Efficient, precompression, bandwidth-tolerant, digital pulse expander-compressor

摘要

A digital pulse expander-compressor for use in pulse compression radars and having the advantage of precompression bandwidth tolerance. The pulse expander-compressor exploys a discrete Fourier transform circuit and multi-stage delay line feeding inputs x(n) to the discrete Fourier transform circuit to generate outputs in accordance with the formula where n is the sequence number of the clock pulse; N is the number of delay stages plus one; and k is the number of the output subpulse from the transform circuit. An arrangement of delay stages differentially delays the output subpulses from the discrete Fourier transform circuit, and a coherent summer adds the real and imaginary parts of the signals from the delay lines. The delay stages delay the subpulse s(k), O clock pulse intervals, while delaying the subpulse s(k), N/2+1 clock pulse intervals. The subpulse s(k), k=N/2, is not used. The pulse expander-compressor generates and compresses a polyphase code pulse with a pulse compression ratio of M2 where M is an odd integer less than N. An odd integer is desired so that the code can be made to have conjugate symmetry about the zero modulation frequency code subsequence.