Acoustooptical processor for radio signals with discrete frequency modulation

A study is made of a processor for pulsed radio signals with discrete frequency modulation, where the frequency varies discontinuously within a pulse and takes on N different values. The spectral components are separated with an acoustooptic spectrum analyzer whose spectral plane is imaged onto a linear charged-coupled photodetector by means of a planar (one-dimensional) spatial converter made of optical fibers. In the imaging, the spectral components of the signal injected into the fiber are transposed by a special arrangement (permutation) of the fibers. The charge-coupled detector, which operates in the time-delay and accumulation mode, detects the spectral components and sums them with the required delay, and thereby compresses the signal and separates it from the noise. The compression factor is limited by the value of N and can be several hundred. Results of experimental investigations of a prototype of the processor are presented. Pis’ma Zh. Tekh. Fiz. 23, 12–19 (January 26, 1997)