A radar signal processor implemented with surface acoustic waves devices

A spectrum analyzer using the chirp Fourier transform is presented. Algorithms used to implement the Fourier transform for analog and digital cases are analyzed. The Fourier transform is evaluated by multiplying the signal by a down chirp, then convolving the result with an up chirp with the same slope and multiplying the output of the convolver with a chirp equal to the first used. In the spectrum analyzer, the pulse is created by a ringing oscillator at a frequency of 60 MHz and is amplified to a peak power of 20 dBm. This pulse is used to trigger the first chirp generator. Due to the SAW device insertion loss, a second amplifier is used to feed the input mixer with power = + 13 dBm. The ringing oscillator synchronizes a pulse generator with a variable delay. A PROM simulates input signals (of sine type). The number of pulses can be changed to simulate different signals. The Hamming weights are inserted in proper sequences loaded in the PROM whose output is converted and translated to the right frequency.