An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum (DSSS) receivers is proposed and analyzed in this paper. The system consists of two major parts: a phase region estimator ...An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum (DSSS) receivers is proposed and analyzed in this paper. The system consists of two major parts: a phase region estimator and a phase alignment detector. We use an auxiliary sequence to correlate the incoming signal in the phase region estimator. Since the cross-correlation value between the auxiliary sequence and the incoming PN signal has linear magnitude, and can provide the direction for the phase updating, an optimum search algorithm, try and error method, can be adopted to obtain the phase region information of the incoming signal. The mean acquisition time is derived through the signal flow graph theory. The time is compared with that of the conventional serial search scheme, and the results show that the proposed scheme can achieve coarse acquisition significantly faster than the conventional scheme.展开更多
This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) dire...This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.展开更多
An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extr...An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals.展开更多
In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and ...In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and extraction of unsupervised neural networks adequately, in addition to its higher-speed operation ability, successfully solve the difficult problem about PN sequence blind estimation. The theoretic analysis and experimental results show that this approach can work very well on lower SNR input signals.展开更多
Generalized Bent function and generalized Bent function sequences are introduced in this paper.The main performance or these sequences used as SW/SFH(Short Wave/Slow Frequency Hopping) code are studied. And the hardwa...Generalized Bent function and generalized Bent function sequences are introduced in this paper.The main performance or these sequences used as SW/SFH(Short Wave/Slow Frequency Hopping) code are studied. And the hardware circuit and the soflware program flow chart of the SW/SFH PN code generator are also given,which is based on generalized Bent function sequence generator by using a single chip mlcrocomputer.展开更多
A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, w...A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts.展开更多
A scheme for the generation of a pseudo noise(PN)sequence in the optical domain is proposed.The cascaded units of micro-ring resonator(MRR)-based D flip-flop are used to design the device.D flip-flops consist of a sin...A scheme for the generation of a pseudo noise(PN)sequence in the optical domain is proposed.The cascaded units of micro-ring resonator(MRR)-based D flip-flop are used to design the device.D flip-flops consist of a single MRR and share the same optical pump signal.Numerical analysis is performed,and simulated results are discussed.The proposed device can be used as a building block for optical computing and for creating an information processing system.展开更多
The sequential estimation (SE) algorithm has a poor performance in the environment with a low signalto-noise ratio (SNR) and a high bit error rate (BER), especially for unknown initial acquisition sequence. This...The sequential estimation (SE) algorithm has a poor performance in the environment with a low signalto-noise ratio (SNR) and a high bit error rate (BER), especially for unknown initial acquisition sequence. This paper summarizes the conventional sequence acquisition model, and discovers its several problems, which are caused by accumulating sequence innovation to all of the received sequences dispersedly. To solve these problems, the paper presents a new algorithm, CSAS-SA (controllable single accumulated state-sequential acquisition). This algorithm accumulates the sequence innovation to a single appointed sequence state and makes the useful information accumulated effectively. Through simulation, CSAS-SA has a higher probability of success acquisition. When SNR equals -3 dB, the performance can be improved by 70%.展开更多
文摘An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum (DSSS) receivers is proposed and analyzed in this paper. The system consists of two major parts: a phase region estimator and a phase alignment detector. We use an auxiliary sequence to correlate the incoming signal in the phase region estimator. Since the cross-correlation value between the auxiliary sequence and the incoming PN signal has linear magnitude, and can provide the direction for the phase updating, an optimum search algorithm, try and error method, can be adopted to obtain the phase region information of the incoming signal. The mean acquisition time is derived through the signal flow graph theory. The time is compared with that of the conventional serial search scheme, and the results show that the proposed scheme can achieve coarse acquisition significantly faster than the conventional scheme.
基金supported by the National Natural Science Foundation of China (10776040 60602057)+4 种基金Program for New Century Excellent Talents in University (NCET)the Project of Key Laboratory of Signal and Information Processing of Chongqing (CSTC2009CA2003)the Natural Science Foundation of Chongqing Science and Technology Commission (CSTC2009BB2287)the Natural Science Foundation of Chongqing Municipal Education Commission (KJ060509 KJ080517)
文摘This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.
文摘An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals.
文摘In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and extraction of unsupervised neural networks adequately, in addition to its higher-speed operation ability, successfully solve the difficult problem about PN sequence blind estimation. The theoretic analysis and experimental results show that this approach can work very well on lower SNR input signals.
文摘Generalized Bent function and generalized Bent function sequences are introduced in this paper.The main performance or these sequences used as SW/SFH(Short Wave/Slow Frequency Hopping) code are studied. And the hardware circuit and the soflware program flow chart of the SW/SFH PN code generator are also given,which is based on generalized Bent function sequence generator by using a single chip mlcrocomputer.
基金Supported by the Doctoral Program Foundation of Institutions of Higher Education of China (No.20120111120008)State Key Lab of ASIC & System(Fudan University) (No. 11KF001)Special Fund for Doctoral Program (Hefei University of Technology) (No.2011HGBZ0953)
文摘A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts.
文摘A scheme for the generation of a pseudo noise(PN)sequence in the optical domain is proposed.The cascaded units of micro-ring resonator(MRR)-based D flip-flop are used to design the device.D flip-flops consist of a single MRR and share the same optical pump signal.Numerical analysis is performed,and simulated results are discussed.The proposed device can be used as a building block for optical computing and for creating an information processing system.
基金Supported by the Program for New Centery Excellent Talents in University and the National High-Tech Research and Development Program of China (Grant No. 2007AA01Z434)
文摘The sequential estimation (SE) algorithm has a poor performance in the environment with a low signalto-noise ratio (SNR) and a high bit error rate (BER), especially for unknown initial acquisition sequence. This paper summarizes the conventional sequence acquisition model, and discovers its several problems, which are caused by accumulating sequence innovation to all of the received sequences dispersedly. To solve these problems, the paper presents a new algorithm, CSAS-SA (controllable single accumulated state-sequential acquisition). This algorithm accumulates the sequence innovation to a single appointed sequence state and makes the useful information accumulated effectively. Through simulation, CSAS-SA has a higher probability of success acquisition. When SNR equals -3 dB, the performance can be improved by 70%.