Topic
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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Patent•
30 Jan 2004
TL;DR: A digital signal recording disc has a first area storing an audio title set and a second area storing a video title set as discussed by the authors, which is void of a pack of data for playback control.
Abstract: A digital signal recording disc has a first area storing an audio title set. The audio title set has data representing audio information and data representing a still picture. The audio title set is void of a pack of data for playback control. The first area also stores information for managing the audio title set. The digital signal recording disc is void of a second area storing a video title set and information for managing the video title set.
54 citations
Patent•
11 May 2005TL;DR: In this article, the authors propose a method to compensate for the non-linear characteristic of a wideband power amplifier in a transmitter for a communication system, which has the wideband Power Amplifier for amplifying a digital input signal.
Abstract: A method and apparatus compensate for a non-linear characteristic of a wideband power amplifier in a transmitter for a communication system, which has the wideband power amplifier for amplifying a digital input signal. The method involves the steps of (a) generating an address based on the digital input signal, reading a distortion control value corresponding to the address from a look-up table, and applying the read distortion control value to the digital input signal to predistort the digital input signal; (b) frequency up-converting the predistorted signal and amplifying the frequency up-converted signal; (c) frequency down-converting the amplified signal and compensating for a delay of the frequency down-converted signal; and (d) updating a predetermined distortion control value in the look-up table to compensate for an error value generated in the power amplifier and an analog path occurring in steps (b) and (c) based on the compensated signal.
54 citations
Patent•
15 Dec 1997TL;DR: In this article, a delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce effect of fading losses within an enclosed propagation environment, where the carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals.
Abstract: A delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce the effect of fading losses within an enclosed propagation environment. The delay spread is introduced into the signal in several ways. One technique disclosed employs a transmitter (21) with two separate antennas (26, 27) one of which transmits the digital signal and the other of which transmits the same signal after a phase delay (25) has been introduced into the signal. The carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals. In another embodiment, a single transmit antenna (42) is used but the signal is received by two different antennas (43, 44) with the output signal from one of those antennas being phase delayed (45) before combining (46) it with the other prior to processing by the receiver circuitry (47). Phase delay (115) is also introduced at baseband into the signals to be transmitted by rotating the I and Q components of the waveforms before modulation.
54 citations
Patent•
20 Dec 1994TL;DR: An inverse discrete cosine transform (IDCT) implementation specifically for the decompression of JPEG, MPEG and Px64 encoded image and video data uses a preprocessing step embedded in a Huffman decoding process to classify data blocks prior to computing the IDCT.
Abstract: An inverse discrete cosine transform ("IDCT") implementation specifically for the decompression of JPEG, MPEG and Px64 encoded image and video data uses a preprocessing step embedded in a Huffman decoding process to classify data blocks prior to computing the IDCT. The use of data block classification, along with the use of pruned IDCTs appropriate for the specific block class, reduces the total number of multiply and addition operations necessary to decompress an encoded data block, and thereby allows faster data decompression. Synthesis of coefficients suitable for multiplication allows efficient implementation of the novel decompression technique in typical microprocessor architectures, including RISC processor architectures.
54 citations
Patent•
29 Sep 1989
TL;DR: In this paper, the current signal from an infrared radiation sensor comprising a pyroelectric cell was used to detect overheated railroad journal bearings, wheels, and other wheel components on a moving or stationary railroad train.
Abstract: Overheated railroad journal bearings, wheels, and other wheel components on a moving or stationary railroad train are detected by amplifying the current signal from an infrared radiation sensor comprising a pyroelectric cell. A reference temperature is sensed by chopping the incident infrared radiation with an asynchronous shutter that momentarily closes at successive time spacings of shorter duration than the scanning period of the sensor. The amplified signal is converted to a digital signal and processed by a microcontroller and associated hardware and software. The detector automatically and periodically calibrates itself and compensates the temperature signals for any temperature difference between the ambient external temperature and the temperature inside the detector housing. The output signal may be digital or analog.
54 citations