Digital signal

About: Digital signal is a research topic. Over the lifetime, 44213 publications have been published within this topic receiving 345279 citations.

Two wire voice and data subscriber loop

Abstract: A circuit for transmitting both voice and data at the same time between a subscriber's set and a switching exchange via a bidirectional two wire link The invention is comprised of a subscriber's set adapted to generate and receive baseband voice signals and data signals, a circuit for 100% amplitude modulating the generated data signal on a carrier signal having its lowest sideband after filtering above the voice signal base band, a circuit for applying the voice signals and modulated carrier to a two-wire subscriber's line, a circuit for separating the voice signals and modulated carrier, and a circuit for demodulating the digital signal and applying the digital signal to control circuits of a switching exchange Voice signals are applied to voice handling circuits such as the voice switching circuits of the switching machine

Digital network synchronization

Abstract: With respect to network timing, the introduction of SONET equipment into the public network offers both problems and opportunities. Wide-scale deployment of SONET equipment and the use of SONET line timing for reference distribution will eventually provide improved timing performance in terms of both wander and jitter. One of the main motivations for developing the SONET architecture was to establish standards for interconnecting optical transmission equipment from different suppliers. In the process of establishing the SONET standard other (e.g. synchronization) technical issues were addressed. The article compares the existing (asynchronous) network architecture with the new (synchronous) architecture in terms of their respective performance in transporting the clock rates of tributary digital signals. Of primary interest is the timing quality of a first level digital signal such as the North American DS1 signal or the ITU-T (formerly CCITT) El signal. Although the new architecture offers eventual promise in solving numerous timing and interfacing problems for such tributary signals, the new equipment must necessarily co-exist and inter-operate with the existing facilities. Thus, another major topic of the article concerns the performance of interim networks with mixtures of asynchronous and synchronous multiplexing. >

Digital signal processor exciter

Abstract: A digital exciter (30) for selectively modulating digital or analog input data. The digital exciter includes a digital signal modulator (32) and a digital quadrature modulator (DQM) (36) comprising two digital signal processors (DSPs). The signal modulator is controlled by a control (40). An operator can selectively determine whether the digital exciter is used for modulating either two level or four level NRZ digital data and whether the device is to provide linear modulation or frequency modulation (FM) of the input signal. An interpolator (38) interpolates a 66-2/3 kHz timer interrupt rate used in the signal modulator to a 400 kHz rate, thereby reducing the processing load on the DSP comprising the DQM by simplifying the sine and cosine values used in the quadrature modulation. An operator can select from among a plurality of operating parameters on a menu for controlling the signal modulator, either from a local or a remote video display terminal (VDT).

Enhancing security and efficiency of wireless communications through structural embedding

Abstract: By embedding as a Physical Layer (PHY) Applique patterns (time, frequency, tone multiplexed, control signal, explicit network authentication, projective, other, or combined) on wireless electronic communications network (WECN) digital signal packets, and using a QRD-based auto-SCORE adaptation algorithm to maximize the signal-to-interference-and-noise ratio (SINR) attainable by multielement arrays over very small time-bandwidth products, differentiation and detection of signals from environmental noise (particularly from other or non-network signals) can be improved, allowing more compressed, secure, efficient network operations. By projecting the signal embedding onto a known linear subspace and using integrated transmit/receive structures, packet detection algorithms, and blind array adaptation algorithms, the WECN processes the data received with constant false-alarm rate, generalized, maximum-likelihood detectors and multilink signal estimation algorithms, based only on knowledge of the embedding pattern used at the transmit node. The resultant system provides PHY information-assured (PHY-IA) data transmission with improved network efficiency and security.

Well logging system

Abstract: A well logging system includes a logging tool adapted to be passed through a borehole traversing an earth formation. The logging tool contains a sensor sensing a condition of the earth formation and providing electrical pulses corresponding in number and peak amplitude to the sensed condition. A first electrical pulse from the sensor occurring during each predetermined time period of a plurality of predetermined time periods, is stretched and then converted to parallel digital signals. A register receives the parallel digital signals and provides a serial digital signal in response to the shift pulses. A network provides an electrical synchronization pulse each time period prior to the occurrence of the shift pulses. A light emitting diode converts the synchronization pulses and the serial digital signals to corresponding light pulses. A cable including a fiber optic conductor transmits the light pulses uphole to the surface. Surface electronics includes a light-to-electrical converter for providing corresponding electrical pulses in accordance with the light pulses, so that the light-to-electrical converter provides a synchronization pulse followed by a serial digital signal each time period. Another circuit provides a set of shift pulses in response to the synchronizing pulse from the light-to-electrical converter, and an output circuit provides parallel output digital signals corresponding to the sensed condition in accordance with the shift pulses and the serial digital signals from the light-to-electrical converter.