Abstract: A frequency detector of a phase-lock-loop circuit is used for measuring a frequency error between a frequency of an output signal of an oscillator and a frequency of a synchronizing signal. When the frequency error in each of 32 periods of the synchronizing signal exceeds a predetermined magnitude, the phase-lock-loop circuits begins operating in a coarse frequency correction mode. As long as the 32 periods have not lapsed, the phase-lock-loop circuit operates in an idle mode of operation and the oscillator is not corrected. As a result, during vertical retrace, when equalizing pulses occur, the phase-lock-loop circuit is not disturbed by a large frequency error.

Abstract: A phase-locked-loop circuit includes an oscillator having switched capacitors that are selectively coupled to a positive feedback path of the oscillator in a coarse frequency error correction mode of operation. When the frequency error is small, the circuit operates in a fine error correction mode without varying the selection of the switched reactive elements.

Abstract: A phase detector of a phase-lock-loop circuit measures a phase error between an output signal of an oscillator and a synchronizing signal. When a difference between the phase error that is measured in a pair of horizontal line periods exceeds a first magnitude, that is indicative of phase error inconsistency, the phase of the oscillator output signal is not corrected and the phase-lock-loop circuit operates in an idle mode of operation.

Abstract: In a phase-lock-loop circuit a frequency detector measures a frequency error between an oscillatory signal and a synchronizing signal in alternate horizontal line periods for generating a frequency error indicative signal. The frequency error indicative signal is applied to an oscillator for correcting the frequency error in other alternate horizontal line periods in a manner to prevent frequency error measurement and correction from occurring in the same horizontal line period.

Abstract: A television signal ghost cancellation system is described in which a microprocessor is used to develop a mathematical model of the transmission channel which produced a ghosted video signal. The microprocessor determines the coefficient values and delay values for a digital IIR filter from this model. The system uses the IIR filter to cancel ghost signals from the ghosted video signal. The IIR filter includes circuitry for interpolating between successively delayed sample values to cancel ghost signals which are delayed by a non-integer number of sample periods.

Abstract: A system is disclosed for partially decoding an encoded widescreen, extended definition television signal into a signal that is compatible with existing consumer video cassette recorders (VCRs) and video monitors. The encoded signal is compatible with existing television standards to produce a video image having a conventional 4:3 aspect ratio. Signals representing side panel information, to be appended onto either side of the 4:3 center panel, are encoded in the signal and are not visible in the image produced by a conventional receiver. The disclosed system includes decoding circuitry which recovers the side panel signals, appends them to the center panel signal and changes the time correspondence of the total signal so that it represents an image having a 5:3 aspect ratio. Luminance and chrominance components of the decoded video signal are provided as output signals of the decoder and to input ports of a conventional video cassette recorder (VCR) such as an S-VHS or ED-Beta machine.

Abstract: A television receiver which includes an automatic deghosting system synchronously demodulates IF television signals to generate baseband signals representing the in-phase and quadrature phase modulation components of the IF signals. A signal representing the phase difference between the carrier of the signal as broadcast and the carrier of the received signal, which may include ghosts, is generated from the in-phase and quadrature signals. This signal is applied to circuitry which develops signals proportional to the sine and cosine of the phase angle separating the broadcast carrier phase and the received carrier phase. The demodulated in-phase and quadrature phase baseband signals are multiplied by the sine and cosine signals in a complex multiplier to correct distortion resulting from the synchronous demodulation using the carrier of the received signal.

Abstract: An automatic deghosting system synchronously demodulates IF television signals to generate baseband composite video signals. A strong RF ghost signal having a carrier phase that differs from that of the desired signal may cause demodulation phase errors, causing quadrature distortion in the baseband video signals. The circuitry shown in this disclosure synchronously demodulates the quadrature component of the IF television signals and develops a signal proportional to the difference between the values of the baseband quadrature signal immediately before and immediately after the leading edge of the vertical sync pulse. This signal, which is proportional to the demodulation phase error, is used to control a phase locked loop that regenerates the in-phase and quadrature carrier signals used by the synchronous demodulators to substantially eliminate any demodulation phase error.