Digital signal

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

Correcting non-uniformity in displays

Abstract: In calibrating displays, analog information may be converted into digital information to control the display. The requirements of the analog to digital converter may be decreased by decreasing the necessary dynamic range for the analog to digital converter. This may be done by developing a first calibration signal indicative of a first plurality of pixels of the display and developing a second calibration signal indicative of a second plurality of the display. The first and second signals may be subtracted from each other and that signal may then be converted to a digital signal with reduced dynamic range requirements for the analog to digital converter.

Method and device for estimating transmitted signals in a receiver in digital signal transmission operations

Abstract: In a digital signal transmission system, a receiver receives a signal, wherein the signal bandwidth of the system exceeds the system symbol rate. A correlation and sampling circuit receives a baseband signal, samples the signal eight times per symbol time, correlates, generates a channel estimate and down-samples the sampled signal to form an observed signal. This signal is filtered in a prefilter, whose output is sampled at symbol rate and the obtained signal is delivered to a channel equalizer which performs a viterbi algorithm with non-quadratic metric calculation and generates estimated symbols. A channel estimation filter receives a symbol sequence which contains alternate zero-value symbols and the estimated symbols and generates an estimated signal. An error signal is generated and used to adapt the channel estimate and also to generate weight factors. The coefficients of the prefilter are generated as a function of the channel estimate and the weight factors. Coefficients are generated in a metric calculation filter, by convolving the channel estimate with the prefilter and are used to generate the estimated symbols. The transmission channel, excluding the prefilter, is estimated explicitly so as to enable fast channel changes to be followed. The use of the weight factors enables a short channel estimate to be used. The insertion of the zero-value symbols simplifies adaptation of the channel estimate.

Portable information terminal apparatus having image processing function

Abstract: A portable terminal apparatus provided with an image processing function permitting automatic image-pickup without manual focusing which includes an optical system for forming an optical image of a surface of a subject, a two-dimensional photoelectric conversion element for performing photoelectric conversion onto the formed optical image, a signal conversion device for converting an output signal of the photoelectric conversion element into a digital signal, a memory device for temporarily storing the two-dimensional image signal digitized by the signal conversion device, a subject position detecting device storing the optimum image-formation distance of the optical system in advance and for detecting the distance between the subject and the optical system, and an image inputting device including an electronic shutter device which supplies a video signal on the two-dimensional photoelectric conversion element to the memory device to hold the video signal in the memory device instantaneously when the subject position detecting device detects that the subject is located at an image-forming distance.

Reference-free clock generation and data recovery PLL

Abstract: An apparatus comprising a first circuit, a second circuit, and a logic circuit. The first circuit may be configured to generate one or more first control signals having a first data rate in response to an input signal having a second data rate and a clock signal having the first data rate. The second circuit may be configured to generate one or more second control signals in response to the input signal and the clock signal. The first logic circuit may be configured to generate the clock signal in response to the one or more first control signals, the one or more second control signals and a third control signal.

The effect of quantization in a digital signal component separator for LINC transmitters

Abstract: Spectrally efficient modulation schemes have been chosen for the second generation of cellular systems in the United States and Japan, as well as for private mobile radio (PMR) systems This paper analyzes the effect of quantization in a digital signal component separator (SCS) for linear amplification with nonlinear components (LINC) transmitters The analysis relies on the fact that the two signal components can be obtained as the source signal plus/minus a signal in quadrature to the source signal The equations derived are vital because they allow the designer to optimize digital signal processor (DSP) power consumption and bandwidth The word lengths that are required for the source signal and the quadrature signal can be calculated from the amplifier gain characteristic, the probability density function for the modulation scheme, and the specified adjacent channel interference (ACI) The validity of the analysis has been verified by means of simulations