Filter which tracks changing frequency of input signal
US4032852A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 2, 1976 |
| Grant date | Jun 28, 1977 |
| Priority date | — |
| Expiry date | Jan 2, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A signal-frequency tracking band-pass filter useful for passing an input signal which changes rapidly in frequency. The tracking filter includes a voltage-controlled band pass filter, and a frequency-to-voltage converter for translating the output frequency of the filter to a voltage for controlling the pass band center frequency of the filter. The Q of the filter is controlled by a feedback circuit which makes the Q vary inversely with output signal amplitude. The Q is high for weak signals that are hard to lock on to, and the Q is low for strong signals to facilitate tracking of signals which change rapidly in frequency. The filter is especially useful for inclusion in internal combustion engine diagnostic equipment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.