Inventors:
Luiz Peregrino - Cupertino CA
Darwin H. Throne - Cupertino CA
Assignee:
Hewlett-Packard Company - Palo Alto CA
International Classification:
G01R 2314
Abstract:
An input signal of unknown frequency is applied to a sampler which is driven by a sampling signal of frequency f. sub. O to produce an intermediate signal of frequency f. sub. IF. The sampling frequency f. sub. O varies in response to a randomly, or pseudo-randomly varying signal which in turn causes the signal of frequency f. sub. IF to also vary. f. sub. IF will vary in the same way as f. sub. O, but with a scale factor of. +-. N, where N is the harmonic number. Correlation techniques are used to determine the harmonic number and the sideband to enable calculation of the input frequency. Errors in the determination of the harmonic number and sideband due to frequency modulation of the input signal are reduced, due to the variation imposed on the sampling frequency f. sub. O.