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The Over-the-Horizon Radar (OTHR) is an effective approach for long-range target detection. However, most existing OTHR systems resort to receive array with quite large aperture, which makes them difficult to deploy. Based on the small aperture receive array, this paper presents a new architecture of long-range target detection system. The shortage of small aperture receive array on echo signal-to-noise...
In this paper, we study on the blind periodic estimation of the pseudo-noise (PN) sequence in variable-spreading-length (VSL) multi-rate direct-sequence code division multiple access (DS/CDMA) systems. The reprocessing of the power spectrum method which is used to estimate the period of general direct-sequence spread spectrum signals is extended to solve the periodic estimation of the PN sequence...
We introduced a wireless optical communication system in this paper. Through the analysis of two main channels in the system: diffuse channel and light of sight (LOS) channel, we researched the influence of the multipath effect on the optical power distribution of the system and the influence of the SNR of the system under a given transmission rate. The method of reasonable layout of the LED array...
Bit-Interleaved Coded Modulation with iterative decoding (BICM-ID) is a technique with combination of coding and high-order modulation. Its many outstanding merits such as it can advance the coding gain, suit the fading channel and separately design the encoding part and the modulation part, make it a very competitive technology in the new generation wireless transmission system. This paper analyzed...
STSA(symbolic time series analysis) is a effective tool used in many fields to measure randomness and deterministic of nonlinear system. In order to investigate the complex characteristics of radar intrapulse modulation signals in modern electronic warfare, the entropy statistics of STSA is defined in this paper. The symbolic entropy algorithm of STSA based on information theory, chaos time series...
The presence of sensor array errors due to mutual coupling and channel mismatch among array sensors severely degrades the performance of direction-of-arrival (DOA) estimation algorithms. This paper proposes a novel sensor array errors calibration algorithm based on iterative least squares with projection (ILSP) algorithm, which suits for arbitrary array and only needs one auxiliary signal source....
When radar transmits wideband signals, the range resolution is smaller than the size of the target. Then the target is spread in the range dimension and the energy is scattered. In this paper, the characteristic of the echoes for wideband radar is firstly described. Then a new method called segment integrated correlation detection (SICD) is proposed for moving target detection in a wideband radar...
For poor robustness issues of pitch detection of noisy speech, the improved pitch detection method combined with speech enhancement is proposed in this paper. Firstly, in order to reduce background noise and receive the clean speech relatively, we use the multi-band spectral subtraction and the masking properties of human auditory system to work on the noisy speech, and next use the energy and zero-crossing...
For the problem of Direct Sequence spread spectrum unbalance Quadrature Phase Shift Keying (DSSS/UQPSK) signal can't be detected easily, the method of the fourth-order cumulant detection is proposed in this paper. On the basis of the fourth-order cumulant of the Gaussian White Noise is equal to zero, Firstly, the paper analyzes the theory knowledge of direct sequence unbalance QPSK signal and the...
ECG (Electrocardiography) signal is one of important means of clinical diagnosis for heart disease which has great significance in clinical medicine. De-noising is a critical task in the preprocess of ECG signal. This paper proposed a dual thresholding function and a level-dependent threshold estimator by the different thresholds estimated based on wavelet coefficients in different layers. Experiments...
Over the decades, two major methods have been developed to deal with the underdetermined Direction-of-Arrival (DOA) estimation problem where there are more sources than sensors. One is based on the higher-order statistics of the received signals, which needs a plenty number of snapshots to guarantee the estimation accuracy and thus is computational complex. The other relies on the sparsity of sources,...
For the blind estimation problem of period of the PN (Pseudo Noise) code and the combination code (combination of spread spectrum sequence and subcarrier sequence) in BOC (Binary Offset Carrier) signal with the residual carrier in the low SNR (signal-to-noise ratio), the method which combines the reprocessing of the power spectral density with matrix decomposition is developed. Firstly, the reprocessing...
In this paper, the main purpose of our algorithm is to solve the two-dimensional estimation problem under the more practical case of circular and non-circular signals coexist. Firstly, taking advantage of non-circularity properties, we extend the received data matrix to augment the maximum number of detectable signals. Secondly, utilizing unitary extended propagator method (UEPM), we obtained a higher...
As a key point of orthogonal frequency division multiplexing (OFDM) technology, carrier frequency offset (CFO) has a significant effect on OFDM system performance. This paper proposes a CFO estimation method by using complementary sequence (CS) as training sequence. The proposed CS-based method can operate integer CFO and fractional CFO estimations on the basis of the same training sequence. The fractional...
Owing to the frequency-selective fading channel with a carrier frequency of OFDM (orthogonal frequency division multiplexing) signal to noise ratio (SNR) estimation problem, we proposed SNR blind estimation method based on air carrier OFDM system. Due to the inconsistency between the oscillator and the received signal, the received signal will be with a certain deviation. The presence of frequency...
In this paper, we model the magnetic target. Then we use nonlinear least square method to locate the magnetic target and estimate its parameter. The simulation results show that the nonlinear least square method can work well when the signal to noise ratio is greater than 6dB.
Conventional radar recognition methods have low recognition rate and are sensitive to changes in signal to noise ratio. In this paper, a new method of radar emitter recognition signal is proposed. The Wigner trispectrum (WT) is extract from the received signal and simplified into two dimensional characteristic. The resemblance coefficients of the two dimensional characteristic are extracted and used...
Huge structures navigating underwater always have multi radiated noise sources distributed on different part. Therefore, noise source positioning is regarded as the core of noise control. In order to make the measuring system more effective, a new method for underwater near field moving sources is proposed in this paper. The new method establishes a mathematical model based on the correlation between...
The estimation of the a priori signal-to-noise ratio (SNR) is a very significant issue for many speech enhancement algorithms. The widely-used decision-directed (DD) algorithm largely depresses the musical noise, but the estimated a priori SNR suffer from one frame delay which results in the degradation of speech quality. In this paper, we propose a novel algorithm to a priori SNR estimation which...
The snowflake noise can bring many problems to the video detection, so we propose an efficient method based on video surveillance, which is to solve the detection of snowflake noise. This method is based on the basic features of snowflake noise. We extract video frame from the video, pick up the complacent pixel point, and get rid of the edge and some interference factor. Then the intermediate results...
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