Rca Inc.

Other

Sarnoff Corporation

Rca Licensing Corporation

M/a -com, Inc.

Pine Valley Investments, Inc.

Harris Semiconductor Patents Inc.

M/a-com Eurotec, B.v.

Steven A Steckler

Alvin R Balaban

Ronald E Fernsler

Glenn Arthur Reitmeier

Eoin Carey

Saeed Abbasi

Tuan H Bui

Donal Bourke

Alvin Reuben Balaban

Chin Li

An apparatus includes a filter module, an amplification module, and an adjustment signal source. The filter module generates a filtered signal based on a received signal. This filtered signal has a level shift corresponding to a difference between a direct current (DC) level of the filtered signal and a DC level of the received signal. From the filtered signal and an adjustment signal, the amplification module generates an amplified signal. The adjustment signal, which is provided by the adjustment signal source, may control (e.g., diminish) an effect of the level shift on a DC level of the amplified signal.

Signal adjustment techniques

Various techniques for biasing a radio frequency digital-to-analog converter are described. In one embodiment, a baseband processor may comprise a plurality of output drivers to generate a plurality of base currents for biasing a radio frequency digital-to-analog converter. The baseband processor may comprise a serial control interface to generate a programming signal for controlling a relationship among the plurality of base currents. Other embodiments are described and claimed.

Techniques for biasing a radio frequency digital to analog converter

A video processing system that automatically adjusts video processor parameters depending upon the format of a received video signal in, e.g., a television receiver capable of receiving a multiplicity of video formats.

Format-responsive video processing system

A hybrid 2-D digital convolver in a video image processor to enhance or supress image characteristics comprises a rectangular array of delay elements of pixel duration arranged in rows and columns. A digital serial stream of data encoding pixel values of a 2-D image is coupled to successive rows of delay elements of the array in horizontal-line lengths. The pixel values are modified in a multiplier of preselected weight in series with the input of each columnar delay element in a row. An adder connected between pixel delay elements in each row combines weighted inputs and outputs from prior delay elements. The output of the last delay element of each row is combined with the row outputs of prior rows and the output of the adder following the output of the last delay element off the last row forms the processed output of the convolver. The arrangement of adders and delay elements in each row avoids cumulative adder delays and thereby improves image processing efficiency.

Two dimensional hybrid digital convolver

A horizontal phase detector of a television apparatus receives an analog composite video signal that is sampled and digitized at a rate determined in accordance with a clock signal. The leading edge of a simulated sync pulse signal is computed from the digitized signal using interpolation. The phase detector also receives a second signal that is indicative of a transition edge of a horizontal oscillator signal. The timing of the transition edge is contained in first and second signal parts. The first part is a periodic signal having a transition edge coincident with that of the clock signal, and the second part is a skew signal that represents a fraction of the period of the clock signal. The leading edge of the computed sync pulse signal is phase-compared with the oscillator transition edge to generate a phase difference signal for synchronizing horizontal oscillator operation.

Phase detector

A sync separator detects, in a corresponding part of the waveform of a video signal, the occurrence of the trailing edge of a corresponding sync pulse, in accordance with the rate of change of the video signal. Information obtained from the sync tip and the back porch portions of the corresponding sync pulse is used for generating a slice level signal. A comparator responsive to the slice level signal separates a sync signal from the video signal.

Sync separator

A sync separator detects the occurrence of a corresponding sync pulse in a corresponding part of the waveform of a composite video signal. The level of the sync tip is used for updating a slice level signal, provided the level of the sync tip is lower than that of the preceding sync tip signal. A time-out signal is generated at the end of a time-out interval that has elapsed from the last time the sync tip signal was updated, provided the sync tip signal was not updated within such time-out interval. The time-out signal is used for updating the sync tip signal. The sync tip signal is updated according to such sync pulse that occurred during the time-out interval, having the lowest level sync tip. Information obtained from the sync tip and back porch portions of the corresponding sync pulse is used for generating a slice level signal. A comparator responsive to the slice level signal separates a sync signal from the composite video signal.

Sync separator with periodic updating

A digital phase-lock-loop circuit includes a generator that produces a horizontal rate output signal at a controlled frequency and a phase detector responsive to the output signal and to an incoming synchronizing signal. The phase detector is coupled to the generator control port via a loop filter. When the phase between the output signal and the synchronizing signal that synchronizes the phase-lock-loop circuit changes as a result of, for example, head switching in a two-head VTR that supplies the synchronizing signal, a signal representative of such phase change is produced. The phase change representative signal is fed forward to the generator, by bypassing the loop filter of the phase-lock-loop circuit. The phase change representative signal produces an immediate phase shift of the output signal such that the loop filter is not affected by the head switching.

Phase-lock-loop circuit for a television apparatus

A phase locked loop system is described in the context of a digital television receiver. The system includes a band-pass filter which shifts the phase of burst samples provided to it by 33.degree.. This phase shift makes the zero-crossing points of the filtered burst signal coincident with the I color difference signal sampling phase relative to the unfiltered burst signal. The phase locked loop uses a zero-crossing phase detector to develop a control signal for a VCO. The oscillatory signal provided by the VCO has a frequency of, for example, four times the frequency of the burst, but shifted in phase relative to the burst to allow sampling composite video signal coincident with the phase of at least one of the I and Q color difference signals.

Phase locked loop system for providing a phase shifted output signal

An automatic gain control (AGC) circuit is described in the context of a phase locking system in a digital television receiver. The signal produced by the phase locking system is used to develop a sampling clock signal that is locked in frequency and phase to the color reference burst signal component of a color television signal. An AGC detector develops a gain control signal by averaging only those samples which would correspond to the peaks of the burst signal if the sampling clock signal were locked to the burst signal. The gain control signal is applied to a multiplier which increases or decreases the magnitude of the television signal samples to bring the calculated peak amplitude value of the burst signal within a predetermined range. The AGC circuitry interacts with the phase locking system to decrease the lock-up time when there is a relatively large difference in phase between the burst signal and the sampling clock signal.

Phase locked loop system incorporating automatic gain control

A phase detector included in a digital television receiver develops first and second phase error signals based on samples of the color reference burst signal taken from one and two horizontal lines respectively. The first phase error signal is used to attain coarse synchronization between a sampling clock signal and the burst signal. The second phase error signal is used to enhance synchronization accuracy after coarse synchronization has been attained.

Digitally controlled phase locked loop system having coarse and fine

A digital television receiver includes an analog-to-digital converter having a controllable scaling factor and offset. To improve resolution of the digital samples, the scaling factor is increased and the offset is changed when the synchronizing and color reference burst portions of the composite video signal are being converted. In addition, the scaling can be greatly increased at selected times so that the phase of the color reference burst can be more accurately determined.

Digital television receiver with analog-to-digital converter having time

In a television (TV) receiver having digital signal processing in which the video and sound signals are separated in the analog processing circuitry, one analog-to-digital converter (ADC) serves both the video and sound signal paths. The analog video and sound signals are multiplexed into the ADC and are demultiplexed out of the ADC to the digital video processor and to the digital sound processor at predetermined times during each horizontal TV line. In one arrangement, the sound signal conversions are periodically interleaved with the video signal conversions during the horizontal lines. In another arrangement, the sound signal is sampled and stored at normal rate over a horizontal TV line, then converted by the ADC and digitally stored at a higher-than-normal rate during the horizontal blanking interval, and then supplied to the digital sound processor periodically at the normal rate.

Digital television receiver with time-multiplexed analog-to-digital

An analog carrier signal and its sidebands contain modulated information which is to be digitally encoded and processed. Demodulation and digital encoding is accomplished in a single process by an analog-to-digital converter, which samples the analog signals in response to a sampling signal of a frequency which is at least twice the bandwidth of the band of frequencies containing the carrier signal and its information-bearing sidebands. The analog signal samples are digitally encoded, producing a band of digital information signals corresponding to baseband signal components. When used in a television receiver to produce digital signal samples, the band of analog signals may include both sound and picture carriers and their audio and video information. By controlling the phase and frequency of the analog carrier signal in relation to the color subcarrier signal, and deriving the sampling signal from the analog carrier, an ease in video signal demodulation is provided.

Digital television receivers

A circuit for supplying first and second currents to a load comprises two current generators for providing those currents during first and second time intervals and a resistance through which those currents flow. Two control potentials developed by two semiconductor junctions are applied across the resistance. First and second control circuits control the two current generators so that the first and second currents are provided during the first and second time intervals, respectively. The current supply circuit is useful in a multivibrator wherein the timing capacitor thereof is the load to which the first and second currents are supplied.

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Clark, NJ, United States of America

Steven A Steckler