Accession Number : ADD010160

Title :   Frequency-Phase Coding Device.

Descriptive Note : Patent,


Personal Author(s) : Lewis,Bernard L

Report Date : 16 Nov 1982

Pagination or Media Count : 7

Abstract : This invention relates to a doppler-tolerant pulse-compression code generator for generating a plurality of approximately orthogonal codes which will prevent radar interference and suppress jamming. These codes are generated by phase-coding the frequency-band steps and also altering the time-sequence of the frequency steps of a step-approximation to a linear FM chirp pulse. Specifically, this code generator may comprise a circuit for modulating a carrier frequency with a video pulse of bandwidth B having a length less than or equal to a desired compressed pulse length, a tapped delay line having n signal taps for sequentially delaying this video pulse, a comb filter comprising a series of n bandpass filter channels each passing different spectral bands in the bandwidth B, a switching matrix for connecting each of the n signal taps to a different one of the n bandpass filters in a controlled manner, a phase-coding circuit in each bandpass filter channel for phase coding the signal passed through the respective bandpass filter channel, and an adding circuit for adding all of the phase-coded signals from the n bandpass filter channels to form one of a set of orthogonally coded pulses. (Author)

Descriptors :   *Patents, *Radar interference, *Chirp radar, *Antijamming, *Radiofrequency interference, *Coders, Jamming, Frequency modulation, Orthogonality, Pulse compression, Phase, Carrier frequencies, Bandpass filters, Pulses, Delay lines, Bandwidth, Switching, Signals, Filters, Taps, Length, Channels, Video signals

Subject Categories : Radio Countermeasures
      Active & Passive Radar Detection & Equipment
      Radiofrequency Wave Propagation
      Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE