Minnesota Mining and Manufacturing Company

Applied Spectrum Technologies, Inc.

Wadia Digital Corporation

Robert S Bradford

Donald W Moses

Charles H Hustig

Jeffrey L Ward

Wayne P Olson

Robert W Moses

James M Kresse

Raymond S Miller

Marshall R Brookhart

Bennett G Dy

Richard D Ebbinga

Peter Amass

James W Kinne

Robert Moses

Alan M Doberstein

Stick figure toy

A direct power output digital to analog conversion of digital audio signals operates to directly convert digital audio signals into an analog power audio output signal capable of driving a speaker, such that there is no need for further amplification or modification of the audio output signal after the direct power output digital to analog conversion of the digital audio signals. The direct power output digital to analog conversion incorporates a digital-to-analog converter within the same feedback circuit as a current-to-voltage power amplifier by using a single resistive feedback network to supply the feedback signal from the output terminal of the current-to-voltage power amplifier to the summing junction of the same current-to-voltage power amplifier.

Direct power output digital to analog conversion of digital audio signals

A method and system is provided for a digital audio system to reconstruct a digital audio signal using time domain interpolation and direct power digital-to-analog conversion. A signal processor performs the time domain interpolation on an original digital audio signal to allow for the proper recreation of the original audio signal and a direct power output digital-to-analog converter generates an analog power audio output signal from the interpolated digital audio signal that can directly drive a speaker to produce the sound waves represented by the audio output signal. The signal processor and direct power output digital-to-analog converter allow a digital audio system to more precisely reconstruct an analog power output audio signal from a digital audio signal such that there is no need for further amplification of the audio output signal and such that there will be no perceptible difference between the reconstructed digital signal and the original analog signal.

Method and system for time domain interpolation of digital audio signals

The data telemetry system disclosed is a complete data communications systems suitable for use by utilities such as electric companies, gas companies and water companies which can be used for meter reading and load management at individual subscribers premises. Elements of the system can also be used as a power load carrier in a premise specific local area network (LAN). With the system is disclosed, all 10,000 subscribers per exchange can be serviced. It will be understood that data can be multiplexed between a central office location and remote subscribers for any suitable purpose with the data system as disclosed. A packet switching structure is disclosed having eight to thirty-two bytes in the data message. This packet is routed between the utility and remote subscriber with routing headers being added and deleted as required by the network modules. Each successive layer of the multiplexing and switching hierarchy submultiplies the aggregate 10,000 channel capacity into fewer channels. Both time and space division switching and multiplexing are used.

Bi-directional data telemetry system

A high speed and relatively error free communications system is disclosed which enables the high speed transmission of data at a 19.2 kilobit per second rate. The data is transmitted over the same communications medium as voice transmissions, the data transmission being virtually imperceptible to the user of the analog telephone system. Connection to and from the data terminals is made through an RS232C interface. A spread spectrum technique is utilized which 'whitens' the signals of the data terminal regardless of whether the terminal is idle, transmitting or receiving data. Virtual error free transmission is achieved by interleaving bits, so that noise does not destroy the data, and by error detection and correction techniques which assure that the data, as received, is identical to that transmitted. By using a variable pseudo random code, privacy of data communications are enhanced and cross-talk is substantially eliminated. The resulting system is one that can use a single twisted pair wire for transmission and is capable of transmitting data at a high rate of speed while leaving the analog voice transmission resident and unaffected on the line.

Data and voice communications system

An automatic track following feature for use with a helical video recorder is disclosed which enables reproduction of video fields at normal speeds, fast and slow forward and reverse speeds, and at stop motion, wherein a mechanism for moving a playback head transverse to the helical tracks on a magnetic tape is provided in order to enable the head to remain centered on the track regardless of tape speeds and directions of movement. A head position control signal is generated for driving the head positioning mechanism based on a comparison of a signal based on the instantaneous tape speed with a reference speed indicating signal.

Automatic track following feature for helical video recorder

A device for recording portions of the signals on the tape in one or more master cassettes in a desired sequence on the tape in a copy cassette. The device includes two cassette stations each including an electronically operated drive mechanism for driving the tape in a cassette at the station in either a forward or reverse direction past a record and playback head. Each station includes means for cycling the drive mechanism between forward and reverse to repetitively play a short segment of the tape in a cassette at the station, and a manually operated control for incrementally changing the segment of the tape played in each repeat cycle. By these controls an operator selects a segment of the tape in a cassette on which signals are to be copied, which segment has an end point at which signals to be added to the tape should start, and selects a segment of a tape in a master cassette from which signals are to be copied which segment has the same beginning point as the signals to be copied. Means are provided for then recording the signals from the master tape onto the copy tape with the signals at the beginning point on the master tape being recorded essentially at the end point on the copy tape.

Compiling device with manually varied automatic location determination

A video compensation network is disclosed in which the pedestal level and the peak white level of a composite video signal are automatically maintained within predetermined limits. The network includes two digital/feedback loops for independently detecting and generating correction signals which are used to control the respective pedestal and peak white levels. The feedback loops are activated to make incremental adjustments to the two levels once per video field.

Growing community of inventors

Woodland Hills, CA, United States of America

Robert S Bradford