Apparatus for regenerating signals within a frequency band

Apparatus for generating signals to interfere with or jam signals detected as unfriendly in a given input frequency band comprises a spectrum analyzer circuit using surface acoustic wave (SAW) chirp filters to provide a transformation of input frequency signals to a series of time displaced signals in a linear frequency-to-time relationship. The analyzer circuit uses the SAW devices to perform multiply-convolve functions that separate the different frequency signals in time and the analyzer is repetitively triggered to perform a spectrum analysis. The time series signals are selectively applied to a frequency synthesizer having a time-to-frequency relationship that matches the analyzer characteristic so as to regenerate signals at the input frequencies. The synthesizer uses two matched chirp filters one activated by a fixed time signal and the other by the time series to generate swept frequencies that are mixed to provide the required frequency outputs. The time series is processed to inhibit those signals corresponding to frequencies identified as friendly. In an alternative synthesizer the time series signals are converted to frequency-representing digital codes which are applied to a programmable frequency generator. Signal processing to protect friendly frequencies is performed on the digital codes.