Color subcarrier frequency comparator
US3958269A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 20, 1974 |
| Grant date | May 18, 1976 |
| Priority date | — |
| Expiry date | Aug 20, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N17/04
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for measuring the frequency of a reference signal which utilizes he color subcarrier signal of a television receiver as a standard frequency signal. In a first embodiment, the reference signal controls a circuit to develop bursts of a synthesized color subcarrier signal, gated at the horizontal line rate of a color television receiver. The synthesized signal is superimposed on the broadcast television signal and applied to the receiver to produce a modulation bar on the screen. Any frequency/phase difference between synthesized and broadcast color subcarrier signals will cause the modulation bar to move laterally across the screen, and/or cause the sequence of colors within the modulation bar to vary. Movement of the modulation bar is a coarse indication of frequency difference and change of the color sequence within the bar is a precise indication of phase difference. In a second embodiment, the locally synthesized color subcarrier signal and the color subcarrier signal of the television receiver are compared in a linear phase comparator to develop a signal having an instantaneous voltage proportional to the phase difference between the two signals. The phase signal cont…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.