Applied Spectrum Technologies, Inc.

Other

Wadia Digital Corporation

Minnesota Mining and Manufacturing Company

Charles H Hustig

Donald W Moses

Robert S Bradford

Jeffrey L Ward

Robert W Moses

Wayne P Olson

C Ray Ballard

James M Kresse

Raymond S Miller

Theodore Antonakopoulos

Vassilios Makios

Alan M Doberstein

Robert Moses

James W Kinne

Norman Durkee

James Kinne

Hossein L Najafi

Antonis Kalis

Provided is an antenna system for operating in clear line of sight and obscured line of sight conditions. The antenna system includes multiple antenna elements arranged to provide both space and angle diversity characteristics. The elements are spaced apart so as to provide independence but may have overlapping radiation patterns. Each element includes a main radiation lobe and the elements are arranged so that the main radiation lobes are oriented at diverse angles.

Antenna system

A frequency diversity digital wireless transmission system and method according to which a number of relatively narrow bands are established, each using multiple averaging interpolators. The serial data bits are divided by a predetermined pattern among the frequency bands providing frequency diversity. In response to one or more of the bands being lost to multipath fading or interference, the interpolated signals of the remaining bands are used.

Frequency diversity digital wireless system

A signal processing system comprises inputs for an analog audio signal and a digital data signal. The digital data signal is modulated to an analog data signal in an inaudible frequency band. Filters are used to ensure that the audio signal is restricted to audible frequencies and that the analog data signal is restricted to inaudible frequencies. The two analog signals are then combined into a composite analog signal. The composite signal is stored on a medium such as a compact disc. Filters are used to extract and separate the two analog signals from the composite signal stored on the medium. The analog data signal is demodulated to retrieve the original digital data signal.

System for carrying transparent digital data within an audio signal

The present invention provides an apparatus for decoding and classifying a digital audio input signal and for reconstructing the digital audio input signal, so that when the reconstructed signal is converted to an analog signal by a digital to analog converter ('DAC'), the analog signal can drive a preamplifier, power amplifier or speakers directly. In particular, the present invention proposes a digital filter than can be adapted to have appropriate filtering characteristics based on the signal being filtered. The invention uses a neural network to adjust coefficients of a digital filter, depending on whether the digital audio input signal is more periodic or more aperiodic. If the digital audio input signal is more periodic, the coefficients will configure the digital filter so that the filter has the characteristics of an analog brickwall filter. Whereas if the digital audio input signal is more aperiodic, the coefficients produced by the neural network will configure the digital filter to have more characteristics of an interpolation filter. The neural network is trained to recognize certain periodic and aperiodic signals and to produce digital filter parameters, preferably polynomial coefficients, correspondingly. The coefficients are selected to respond to the pure or blended periodic and aperiodic features of certain archetypal input signals.

Dynamic digital filter using neural networks

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 communications system which enables enhanced services to be provided over cable TV systems. The design of the system is such that amplification is not required. Therefore, two-way transmission is possible on the low band of 'two-way capable' cable systems and intermediate power failures do not affect transmission. Transmission of data takes place in the low band frequency range of five to thirty megahertz. The system design is such that it can withstand over a hundred dB loss between the remote terminal and the head-end. Carrier frequencies, when received, are interleaved for purposes of decoding and microprocessor based controls are used for automatic gain control and error correction. In a preferred embodiment of the invention, two thousand five hundred carriers, each transmitting eight digital data channels of information can be simultaneously transmitted from remote terminals without any effect whatsoever on the TV signals being transmitted at the high band frequencies. The resulting system is a very economical and dependable method to achieve passive transmission of data over cable TV systems.

Passive transmission of data over cable TV systems

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

A circuit for coupling digital or analog data signals to a telephone line. A direct coupled transistorized circuit is disclosed having three different impedance conditions: on-hook, off-hook, and loop-test. Consequently, data can be transmitted regardless of the on-hook or off-hook status of the associated telephone sets and regardless of whether or not the telephone sets are in use. In addition, data transmission can range over a frequency spectrum of approximately d-c to frequencies in the data-over-voice range. Because of the variable bridging impedance, the drive impedance is not too low during on-hook ringing and the circuit need not be disconnected during ringing or testing.

Telephone line interface circuit

A communications system capable of simultaneously transmitting voice and data information. The spectral energy of the data signal is smeared by spreading it in a spectrum with energy packed in the lower frequency range under the conventional voice signal frequency in a manner which complements the standard C-message weighting curve. The use of the spread spectrum technique also eliminates thumping at the data rate since the harmonics that produce thumping are also spread throughout the bandwidth.

Data under voice communications system

A co-channel communications system is disclosed which permits a digital data signal to be simultaneously transmitted with a communications medium signal such as telephone voice or television video. The data signal or signals are converted into very low multifrequency signals consisting of fundamental frequencies and harmonics which span the communications bandwidth. Because a number of frequencies are used for each data signal, the signal level of the data signals can be greatly suppressed relative to the communications medium signal to a level such that there is no perceptible degradation of the telephone voice or television video. Synchronous detectors for each frequency transmitted, including harmonic frequencies, are utilized to recapture and regenerate the data signals transmitted.

Simultaneous transmission of two information signals within a

Circuitry is disclosed for transmitting clock signal information with a transmitted signal. The transmitted signal is obtained by applying non-return to zero input pulse signals, provided at one-half the frequency of the clock signal, with alternate '1' logic and '0' logic signals, which are coincident with the transitions in the pulse signals, to an exclusive-or logic circuit and combining the output of the exclusive-or logic circuit with the alternate '1' and '0' logic signals at an adder circuit. The adder circuit provides an output that is a succession of signals at one-half the frequency of the clock signal with each of the successive signals having an amplitude different than the amplitude of the preceding signal. The logic signals provided to the adder circuit have an amplitude equal to or greater than the output of the exclusive-or logic circuit. Circuitry is also disclosed for recovering the clock information from the signal provided from the adder and for reconstructing the input pulse signals.

Circuitry for transmitting clock information with pulse signals and for

Digital communication system of the type having a commutating N:1 multiplexer and a commutating 1:N demultiplexer. One of the N sources is inverted prior to being applied to the multiplexer. Automatic frame synchronization and detection circuitry is provided which repeatedly monitors the output of the demultiplexer at which the inverted signal is to appear when frame synchronization is present. Such output is monitored for signals of one logic during each monitoring time period to determine whether frame synchronization is present. A signal is obtained by such circuitry when frame synchronization is not present and is used to commutate the demultiplexer a predetermined number of steps whereby frame synchronization is attained.

Growing community of inventors

Hudson, WI, United States of America

Charles H Hustig