Abstract: A TV circuit for generating a synchronized horizontal frequency signal has an oscillator and a phase discriminator. The discriminator has a current applied to it that is derived from and proportional to a current in the oscillator so as to eliminate the effects of temperature and voltage variations.

Abstract: The television digital time base corrector comprises an analogue to digital converter for receiving a video analogue signal, a store for receiving the successive line information in digital form from the output of the analogue to digital converter, a digital to analogue converter for receiving the stored signal, a read/write control circuit for writing the digital information into said store, an input oscillator for determining the rate of conversion of the analogue signal and the rate of writing the store, and an output oscillator for controlling the rate of reading out of the digital information from the store and the rate of conversion of the digital information in the store. The input oscillator is in the form of a triggered oscillator which is switched on and off in timed relationship with the video sync pulse and/or sub-carrier color burst. The oscillator thus commences its pulse generation at a time which is directly related to the timing of the sync pulse.

Abstract: A voltage controlled crystal oscillator is disclosed suitable to be included in a subcarrier regeneration stage for a color television receiver. The oscillator includes a novel phase shifting network in the feedback loop thereof for maintaining the oscillator in phase synchronism with a received NTSC reference burst signal. The phase shifting network comprises a first differential amplifier being adapted to receive a voltage oscillation signal having a 90.degree. phase lag with respect to the oscillation signal generated by the crystal. The differential outputs from the first differential amplifier are respectively connected to the common terminal of a second differential amplifier and to a phase shifting circuit. The output of the phase shifting circuit is a first current signal having a predetermined phase relation to the input signal applied thereto.

Abstract: The television digital time base corrector for television equipment comprises an analogue to digital converter for receiving a video analogue signal, a store for receiving the successive line information in digital form from the output of the analogue to digital converter, a digital to analogue converter for receiving the stored signal, a read/write control circuit for writing the digital information into the store, an input oscillator for determining the rate of conversion of the analogue signal and the rate of writing into the store and output oscillator for controlling the rate of reading out of the digital information from the store and the rate of conversion of the digital information in the store. The input oscillator is in the form of a triggered oscillator which is switched on and off in time relationship with the video sync pulse and/or sub-carrier color burst, the period of switching on and off and the frequency of the oscillator being dependent upon the duration of the lines.

Abstract: Apparatus and method for providing an automatic frequency tuning system capable of supplying a local oscillator signal with a preselected frequency. The frequency of an output signal of the local oscillator is electronically varied across a frequency region which includes the preselected frequency. The output signal of the local oscillator is combined with the output signal of a reference signal generator. After the combination of the local oscillator signal with the reference oscillator signal produces a preestablished condition which is the result of the local oscillator signal attaining the preselected frequency, the frequency of the local oscillator signal is held constant. The local oscillator signal is thereafter compared to the reference oscillation signal and a change in the local oscillator signal frequency is corrected by means of an automatic frequency control feedback loop containing a discriminator circuit.BACKGROUND OF THE INVENTION1.

Abstract: The invention provides a circuit for centrally generating the horizontal and vertical sweep frequencies in a TV receiver. A central oscillator provides a frequency which is divided to obtain the horizontal frequency. A periodic counter with adjustable final counting value divides the central oscillator frequency to establish a vertical sweep signal. Phase comparators and gate circuits are used to gate the oscillator signal to the periodic counter to synchronize the vertical sweep with the transmitted vertical sync signal.