Monotonically ranging FM-CW radar signal processor
AssigneeRCA Corporation
InventorHenry C. Johnson
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Abstract
A signal processor for monotonic FM-CW ranging system having reduced quantization error. The difference signal from FM-CW radar is applied to two cascaded phase locked loops (PLL). The second PLL is modified for unidirectional frequency tracking.
Claims4
In a continuous wave radar ranging system of the type wherein a signal is transmitted in the direction of a target and is reflected from said target back to the source of said transmitted signal, the range of said target from said ranging system varying monotonically, said transmitted signal being frequency modulated in accordance with a given periodic waveform, said ranging system including means for deriving from said transmitted signal and said reflected signal a difference signal indicative of the frequency difference of said reflected signal from the instantaneous frequency of said transmitted signal, and signal processor means, responsive to said difference signal, for generating an output signal indicative of the range of said target;
- the improvement wherein said signal processor comprises:
- first frequency tracking means, responsive to said difference signal, for generating an output signal having continuous phase velocity at a frequency indicative of said difference frequency;
- and
- second frequency tracking means, responsive to said first frequency tracking means output signal, for generating an output signal indicative of the value of a predetermined frequency extremum attained by said difference signal, said second frequency tracking means output signal being indicative of said range.
Dependencies are inferred from the claim text.