Multistandard clock recovery circuit
OwnerUlrich Englertinventor
Life of this patent
Estimating the term…
Abstract
The circuit recovers teletext signals, notably VPS, TXT, WSS and similar signals, from a video signal with concurrent production of the standard scanning frequency of the respective teletext signal. The recovery circuit has a single phase locked loop circuit which generates a reference frequency from a basic frequency supplied by an oscillator circuit. The reference frequency is a multiple of the scanning frequency in question. To scanning frequency is extracted from the reference frequency with a frequency divider.
Claims8
A multistandard clock recovery circuit for recovering individual teletext signals from a video signal with a plurality of teletext signals of mutually different standards each having a respective standardized sampling frequency, comprising:
- a single PLL circuit configured to generate from a basic frequency provided by an oscillator circuit a standard-independent reference frequency, the reference frequency being a multiple of a respective sampling frequency of a given standard;
- and
- a frequency divider connected to generate from the reference frequency the respective sampling frequency of the given standard.
A multistandard clock recovery circuit for recovering individual teletext signals from a video signal with a plurality of teletext signals of mutually different standards each having a respective standardized sampling frequency, comprising:
- a single PLL circuit configured to generate from a basic frequency provided by an oscillator circuit a reference frequency independently of a given standard of a teletext signal to be processed, the reference frequency being a multiple of a respective sampling frequency of the given standard;
- and
- a frequency divider connected to generate from the reference frequency the respective sampling frequency of the given standard.
Dependencies are inferred from the claim text.