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US 5,175,509 AGranted
Frequency control circuit for swept frequency oscillator
AssigneeGEC-Marconi Limited
InventorKevin B. Taylor
Life of this patent
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Abstract
Linearizing circuitry for an FMCW transmitter (1,2) employing a linear modulation waveform. The output signal is sampled (3,4,5) in successive intervals, small compared to the modulation period, and a cycle count (16) taken in each interval; a reference count is derived for each interval, either by way of a look-up table (21) triggered by a clock count (17) or derived by way of a clock driven processor (18). A comparison (20) is made and any error (22) is used to control (11) the phase of the modulation waveform.
Claims9
A frequency modulated signal generator circuit comprising:
- (a) a voltage controlled oscillator,
- (b) a ramp signal generator for producing a ramp signal comprising a succession of waveform sweeps, said generator being coupled to said oscillator for producing an output signal whose frequency is swept repeatedly,
- (c) sampling means for providing a check signal whose frequency corresponds to that of said output signal,
- (d) counter means for providing a check count corresponding to the number of cycles of said check signal in each of a plurality of intervals, said intervals being of substantially less duration than the duration of each sweep of said ramp signal generator,
- (e) reference means for providing a respective reference count corresponding to each said check count,
- (f) comparator means for comparing each said check count with the corresponding reference count and producing an error signal corresponding to the disparity between the reference count and the check count, and
- (g) means for correcting said ramp signal in dependence upon said error signal.
4 more elements
Dependencies are inferred from the claim text.