Accession Number : ADD011812

Title :   Phase-Coded Pulse Expander-Compressor.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Lewis,B L

Report Date : 02 Apr 1985

Pagination or Media Count : 11

Abstract : A pulse expansion and compression system, especially useful for radar ranging, comprising a pulse coder for expanding an input pulse and a pulse compressor of the matched-filter type. The coder consists of a plurality of delay stages into which the input pulse is fed, a discrete Fourier transform (DFT) circuit to which the output signals of the delay stages are fed by way of respective phase weights and for which every other frequency port is inverted prior to entry to a time-dispersion-means (TDM) comprising an arrangement of adders interconnected by delay stages for differently delaying the output signals from the DFT. The adders are connected in N/2-fold cyclically permutated order to the frequency ports, where N is the number of frequency ports if that number is even, and N is the number of frequency ports less one if that number is odd. The TDM output is fed to a phase modulator and then to the transmitter. The echo signals are conjugated, time-inverted, and passed through the same DFT as the input pulse signal by way of the phase weights. The outputs of the DFT are then inverted at every other frequency port and passed through the TDM, but this time in time-inverted order. The outputs of the TDM are fed through an envelope detector to provide a cross-correlated facsimile of the original input pulse. (Author)

Descriptors :   *PATENTS, *PULSE COMPRESSION, *MATCHED FILTERS, *DOPPLER RADAR, *EXPANSION, *CODING, RADAR PULSES, PHASE MODULATION, FAST FOURIER TRANSFORMS, FREQUENCY MODULATION, ANALOG TO DIGITAL CONVERTERS, DIGITAL TO ANALOG CONVERTERS, DISCRETE FOURIER TRANSFORMS, DOPPLER EFFECT, DISPERSION RELATIONS, ENVELOPE(SPACE), INPUT, MODULATORS, DELAY, ECHOES, DETECTORS, COMPRESSION, BANDWIDTH, CLOCKS, PULSES, PHASE

Subject Categories : Electrical and Electronic Equipment
      Numerical Mathematics
      Cybernetics
      Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE