Analysis of a Proposed Two-Frequency Radar Waveform
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
The report examines a proposed unsuccessful method for achieving frequency agility by radiating two frequencies which may take on any value from pulse to pulse, provided the mean frequency remains unchanged. On reception, the signals are combined so as to process the mean-frequency component. The receiver uses an envelope detector as well as a coherent reference at the mean frequency. It is shown that the signal received from a single echo depends only on the mean frequency and not on the difference. This gave encouragement to the idea that MTI processing could be undertaken even though the difference between the two-frequencies was changed pulse-to-pulse. Unfortunately, when clutter was considered, the phase of the processed signal was found to depend on the difference between the two frequencies. This gives rise to an uncancelled residue. Hence, this form of frequency agility is incompatible with MTI. It is possible, however, to use two or more widely spaced frequencies, either simultaneously or in time sequence, in a more conventional MTI system if the same frequencies are repeated.
- Active and Passive Radar Detection and Equipment