An approach is proposed for selecting the thresholds of edge strength maps from their local histograms. This threshold selection technique is based on finding the threshold for small blocks of the edge map. For each b...
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An approach is proposed for selecting the thresholds of edge strength maps from their local histograms. This threshold selection technique is based on finding the threshold for small blocks of the edge map. For each block the threshold is chosen using an iterative procedure. Also, an approach to edge detection based on DPCM image processing is presented. A DPCM coder is used as a method of computing the differential image rather than the conventional edge detection operators. The merits of using the DPCM coder to compute the differential image is that the computations required by the iterative threshold selection technique is reduced considerably.< >
This paper describes two techniques that can be used within the ADPCM decoder in the CT2 (Second Generation Cordless Telephone) handset or base station to detect errors in the radio link without interfering with the o...
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This paper describes two techniques that can be used within the ADPCM decoder in the CT2 (Second Generation Cordless Telephone) handset or base station to detect errors in the radio link without interfering with the operation of the ADPCM voice coder. One technique is based on the reception of illegal values, the other on the detection of unlikely coding sequences.< >
Since a large majority of telecommunication connections now involve digital PCM, the quantisation noise from PCM codecs is of concern to those transmitting data. The authors present the effect on performance of passin...
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Since a large majority of telecommunication connections now involve digital PCM, the quantisation noise from PCM codecs is of concern to those transmitting data. The authors present the effect on performance of passing a modem signal through PCM systems. They also assess the effectiveness of some simple coding schemes in counteracting the quantisation noise produced by PCM codecs.< >
A new, nonlinear, neural network based, predictor has been devised for the encoding of speech data. It may be used in the design of a differential pulse code modulation (DPCM) coder for speech. A hybrid neural network...
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A new, nonlinear, neural network based, predictor has been devised for the encoding of speech data. It may be used in the design of a differential pulse code modulation (DPCM) coder for speech. A hybrid neural network architecture has been employed which combines the perceptron and back-propagation paradigms, thus called the PB-hybrid (PBH). Only two neurons are needed in the backpropagation section, keeping the required overhead modest. This predictor is designed by supervised training, based on a typical sequence of digitised values of samples in a speech frame. Simulation experiments have been carried out using 15 ms frames of 16 kHz speech data. The results obtained for the prediction gain show a 3 dB advantage of the PBH network over the linear predictor.
A one-chip 16 x 16 digital switch (SWEL) is presented, designed for use in a wide variety of applications, ranging from digital mobile radio and satellite applications, to PCM switching systems (ISDN). It provides a c...
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A one-chip 16 x 16 digital switch (SWEL) is presented, designed for use in a wide variety of applications, ranging from digital mobile radio and satellite applications, to PCM switching systems (ISDN). It provides a compact, low-power solution to perform in channel-controlled switching of 64-kb/s or 2-Mb/s channels. Both architecture and design issues are discussed in detail.
The simulator of PCM data stream is an important apparatus. Without an advanced high data rate simulator, were not there a PCM system with advanced performance. After careful study, a simulator in laboratory of PCM st...
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ISBN:
(纸本)1556173296
The simulator of PCM data stream is an important apparatus. Without an advanced high data rate simulator, were not there a PCM system with advanced performance. After careful study, a simulator in laboratory of PCM stream with the data rate up to 30 Mbps is now designed. Our simulator differs from the traditional ones in the design principle and can bring all potentialities into play. It is more powerful in function, easier to test and more accurate in control. In the meanwhile, it can keep compatible with old simulators.
In a PCM-FM-FM/FM modulation scheme, one PCM signal is added to a series of FM subcarrier modulated signals, and the sum is modulated on one FM carrier frequency. After the signal is carrier demodulated at the receive...
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ISBN:
(纸本)1556173296
In a PCM-FM-FM/FM modulation scheme, one PCM signal is added to a series of FM subcarrier modulated signals, and the sum is modulated on one FM carrier frequency. After the signal is carrier demodulated at the receiver and the signals modulating the subcarriers are individually filtered and demodulated, the information carried by the subcarrier frequencies may be distorted or lost due to the interference power of the PCM signal that is passed by the subcarrier signal's bandpass filters. The effect of the interference power may be reduced when the subcarrier frquencies are chosen to coincide with the zero crossing frequencies of the PCM signal. It will be shown that this choice results in a lower interference power when the subcarrier frequencies come between the zero crossings.
This paper presents an overview of a digital PCM adaptive bit synchronizer capable of bit synchronization down to an Eb/No of -20 dB where Eb/No is the energy contrast ratio. The topics addressed include: 1. Functiona...
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ISBN:
(纸本)1556173296
This paper presents an overview of a digital PCM adaptive bit synchronizer capable of bit synchronization down to an Eb/No of -20 dB where Eb/No is the energy contrast ratio. The topics addressed include: 1. Functional block diagrams. 2. Loop bandwidth as a function of synchronization threshold. 3. Accuracy, resolution and stability requirements of the Numerically Controlled Oscillator (NCO) and Loop Filter (LF). 4. Performance data. The purpose of this paper is to highlight the major components of a unit capable of performing this task based on an actual development program.
This paper is a brief final report for researching optimum PCM group synchronization codes. The pattern and the main characteristics of those 34 optimum codes (length N = 31 to 64 bits) are presented. Those optimum co...
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This paper is a brief final report for researching optimum PCM group synchronization codes. The pattern and the main characteristics of those 34 optimum codes (length N = 31 to 64 bits) are presented. Those optimum codes are the newest efforts for the research of the optimum PCM group synchronization codes up to now in the world.
A novel approach is proposed to increase the throughput rate and reduce the hardware cost requirement of the linear systolic matrix-vector multiplication architecture for 2D Fourier transform implementation. This is a...
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A novel approach is proposed to increase the throughput rate and reduce the hardware cost requirement of the linear systolic matrix-vector multiplication architecture for 2D Fourier transform implementation. This is achieved by coding video signal/images more efficiently using 6-bit 1D DPCM coding system prior to processing. It is shown that using 6-bit DPCM processing results in 64% improvement in speed and a significant saving in the hardware cost. The effect of quantisation errors on DPCM video signal/image Fourier transforms is also presented.< >
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