Transmission of data with a video signal
First Claim
1. A method of transmitting binary data with a video signal, comprising modulating horizontal line synchronizing pulses of the video signal with said data, each bit (binary digit) of said data modulating a respective horizontal line synchronizing pulse and being constituted by the presence or absence of the respective horizontal line synchronizing pulse.
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Accused Products
Abstract
The horizontal line synchronizing pulses of a video signal are selectively replaced with a video signal blanking level in dependence upon bits of data, whereby the data is transmitted with the video signal. Such data transmission is particularly applicable to a pay TV system in which the video signal is scrambled, because the selective absence of horizontal line synchronizing pulses enhances the video signal scrambling. In this case the data can comprise information relating to the scrambling of the video signal.
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Citations
6 Claims
- 1. A method of transmitting binary data with a video signal, comprising modulating horizontal line synchronizing pulses of the video signal with said data, each bit (binary digit) of said data modulating a respective horizontal line synchronizing pulse and being constituted by the presence or absence of the respective horizontal line synchronizing pulse.
- 4. Apparatus for transmitting binary data with a video signal which comprises video signal lines including line synchronizing pulses, comprising means for modulating said pulses with said data, each bit (binary data) of said data modulating a respective pulse, said means for modulating said pulses comprising timing means for generating a timing signal during each line synchronizing pulse, gating means for gating said timing signal with each bit of said data to produce a control signal, and means responsive to said control signal to selectively replace each said pulse with a video signal blanking level.
Specification