Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar
The GNSS-S radar utilizes the signals of a global navigation satellite system (GNSS) to carry out target detection. Due to the very low power of GNSS signals, long-term accumulation is needed to improve the gain of the echo signals. However, when it is used for moving object detection, the random mo...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-09-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/18/4519 |
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| author | Wenning Gao Fuzhan Yue Zhenghuan Xia Xin Liu Zhilong Zhao Yao Zhang Zongqiang Liu |
| author_facet | Wenning Gao Fuzhan Yue Zhenghuan Xia Xin Liu Zhilong Zhao Yao Zhang Zongqiang Liu |
| author_sort | Wenning Gao |
| collection | DOAJ |
| description | The GNSS-S radar utilizes the signals of a global navigation satellite system (GNSS) to carry out target detection. Due to the very low power of GNSS signals, long-term accumulation is needed to improve the gain of the echo signals. However, when it is used for moving object detection, the random movement of the target will cause residual Doppler frequency after the echoes are correlated and compressed through the direct signal. The residual Doppler frequency will cause two problems: on the one hand, the signal coherence will deteriorate, affecting the coherent accumulation gain; on the other hand, the amplitude of the signal after compression will decrease due to the sensitivity of GNSS signals to Doppler frequency. Therefore, how to increase the signal amplitude and eliminate the phase fluctuation caused by the Doppler frequency shift in the GNSS echoes of moving targets is an important issue for GNSS-S radar to detect moving targets. This paper proposes a dual-frequency GNSS echo enhancement method that uses the dual-frequency signals transmitted by the GNSS satellites to enhance and regularize the target echo. First, the phase relationship model of the GNSS dual-frequency echo is constructed, and the phase difference is made to the compressed dual-frequency echo signal to obtain the differential phase without fluctuation; then, the amplitudes of the dual-frequency echo signals are added together; and finally, a new signal with enhanced amplitude and consistent phase is constructed by using the dual-frequency additive amplitude and differential phase, and the long-term coherent accumulation of the signal is carried out, which can improve the processing gain of the weak echo signal of the moving target. The simulation and field experiments show that this method makes full use of the energy of the GNSS dual-frequency signal and eliminates the phase fluctuation in the echo signal of the moving target so that the compressed signal energy remains consistent in the slow-time dimension. After long-term coherent accumulation, the echo SNR was greatly improved, which enabled the detection of two high-speed cars by GNSS-S radar in the experiment. |
| first_indexed | 2024-03-10T22:05:33Z |
| format | Article |
| id | doaj.art-8ff543e3fe3d439b93febb92d0b59341 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T22:05:33Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-8ff543e3fe3d439b93febb92d0b593412023-11-19T12:48:51ZengMDPI AGRemote Sensing2072-42922023-09-011518451910.3390/rs15184519Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S RadarWenning Gao0Fuzhan Yue1Zhenghuan Xia2Xin Liu3Zhilong Zhao4Yao Zhang5Zongqiang Liu6State Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaState Key Laboratory of Space-Earth Integrated Information Technology, Beijing 100095, ChinaThe GNSS-S radar utilizes the signals of a global navigation satellite system (GNSS) to carry out target detection. Due to the very low power of GNSS signals, long-term accumulation is needed to improve the gain of the echo signals. However, when it is used for moving object detection, the random movement of the target will cause residual Doppler frequency after the echoes are correlated and compressed through the direct signal. The residual Doppler frequency will cause two problems: on the one hand, the signal coherence will deteriorate, affecting the coherent accumulation gain; on the other hand, the amplitude of the signal after compression will decrease due to the sensitivity of GNSS signals to Doppler frequency. Therefore, how to increase the signal amplitude and eliminate the phase fluctuation caused by the Doppler frequency shift in the GNSS echoes of moving targets is an important issue for GNSS-S radar to detect moving targets. This paper proposes a dual-frequency GNSS echo enhancement method that uses the dual-frequency signals transmitted by the GNSS satellites to enhance and regularize the target echo. First, the phase relationship model of the GNSS dual-frequency echo is constructed, and the phase difference is made to the compressed dual-frequency echo signal to obtain the differential phase without fluctuation; then, the amplitudes of the dual-frequency echo signals are added together; and finally, a new signal with enhanced amplitude and consistent phase is constructed by using the dual-frequency additive amplitude and differential phase, and the long-term coherent accumulation of the signal is carried out, which can improve the processing gain of the weak echo signal of the moving target. The simulation and field experiments show that this method makes full use of the energy of the GNSS dual-frequency signal and eliminates the phase fluctuation in the echo signal of the moving target so that the compressed signal energy remains consistent in the slow-time dimension. After long-term coherent accumulation, the echo SNR was greatly improved, which enabled the detection of two high-speed cars by GNSS-S radar in the experiment.https://www.mdpi.com/2072-4292/15/18/4519GNSS-based moving target detectionweak signaldual-frequency differenceGNSS-S radar |
| spellingShingle | Wenning Gao Fuzhan Yue Zhenghuan Xia Xin Liu Zhilong Zhao Yao Zhang Zongqiang Liu Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar Remote Sensing GNSS-based moving target detection weak signal dual-frequency difference GNSS-S radar |
| title | Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar |
| title_full | Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar |
| title_fullStr | Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar |
| title_full_unstemmed | Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar |
| title_short | Dual-Frequency Signal Enhancement Method of Moving Target Echoes for GNSS-S Radar |
| title_sort | dual frequency signal enhancement method of moving target echoes for gnss s radar |
| topic | GNSS-based moving target detection weak signal dual-frequency difference GNSS-S radar |
| url | https://www.mdpi.com/2072-4292/15/18/4519 |
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