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Digital signal

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


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PatentDOI
Danny Thomas Pinckley1
TL;DR: An automatic gain control circuit uses a speech recognizer to obtain smoothautomatic gain control and AGC is not used until it is required (i.e., when speech is present).
Abstract: An automatic gain control circuit uses a speech recognizer to obtain smooth automatic gain control. An analog audio input signal is converted to a digital signal by an analog-to-digital converter and delayed by a delay circuit. A frame power (or alternatively, rectified peak amplitude) detector determines the power of each frame (or alternatively, the rectified peak amplitude) of the audio input signal, after applied to the A/D converter. A linear-to-log converter converts those values to a logarithmic form (for gain control over a broad range of values). A detected speech smoothing circuit smooths the variation in the values determined by the frame power (or peak amplitude) detector. A summer subtracts the output of the detected speech smoothing means from a fixed reference level, and thus obtains an error signal from the desired reference. A gain smoothing circuit smooths the resulting error signal (which is the logarithmically-shaped gain signal). A logarithm-to-linear converter converts the logarithmic gain signal to a linear form; and a multiplier multiplies the input signal by this smoothed gain. In accordance with the invention, a speech recognizer determines whether the audio input signal represents speech. An output of the speech recognizer is used to enable the detected speech smoothing circuit and the gain smoothing means when the audio input signal represents speech. Thus AGC is not used until it is required (i.e., when speech is present).

86 citations

Patent
12 Oct 2006
TL;DR: In this article, a system for transmitting digital information includes a transmitting apparatus (100) for generating an optical signal bearing digital information, a dispersive optical channel (104), and a receiving apparatus (110) for receiving the optical signal.
Abstract: A system (100) for transmitting digital information includes a transmitting apparatus (102) for generating an optical signal bearing digital information, a dispersive optical channel (104), and a receiving apparatus (110) for receiving the optical signal. The dispersive optical channel (104) is disposed to convey the optical signal from the transmitting apparatus (102) to the receiving apparatus (110). The transmitting apparatus includes an encoder (114) for encoding digital information into a series of blocks, each including a plurality of data symbols corresponding with one or more bits of digital information. A signal generator (118) generates a time-varying signal corresponding with each of said blocks. An optical transmitter (136) is arranged to apply the time-varying signal to an optical source (138) to produce an optical signal which includes an optical carrier and substantially only a single information bearing optical sideband in an optical frequency domain, the sideband corresponding with the time-varying signal. The receiving apparatus (110) includes an optical detector (146) for detecting the optical signal to produce a corresponding received time-varying electrical signal. The receiver further includes means (166) for generating a series of received data blocks from the time-varying electrical signal. An equaliser (168) performs an equalisation of received data symbols included in each data block to mitigate the effect of dispersion of the optical channel, thereby enabling the transmitted data symbols to be recovered.

86 citations

Patent
17 Jul 2007
TL;DR: In this paper, the authors proposed an antenna system comprising a digital radio unit (200) connectable to at least one antenna element (220), where the digital radio units consist of: at least 1 micro radio (230) for receiving/sending digital radio signals having a digital down-converter (350) / a digital up-converster (310) and a digital signal converter (234; 235).
Abstract: Antenna system connectable to a base station, the antenna system comprising a digital radio unit (200) connectable to at least one antenna element (220), wherein the digital radio unit (200) comprises: at least one micro radio (230) for receiving/sending digital radio signals having a digital down-converter (350) / a digital up-converter (310) and a digital signal converter (234; 235). The at least one micro radio (230) converts the digital radio signals to analogue RF (radio frequency) signals and vice versa. The at least one micro radio (23) has at least one hub (240) for processing digital radio signals and control signals and for routing said digital radio signals and control signals via at least one serial link (260) and at least one interface (258, 259). The at least one serial link (260) is provided between the at least one hub (240) and the at least one micro radio (230).

86 citations

Proceedings ArticleDOI
07 May 2001
TL;DR: Experiments demonstrating the subliminal channel capacity of the speech data embedding technique developed here, which may design an effective data signal that can be used to hide an arbitrary message in a speech signal.
Abstract: The technique of embedding a digital signal into an audio recording or image using techniques that render the signal imperceptible has received significant attention. Embedding an imperceptible, cryptographically secure signal, or watermark, is seen as a potential mechanism that may be used to prove ownership or detect tampering. While there has been a considerable amount of attention devoted to the techniques of spread-spectrum signaling for use in image and audio watermarking applications, there has only been a limited study for embedding data signals in speech. Speech is an uncharacteristically narrow band signal given the perceptual capabilities of the human hearing system. However, using speech analysis techniques, one may design an effective data signal that can be used to hide an arbitrary message in a speech signal. Also included are experiments demonstrating the subliminal channel capacity of the speech data embedding technique developed here.

86 citations

Patent
Giordano B. Beretta1
29 Oct 1993
TL;DR: A correlated color temperature measuring device for measuring the color temperature of light includes a sensor which individually senses plural light components of light incident thereon and for providing plural corresponding digital color component signals representative thereof, a memory which stores correction data for correcting the plural digital color temperature component signals, and a processor which receives the plural signal from the sensor as discussed by the authors.
Abstract: A correlated color temperature measuring device for measuring the color temperature of light includes a sensor which individually senses plural light components of light incident thereon and for providing plural corresponding digital color component signals representative thereof, a memory which stores correction data for correcting the plural digital color temperature component signals, and a processor which receives the plural digital color component signals from the sensor. The processor accesses the correction data in the memory, corrects the plural color component signals from the sensor based on the correction data and derives a digital signal representative of the color temperature of the incident light. The derived digital signal may be displayed on a digital display or may be outputted on a digital I/O interface in response to a request for digital color temperature information.

86 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239
202225
2021190
2020755
2019942
2018915