Abstract: A method and system generates a modulated chirp signal in accordance with the present invention. A phase-locked loop output signal is generated, together with a sampled feedback signal from a voltage controlled oscillator. The sampled feedback signal is received within a quadrature I/Q phase modulator. I/Q quadrature signals are generated from an I/Q generator circuit to the quadrature I/Q phase modulator to produce a desired modulation of a sampled feedback signal as a string of +/−90 degree phase shifts to create a desired offset at the voltage controlled oscillator. The I/Q quadrature signals are chirp modulated and the resultant phase-locked loop output signal is chirp modulated by the chirp signal that comprises a sequence of chirps having a reference chirp followed by a plurality of data chirps.

Abstract: A FDM/TDM transmultiplexer uses sampling rate multiplication to increase the sampling rate for time division multiplexed (TDM) to frequency division multiplexed (FDM) conversion and decrease the sampling rate for FDM to TDM conversion. The rate multiplication filters are realized digitally in order to exploit the computational advantage of Fast Fourier Transform (FFT) algorithm, and channel filtering is implemented by a single time-shared sixth-order elliptic digital recursive filter. A novel FFT processor and recursive filter are disclosed which may be used in the system.