Abstract: The frequency of a signal is determined using a signal filter having a signal filter skirt band frequency range wherein an intermediate fraction of an initial amplitude of an introduced signal passes through the signal filter. The magnitude of the transmitted intermediate fraction varies with the frequency of the introduced signal. A test applied signal having a frequency which lies within the signal filter skirt band frequency range is introduced into the signal filter. The transmitted amplitude of the test applied signal is measured after the test applied signal has passed through the signal filter. The transmitted amplitude is utilized as an indicator of the frequency of the test applied signal, either directly or through a calibration relation for amplitude as a function of frequency in the signal filter skirt band frequency range.

Abstract: A portion of a radar transmit pulse is inserted into a recirculating delay line having a one cycle delay equal to the duration of a transmit pulse. A pulse train coupled from the recirculating delay serves as a local oscillator for the radar receiver. The delay medium may be an optical fiber, a coaxial transmission line or a surface acoustic wave (SAW) device.