Filter which tracks changing frequency of input signal
US4204171A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 30, 1978 |
| Grant date | May 20, 1980 |
| Priority date | — |
| Expiry date | May 30, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K7/08
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A tracking band-pass filter useful for locking onto, and passing, an input signal which changes rapidly in frequency. The filter has a frequency pass band controlled by a rectangular voltage waveform which is derived from the output signal passed by the filter. The filter output signal is translated from a sine wave to a pulse wave. The period between each two successive pulses is measured by counting the cycles of an oscillator during each respective period. The time-representing count is inverted to a frequency-representing count which controls the duty cycle of a rectangular wave used to make the filter track the changing frequency of the input signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.