Application of Keystone transform and MDCFT in long term coherent integration

2012 ◽  
Author(s):  
Lei Yi ◽  
Lixiao Zhan ◽  
Ziyue Tang ◽  
Zhenbo Zhu
Keyword(s):  
Keystone Transform ◽  
Coherent Integration

scholarly journals A BeiDou Signal Acquisition Approach Using Variable Length Data Accumulation Based on Signal Delay and Multiplication

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1309 ◽  
Author(s):  
Menghuan Yang ◽  
Hong Wu ◽  
Qiqi Wang ◽  
Yingxin Zhao ◽  
Zhiyang Liu
Keyword(s):  
Doppler Frequency ◽  
Variable Length ◽  
Signal Acquisition ◽  
Noise Power ◽  
Signal Delay ◽  
Coherent Integration ◽  
Transition Problem ◽  
Data Accumulation ◽  
Length Data

The secondary modulation with the Neumann-Hoffman code increases the possibility of bit sign transition. Unlike other GNSS signals, there is no pilot component for synchronization in BeiDou B1/B3 signals, which increases the complexity in acquisition. A previous study has shown that the delay and multiplication (DAM) method is able to eliminate the bit sign transition problem, but it only applies to pretty strong signals. In this paper, a DAM-based BeiDou signal acquisition approach, called variable length data accumulation (VLDA), is proposed to acquire weak satellite signals. Firstly, the performance of DAM method versus the different delays is analyzed. The DAM operation not only eliminates bit sign transition, but it also increases noise power. Secondly, long-term signal is periodically accumulated to improve signal intensity in order to acquire weak signals. While considering the Doppler frequency shift of ranging codes, the signal length must be compensated before accumulating long-term signal. Finally, the fast-Fourier-transform based parallel code phase algorithm are used for acquisition. The simulation results indicate that the proposed VLDA method has better acquisition sensitivity than traditional non-coherent integration method under the same calculation amount. The VLDA method only requires approximately 27.5% of calculations to achieve the same acquisition sensitivity (35 dBHz). What is more, the actual experimental results verify the feasibility of the VLDA method. It can be concluded that the proposed approach is an effective and feasible method for solving the bit sign transition problem.

scholarly journals ISAR Autofocus Imaging Algorithm for Maneuvering Targets Based on Phase Retrieval and Keystone Transform

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Hongyin Shi ◽  
Ting Yang ◽  
Yue Liu ◽  
Jingjing Si
Keyword(s):  
Rotational Motion ◽  
Phase Retrieval ◽  
Translational Motion ◽  
Retrieval Algorithm ◽  
Imaging Method ◽  
Keystone Transform ◽  
Maneuvering Targets ◽  
Coherent Integration ◽  
Motion Parameters ◽  
Phase Retrieval Algorithm

In the current scenario of high-range resolution radar and noncooperative target, the rotational motion parameters of the target are unknown and migration through resolution cells (MTRC) is apparent in the obtained inverse synthetic aperture radar (ISAR)images, in both slant-range and cross-range directions. In the case of the high-speed maneuvering target with a small value of rotation, the phase retrieval algorithm can be applied to compensate for the translational motion to form an autofocusing image. However, when the target has a relatively large rotation angle during the coherent integration time, phase retrieval method cannot get an acceptable image for viewing and analysis as the location of the scatterer will not be true due to the Doppler shift imposed by the target’s rotational motion. In this paper, a novel ISAR imaging method for maneuvering targets based on phase retrieval and keystone transform is proposed, which can effectively solve the above problems. First, the keystone transform is used to solve the MTRC effects caused by the rotation component. Next, phase errors caused by the remaining translational motion will be removed by employing phase retrieval algorithm, allowing the scatterers are always kept in their range cells. Finally, the Doppler frequency shifts of scatterers will be time invariant in the phase of the received signal. Furthermore, this approach does not need to estimate the motion parameters of the target, which simplifies the processing steps. The simulated results demonstrate the validity of this method.

scholarly journals Generalized Dechirp-Keystone Transform for Radar High-Speed Maneuvering Target Detection and Localization

2021 ◽  
Vol 13 (17) ◽  
pp. 3367
Author(s):  
Jibin Zheng ◽  
Kangle Zhu ◽  
Zhiyong Niu ◽  
Hongwei Liu ◽  
Qing Huo Liu
Keyword(s):  
Target Detection ◽  
High Speed ◽  
Computational Cost ◽  
Noise Performance ◽  
Maneuvering Target ◽  
Keystone Transform ◽  
Coherent Integration ◽  
Range Function ◽  
Long Time ◽  
Detection And Localization

The multivariate range function of the high-speed maneuvering target induces modulations on both the envelop and phase, i.e., the range cell migration (RCM) and Doppler frequency migration (DFM) which degrade the long-time coherent integration used for detection and localization. To solve this problem, many long-time coherent integration methods have been proposed. Based on mechanisms of typical methods, this paper names two signal processing modes, i.e., processing unification (PU) mode and processing separation (PS) mode, and presents their general forms. Thereafter, based on the principle of the PS mode, a novel long-time coherent integration method, known as the generalized dechirp-keystone transform (GDKT), is proposed for radar high-speed maneuvering target detection and localization. The computational cost, energy integration, peak-to-sidelobe level (PSL), resolution, and anti-noise performance of the GDKT are analyzed and compared with those of the maximum likelihood estimation (MLE) method and keystone transform-dechirp (KTD) method. With mathematical analyses and numerical simulations, we validate two main superiorities of the GDKT, including (1) the statistically optimal anti-noise performance, and (2) the low computational cost. The real radar data is also used to validate the GDKT. It is worthwhile noting that, based on closed analytical formulae of the MLE method, KTD method, and GDKT, several doubts in radar high-speed maneuvering target detection and localization are mathematically interpreted, such as the blind speed sidelobe (BSSL) and the relationship between the PU and PS modes.

Dim Moving Target’s Detection Based on Keystone Transform

2013 ◽  
Vol 303-306 ◽  
pp. 986-990
Author(s):  
Yun Fei Guo ◽  
Ting Ting Feng ◽  
Xin Liu ◽  
Kong Shuai Fan
Keyword(s):  
Detection System ◽  
Integration Time ◽  
Integration Algorithm ◽  
Keystone Transform ◽  
System A ◽  
Coherent Integration ◽  
Integration Period ◽  
Long Time ◽  
Integration Effect ◽  
Range Migration

For the problem of weak target’s detection under lower signal noise ratio in radar detection system, a key technique is to enhance target echo energy by long time coherent integration. During the integration period, the target may migrate across radar range cells with integration time increasing. Direct coherent integration will lead to echo energy spread in range cells and deteriorate integration effect. A coherent integration algorithm based on a modified keystone transform is proposed in this paper. It can correct range migration caused by the radial velocity of the moving target before coherent integration. Simulation result shows that the proposed algorithm can correct range migration efficiently and improve coherent integration capability.

Sign in / Sign up

Export Citation Format

Share Document