter 8 to select only the frequency component of the correlation peak. A multi-stage arrangement with a plurality of mixers 6, 10, 14 and filters 8, 12, 16 may be used to remove a plurality of disturbing signals. In a second embodiment, a reference signal input to the correlator 17 is frequency modulated and is provided by a mixer (18) which multiplies the output of an FM modulating oscillator (19) by the output of a pseudo noise code generator (20). In a third embodiment, a notch filter (22) preceding the correlator blocks a centre part of the spectrum of the spread spectrum signal, which part is particularly weak against disturbance. The first embodiment may be combined with the second and/or third embodiment. (Figs 9 to 14).