Digital processing disruption systems
A method and apparatus are described for modifying an analogue video signal to impair its conversion to a digital signal by an analogue to digital converter. The resulting modified signal may prevent the operation of the analogue to digital converter altogether, or even if a digital signal can be output and recorded, may result in a signal which is difficult to view due to a reduction in quality on playback. The modifications made to the signal include altering the amplitude of the horizontal synchronization pulses in the original signal, and/or modifying the level of the back porch, or the region of the signal adjacent the back porch. Additionally, methods are contemplated for the use of specific response models for target analogue to digital converters, and display devices.
1. A method executable by a device to modify an analog video signal and thereby impair analog to digital conversion of the signal, the analog video signal comprising a plurality of horizontal synchronization pulses, each adjacent a respective back porch, the method comprising:
receiving the analog video signal for modification at the device;
receiving disruption components from a remote source;
modifying, by the device, at least one of the horizontal synchronization pulses of the signal from its original form to have a different amplitude over at least a part of the pulse width, wherein the modifying is configurable to be based upon the disruption components received from the remote source;
additionally modifying the region of the signal following the horizontal synchronization pulse from its original form, wherein the additional modifying of the region following at least one of the horizontal synchronization pulses is configurable to be based upon the disruption components received from the remote source; and
outputting the modified video signal by the device, wherein the modified video signal is such that the modified video signal interferes with the operation of an analog to digital video conversion system to such an extent that the output of the analog to digital video conversion system has a reduced quality on playback in comparison to the original analog video signal.
2. The method of claim 1 wherein the modified region of the signal following at least one of the horizontal synchronization pulses is the back porch that follows the at least one of the horizontal synchronization pulses.
3. The method of claim 1 wherein the modified region of the signal following at least one of the horizontal synchronization pulses is adjacent to the backporch that follows the at least one of the horizontal synchronization pulses.
4. The method of claim 1 wherein the modifying comprises varying an amplitude of the modifications over time.
5. The method of claim 1 wherein the disruption components are based upon a response model for an analog to digital converter that is associated with the device.
6. A method executable by a device to modify an analog video signal and thereby impair analog to digital conversion of the signal, the signal comprising a plurality of horizontal synchronization pulses, each adjacent a respective back porch, the method comprising:
receiving disruption components from a remote source;
receiving the analog video signal by the device;
modifying, by the device, a region of the analog video signal following at least one of the horizontal synchronization pulses from its original form, wherein the modifying is configurable to be based upon the disruption components received from the remote source; and
outputting the modified video signal by the device, wherein the modified video signal is such that the modified video signal interferes with the operation of an analog to digital video conversion system to such an extent that the output of the analog to digital video conversion system has a reduced quality on playback in comparison to the original analog video signal.
7. The method of claim 6 wherein the region that is modified is in the back porch following at least one of the horizontal synchronization pulses.
8. The method of claim 6 wherein the region that is modified is adjacent to the back porch of the signal following at least one of the horizontal synchronization pulses.
9. The method of claim 6 comprising further modifying, by the device, at least one of the horizontal synchronization pulses of the signal from its original form so that the at least one of the horizontal synchronization pulses has a different amplitude over at least a part of its pulse width.
10. The method of claim 9 wherein an amplitude of the modification to the at least one horizontal synchronization pulse changes over time.
11. The method of claim 6 wherein an amplitude of the modification to the modified region following at least one of the horizontal synchronization pulses changes over time.
12. The method of claim 6 wherein the disruption components are based upon a response model for an analog to digital converter that is associated with the device.
13. An apparatus to process an analog video signal that comprises a plurality of horizontal synchronization pulses, the apparatus comprising:
an input configured to receive the analog video signal for modification;
an analog-to-digital conversion circuit; and
circuitry configured to modify at least a region of the signal following at least one of the horizontal synchronization pulses from its original form to have a different amplitude based upon disruption components received from a remote source, and to output the modified video signal to the analog-to-digital conversion circuit, wherein the modified video signal is such that the modified video signal interferes with the operation of the analog to digital video conversion circuit to such an extent that the output of the analog-to-digital circuit has a reduced quality on playback in comparison to the original analog video signal.
14. The apparatus of claim 13 wherein the disruption components are based upon a response model for an analog to digital converter that is associated with the device.
15. The apparatus of claim 14 wherein the modified region of the signal is a back porch adjacent at least one of the horizontal synchronization pulses.
16. The apparatus of claim 14 wherein the modified region of the signal is adjacent to a back porch that follows at least one of the horizontal synchronization pulses.