Method, system, medium, and apparatus for interpolation of delay pulse number based imaging

Abstract

The application provides an imaging interpolation calibration method and system based on a delay pulse number, a medium and equipment, and mainly solves the imaging frame loss problem caused by interrupted transmission during the interpolation calibration of a spaceborne SAR imaging. The implementation steps of the application are as follows: (1) reading a delay pulse number N and an interpolation calibration cycle number M; (2) constructing an interpolation calibration small cycle based on the delay pulse number and constructing an interpolation calibration large cycle based on the interpolation calibration cycle number; and (3) generating a calibration signal. The application can solve the imaging pulse interruption problem caused by the imaging interpolation calibration to a certain extent, and effectively guarantee the ground observation performance of the SAR system.

Description

Technical Field

[0001] This invention relates to the field of signal and information processing technology, and more specifically, to an imaging interpolation calibration method, system, medium, and device based on the number of delayed pulses. Background Technology

[0002] Synthetic Aperture Radar (SAR) has been widely used in military and civilian fields due to its all-weather, high-resolution Earth observation capabilities, such as battlefield reconnaissance, marine monitoring, agricultural surveys, and topographic mapping.

[0003] When a spaceborne SAR payload operates in orbit, variations in system temperature, on-orbit environment, and system aging can cause changes in the amplitude and phase characteristics of the SAR system, thus affecting imaging, interferometry, and other applications. Generally, spaceborne SAR systems are designed with an internal calibration system to measure and compensate for amplitude and phase errors caused by temperature and other variations. Internal calibration typically only includes initial calibration before imaging and final calibration after imaging. With the development of multi-channel systems, higher requirements have been placed on inter-channel errors. Simultaneously, to maximize the performance of the spaceborne SAR system, the SAR payload needs to be powered on for as long as possible. In this case, initial and final calibration alone are no longer sufficient to accurately invert the amplitude and phase changes of the spaceborne SAR system; therefore, interpolation calibration during imaging is designed. However, interpolation calibration during imaging interrupts the imaging process, resulting in the loss of imaging pulses. Assuming 1000 calibration signals are interpolated during imaging, considering the time delay between the satellite and ground, a total of 2000 frames of imaging signal will be lost. The more calibration pulses interpolated, the more imaging frames are lost, impacting image quality. Therefore, it is necessary to study how to reduce or eliminate the imaging frame loss problem caused by interpolation calibration.

[0004] Currently, there is considerable research on the design of internal calibration systems. Papers such as *A Processing Method for SAR Internal Calibration Signals* (CN113391278A), *An Internal Calibration Device and Method for DBF Spaceborne SAR System* (CN112698282A), *A Design and Data Analysis Method for Internal Calibration Mode of Multi-Polarization SAR Payload* (CN112098961A), and *An Antenna Pattern Testing Method Based on Internal Calibration Multi-Wavelength Testing* (CN113281576A) have designed internal calibration modes and methods for different systems. However, these methods cannot solve the problem of lost imaging pulses during calibration. *A Non-Disruptive Phase Synchronization Method and Device for Bistatic SAR* (CN107422323B) proposes a scheme of performing two samplings within one pulse repetition period, which can solve the problem of lost calibration imaging pulses. However, this method sacrifices part of the swath width to obtain an additional echo window, placing additional demands on the hardware system and requiring extra hardware resources, resulting in a high cost.

[0005] For conventional, undesigned spaceborne SAR systems, there is currently no effective and low-cost method to solve the problem of image frame loss caused by interpolation calibration during imaging.

[0006] Therefore, a new technical solution is needed to improve the above-mentioned technical problems. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the purpose of this invention is to provide an imaging interpolation calibration method, system, medium and device based on the number of delayed pulses.

[0008] According to the present invention, an imaging interpolation calibration method based on the number of delayed pulses is provided, the method comprising the following steps:

[0009] Step S1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M recorded in the command packet;

[0010] Step S2: Construct a small interpolation calibration loop based on the number of delay pulses;

[0011] Step S3: Construct the imaging loop based on the number of interpolation calibration cycles;

[0012] Step S4: Generate calibration signals according to the calibration cycle.

[0013] Preferably, step S2 includes the following steps:

[0014] Step S2.1: Design a calibration queue containing k pulses;

[0015] Step S2.2: Design a small calibration loop, with an interval of N-1 delayed pulses, and insert the calibration queue pulses sequentially in the imaging.

[0016] Preferably, step S3 involves performing M small interpolation calibration cycles based on the number of delayed pulses to form a large imaging cycle.

[0017] The present invention also provides an imaging interpolation calibration system based on the number of delayed pulses, the system comprising the following modules:

[0018] Module M1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet.

[0019] Module M2: Constructs a small interpolation calibration loop based on the number of delay pulses;

[0020] Module M3: Constructs a large imaging loop based on the number of interpolation calibration cycles;

[0021] Module M4: Generates calibration signals according to the calibration cycle.

[0022] Preferably, module M2 includes the following modules:

[0023] Module M2.1: Design a calibration queue containing k pulses;

[0024] Module M2.2: Design a small calibration loop, with a delay pulse number N-1 as the interval, to sequentially insert the calibration queue pulses in the imaging process.

[0025] Preferably, module M3 performs M small interpolation calibration cycles based on the number of delayed pulses to form a large imaging cycle.

[0026] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the imaging interpolation calibration method based on the number of delayed pulses described above.

[0027] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the imaging interpolation calibration method based on the delay pulse number described above.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The processing approach of this invention differs from existing internal calibration methods. Starting from the perspective of satellite-to-ground transmission delay, it makes full use of the number of delayed pulses to minimize the loss of imaging frames caused by calibration. Conventional methods will lose 2n imaging frames when calibrating n pulses. Under the same conditions, this invention can reduce the number of lost frames by about half.

[0030] 2. The imaging interpolation calibration method and system based on the number of delayed pulses proposed in this invention have no additional requirements for the hardware system and are compatible with various internal calibration schemes. Attached Figure Description

[0031] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the processing flow provided by the present invention;

[0033] Figure 2 This is a schematic diagram of interpolation calibration based on the number of delay pulses N provided by the present invention;

[0034] Figure 3 This is an example diagram of the interpolation calibration based on the number of delay pulses N provided by the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] Example 1:

[0037] According to the present invention, an imaging interpolation calibration method based on the number of delayed pulses is provided, the method comprising the following steps:

[0038] Step S1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M recorded in the command packet; assuming N = 9 and M = 120.

[0039] Step S2: Construct a small interpolation calibration loop based on the number of delay pulses;

[0040] Step S2.1: Design a calibration queue containing k pulses;

[0041] Step S2.2: Design a small calibration loop, with an interval of N-1 delayed pulses, and insert the calibration queue pulses sequentially in the imaging.

[0042] Step S3: Construct a large imaging loop based on the number of interpolation calibration cycles; perform M small interpolation calibration cycles based on the number of delayed pulses to form a large imaging loop.

[0043] Step S4: Generate calibration signals according to the calibration cycle.

[0044] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the imaging interpolation calibration method based on the number of delayed pulses described above.

[0045] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the imaging interpolation calibration method based on the delay pulse number described above.

[0046] The present invention also provides an imaging interpolation calibration system based on the number of delayed pulses. The imaging interpolation calibration system based on the number of delayed pulses can be implemented by executing the process steps of the imaging interpolation calibration method based on the number of delayed pulses. That is, those skilled in the art can understand the imaging interpolation calibration method based on the number of delayed pulses as a preferred embodiment of the imaging interpolation calibration system based on the number of delayed pulses.

[0047] Example 2:

[0048] The present invention also provides an imaging interpolation calibration system based on the number of delayed pulses, the system comprising the following modules:

[0049] Module M1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet; assuming N = 9 and M = 120.

[0050] Module M2: Constructs a small interpolation calibration loop based on the number of delay pulses;

[0051] Module M2.1: Design a calibration queue containing k pulses;

[0052] Module M2.2: Design a small calibration loop, with a delay pulse number N-1 as the interval, to sequentially insert the calibration queue pulses in the imaging process.

[0053] Module M3: Constructs a large imaging loop based on the number of interpolation calibration cycles; performs M small interpolation calibration cycles based on the number of delayed pulses to form the large imaging loop.

[0054] Module M4: Generates calibration signals according to the calibration cycle.

[0055] Example 3:

[0056] To address the problem of image frame loss caused by interpolation calibration during imaging, this invention provides an imaging interpolation calibration method based on the number of delayed pulses, comprising:

[0057] Parameter extraction steps: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet.

[0058] The calibration loop design is as follows: a small calibration loop is constructed based on the number of delayed pulses; an imaging loop is constructed based on the number of calibration loops; and a calibration signal is generated according to the calibration loop.

[0059] The interpolation calibration loop includes:

[0060] Design a calibration queue containing k pulses (which may contain different calibration combinations).

[0061] The design incorporates a small calibration loop, with a delay pulse number of N-1 intervals, to sequentially insert calibration queue pulses during imaging.

[0062] The imaging loop includes:

[0063] Perform M small-loop interpolation calibrations based on the number of delayed pulses to form a large imaging loop.

[0064] An imaging interpolation calibration system based on delayed pulse number includes:

[0065] Parameter extraction module: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet.

[0066] The calibration loop module constructs a small calibration loop based on the number of delayed pulses; constructs a large imaging loop based on the number of calibration loops; and generates a calibration signal according to the calibration loop.

[0067] The interpolation calibration loop module includes:

[0068] Design a calibration queue containing k pulses.

[0069] The design incorporates a small-loop calibration module that sequentially inserts calibration queue pulses during imaging at intervals of N-1 delayed pulses.

[0070] The imaging loop module includes:

[0071] Perform M small-loop interpolation calibrations based on the number of delayed pulses to form a large-loop imaging module.

[0072] During calibration in spaceborne synthetic aperture radar (SAR) imaging, since no signal can be transmitted in the current frame of calibration, there is no imaging signal in the echo reception window after a delay of N pulses. Since no signal can be received in the current frame of calibration, the echoes of the K pulses transmitted before the delay of N pulses cannot be received during the calibration period. Therefore, assuming a total of m calibration pulses are lost, a total of 2m imaging frames are lost.

[0073] According to the method of the present invention, the interpolation calibration process is designed based on the number of delay pulses N, which can reduce the number of lost imaging frames to m+1, and reduce the number of lost imaging frames by about 50%.

[0074] This invention minimizes imaging frame loss caused by interpolation by fully utilizing the mechanism that there is no echo after a N-pulse delay of the current pulse during interpolation calibration. The specific implementation steps of this invention are as follows: Figure 1 As shown, it specifically includes:

[0075] Parameter extraction: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet. Here, we assume that N = 9 and M = 120.

[0076] Design a small calibration loop:

[0077] Design a calibration queue containing k pulses (here, we assume k = 12, including 4 pulses for reference calibration, 4 pulses for full-array transmit calibration, and 4 pulses for full-array receive calibration).

[0078] The design incorporates a small calibration loop, with an interval of N-1=8 delayed pulses, to sequentially insert calibration queue pulses during imaging.

[0079] Imaging loop steps:

[0080] Perform M=120 small interpolation calibration cycles based on the number of delayed pulses to form a large imaging cycle; the final interpolation calibration cycle designed in this example is as follows: Figure 3 As shown.

[0081] According to the parameters in this example, the number of lost imaging frames using the conventional method is 2*k*M=2*12*120=2880, while the number of lost imaging frames using the method of this invention is (k+1)*M=13*120=1560, reducing the number of lost imaging pulses by 46%.

[0082] Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1 and Embodiment 2.

[0083] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0084] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An imaging interpolation calibration method based on delayed pulse number, characterized in that, The method includes the following steps: Step S1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M recorded in the command packet; Step S2: Construct a small interpolation calibration loop based on the number of delay pulses; Step S3: Construct the imaging loop based on the number of interpolation calibration cycles; Step S4: Generate calibration signals according to the calibration cycle; Step S2 includes the following steps: Step S2.1: Design a calibration queue containing k pulses; Step S2.2: Design a small calibration loop, with an interval of N-1 delayed pulses, and insert the calibration queue pulses sequentially in the imaging process; Step S3 involves M small interpolation calibration cycles based on the number of delayed pulses to form a large imaging cycle.

2. An imaging interpolation calibration system based on delayed pulse number, characterized in that, The system includes the following modules: Module M1: Before imaging begins, the SAR control software reads the number of delayed pulses N and the number of calibration cycles M from the instruction packet. Module M2: Constructs a small interpolation calibration loop based on the number of delay pulses; Module M3: Constructs a large imaging loop based on the number of interpolation calibration cycles; Module M4: Generates calibration signals according to the calibration cycle; Module M2 includes the following modules: Module M2.1: Design a calibration queue containing k pulses; Module M2.2: Design a small calibration loop, with an interval of N-1 delayed pulses, to sequentially insert calibration queue pulses during imaging; The module M3 performs M small interpolation calibration cycles based on the number of delayed pulses to form a large imaging cycle.

3. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the imaging interpolation calibration method based on the number of delayed pulses as described in any one of claims 1 to 2.

4. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by the processor, it implements the steps of the imaging interpolation calibration method based on the number of delayed pulses as described in any one of claims 1 to 2.

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