Pulse Interference Cancelling System for Spread Spectrum Signals Utilizing Active Coherent Detection.
DEPARTMENT OF THE ARMY WASHINGTON DC
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Disclosed is a pulse interference cancelling system for spread spectrum signals utilized in a digital noise coded communications system. The system includes a first and second noise coded signal channel located in a noise coded signal receiver which also includes a demultiplexer for providing a pair of received noise coded signals which were initially generated, multiplexed and transmitted to the receiver. First and second coherent detector means are coupled to both signal channels, the first being directly coupled thereto so that no signal delay exists but the second is coupled to the two signal channels by means of respective first and second variable time delay circuits having a delay substantially equal to the bit width of each digital code as well as a vernier delay which is adapted to delay the phase of any received pulse interference in the respective channel so that it is exactly 180 deg out of phase with the same undelayed pulse interference. Signal summing means are coupled to the outputs of the two coherent detectors which operate to completely cancel the interference pulse signal while leaving the desired noise coded signal at its peak amplitude.
- Electrical and Electronic Equipment