Abstract: An apparatus and method for tuning a filter (11) with oscillator alignment for applications where the filter tuning signal (19, 27) is generated independently of the local oscillator tuning signal and the tuning range is large, for example such as terrestrial and cable TV broadcasting (40 to 860 MHz). The filter being adapted to a filter tuning modulation signal (25) having a first frequency (F1) and a second frequency (F2). Values of the output signal (28) are measured, a first value (S1) at the first frequency, and a second value (S2) at the second frequency, and a comparison signal (26) is generated in comparing the first value and the second value to adjust filter with the tuning control signal in response to the comparison signal, modulation signal and an approximate filter tuning signal to provide a desired signal at the output signal.

Abstract: An apparatus and method for tuning a filter (11) with oscillator alignment for applications where the filter tuning signal (19,27) is generated independently of the local oscillator tuning signal and the tuning range is large, for example such as terrestrial and cable TV broadcasting (40 to 860 MHz). The filter being adapted to a filter tuning modulation signal (25) having a first frequency (F1) and a second frequency (F2). Values of the output signal (28) are measured, a first value (S1) at the first frequency, and a second value (S2) at the second frequency, and a comparison signal (26) is generated in comparing the first value and the second value to adjust filter with the tuning control signal in response to the comparison signal, modulation signal and an approximate filter tuning signal to provide a desired signal at the output signal.

Abstract: A television vertical timebase circuit includes an arrangement (10, 25, 30, 35, 40, 45) for generating a vertical ramp voltage of first and second slopes corresponding to 4:3 and 16:9 aspect ratios. An arrangement (50,55,65) adds a predetermined voltage to a predetermined portion of the 16:9 ratio ramp voltage such that unwanted visible signals are positioned outside the visible screen area when displaying 16:9 aspect ratio pictures.

Abstract: A limiter device essentially includes a comparator connected to a capacitor charged by a current proportional to the beam current and short-circuited by pulses during one line just after the frame return pulses. This comparator receives a threshold voltage and its output is connected to a capacitor connected to another reference voltage, and this comparator is validated by the frame return pulses.

Abstract: A frequency control apparatus automatically sets minimum and maximum reference frequencies (f.sub.min and f.sub.max) of a frequency modulated video luminance signal. An insertion circuit receives first and second reference voltages corresponding to f.sub.min and f.sub.max output from an AGC amplifier of a video tape recorder, wherein f.sub.min and f.sub.max are synchronized with first and second control signals. A discriminator receives one of the reference frequencies, f.sub.min or f.sub.max, together with the frequency modulated video signal from a voltage controlled oscillator of the video tape recorder and generates two voltage levels related to the input frequencies. A comparator receives one of the two voltage levels from the discriminator, generating a difference voltage corresponding to the difference between the two input voltage levels.

Abstract: A voltage-controlled oscillator in which a phase shifter is connected to a ceramic piezoelectric resonator. The phase shifter has a first circuit branch containing an amplifier. A second circuit branch is connected in parallel with the first circuit branch and includes a low-pass filter connected in series with a controllable amplifier and switch. The output of the controllable amplifier is applied to a first input of the switch, and a source of reference potential is connected to a second input of that switch. The switch has an output connected to a summing element at a first input of the summing element. A second input of that summing element is connected to the amplifier in the first circuit branch. The output of the summing element is fed back to the ceramic piezoelectric resonator.

Abstract: In a multiple reference frequency generator, instead of using a quartz crystal for each of the accurate frequencies to be produced, a single quartz crystal is used together with a current controlled oscillator (ICO) and a phase loop comprising a phase comparator (PHC) and a control current generator (GC). The current generator provides a current varying as a function of a voltage and inversely proportional to a resistor value. In a first step, the phase loop causes the oscillator to oscillate at a frequency F0 and the resistor has a value R0. In a second phase, the loop is opened and the resistor is given a value R1 causing the oscillator to oscillate at a frequency F1=F0.times.R0/R1.

Abstract: An automatic gain control device for video signals in the form of an integrated circuit uses a loop comprising comparators (3, 4) for comparing the video signal to various thresholds. Up-down counters and driving circuit (5) up-down the comparison output signals, so that, in connection with the comparators output signals, different time constants are obtained to control the gain of an input circuit.

Abstract: The present invention relates to chrominance decoding circuits and more particularly to a novel circuit for demodulating chrominance signals, B-Y or R-Y. This circuit comprises, connected in series, a multiplier multiplying the U or V-modulated chrominance signal by itself, a filter giving at the output the square (B-Y).sup.2 or (R-Y).sup.2 of the chrominance signal, a device for extracting the square root giving an absolute value .tbd.B-Y.tbd. or .tbd.R-Y.tbd. of the chrominance signal, and a multiplier multiplying said absolute value by the sign of the chrominance signal B-Y or R-Y to obtain at the output said chrominance signal, B-Y or R-Y.

Abstract: A conventional phase locking loop for locking a local oscillator in phase and frequency to a color burst signal in a television system requires a highly stable (i.e. crystal controlled) oscillator whose free running frequency must be individually adjusted to be as close as possible to the desired frequency. The present invention enables such adjustment to take place automatically in operation rather than as a separate manufacturing step. The output from the oscillator is compared in phase with the color burst signal to which it is to be locked. The output from the phase comparator is applied to one input of a differential amplifier whose output constitutes an error signal for application to a frequency controlling input of the oscillator. The error signal is also applied to a threshold control circuit which causes an up/down counter to count up or down when the error signal lies outside a predetermined range.

Abstract: The present invention provides a matching circuit for connecting a chrominance decoding integrated circuit normally connected by terminals to a conventional analog delay line so as to make it compatible with a digital delay line. This matching circuit comprises a switch connecting alternately each of the outputs of the integrated circuit to an analog-digital convertor connected to a digital delay line, to a digital-analog convertor, then to a switch routing the signal alternately to each of the two summators whose other inputs receive directly the output of the integrated circuit. The summators supply then respectively the chrominance signals R-Y and B-Y.