Abstract: An earth-penetrating synthetic image radar system includes a frequency generator, a transmitter, a microprocessor-based timing and frequency controller, a reference receiver, a parallel polarized receiver, an orthogonal polarized receiver, a digitizer, a calibration processor, a position measurement reference, and an image processor. A plurality of frequency synthesizers are utilized within a single frequency generator to transmit a fast-stepped synthetic image containing a series of discrete frequencies. A switch is used to select between the outputs of the synthezisers for control of the transmitter's frequency output. With a first synthesizer of a frequency f.sub.1 selected, a second synthesizer is being directed digitally to change to the next step in the frequency stepping sequence, frequency f.sub.2.

Abstract: Automatic gain control circuitry for high range resolution correlation ra systems used with passive-active missile seeker weapons to provide RF and IF gain control, acceptable angle track nutation signals, AGC video delay for low frequency signal variations, and minimum AGC response time compatible with system stability. AGC processing is initiated when the acquisition or active track mode is selected, if video presence exists as an output from a video presence integrator. Likewise active mode automatic angle tracking is interfaced through the AGC circuit and is inhibited when the received target amplitude is less than a selectively predetermined AGC amplitude delay.