Rca Inc.

Sarnoff Corporation

Edward Coley Fox

Alvin R Balaban

Charles M Wine

Paul Wallace Lyons

Krishnamurthy Jonnalagadda

Michael Louie Low

Liston Abbott

William E Barnette

A receiver requiring only a single IF SAW filter and IF amplifier receives signals in both analog format and in digital format, such as the NTSC, PAL and SECAM analog television signal formats and the ATSC and DVB digital television signal formats. IF signals from the IF amplifier are sub-sampled to digital signal form and are processed by respective analog format and digital format processors. Control circuitry responsive to the presence of certain unique components of the signals in analog format and digital format determine which of the analog format and digital format processors is producing valid data and selects the valid data to be utilized. In a television receiver, the unique components of the signals may include carrier signals, synchronization signals, pilot signals and symbol timing, and valid data is applied to a television display.

Receiver for analog and digital television signals

A method and apparatus for preserving audio and video presentation synchronization during the splicing operation by selectively deleting, if necessary, an audio/video access unit to avoid overlapping of audio/video frames in the spliced output stream.

Method and apparatus for preserving synchronization of audio and video presentation when splicing transport streams

A method and apparatus for recovering an information carrier which has been transmitted as a sub-carrier in the lower VSB spectral region of a television signal. The invention utilizes a spectral inversion method to shift the data carrier frequency from the normal VSB spectral region to a spectral region normally associated with video information in a standard television signal. The data carrier is then recovered using a standard video demodulator and provided to a data utilization circuit, such as a QPSK demodulator.

Recovering data from a vestigial sideband of a standard television signal

In a capacitance distance sensor apparatus in a focus servo loop for an optical disc playback and record system, stable high servo loop gain and small closed-loop error correction signals are achieved despite surface variations of the disc by compensating for the periodic error command signals generated by the surface variations. A comb filter is provided in the loop tuned to major error component frequencies. The comb filter is formed of a plurality of parallel, bandpass filters that are tuned to frequencies substantially corresponding to the disc rotation frequency and several harmonics thereof. In the distance sensor servo focus control loop, the loop gain can be maintained at a high value to achieve proper beam focus within 0.5 micron (0.5.times.10.sup.-6 meters) for disc surface amplitude variation of three mils (0.0075 centimeters) peak-to-peak.

Compensation apparatus for a servo system with periodic command signals

A peak detector circuit is provided for detecting the maximum excursions of an amplitude varying signal. The circuit includes a network comprising a capacitor serially coupled to a charging impedance and having a time constant suitable for responding to the maximum excursions of the amplitude varying signal. A semiconductor means has an input terminal for receiving the amplitude varying signal and an output terminal coupled to the charging impedance for charging the capacitor toward the maximum excursions of the amplitude varying signal. The semiconductor means exhibits an impedance which is subject to increase with a decrease in current drawn therethrough. A controllable current sink is responsive to the amplitude varying signal at the input terminal of the semiconductor means and is coupled to the output terminal of the semiconductor means for drawing a component of current through the semiconductor means during the charging of the capacitor which is supplemental to the capacitor charging current drawn therethrough. The supplemental current component is of a sufficient magnitude to preclude increase of the impedance exhibited by the semiconductor means during the charging of the capacitor beyond a value which is substantially less than the charging impedance.

Peak detector circuit

Information processing system, for use with a source of carrier waves modulated with audio information, includes in respective audio channels a demodulator and for recovery of the audio information and track-and-hold amplifiers. Separate circuits are provided for detecting carrier drop-outs and impulse noise occurrences. The output of the detecting circuits is utilized to control the operation of the track-and-hold amplifiers to effect a masking of these occurrences. Signal de-emphasis is accomplished in each channel by means of two separate filters respectively arranged to operate on the input and output signal of the track-and-hold amplifier to minimize noise input to the track-and-hold amplifier.

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Cranbury, NJ, United States of America

Edward Coley Fox