摘要 :
The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a...
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The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a rotating target for the next processing. But in this method, scatterers' migration through resolution cells (MTRC) caused by rotational motion is neglected. However in practice, MTRC exists with the improvement of resolution or for big target. For MTRC compensation, a keystone transformation in SAR is used in this paper. Before keystone transformation, it is demanded that the raw data is coherent, while in fact, the ISAR raw data is usually not. So a coherent processing of raw data is proposed. In this paper, the coherent processing of raw data is firstly done and the next step is to correct MTRC. Finally a parameter estimation method of multi-component amplitude modulation and linear frequency modulation (AM-LFM) signal is proposed to estimate the scatterers' instantaneous amplitudes and frequencies, and the range-Instantaneous Doppler (RID) ISAR image is obtained. The effective of this algorithm is testified by the processing of simulation data.
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摘要 :
The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a...
展开
The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a rotating target for the next processing. But in this method, scatterers' migration through resolution cells (MTRC) caused by rotational motion is neglected. However in practice, MTRC exists with the improvement of resolution or for big target. For MTRC compensation, a keystone transformation in SAR is used in this paper. Before keystone transformation, it is demanded that the raw data is coherent, while in fact, the ISAR raw data is usually not. So a coherent processing of raw data is proposed. In this paper, the coherent processing of raw data is firstly done and the next step is to correct MTRC. Finally a parameter estimation method of multi-component amplitude modulation and linear frequency modulation (AM-LFM) signal is proposed to estimate the scatterers' instantaneous amplitudes and frequencies, and the range-Instantaneous Doppler (RID) ISAR image is obtained. The effective of this algorithm is testified by the processing of simulation data.
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摘要 :
The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a...
展开
The general approach to ISAR imaging is range-Doppler (RD) imaging approach. For this approach, the translational motion compensation (TMC) is firstly obtained by envelope alignment and autofocus, so the target can be treated as a rotating target for the next processing. But in this method, scatterers' migration through resolution cells (MTRC) caused by rotational motion is neglected. However in practice, MTRC exists with the improvement of resolution or for big target. For MTRC compensation, a keystone transformation in SAR is used in this paper. Before keystone transformation, it is demanded that the raw data is coherent, while in fact, the ISAR raw data is usually not. So a coherent processing of raw data is proposed. In this paper, the coherent processing of raw data is firstly done and the next step is to correct MTRC. Finally a parameter estimation method of multi-component amplitude modulation and linear frequency modulation (AM-LFM) signal is proposed to estimate the scatterers' instantaneous amplitudes and frequencies, and the Range-Instantaneous Doppler (RID) ISAR image is obtained. The effective of this algorithm is testified by the processing of simulation data.
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摘要 :
The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to devel...
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The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to develop processing approaches that exploit the added degrees of freedom of a spatially diverse formation to resolve inherent ambiguities of this sparse aperture distributed micosateliites radar system. In the paper, a beamform processing method of three-dimensional sparse arrays is proposed to spatially null Doppler ambiguities. This method first filters out each unambiguous frequency point from ambiguous Doppler channels of a few different phase centers by using spatial filter, this processing can be regard as a space-time processing, then combines all unambiguous frequency point to a whole unambiguous Doppler band, after that, does imaging processing. Theoretical derivation, performance analysis, and simulation of this method are discussed in the paper.
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摘要 :
The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to devel...
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The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to develop processing approaches that exploit the added degrees of freedom of a spatially diverse formation to resolve inherent ambiguities of this sparse aperture distributed micosateliites radar system. In the paper, a beamform processing method of three-dimensional sparse arrays is proposed to spatially null Doppler ambiguities. This method first filters out each unambiguous frequency point from ambiguous Doppler channels of a few different phase centers by using spatial filter, this processing can be regard as a space-time processing, then combines all unambiguous frequency point to a whole unambiguous Doppler band, after that, does imaging processing. Theoretical derivation, performance analysis, and simulation of this method are discussed in the paper.
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摘要 :
The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to devel...
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The anntenna area of distributed micosateliites radar system is usually smaller than the minimum SAR antenna area constraint, and there are range-Doppler ambiguities. So one key focus of this signal processing research is to develop processing approaches that exploit the added degrees of freedom of a spatially diverse formation to resolve inherent ambiguities of this sparse aperture distributed micosateliites radar system. This paper proposed a Doppler ambiguity resolving method which makes the Doppler ambiguities null in Doppler domain using spatial filter of multiple phase centres.
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摘要 :
It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and l...
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It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and low rate ADCs performs sampling broadband signal, then presents a novel method of utilizing adaptive beam forming technique to recover complete bandwidth of the broadband signal. Application of this method can implement both low rate sampling and high accuracy; in addition, it is robust to channel delay and other errors. The result of processing the simulated data has verified the effectiveness of this method.
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摘要 :
It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and l...
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It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and low rate ADCs performs sampling broadband signal, then presents a novel method of utilizing adaptive beam forming technique to recover complete bandwidth of the broadband signal. Application of this method can implement both low rate sampling and high accuracy; in addition, it is robust to channel delay and other errors. The result of processing the simulated data has verified the effectiveness of this method.
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摘要 :
It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and l...
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It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and low rate ADCs performs sampling broadband signal, then presents a novel method of utilizing adaptive beam forming technique to recover complete bandwidth of the broadband signal. Application of this method can implement both low rate sampling and high accuracy; in addition, it is robust to channel delay and other errors. The result of processing the simulated data has verified the effectiveness of this method.
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摘要 :
Radar target constant false alarm rate (CFAR) detection in wavelet domain is elementarily investigated in this paper. Theoretical analysis shows that independent and identically distributed Gaussian noise keeps the independence an...
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Radar target constant false alarm rate (CFAR) detection in wavelet domain is elementarily investigated in this paper. Theoretical analysis shows that independent and identically distributed Gaussian noise keeps the independence and variance invariable through the orthogonal wavelet transform. In the proposed detector, orthogonal wavelet transform is applied to radar echo signal and the wavelet coefficients are obtained. And then a squarer detector is utilized. After that, according to the characteristic of Gaussian noise in orthogonal wavelet domain, a cell average-CFAR detector model based on orthogonal wavelet transform is established. The probability equations of false alarm and detection are also deduced, and the influence of the wavelet coefficient length on detection performance is analyzed. Finally, the experiment results demonstrate that the proposed method can detect target under different false alarm rates effectively and adaptively.
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