Method for calibrating the high-frequency polarization channel amplitude of a mars rover subsurface sounding radar

Abstract

This disclosure provides a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar, comprising: obtaining the average signals of the HH channel and VV channel respectively through the reflected signals of a metal plate; extracting the effective reflected signals of the HH channel and VV channel respectively based on the average signals; calculating the sum of the amplitude moduli of the effective reflected signals of the HH channel and VV channel respectively; calculating the ratio of the sum of the amplitude moduli of the effective reflected signals of the HH channel to the sum of the amplitude moduli of the effective reflected signals of the VV channel to obtain a correction coefficient; and reading the measured data of the Mars rover radar polarization channel and multiplying the measured data of the HH channel or VV channel by the correction coefficient to complete the polarization channel amplitude calibration.

Description

Technical Field

[0001] This disclosure relates to the field of radar signal technology, and in particular to a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover subsurface detection radar using a metal plate. Background Technology

[0002] Radar detection is convenient, fast, and has high resolution, making it widely used in archaeology, construction, geological exploration, astronomical observation, and other fields. The Mars rover's radar has full polarization detection capability, with four polarization channels: HH, VV, HV, and VV. Current technology cannot accurately calibrate the signal amplitude of the high-frequency polarization channels of the Mars rover's radar, thus making it difficult to avoid errors in subsequent signal processing due to polarization channel amplitude instability.

[0003] Therefore, how to provide a more effective method for calibrating the amplitude of radar high-frequency polarization channels is a technical issue that urgently needs to be addressed. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the aforementioned issues, this disclosure provides a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar, thereby alleviating technical problems such as errors in subsequent signal processing caused by the instability of the polarization channel amplitude during radar high-frequency polarization channel amplitude calibration in the prior art.

[0006] (II) Technical Solution

[0007] This disclosure provides a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar, comprising: obtaining the average signals of the HH channel and VV channel respectively through the reflected signals of a metal plate; extracting the effective reflected signals of the HH channel and VV channel respectively based on the average signals; calculating the sum of the amplitude moduli of the effective reflected signals of the HH channel and VV channel respectively; calculating the ratio of the sum of the amplitude moduli of the effective reflected signals of the HH channel to the sum of the amplitude moduli of the effective reflected signals of the VV channel to obtain a correction coefficient; and reading the measured data of the Mars rover radar polarization channel and multiplying the measured data of the HH channel or VV channel by the correction coefficient to complete the polarization channel amplitude calibration.

[0008] According to an embodiment of this disclosure, the metal plate reflection signal is obtained by sampling the metal plate reflection at high frequency from the ground to the rover's penetrating radar.

[0009] According to an embodiment of this disclosure, the metal plate reflection signal includes multiple polarization channel reflection signals HH, VV, HV, and VH, and the metal plate reflection signals of the HH and VV channels are selected for processing.

[0010] According to an embodiment of this disclosure, effective reflection signals for the HH channel and VV channel are obtained by truncating the average signal; including: truncating 0-80ns from the average signal as an effective information segment; removing the antenna coupling signal at the beginning of the effective information segment in the average signal; and truncating the remaining part of the average signal, excluding the weak signal region, to obtain the effective reflection signals for the HH channel and VV channel.

[0011] According to embodiments of this disclosure, calculating the sum of the amplitude magnitudes of the effective reflected signals of the HH channel and the VV channel respectively includes: calculating the sum A of the amplitude magnitudes of the effective reflected signals of the HH channel. HH :

[0012]

[0013] Where t1 represents the start time of the captured effective reflected signal, t2 represents the end time of the captured effective reflected signal, and a HH (t) represents the amplitude of the HH polarization channel signal.

[0014] According to embodiments of this disclosure, calculating the sum of the amplitude magnitudes of the effective reflected signals of the HH channel and the VV channel respectively further includes: calculating the sum A of the amplitude magnitudes of the effective reflected signals of the VV channel. VV :

[0015]

[0016] Where t1 represents the start time of the captured effective reflected signal, t2 represents the end time of the captured effective reflected signal, and a VV (t) represents the amplitude of the VV polarization channel signal.

[0017] According to an embodiment of this disclosure, if the correction coefficient is set to k, then:

[0018]

[0019] According to the embodiments of this disclosure, the measured data of the HH channel or VV channel are multiplied by a correction factor so that the sum of the signal amplitude moduli of the HH channel and the VV channel is equal, thereby completing the polarization channel amplitude calibration. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar, as described in this embodiment of the present disclosure.

[0021] Figure 2 This is a schematic diagram of the average signal of the complete HH channel and VV channel according to an embodiment of the present disclosure;

[0022] Figure 3 for Figure 2The diagram shows a segment of the average signal from 0 to 80 ns; the dashed box on the left represents the antenna-coupled signal, and the dashed box on the right represents the effective reflected signal. Detailed Implementation

[0023] This disclosure provides a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar. Since the Mars radar has four high-frequency polarization modes, data from all four channels needs to be analyzed when processing the high-frequency data. Therefore, calibrating the signal amplitude of the high-frequency polarization channel of the Mars rover radar can effectively reduce errors in subsequent signal processing caused by polarization channel instability.

[0024] In realizing this disclosed concept, the inventors discovered that the reflection from the metal plate can be considered as total internal reflection. Under the condition of total internal reflection, the reflection coefficients for both vertical and horizontal reflections are 1. Therefore, the total amplitude range of the signals received by the HH channel and VV channel should be consistent. Thus, by using the amplitude ratio of the HH channel and VV channel signals obtained from total internal reflection, the HH channel and VV channel data detected by radar from Mars can be corrected, thereby ensuring that the amplitudes of the two are consistent and reducing errors in subsequent signal processing caused by the instability of polarization channel amplitude. However, some problems still exist in related technologies, such as the ability to correct only HH and VV signals, but not HV and VH signals.

[0025] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0026] In this embodiment of the disclosure, a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar is provided, such as... Figure 1 As shown, the method includes:

[0027] Operation S1: Obtain the average signals of the HH channel and VV channel respectively by reflecting the signal through the metal plate;

[0028] Operation S2: Based on the average signal, extract the effective reflection signals of the HH channel and VV channel respectively;

[0029] Operation S3: Calculate the sum of the amplitude magnitudes of the effective reflected signals in the HH and VV channels respectively;

[0030] Operation S4: Calculate the ratio of the sum of the amplitude magnitudes of the effective reflected signals in the HH channel to the sum of the amplitude magnitudes of the effective reflected signals in the VV channel to obtain the correction coefficient; and

[0031] Operation S5: Read the measured data of the Mars rover radar polarization channel, and multiply the measured data of the HH channel or VV channel by the correction coefficient to complete the polarization channel amplitude calibration.

[0032] According to an embodiment of this disclosure, the metal plate reflection signal is obtained by sampling the metal plate reflection at high frequency from the ground to the rover's penetrating radar.

[0033] According to an embodiment of this disclosure, the metal plate reflection signal includes four polarization channel reflection signals: HH, VV, HV, and VH. The metal plate reflection signals of the HH and VV channels are selected for processing.

[0034] This embodiment of the disclosure uses the HH channel and VV channel signals as examples to illustrate amplitude calibration. Based on the metal plate reflection signals of the HH channel and VV channel, the average signals of the corresponding HH channel and VV channel are generated. The metal plate reflection signals are obtained by conducting a metal plate reflection experiment on the ground at the high frequency of the rover's penetrating radar. Figure 2 This is a complete schematic diagram of the average signals of the HH channel and VV channel according to an embodiment of this disclosure, with a cropped section. Figure 2 The first 0-80ns of the complete average signal shown is considered the effective information segment, such as... Figure 3 As shown in the diagram. The area enclosed by the dashed line on the left represents the antenna coupling signal, which can be considered as antenna interference. Following the antenna coupling signal is the reflected signal. The area enclosed by the dashed line on the right can be considered the effective reflected signal, which contains signals with significant amplitude changes. The signal following this area is relatively weak, almost zero, and shows little variation, and can be discarded.

[0035] According to an embodiment of this disclosure, operation S2 includes:

[0036] Operation S21: Extract the 0-80ns segment from the average signal as the valid information segment;

[0037] Operation S22: Remove the antenna coupling signal from the beginning of the effective information segment in the average signal; and

[0038] Operation S23: Extract the portion of the average signal excluding the weak signal region to obtain the effective reflected signals of the HH and VV channels.

[0039] According to embodiments of this disclosure, each data in the effective reflected signal is a complex number consisting of a real part and an imaginary part. Therefore, calculating the modulus of the signal is equivalent to calculating the absolute value of each sampled data.

[0040] According to an embodiment of this disclosure, operation S3 includes:

[0041] Operation S31: Calculate the sum of the magnitudes A of the effective reflected signals in the HH channel. HH :

[0042]

[0043] Operation S3 also includes operation S32: calculating the sum of the magnitudes A of the effective reflected signals of the VV channel. VV :

[0044]

[0045] Where t1 represents the start time of the captured effective reflected signal, t2 represents the end time of the captured effective reflected signal, and a HH (t) represents the amplitude of the HH channel signal. VV (t) represents the amplitude of the VV channel signal.

[0046] According to an embodiment of this disclosure, in operation S4, the correction coefficient is set to k, then: k = A VV / A HH Theoretically, metal plate reflection can be considered total internal reflection, meaning that electromagnetic waves incident from the air onto the metal plate interface only undergo reflection without refraction. Therefore, the reflected wave and the radiated wave have the same amplitude. The difference between HH and VV channels lies only in their polarization direction (HH means horizontal signal transmission and reception; VV means vertical signal transmission and reception), which does not affect the signal amplitude. Therefore, under the premise of metal plate reflection, the HH and VV channel signals should have the same amplitude range, i.e., k = 1. However, in reality, due to interference or errors caused by hardware devices, the H and V channels are not completely identical. Therefore, it is necessary to adjust the amplitude of the HH and VV channel signals using the ratio k to ensure that their final ratio is 1.

[0047] According to the embodiments of this disclosure, in operation S5, the measured data of the Mars rover radar polarization channel is read, and the measured signal data of HH and VV polarization channels are multiplied by the correction coefficient so that the sum of the amplitude moduli of the HH channel and VV channel signals is equal, thus completing the polarization channel amplitude calibration.

[0048] For example, the amplitude a of the measured signal in the HH channel. HH (t) Multiply by the correction factor k to obtain the calibrated HH channel signal amplitude data a′ HH (t), a′ HH (t)=k·a HH (t).

[0049] Make A VV / A HH =1. In this case, the influence of the radar polarization channel on the HH and VV signals is corrected.

[0050] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0051] Based on the above description, those skilled in the art should have a clear understanding of the method for calibrating the amplitude of the high-frequency polarization channel of the Mars rover's subsurface detection radar as disclosed in this disclosure.

[0052] In summary, this disclosure provides a method for calibrating the amplitude of the high-frequency polarization channel of a Mars rover's subsurface exploration radar. This method mainly corrects the amplitude of the HH and VV channel signals collected by the Mars rover's high-frequency radar from Mars by analyzing the amplitude relationship between the reflected signals from the HH and VV channels of a ground metal plate by the high-frequency radar.

[0053] It should also be noted that the above are different embodiments provided by this disclosure. These embodiments are used to illustrate the technical content of this disclosure and are not intended to limit the scope of protection of this disclosure. A feature of one embodiment can be applied to other embodiments through suitable modifications, substitutions, combinations, or separations.

[0054] It should be noted that, unless otherwise specified herein, having "a" element is not limited to having a single element, but may include one or more of the element.

[0055] Furthermore, unless otherwise specified, the ordinal numbers such as "first," "second," etc., used herein are merely for distinguishing multiple elements with the same name and do not indicate any hierarchy, order of execution, or process sequence among them. A "first" element and a "second" element may appear together in the same component or separately in different components. The presence of an element with a higher ordinal number does not necessarily indicate the presence of another element with a lower ordinal number.

[0056] In this document, unless otherwise specified, the term "characteristic A" or "and / or" and "characteristic B" means that A exists alone, B exists alone, or A and B exist simultaneously; the term "characteristic A" and "and" or "and" and "and" and "characteristic B" means that A and B exist simultaneously; the terms "including", "containing", "having", and "containing" refer to, but are not limited to, these.

[0057] Furthermore, in this document, terms such as "up," "down," "left," "right," "front," "back," or "between" are used only to describe the relative positions of multiple elements and can be extended to include translation, rotation, or mirroring. Additionally, unless otherwise specified, the statement "one element is on another element" or similar statements do not necessarily indicate that the element is in contact with the other element.

[0058] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0059] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar, comprising: obtaining average signals of HH and VV channels by reflecting signals through a metal plate; obtaining effective reflection signals of the HH and VV channels by intercepting the average signals; calculating the sum of the amplitude modulus of the effective reflection signals of the HH and VV channels respectively; calculating a correction coefficient by calculating the ratio of the sum of the amplitude modulus of the effective reflection signals of the HH channel to the sum of the amplitude modulus of the effective reflection signals of the VV channel; and reading the measured data of the HH or VV channel of the Mars rover radar polarization channel, and multiplying the measured data of the HH or VV channel by the correction coefficient to complete the amplitude calibration of the polarization channel. 2.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 1, wherein the metal plate reflection signals are obtained by reflecting the high frequency of the Mars rover penetrating radar through a metal plate on the ground. 3.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 2, wherein the metal plate reflection signals include HH, VV, HV, and VH polarization channel reflection signals, and the metal plate reflection signals of the HH and VV channels are selected for processing.

4. The method of calibrating the high frequency polarization channel amplitude of a Mars rover subsurface sounding radar according to claim 1, wherein the effective reflection signals of the HH channel and the VV channel are obtained by intercepting the average signals respectively. comprising: intercepting 0-80 ns in the average signal as an effective information segment; eliminating the antenna coupling signal of the front part of the effective information segment in the average signal; and intercepting the part of the average signal after the weak signal area to obtain the effective reflection signals of the HH and VV channels. 5.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 1, wherein the calculation of the sum of the amplitude modulus of the effective reflection signals of the HH and VV channels respectively comprises: calculating the sum A of the magnitudes of the effective reflection signals of the HH channels HH : where t1 represents the time at which the effective reflected signal starts to be intercepted, t2 represents the time at which the effective reflected signal ends to be intercepted, a HH (t) represents the HH polarized channel signal amplitude. 6.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 5, wherein the calculation of the sum of the amplitude modulus of the effective reflection signals of the HH and VV channels respectively further comprises: calculating a sum A of the magnitudes of the effective reflection signals of the VV channel VV : where t1 represents the time at which the effective reflected signal starts to be intercepted, t2 represents the time at which the effective reflected signal ends to be intercepted, a VV (t) represents the amplitude of the VV polarization channel signal. 7.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 6, wherein the correction coefficient is set as k, and: 8.The method for calibrating the amplitude of high frequency polarization channels of a Mars rover subsurface sounding radar according to claim 7, wherein the measured data of the HH or VV channel is multiplied by the correction coefficient, so that the sum of the amplitude modulus of the HH and VV channels is equal, and the amplitude calibration of the polarization channel is completed.

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