Abstract: A controller controls the automatic positioning of an antenna. The controller is arranged to position the antenna dependent upon a channel selected by a user, a location of a receiver tuned to the selected channel, and a location of a source of a signal associated with the selected channel.

Abstract: A television receiver includes a tuner for receiving either analog or digital signals. Separate analog and digital demodulators are selectively coupled to the tuner through an RF switch that is controlled by the signal from a sync detector in the output of the analog demodulator. The selected one of the demodulators develops an AGC signal that is coupled to the tuner through a current mirror. Operating potential for the demodulators is coupled through the RF switch so that the oscillator in the non-selected demodulator is disabled and precluded from interfering with the oscillator in the enabled demodulator.

Abstract: A television receiver includes a tuner for receiving either analog or digital signals. Separate analog and digital demodulators are selectively coupled to the tuner through an RF switch that is controlled by a sync detector in the output of the analog demodulator. The selected one of the demodulators develops an AGC signal that is coupled to the tuner through the RF switch. In one embodiment, a two pole RF switch is used with one pole switching the IF signal and the other pole switching the AGC signal In another embodiment, a single pole RF switch is used with the tuner signal and the AGC signal being multiplexed through the switch. This is accomplished by the provision of a high frequency path and a low frequency path between each of the RF switch and the tuner, the RF switch and the analog demodulator, and the RF switch and the digital demodulator.

Abstract: A cable ready television receiver includes a set back decoder that communicates with the microprocessor in the television receiver via its own microprocessor. A synchronous demodulator in the television receiver is operated normally for unscrambled television signals and is operated to quadrature demodulate scrambled television signals. The quadrature demodulation develops only high frequency video, modulated chroma, FM modulated audio and DC. The demodulator output is applied to the audio circuit and to the AGC circuit in the television receiver. A descrambler in the decoder develops the video signal for application to the video circuitry in the television receiver.

Abstract: A cable-ready television receiver including a tuner switchable between cable and off-air signals has an LC trap tuned to the audio carrier frequency coupled between the tuner and a SAW IF amplifier. The trap includes a varactor diode that, when it exhibits a large capacitance, effectively disables the trap. This occurs when the receiver is used with cable signals. In the event the receiver is used for off-air signals, the voltage applied to the varactor diode causes it to exhibit a much smaller capacitance which effectively enables the trap.

Abstract: A TV SAP/stereo audio system includes a DC switch for selectively coupling the output of a stereo decoder and the output of a SAP detector to a stereo amplifier. A DC voltage, representative of the SAP carrier level, is developed and applied to a pair of threshold transistors. The lower threshold transistor is driven conductive when the DC voltage is below a first voltage and the upper threshold transistor is driven conductive when the DC voltage is above a second voltage. The threshold voltages are established by a pair of voltage dividers. A SAP control transistor is coupled to the collectors of the threshold transistors and is driven conductive when either threshold transistor is in conduction. The SAP control transistor is connected to the DC switch and prevents coupling of the SAP detector output to the stereo amplifier when it is conducting.

Abstract: A controller controls the automatic positioning of an antenna. The controller is arranged to position the antenna dependent upon a channel selected by a user, a location of a receiver tuned to the selected channel, and a location of a source of a signal associated with the selected channel.