Digital signal

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

Method of digital process variable transmitter calibration and a process variable transmitter system utilizing the same

Abstract: A method of digital process variable transmitter calibration includes the steps of sensing the process variable (PV) to produce an analog output which is converted to a digital signal representation. The digital signal is corrected by a microprocessor using a characterization equation previously individually developed during a manufacturing testing of the process variable transmitter over a predetermined range of environmental stimuli to ascrtain the coefficients for a polynomial in the form of PV=Ao =A1 P+A2 +. . . Ai Pi. Thus, the digital computer produces a process variable representation as a modified digital output. Subsequently, the digital output from the computer is converted to a conventional 4-20 mA analog signal for use as a process control signal. The process variable transmitter apparatus utilizing the aforesaid method includes means for receiving an output from a process variable sensor, an analog-to-digital converter for converting the received output from the sensor to a digital representation, a digital computer, a non-volatile memory for storing an individualized correction equation determined during the manufacturing testing of the transmitter and a digital-to-analog converter for converting the computer output to an analog control signal.

Method and apparatus for digital detection of electromagnetic signal strength and signal direction in metallic pipes and cables

Abstract: A new digital architecture for metallic pipe and cable locators, providing accurate estimation of the fundamental locate parameters, electromagnetic signal strength and signal direction, and utilizing a nested Digital Phase-Locked Loop (DPLL) structure is disclosed. The obstacles to signal direction measurement in low SINR environments using the signal select method are overcome and a more precise phase comparison between the carrier and the FM modulation signals is obtained. The architecture further significantly reduces analog front-end hardware requirements, offers wider resistance to component tolerances, lower calibration and test time, and provides flexible frequency selectivity. Locators according to the present invention provide accurate estimation of the fundamental physical parameters of line location (electromagnetic signal strength and signal direction) in extremely noisy environments, using Digital Signal Processing (DSP) methods.

Rapid-update adaptive channel-equalization filtering for digital radio receivers, such as HDTV receivers

Abstract: In response to a received carrier wave modulated in accordance with a digital signal, a digital radio receiver recovers in digital form a modulating signal that is at times subject to undesirable amounts of multipath distortion This recovered modulating signal is applied as respective input signals to first and second finite-impulse-response (FIR) filters, each of an N-tap type, the taps of which are adaptively weighted The first FIR filter responds to the modulating signal to supply an output signal in which multipath distortion is suppressed The second FIR filter responds to the modulating signal to generate corrections for the tap weights of the first FIR filter, which corrections are generated more rapidly than can be done with a microprocessor of the type commonly known as a "digital signal processor" or "DSP" A digital comparator compares samples of the first FIR filter response to corresponding samples of an ideal response, thereby to generate updated tap weights for the second FIR filter

Systems and methods of waveform and/or information splitting for wireless transmission of information to one or more radioterminals over a plurality of transmission paths and/or system elements

Abstract: Methods of transmitting an information signal in a satellite communications system include splitting the information signal into a first signal component and a second signal component, transmitting the first signal component to a first system element of the satellite communications system, transmitting the second signal component to a second system element of the satellite communications system, combining the first signal component and the second signal component to form a combined signal, and recovering the information signal from the combined signal. Related systems and components are also disclosed.

Computer-controlled uninterruptible power supply

Abstract: A computer-controlled, uninterruptible power supply system is disclosed. The system selectively operates from more than one input source of power, e.g. an AC line input, an external DC input and internal batteries. The system is of the type which utilizes one or more switch mode converters and is well suited for use in computer systems. The switch mode regulator has a PWM clock signal and provides a PWM drive signal. The PWM clock signal frequency is substantially greater than the PWM drive signal frequency. Transferring between the DC power sources is done in a manner substantially transparent to the regulator and the load, generally as follows. A signal indicating a transfer to a selected one of the DC power sources is gated in response to the PWM clock signal to form a first logic signal that is synchronized to the PWM clock signal. The first logic signal is gated in response to the PWM drive signal so as to form a second logic signal that is further synchronized to the PWM drive signal. Finally, the PWM drive signal is gated to a selected switching circuit responsive to the second logic signal, so that transfers between the DC power sources are fully synchronized to the PWM clock signal and to the PWM drive signal.