Ultrahigh-sensitivity radiation source detection method

Abstract

The invention relates to an ultrahigh-sensitivity radiation source detection method, which comprises the following steps of: receiving an initial signal by adopting an array antenna, completing comprehensive aperture electromagnetic imaging processing to obtain a radiation source energy distribution image, extracting the signal-to-noise ratio of each pixel point in the radiation source energy distribution image, and determining whether the target is an effective target or not through threshold detection; if the effective target is detected, recording the position, the processing frequency, the bandwidth and the time width of the signal; if no effective signal is detected, traversing the signal processing bandwidth and the time domain accumulation time of the synthetic aperture electromagnetic imaging processing, carrying out the synthetic aperture electromagnetic imaging processing until an effective target can be detected, and recording the position, the processing frequency, the bandwidth and the time width of the signal; a target signal incoming wave direction angle and a target position are extracted based on a radiation source energy distribution image, coherent synthesis of N sub-array sampling signals is completed based on the incoming wave direction angle and position parameters of the N sub-arrays, and parameter measurement is completed based on a synthesis signal.

Description

A method for detecting ultra-high sensitivity radiation sources Technical Field

[0001] This invention belongs to the field of spaceborne microwave electronics technology and relates to a method for detecting ultra-high sensitivity radiation sources. Background Technology

[0002] Traditional receivers primarily intercept signals by detecting their peak power. Their system sensitivity is determined by the antenna gain (either a single-element antenna gain or a phased array antenna gain) and the receiver's sensitivity.

[0003] Where S1 is the system sensitivity in dBW / m2; Pr1min is the receiver sensitivity in dBm; Gr1 is the antenna gain in dB; λ is the signal wavelength; and L is the various system losses in dB.

[0004] Since a frequency domain power detection method is used, the receiver sensitivity mainly depends on the receiving processing bandwidth, receiver noise figure, etc., as calculated by the following formula.

[0005] Where Ft is the receiver noise figure, B is the receiver processing bandwidth, and This represents the signal detection and recognition coefficient (generally, SNRmin is calculated as 12 or 13 dB). This refers to receiver loss.

[0006] The more energy a radiation source emits per unit time, the easier it is to be detected by the receiver. The emitted energy is determined by the average power, while traditional passive receivers detect the peak power of the radiation source. For signals with a large time bandwidth, the energy is dispersed in the time and frequency domains, reducing the peak power and significantly decreasing the probability of reception. Summary of the Invention

[0007] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose an ultra-high sensitivity radiation source detection method, which solves the problem that the detection capability of traditional passive receivers is limited by the peak power of the radiation source and the probability of intercepting weak signals is low.

[0008] The technical solution of this invention is: a method for detecting ultra-high sensitivity radiation sources, comprising: 1) receiving an initial signal using an array antenna, setting the signal processing frequency, bandwidth, and time-domain accumulation time of the initial signal, completing integrated aperture electromagnetic imaging processing to obtain a radiation source energy distribution image, extracting the signal-to-noise ratio of each pixel in the radiation source energy distribution image, and determining whether it is a valid target through threshold detection; 2) if a valid target is detected, recording the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid signal is detected, traversing the signal processing bandwidth and time-domain accumulation time of the integrated aperture electromagnetic imaging processing, performing integrated aperture electromagnetic imaging processing until a valid target can be detected, and recording the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid target is obtained after traversal, changing the signal processing frequency and returning to step 1) until a valid target can be found or the traversal of signal frequencies is completed.

[0009] 3) After detecting a valid target, extract the direction angle of arrival of the target signal and the target position based on the radiation source energy distribution image. Based on the direction angle of arrival and the position parameters of N subarrays, complete the coherent synthesis of the sampled signals of N subarrays. Based on the synthesized signal, complete the parameter measurement.

[0010] The process of obtaining the radiation source energy distribution image by completing the integrated aperture electromagnetic imaging processing includes: electromagnetic imaging technology based on sparse integrated aperture array processing, which transforms the problem of locating the radiation source into the problem of inversion and reconstruction of the electromagnetic radiation energy distribution in the observation space domain; using sparse array interferometry to achieve spatial frequency domain sampling of the radiation source signal, obtaining the visibility function through the correlation accumulation between channels, and reconstructing the energy distribution map of the electromagnetic radiation source in the observation field of view through the inversion algorithm.

[0011] The method of using sparse array interferometry to achieve spatial frequency domain sampling of radiation source signals, obtaining the visibility function through inter-channel correlation accumulation, and reconstructing the energy distribution map of the electromagnetic radiation source within the observation field of view using an inversion algorithm includes: setting the spatial energy distribution image in the observation scene as... Establish its relationship with the visibility function The relationship between the signals received by the array antenna and the visibility function obtained through the mutual interference of the sub-antenna signals. By leveraging its relationship with the visibility function, the spatial energy distribution image of the observed scene can be retrieved through inversion. Set a threshold value in the spatial energy distribution image. The pixel with significantly higher energy than other areas is identified as the radiation source, thus completing the detection and localization of the target.

[0012] The visibility function , refers to the function that corresponds to the baseline distribution of the interferometric measurement data obtained by using a two-dimensional sparse synthetic aperture array to perform interferometric measurements on the radiation source signals in the field of view.

[0013] Spatial energy distribution image With visibility function The relationship between them is represented as follows: ;in, Indicates the direction of incoming wave. Indicates the direction angle and elevation angle of the incoming wave from the target. and Indicates the spatial frequency parameters in the pitch and azimuth directions. It is the wavelength of the signal. It is the direction of the first The Cartesian coordinates of the k-th antenna and its elevation.

[0014] The process involves traversing the signal processing bandwidth and time-domain accumulation time of the synthetic aperture electromagnetic imaging (SEMI) process until a valid target can be detected. The signal position, processing frequency, bandwidth, and time width are recorded. This includes: traversing the signal processing bandwidth and time-domain accumulation time of the signal processing process, performing SEMI processing, and acquiring a spatial energy distribution image. Extract the signal-to-noise ratio (SNR) of each point in the image domain, set the detection threshold P, and complete the SNR threshold detection. If a pixel passes the threshold detection, it can be considered as a valid target. Adjust the processing bandwidth and processing time for a pixel that has passed the detection in the image until the SNR is maximized. At this time, the optimal signal processing gain is obtained, and the signal processing bandwidth and time at this time are recorded.

[0015] The synthetic aperture electromagnetic imaging processing, namely sparse synthetic aperture array processing, increases the time-frequency processing gain compared to the traditional system, as expressed as... ;in, For receiving sensitivity, The system noise figure; D is the signal processing bandwidth; D is the signal detection signal-to-noise ratio. For array synthesis gain; The signal processing gain is determined by the signal processing bandwidth. and time-domain waveform accumulation time Decide.

[0016] The method involves extracting the direction angle of arrival and target position of the target signal from the radiation source energy distribution image, and performing coherent synthesis of the sampled signals of N subarrays based on the direction angle of arrival and the position parameters of N subarrays, thereby improving the time-frequency domain signal-to-noise ratio by N times. Parameter measurement is then performed based on the synthesized signal, including: 11) setting the operating frequency point within the operating frequency range of the receiver. , …, setting different time widths at different frequency points , …and bandwidth , …; 12) Select a set of signal processing parameters The visibility function is obtained by performing integrated aperture electromagnetic imaging processing on the received signals from N antenna arrays. , Acquire spatial energy distribution image Extract the signal-to-noise ratio (SNR) of each point in the image domain, set a detection threshold P, and complete the SNR-threshold detection. If a pixel can detect the target, record the position parameters. 13) If the target can be detected, record the detected target location parameters. The signal-to-noise ratio (SNR) is calculated and recorded. If no target is detected, the bandwidth parameter in the signal processing parameters is changed sequentially. The SNR is calculated and recorded each time, and the maximum SNR value (SNRmax) obtained during the polling process is also recorded. Corresponding parameters; 14) If no target is detected after the bandwidth polling process is completed, then the time-domain accumulation parameters will be replaced sequentially. The parameters used are Until a valid target is detected, or all time-width parameters are calculated, record the target location parameters that have been detected. And signal-to-noise ratio (SNR); 15) sequentially adjust the frequency points , …Repeat steps 12) to 14), record all detected targets and their corresponding signal processing parameters, according to the target position parameters ( 1) The signal processing parameters are used to complete the coherent synthesis of signals between arrays. Based on the synthesized signal, signal extraction is completed to obtain an effective signal with a high signal-to-noise ratio; 16) The pulse width, carrier frequency, and signal pattern characteristic parameters of the coherently synthesized signal are measured to realize signal recognition and complete the demodulation and interpretation of the signal, thus completing the ultra-high sensitivity radiation source detection processing.

[0017] The advantages of this invention compared to existing technologies are as follows: Traditional systems rely on peak power detection, resulting in extremely low sensitivity for wide-bandwidth signals and an inability to effectively detect low-power signals with large bandwidth. This method, based on integrated aperture electromagnetic imaging technology, achieves energy accumulation in the time and frequency domains of the signal through inter-channel correlation accumulation processing. Target detection is then performed via energy detection, offering unique advantages for signals with large temporal and bandwidth capabilities. Compared to traditional systems, this method can improve system sensitivity by 10-30 dB.

[0018] Traditional systems primarily improve system sensitivity by increasing the gain of the receiving antenna. However, increasing the array size leads to a significant reduction in antenna beamwidth, requiring time-division multiplexing (TDM) coverage of the designated area through beam scanning, resulting in a marked decrease in efficiency. This new method employs a sparse synthetic aperture array for signal reception. It achieves gain synthesis of N sub-apertures through correlation accumulation processing between channels, meaning that no single sub-aperture is required to meet the target's receiving sensitivity requirements. Therefore, the antenna size of the sub-apertures can be reduced, allowing the beamwidth of a single sub-aperture to be expanded to a level comparable to traditional systems. The coverage area is expanded by N times, which can effectively solve the contradiction between the high sensitivity and wide beam coverage of the traditional system. Attached Figure Description

[0019] Figure 1 is a flowchart of the method for detecting ultra-high sensitivity radiation sources according to the present invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] As shown in Figure 1, a method for detecting ultra-high sensitivity radiation sources includes: 1) receiving an initial signal using an array antenna, setting the signal processing frequency, bandwidth, and time-domain accumulation time of the initial signal, completing synthetic aperture electromagnetic imaging (SAR) processing to obtain a radiation source energy distribution image, extracting the signal-to-noise ratio of each pixel in the radiation source energy distribution image, and determining whether it is a valid target through threshold detection; 2) if a valid target is detected, recording the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid signal is detected, traversing the signal processing bandwidth and time-domain accumulation time of SAR processing, performing SAR processing until a valid target can be detected, and recording the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid target is obtained after traversal, changing the signal processing frequency and returning to step 1) until a valid target can be found or the traversal of signal frequencies is completed.

[0022] 3) After detecting a valid target, extract the direction angle of arrival of the target signal and the target position based on the radiation source energy distribution image. Based on the direction angle of arrival and the position parameters of N subarrays, complete the coherent synthesis of the sampled signals of N subarrays. Based on the synthesized signal, complete the parameter measurement.

[0023] The process of obtaining the radiation source energy distribution image by completing the integrated aperture electromagnetic imaging processing includes: electromagnetic imaging technology based on sparse integrated aperture array processing, which transforms the problem of locating the radiation source into the problem of inversion and reconstruction of the electromagnetic radiation energy distribution in the observation space domain; using sparse array interferometry to achieve spatial frequency domain sampling of the radiation source signal, obtaining the visibility function through the correlation accumulation between channels, and reconstructing the energy distribution map of the electromagnetic radiation source in the observation field of view through the inversion algorithm.

[0024] The method of using sparse array interferometry to achieve spatial frequency domain sampling of radiation source signals, obtaining the visibility function through inter-channel correlation accumulation, and reconstructing the energy distribution map of the electromagnetic radiation source within the observation field of view using an inversion algorithm includes: setting the spatial energy distribution image in the observation scene as... Establish its relationship with the visibility function The relationship between the signals received by the array antenna and the visibility function obtained through the mutual interference of the sub-antenna signals. By leveraging its relationship with the visibility function, the spatial energy distribution image of the observed scene can be retrieved through inversion. Set a threshold value in the spatial energy distribution image. The pixel with significantly higher energy than other areas is identified as the radiation source, thus completing the detection and localization of the target.

[0025] The visibility function , refers to the function that corresponds to the baseline distribution of the interferometric measurement data obtained by using a two-dimensional sparse synthetic aperture array to perform interferometric measurements on the radiation source signals in the field of view.

[0026] Spatial energy distribution image With visibility function The relationship between them is represented as follows: ;in, Indicates the direction of incoming wave. Indicates the direction angle and elevation angle of the incoming wave from the target. and Indicates the spatial frequency parameters in the pitch and azimuth directions. It is the wavelength of the signal. It is the direction of the first The Cartesian coordinates of the k-th antenna and its elevation.

[0027] The process involves traversing the signal processing bandwidth and time-domain accumulation time of the synthetic aperture electromagnetic imaging (SEMI) process until a valid target can be detected. The signal position, processing frequency, bandwidth, and time width are recorded. This includes: traversing the signal processing bandwidth and time-domain accumulation time of the signal processing process, performing SEMI processing, and acquiring a spatial energy distribution image. Extract the signal-to-noise ratio (SNR) of each point in the image domain, set the detection threshold P, and complete the SNR threshold detection. If a pixel passes the threshold detection, it can be considered as a valid target. Adjust the processing bandwidth and processing time for a pixel that has passed the detection in the image until the SNR is maximized. At this time, the optimal signal processing gain is obtained, and the signal processing bandwidth and time at this time are recorded.

[0028] The synthetic aperture electromagnetic imaging processing, namely sparse synthetic aperture array processing, increases the time-frequency processing gain compared to the traditional system, as expressed as... ;in, For receiving sensitivity, The system noise figure; D is the signal processing bandwidth; D is the signal detection signal-to-noise ratio. For array synthesis gain; The signal processing gain is determined by the signal processing bandwidth. and time-domain waveform accumulation time Decide.

[0029] The method involves extracting the direction angle of arrival and target position of the target signal from the radiation source energy distribution image, and performing coherent synthesis of the sampled signals of N subarrays based on the direction angle of arrival and the position parameters of N subarrays, thereby improving the time-frequency domain signal-to-noise ratio by N times. Parameter measurement is then performed based on the synthesized signal, including: 11) setting the operating frequency point within the operating frequency range of the receiver. , …, setting different time widths at different frequency points , …and bandwidth , …; 12) Select a set of signal processing parameters The visibility function is obtained by performing integrated aperture electromagnetic imaging processing on the received signals from N antenna arrays. , Acquire spatial energy distribution image Extract the signal-to-noise ratio (SNR) of each point in the image domain, set a detection threshold P, and complete the SNR-threshold detection. If a pixel can detect the target, record the position parameters. 13) If the target can be detected, record the detected target location parameters. The signal-to-noise ratio (SNR) is calculated and recorded. If no target is detected, the bandwidth parameter in the signal processing parameters is changed sequentially. The SNR is calculated and recorded each time, and the maximum SNR value (SNRmax) obtained during the polling process is also recorded. Corresponding parameters; 14) If no target is detected after the bandwidth polling process is completed, then the time-domain accumulation parameters will be replaced sequentially. The parameters used are Until a valid target is detected, or all time-width parameters are calculated, record the target location parameters that have been detected. And signal-to-noise ratio (SNR); 15) sequentially adjust the frequency points , …Repeat steps 12) to 14), record all detected targets and their corresponding signal processing parameters, according to the target position parameters ( 1) The signal processing parameters are used to complete the coherent synthesis of signals between arrays. Based on the synthesized signal, signal extraction is completed to obtain an effective signal with a high signal-to-noise ratio; 16) The pulse width, carrier frequency, and signal pattern characteristic parameters of the coherently synthesized signal are measured to realize signal recognition and complete the demodulation and interpretation of the signal, thus completing the ultra-high sensitivity radiation source detection processing.

[0030] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for detecting ultra-high sensitivity radiation sources, characterized in that, include: 1) Receive the initial signal using an array antenna, set the signal processing frequency, bandwidth, and time-domain accumulation time of the initial signal, complete the synthetic aperture electromagnetic imaging (SAR) processing to obtain the radiation source energy distribution image, extract the signal-to-noise ratio of each pixel in the radiation source energy distribution image, and determine whether it is a valid target through threshold detection; 2) If a valid target is detected, record the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid signal is detected, traverse the signal processing bandwidth and time-domain accumulation time of the SAR processing, perform SAR processing until a valid target can be detected, and record the signal position and processing frequency, bandwidth, and time-domain accumulation time; if no valid target is obtained after traversal, change the signal processing frequency and return to step 1) until a valid target can be found or the traversal of signal frequencies is completed; 3) After detecting a valid target, extract the target signal direction angle and target position based on the radiation source energy distribution image, complete the coherent synthesis of the N subarray sampling signals based on the direction angle and the position parameters of the N subarrays, and complete the parameter measurement based on the synthesized signal.

2. The method for detecting an ultra-high sensitivity radiation source according to claim 1, characterized in that: The process of obtaining the radiation source energy distribution image by completing the integrated aperture electromagnetic imaging processing includes: electromagnetic imaging technology based on sparse integrated aperture array processing, which transforms the problem of locating the radiation source into the problem of inversion and reconstruction of the electromagnetic radiation energy distribution in the observation space domain; using sparse array interferometry to achieve spatial frequency domain sampling of the radiation source signal, obtaining the visibility function through the correlation accumulation between channels, and reconstructing the energy distribution map of the electromagnetic radiation source in the observation field of view through the inversion algorithm.

3. The method for detecting an ultra-high sensitivity radiation source according to claim 2, characterized in that: The method of using sparse array interferometry to achieve spatial frequency domain sampling of radiation source signals, obtaining the visibility function through inter-channel correlation accumulation, and reconstructing the energy distribution map of the electromagnetic radiation source within the observation field of view using an inversion algorithm includes: setting the spatial energy distribution image in the observation scene as... Establish its relationship with the visibility function The relationship between the signals received by the array antenna and the visibility function obtained through the mutual interference of the sub-antenna signals. By leveraging its relationship with the visibility function, the spatial energy distribution image of the observed scene can be retrieved through inversion. Set a threshold value in the spatial energy distribution image. The pixel with significantly higher energy than other areas is identified as the radiation source, thus completing the detection and localization of the target.

4. The method for detecting an ultra-high sensitivity radiation source according to claim 3, characterized in that: The visibility function , refers to the function that corresponds to the baseline distribution of the interferometric measurement data obtained by using a two-dimensional sparse synthetic aperture array to perform interferometric measurements on the radiation source signals in the field of view.

5. The method for detecting an ultra-high sensitivity radiation source according to claim 3, characterized in that: Spatial energy distribution image With visibility function The relationship between them is represented as follows: ;in, Indicates the direction of incoming wave. Indicates the direction angle and elevation angle of the incoming wave from the target. and Indicates the spatial frequency parameters in the pitch and azimuth directions. It is the wavelength of the signal. It is the direction of the first The Cartesian coordinates of the k-th antenna and its elevation.

6. The method for detecting an ultra-high sensitivity radiation source according to claim 1, characterized in that: The process involves traversing the signal processing bandwidth and time-domain accumulation time of the synthetic aperture electromagnetic imaging (SEMI) process until a valid target can be detected. The signal position, processing frequency, bandwidth, and time width are recorded. This includes: traversing the signal processing bandwidth and time-domain accumulation time of the signal processing process, performing SEMI processing, and acquiring a spatial energy distribution image. Extract the signal-to-noise ratio (SNR) of each point in the image domain, set the detection threshold P, and complete the SNR threshold detection. If a pixel passes the threshold detection, it can be considered as a valid target. Adjust the processing bandwidth and processing time for a pixel that has passed the detection in the image until the SNR is maximized. At this time, the optimal signal processing gain is obtained, and the signal processing bandwidth and time at this time are recorded.

7. The method for detecting an ultra-high sensitivity radiation source according to claim 6, characterized in that: The synthetic aperture electromagnetic imaging processing, namely sparse synthetic aperture array processing, increases the time-frequency processing gain compared to the traditional system, as expressed as... ;in, For receiving sensitivity, The system noise figure; D is the signal processing bandwidth; D is the signal detection signal-to-noise ratio. For array synthesis gain; The signal processing gain is determined by the signal processing bandwidth. and time-domain waveform accumulation time Decide.

8. The method for detecting an ultra-high sensitivity radiation source according to claim 1, characterized in that: The process involves extracting the direction angle of arrival and target position of the target signal from the radiation source energy distribution image, performing coherent synthesis of the sampled signals of the N subarrays based on the direction angle of arrival and the position parameters of the N subarrays, and performing parameter measurement based on the synthesized signal, including: 11) setting the operating frequency point within the operating frequency domain of the receiver. 、 …, setting different time widths at different frequency points 、 …and bandwidth 、 …; 12) Select a set of signal processing parameters The visibility function is obtained by performing integrated aperture electromagnetic imaging processing on the received signals from N antenna arrays. ， Acquire spatial energy distribution image Extract the signal-to-noise ratio (SNR) of each point in the image domain, set a detection threshold P, and complete the SNR-threshold detection. If a pixel can detect the target, record the position parameters. 13) If the target can be detected, record the detected target location parameters. The signal-to-noise ratio (SNR) is calculated and recorded. If no target is detected, the bandwidth parameter in the signal processing parameters is changed sequentially. The SNR is calculated and recorded each time, and the maximum SNR value (SNRmax) obtained during the polling process is also recorded. Corresponding parameters; 14) If no target is detected after the bandwidth polling process is completed, then the time-domain accumulation parameters will be replaced sequentially. The parameters used are Until a valid target is detected, or all time-width parameters are calculated, record the target location parameters that have been detected. And signal-to-noise ratio (SNR); 15) sequentially adjust the frequency points 、 …Repeat steps 12) to 14), record all detected targets and their corresponding signal processing parameters, according to the target position parameters ( 1) The signal processing parameters are used to complete the coherent synthesis of signals between arrays. Based on the synthesized signal, signal extraction is completed to obtain an effective signal with a high signal-to-noise ratio; 16) The pulse width, carrier frequency, and signal pattern characteristic parameters of the coherently synthesized signal are measured to realize signal recognition and complete the demodulation and interpretation of the signal, thus completing the ultra-high sensitivity radiation source detection processing.

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