Apparatus for providing television receiver alignment functions
View Patent ↗A method and apparatus within a television receiver for electronically aligning signals within the receiver by controlling support circuitry for an IF module. A control voltage source controls both video alignment and picture IF (PIF) mute functions. The DAC is coupled to a video level control circuit within the video amplifier circuitry of the television receiver. The control signal controls both the video level as well as a PIF mute circuit.
1. Apparatus for aligning signals in a television receiver comprising:
a control signal source;
a mute circuit coupled to said control signal source; and
a video level circuit coupled to said control signal source, where a first portion of a control signal from said control signal source controls said mute circuit and a second portion of said control signal controls said video level circuit.
2. The apparatus of claim 1 wherein said control signal source comprises a digital-to-analog converter.
3. The apparatus of claim 2 wherein the control signal source further comprises a microprocessor coupled to said digital-to-analog converter through a bus.
4. The apparatus of claim 2 wherein an input to said digital-to-analog converter has multiple bits and a predetermined number of bits is used to control said mute circuit and a remaining range of the analog-to-digital converter is used to control the video level circuit.
5. The apparatus of claim 1 further comprising a gain control loop, wherein said gain of said gain control loop is controlled by said video level circuit.
6. The apparatus of claim 5 wherein said mute circuit is coupled to said gain control loop.
7. The apparatus of claim 1 wherein said video level circuit comprises:
a buffer circuit;
a DC level shifting circuit coupled to said buffer circuit.
8. The apparatus of claim 1 wherein said mute circuit, when activated, deactivates an IF AGC circuit.
9. The apparatus of claim 1 wherein said mute circuit, when activated, deactivates both an IF AGC circuit and an RF AGC circuit.
10. A method of providing signal alignment in a television receiver comprising the steps of:
providing an IF AGC loop having a level shifting circuit and an IF AGC mute circuit; and
altering the DC level of a video signal within said IF AGC loop in response to a first portion of a control signal; and
deactivating said IF AGC loop in response to a second portion of said control signal.
11. The method of claim 10 further comprising the step of:
generating said control signal from a multi-bit digital signal, where a predetermined number of bits is used to control said mute circuit and a remaining number of bits are used to control said level circuit.
12. The method of claim 10 wherein said deactivating step further comprises deactivating an RF AGC loop.