Method and system for calibrating input-output power relationship of GNSS-R receiver

Abstract

The application discloses a GNSS-R receiver input-output power relationship calibration method and system, and relates to the technical field of global navigation satellite system reflection signal measurement. The method comprises the following steps: constructing an input power sequence of a ground-based GNSS-R receiver; determining the signal power of each visible star in the waveform sequence corresponding to each input power point according to the waveform sequence corresponding to each input power point in the input power sequence; obtaining the channel output power corresponding to each input power point according to the signal power of all visible stars in the waveform sequence corresponding to each input power point; obtaining an output power sequence of the ground-based GNSS-R receiver according to the channel output power corresponding to all input power points in each input power sequence; and obtaining an input-output power relationship model of the ground-based GNSS-R receiver according to the input power sequence and the output power sequence. The application can realize low-cost and high-precision input-output power relationship calibration of the ground-based GNSS-R receiver.

Description

GNSS-R Receiver Input-Output Power Relationship Calibration Method and System Technical Field

[0001] This invention relates to the field of global navigation satellite system reflected signal measurement technology, and in particular to a GNSS-R receiver input-output power relationship calibration method and system. Background Technology

[0002] Global Navigation Satellite System Reflectometry (GNSS-R) is an opportunistic remote sensing technique that retrieves geophysical parameters by receiving and processing navigation satellite signals reflected from the Earth's surface. It has advantages such as low equipment cost, minimal weather impact, and good spatiotemporal sampling performance, and has shown great application potential in fields such as sea surface height retrieval, sea surface wind speed detection, and soil moisture detection.

[0003] A ground-based GNSS-R receiver is a device for co-processing GNSS direct and reflected signals, mounted on a ground-based observation platform. Its basic structure includes two parts: radio frequency (RF) and baseband. The RF part performs RF adjustment, down-conversion, and digitization on the direct and reflected GNSS signals received by the antenna. The baseband part further completes the acquisition and tracking of the direct signal, receiver positioning, and synchronization of the reflected signal, outputting digital power count values ​​of the direct and reflected signals within a certain delay range as the basic observations for inverting ground feature parameters. Since the digital power count value of the signal is not the true power of the signal, as it includes signal power variations introduced during signal transmission and processing, directly using the digital power count value for ground feature parameter inversion will affect the accuracy of the inversion results. Therefore, it is necessary to convert the digital power count value of the signal output by the receiver into the true power of the input signal, that is, to calibrate the input-output power relationship of the ground-based GNSS-R receiver.

[0004] Currently, the calibration of the input-output power relationship of GNSS-R receivers is mainly accomplished using the blackbody radiation calibration method. The specific procedure involves setting up a blackbody load channel before the low-noise amplifier in the RF section, placing the load noise in parallel with the received signal; periodically switching the load noise and received signal input to the RF channel; calculating the system gain using the load noise power count and the actual load noise power; and using the ratio of the signal power count to the system gain as the calibrated actual input signal power. While the blackbody radiation calibration method offers high accuracy and strong adaptability to environmental temperature changes, it requires the installation of a blackbody radiation calibration component on the receiver, making the calibration process relatively complex. Therefore, it is primarily used for on-orbit calibration of the input-output power relationship of spaceborne GNSS-R receivers. In ground-based scenarios with minimal environmental temperature variations, using the blackbody radiation calibration method for GNSS-R receiver calibration would increase receiver complexity and development costs. Therefore, a new ground-based GNSS-R receiver input-output power relationship calibration method is needed to achieve low-cost, high-precision calibration. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for calibrating the input-output power relationship of a GNSS-R receiver, which can achieve low-cost and high-precision calibration of the input-output power relationship of a ground-based GNSS-R receiver.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for calibrating the input-output power relationship of a GNSS-R receiver includes:

[0008] Construct the input power sequence for a ground-based GNSS-R receiver; the input power sequence is either a direct channel input power sequence including multiple input power points or a reflective channel input power sequence including multiple input power points;

[0009] Obtain the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver; the waveform sequence is the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver.

[0010] For any input power point in the input power sequence, the signal power of each visible star in the waveform sequence corresponding to the input power point is determined based on the waveform sequence corresponding to the input power point.

[0011] The channel output power corresponding to the input power point is obtained by calculating the signal power of all visible stars in the waveform sequence corresponding to the input power point.

[0012] The output power sequence of the ground-based GNSS-R receiver is obtained based on the channel output power corresponding to all input power points in the input power sequence.

[0013] The input-output power relationship model of the ground-based GNSS-R receiver is obtained based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The input-output power relationship model of the ground-based GNSS-R receiver is used to calibrate the relationship between the input power and the output power of the ground-based GNSS-R receiver.

[0014] A GNSS-R receiver input-output power relationship calibration system includes:

[0015] A construction module is used to construct the input power sequence of a ground-based GNSS-R receiver; the input power sequence is a direct channel input power sequence including multiple input power points or a reflection channel input power sequence including multiple input power points;

[0016] The waveform sequence acquisition module is used to acquire the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver; the waveform sequence is the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver.

[0017] The signal power calculation module is used to determine the signal power of each visible star in the waveform sequence corresponding to any input power point in the input power sequence, based on the waveform sequence corresponding to the input power point.

[0018] The channel output power calculation module is used to obtain the channel output power corresponding to the input power point based on the signal power of all visible stars in the waveform sequence corresponding to the input power point.

[0019] The output power sequence calculation module is used to obtain the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in the input power sequence.

[0020] The calibration module is used to obtain an input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The input-output power relationship model of the ground-based GNSS-R receiver is used to calibrate the relationship between the input power and the output power of the ground-based GNSS-R receiver.

[0021] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] This invention constructs the input power sequence of a ground-based GNSS-R receiver; determines the signal power of each visible satellite in the waveform sequence corresponding to each input power point based on the waveform sequence corresponding to each input power point; obtains the channel output power corresponding to each input power point based on the signal power of all visible satellites in the waveform sequence corresponding to each input power point; obtains the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in each input power sequence; and obtains the input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver, calibrating the input power and output power relationship of the ground-based GNSS-R receiver. This enables low-cost, high-precision calibration of the input-output power relationship of the ground-based GNSS-R receiver. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 is a flowchart of the input-output power relationship calibration of a ground-based GNSS-R receiver provided in an embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of the connection of the ground-based GNSS-R receiver input-output power relationship calibration device provided in an embodiment of the present invention;

[0026] Figure 3 shows the measured input-output power data and modeling results of the direct-fire channel provided in the embodiment of the present invention.

[0027] Figure 4 shows the measured input-output power data and modeling results of the reflection channel provided in the embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] As shown in Figure 1, this embodiment of the invention provides a GNSS-R receiver input-output power relationship calibration method. It utilizes a standard dual-channel GNSS signal simulator to achieve low-cost, high-precision calibration of the input-output power relationship of a ground-based GNSS-R receiver. The steps are as follows: Construct a calibration input power sequence; connect the device; for the first input power point, configure and run the GNSS simulator; test the signal; run the GNSS-R receiver to obtain a signal delay power waveform sequence; calculate the average waveform based on the signal delay power waveform sequence; extract the peak value and delay index based on the average power waveform; calculate the average noise power based on the delay index and average waveform; calculate the output power based on the average noise power, delay index, and peak value; determine if all power points have been tested; if so, construct a calibration output power sequence; establish an input-output power relationship model based on the calibration output power sequence and the calibration input power sequence; otherwise, test the next power point. The method specifically includes:

[0031] Step 1: Construct the input power sequence for the ground-based GNSS-R receiver. The input power sequence is either a direct-channel input power sequence with multiple input power points or a reflected-channel input power sequence with multiple input power points. When the input power sequence is a direct-channel input power sequence with I input power points, the calibration of the direct-channel input-output power relationship of the ground-based GNSS-R receiver is performed; I is a positive integer. When the input power sequence is a reflected-channel input power sequence with J input power points, the calibration of the reflected-channel input-output power relationship of the ground-based GNSS-R receiver is performed; J is a positive integer.

[0032] Step 2: Obtain the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver. The waveform sequence is the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver, also called the direct waveform sequence, or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver, also called the reflection waveform sequence. The direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of the GNSS simulator via a first RF connection line, and the reflection signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator via a second RF connection line. The signal delay power waveform sequence includes: M groups of delay power waveforms; each group of delay power waveforms includes: N delay power samples; M and N are both integers greater than zero.

[0033] Step 3: For any input power point in the input power sequence, determine the signal power of each visible star in the waveform sequence corresponding to the input power point based on the waveform sequence corresponding to the input power point.

[0034] Step 4: Obtain the channel output power corresponding to the input power point based on the signal power of all visible stars in the waveform sequence corresponding to the input power point.

[0035] Step 5: Obtain the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in the input power sequence.

[0036] Step 6: Obtain the input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The input-output power relationship model of the ground-based GNSS-R receiver is used to calibrate the relationship between the input power and output power of the ground-based GNSS-R receiver.

[0037] In practical applications, for any waveform sequence corresponding to an input power point in the input power sequence, the signal power of each visible star in the waveform sequence corresponding to the input power point is determined based on the waveform sequence corresponding to the input power point, specifically including:

[0038] For any input power point in the input power sequence, the average delay power waveform of each visible star in the waveform sequence corresponding to the input power point is obtained based on the waveform sequence corresponding to the input power point.

[0039] Peak detection and extraction are performed on the average delay power waveform of each visible star to obtain the peak of each visible star and the delay index of the delay power sample point where the peak of each visible star is located.

[0040] The noise power of each visible star is obtained by using the average delayed power waveform of each visible star and the delay index of the delayed power sample point where the peak of each visible star is located.

[0041] The signal power of each visible star in the waveform sequence corresponding to the input power point is obtained based on the noise power of each visible star and the peak of each visible star.

[0042] In practical applications, constructing the input power sequence for a ground-based GNSS-R receiver specifically includes:

[0043] The input power sequence of the ground-based GNSS-R receiver is constructed based on the channel acquisition sensitivity, the set power adjustment step, and the sequence number of each input power point.

[0044] In practical applications, the channel output power corresponding to the input power point is obtained based on the signal power of all visible stars in the waveform sequence corresponding to the input power point. Specifically, this includes:

[0045] The channel output power corresponding to the input power point is obtained by calculating the average signal power of all visible stars in the waveform sequence corresponding to the input power point.

[0046] When calibrating the input-output power relationship of the direct channel of a ground-based GNSS-R receiver, the input power sequence, i.e., the direct channel input power sequence, is expressed as:

[0047] in, I represents the input power sequence; I is the length of the direct-channel input power sequence. for The first input power point in the system; for The second input power point; for The i-th input power point in; for The I-th input power point in the system.

[0048] In practical applications, according to the formula:

[0049] calculate in, The direct-fire channel capture sensitivity. L is the floor operator. d The insertion loss of the first RF connection line is Δp. d The power adjustment step is set to calibrate the direct channel, where I is the length of the input power sequence for the direct channel.

[0050] According to the formula The calculation yields I, where, Let || be the noise power of the direct channel signal before despreading, and || be the modulus operator. This is the floor operator.

[0051] In practical applications, when calibrating the input-output power relationship of a ground-based GNSS-R receiver's direct channel, for any input power point in the input power sequence (direct waveform sequence), the signal power of each visible satellite in the waveform sequence corresponding to the input power point is determined based on the waveform sequence corresponding to the input power point. The channel output power corresponding to the input power point is obtained based on the signal power of all visible satellites in the waveform sequence corresponding to the input power point. The output power sequence of the ground-based GNSS-R receiver is obtained based on the channel output power corresponding to all input power points in the input power sequence. Finally, the input-output power relationship model of the ground-based GNSS-R receiver is obtained based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver, specifically as follows:

[0052] For any visible star at any input power point, calculate the average delayed power waveform of the direct waveform sequence to obtain the first average waveform of the visible star.

[0053] Peak detection and peak extraction are performed on the first average waveform to obtain the first peak and the first delay index of the visible star; the first delay index is the delay index of the delay power sample point where the first peak is located.

[0054] The first noise power of the visible star is calculated based on the first average waveform and the first delay index; the first noise power is the average noise power of the direct waveform sequence.

[0055] For any input power point, the direct channel output power is calculated based on the first peak and first noise power of all visible stars; the direct channel output power is the statistical mean of the difference between the first peak value and the first noise power of all visible stars.

[0056] Construct the direct-channel calibration output power sequence of the ground-based GNSS-R receiver; each element in the output power sequence corresponds one-to-one with each element in the input power sequence, including I output power samples.

[0057] A curve fitting method is used to establish a relationship expression between the input power sequence and the output power sequence of the direct-view channel, i.e., an input-output power relationship model for the ground-based GNSS-R receiver; the relationship expression is used for the calibration of the input-output power relationship of the direct-view channel of the ground-based GNSS-R receiver.

[0058] In practical applications, for the k-th visible star at the i-th input power point, the direct waveform sequence expression is:

[0059]

[0060] Among them, K i The number of visible stars captured and tracked by the direct channel at the i-th input power point; The direct waveform sequence of the k-th visible star at the i-th input power point; for The first group of delayed power waveforms; for The second group of delayed power waveforms; for The m-th group of delayed power waveforms; for The Mth group of delayed power waveforms.

[0061] The expression is:

[0062]

[0063] in, for Delay power sample with a delay index of 1 in the middle, for Delay power sample with delay index 2 in the middle, for The delay power sample with delay index n in the middle. for The delay power sample with delay index N.

[0064] In practical applications, for the k-th visible star at the i-th input power point, the expression for the first average waveform is:

[0065]

[0066] in, The first average waveform of the k-th visible star at the i-th input power point; for Delay power samples with a delay index of 1; for Delay power sample with a delay index of 2; for Delay power samples with a delay index of n; for The delay power sample with delay index N. The expression is:

[0067]

[0068] In practical applications, for the k-th visible star at the i-th input power point, the expression for the first noise power is:

[0069]

[0070] in, Let be the first noise power of the k-th visible star at the i-th input power point; is the first delay index of the k-th visible star at the i-th input power point; s is the number of delay power samples on a unit pseudocode chip; [] is the rounding operator; for The delay power sample with delay index n.

[0071] In practical applications, This represents the first peak of the k-th visible star at the i-th input power point. For the i-th input power point, the formula for calculating the direct channel output power is:

[0072]

[0073] In practical applications, the expression for the direct-view channel calibration output power sequence is:

[0074]

[0075] In practical applications, the relationship expression between the input power sequence and the output power sequence of the direct-fire channel is constructed using the least squares curve fitting method.

[0076] In practical applications, when calibrating the input-output power relationship of a ground-based GNSS-R receiver's reflection channel, for any input power point in the input power sequence corresponding to the waveform sequence (reflection waveform sequence), the signal power of each visible satellite in the waveform sequence corresponding to the input power point is determined based on the waveform sequence corresponding to the input power point. The channel output power corresponding to the input power point is obtained based on the signal power of all visible satellites in the waveform sequence corresponding to the input power point. The output power sequence of the ground-based GNSS-R receiver is obtained based on the channel output power corresponding to all input power points in the input power sequence. Finally, the input-output power relationship model of the ground-based GNSS-R receiver is obtained based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. Specifically:

[0077] For any visible star at any input power point, calculate the average delayed power waveform of the reflected waveform sequence to obtain the second average waveform of the visible star.

[0078] Peak detection and peak extraction are performed on the second average waveform to obtain the second peak and the second delay index of the visible star; the second delay index is the delay index of the delay power sample point where the second peak is located.

[0079] The second noise power of the visible star is calculated based on the second average waveform and the second delay index; the second noise power is the average noise power of the reflected waveform sequence.

[0080] For any input power point, the output power of the reflection channel is calculated based on the second peak and the second noise power of all visible stars; the output power of the reflection channel is the statistical mean of the difference between the second peak value and the second noise power of all visible stars.

[0081] Construct the calibration output power sequence of the ground-based GNSS-R receiver reflection channel; each element in the output power sequence corresponds one-to-one with each element in the input power sequence, including J output power points. One input power will be obtained under one input power, so the number of input power points and output power points is the same.

[0082] A curve fitting method is used to establish a relational expression between the input power sequence and the output power sequence of the reflection channel, which is the input-output power relationship model of the ground-based GNSS-R receiver; the relational expression is used to calibrate the input-output power relationship of the reflection channel of the ground-based GNSS-R receiver.

[0083] In practical applications, the signal output power setting principle of the first signal output port is: the signal output power is equal to the noise power of the ground-based GNSS-R receiver reflection channel under the test conditions.

[0084] In practical applications, when calibrating the input-output power relationship of the reflection channel of a ground-based GNSS-R receiver, the expression for the input power sequence, i.e., the input power sequence of the reflection channel, is as follows:

[0085]

[0086] in, J represents the input power sequence; J is the length of the input power sequence in the reflection channel. for The first input power point in the system; for The second input power point; for The j-th input power point in; for The Jth input power point in the system.

[0087] In practical applications, according to the formula calculate in, The sensitivity of the reflected channel signal detection is [value]. L is the floor operator. r The insertion loss of the second RF connection line is Δp. r The step size for adjusting the calibration power of the reflection channel is J, where J is the length of the input power sequence of the reflection channel.

[0088] J is based on the formula: calculate.

[0089] In practical applications, for the k-th visible star at the j-th input power point, the expression for the reflected waveform sequence is:

[0090] Among them, K j The number of visible stars processed by the reflection channel at the j-th input power point; The reflected waveform sequence of the k-th visible star at the j-th input power point; for The first group of delayed power waveforms; for The second group of delayed power waveforms; for The m-th group of delayed power waveforms; for The Mth group of delayed power waveforms. The expression is:

[0091]

[0092] in, for Delay power sample with a delay index of 1 in the middle, for Delay power sample with delay index 2 in the middle, for The delay power sample with delay index n in the middle. for The delay power sample with delay index N.

[0093] In practical applications, for the k-th visible star at the j-th input power point, the expression for the second average waveform is:

[0094]

[0095] in, The second average waveform of the k-th visible star at the j-th input power point; for Delay power samples with a delay index of 1; for Delay power sample with a delay index of 2; for Delay power samples with a delay index of n; for The delay power sample with delay index N. The expression is:

[0096]

[0097] In practical applications, for the k-th visible star at the j-th input power point, the expression for the second noise power is:

[0098]

[0099] in, The second noise power of the k-th visible star at the j-th input power point; is the second delay index of the k-th visible star at the j-th input power point; s is the number of delay power samples on a unit pseudocode chip; [] is the rounding operator; for Delay power samples with a delay index of n; This is the second average waveform of the kth visible star.

[0100] In practical applications, for the j-th input power point, the formula for calculating the output power of the reflection channel is:

[0101]

[0102] In practical applications, the expression for the output power sequence of the reflection channel calibration is:

[0103]

[0104] In practical applications, the relationship expression between the input power sequence and the output power sequence of the reflection channel is constructed using the least squares curve fitting method.

[0105] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0106] This invention eliminates the need for additional blackbody radiation calibration components in ground-based GNSS-R receivers, thereby reducing their complexity, size, weight, and manufacturing costs. Therefore, this invention enables low-cost, high-precision calibration of the input-output power relationship of ground-based GNSS-R receivers.

[0107] This invention provides a specific embodiment corresponding to the above method:

[0108] I. The method for calibrating the input-output power relationship of the direct channel of a ground-based GNSS-R receiver in this embodiment includes:

[0109] Step 101: Construct the input power sequence for the direct channel of the ground-based GNSS-R receiver.

[0110] The input power sequence includes: I input power points; denoted by formula (1).

[0111] Calculate each input power point according to formulas (2) and (3).

[0112] Step 102: For any input power point, obtain the direct waveform sequence.

[0113] The direct-sun waveform sequence is a sequence of signal delay power waveforms tracked by the direct-sun channel of a ground-based GNSS-R receiver under a specified input power. The signal delay power waveform sequence includes M groups of delay power waveforms. Each group of delay power waveforms includes N delay power samples; M and N are both positive integers.

[0114] In practical applications, step 102 is implemented as follows:

[0115] 1. Connect the standard dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.

[0116] Referring to Figure 2, the first signal output port (signal output port 1) and the second signal output port (output port 2) of the GNSS simulator are connected to the direct signal input port and the reflected signal input port of the GNSS-R receiver, respectively, using a first RF connection line (i.e., RF connection line 1) and a second RF connection line (i.e., RF connection line 2) with known insertion loss. Let L be the insertion loss of the first RF connection line. d .

[0117] 2. Start, configure, and run the dual-channel GNSS signal simulator.

[0118] Turn on the power, start the dual-channel GNSS signal simulator, select the signal to be calibrated, and configure the ephemeris file, signal simulation start time, receiver spatial coordinates, and signal output power for the first signal output port. Run the simulator until the output signal power stabilizes. The signal output power should be configured to the specified input power value to be calibrated.

[0119] 3. Run the ground-based GNSS-R receiver to acquire the direct channel signal delay power waveform sequence, i.e., the direct waveform sequence.

[0120] Power on and run the ground-based GNSS-R receiver. The direct channel completes signal acquisition and tracking, calculates and outputs the signal delay power waveform sequence for each visible satellite, thus obtaining the direct waveform sequence.

[0121] Assume that the number of visible satellites tracked by the ground-based GNSS-R receiver's direct channel at the i-th input power point is K. i The output signal delay power waveform sequence includes M sets of delay power waveforms, and the number of delay power samples in each set is N. The k-th visible star (1≤k≤K) is output from the direct channel. i The signal delay power waveform sequence (direct waveform sequence) is denoted by formula (4).

[0122] Step 103: For any visible star at any input power point, calculate the average delayed power waveform of the direct waveform sequence to obtain the first average waveform.

[0123] Specifically, the average delay power waveform of each visible star signal in the direct channel is calculated according to formulas (6) and (7), which is the first average waveform.

[0124] Step 104: For any visible star at any input power point, perform peak detection and peak extraction on the first average waveform to obtain the first peak and the first delay index.

[0125] Specifically, for the average delay power waveforms of each visible star signal in the direct-view channel obtained in step 104, peak detection and extraction are performed sequentially. The delay index (i.e., the first delay index) where the peak of the average delay power waveform of each visible star signal in the direct-view channel is located is denoted as... The corresponding peak value (the value of the first peak) is:

[0126] Step 105: For any visible star at any input power point, calculate the first noise power based on the first average waveform and the first delay index.

[0127] Specifically, the average noise power of the delayed power waveform sequence of each visible star signal in the direct channel is calculated according to formula (8), which is the first noise power.

[0128] Step 106: For any input power point, calculate the direct channel output power based on the first peak and the first noise power of all visible stars. Specifically, calculate according to formula (9).

[0129] Step 107: Construct the direct channel output power sequence based on the direct channel output power at all input power points. The specific form is Equation (10).

[0130] Step 108: Based on the input power sequence and the output power sequence, establish a direct-channel input-output power relationship model for the ground-based GNSS-R receiver.

[0131] II. The method for calibrating the input-output power relationship of the reflection channel of a ground-based GNSS-R receiver provided in this embodiment includes:

[0132] Step 201: Construct the input power sequence for the reflection channel of the ground-based GNSS-R receiver.

[0133] The input power sequence includes J input power points, denoted as... As shown in formula (11).

[0134] Specifically, calculate according to formulas (12) and (13). Each input power point

[0135] Step 202: For any input power point, obtain the reflected waveform sequence.

[0136] The reflected waveform sequence is a sequence of signal delay power waveforms output from the reflection channel of a ground-based GNSS-R receiver at a specified input power for each visible satellite. The signal delay power waveform sequence includes M groups of delay power waveforms. Each group of delay power waveforms includes N delay power samples; M and N are both positive integers.

[0137] In practical applications, step 202 is implemented as follows:

[0138] 1. Connect the standard dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.

[0139] Referring to Figure 2, the first signal output port (signal output port 1) and the second signal output port (output port 2) of the GNSS simulator are connected to the direct signal input port and the reflected signal input port of the GNSS-R receiver, respectively, using a first RF connection line (i.e., RF connection line 1) and a second RF connection line (i.e., RF connection line 2) with known insertion losses. Let L be the insertion losses of the first RF connection line and the second RF connection line, respectively. d and L r .

[0140] 2. Start, configure, and run the dual-channel GNSS signal simulator.

[0141] Turn on the power, start the dual-channel GNSS signal simulator, select the signal to be calibrated, configure the same ephemeris file, signal simulation start time, and receiver spatial coordinates for both signal output channels, and configure the output power of each channel to the specified power value. Run the simulator until the output signal power stabilizes. Specifically, the signal output power value of output port 1 is equal to the noise power of the direct channel, and the signal output power value of output port 2 is equal to the current input power value to be calibrated.

[0142] 3. Run the ground-based GNSS-R receiver to acquire the delayed power waveform sequence of the reflected channel signal, i.e., the reflected waveform sequence.

[0143] Power on and run the ground-based GNSS-R receiver. The direct channel acquires and tracks the signal, while the reflection channel, assisted by the direct channel, performs open-loop tracking of the signal in the reflection channel, calculates and outputs the signal delay power waveform sequence of each satellite, i.e., the reflection waveform sequence.

[0144] Assume that the number of visible satellites tracked by the direct channel of the ground-based GNSS-R receiver is K. j The signal delay power waveform sequence output by the reflection channel includes M sets of delay power waveforms, with N delay power samples in each set. The k-th visible star output by the reflection channel (1≤k≤K) j The signal delay power waveform sequence (reflection waveform sequence) is denoted by formula (14).

[0145] Step 203: For any visible star at any input power point, calculate the average delay power waveform of the reflected waveform sequence to obtain the second average waveform.

[0146] Specifically, the average delay power waveform of each visible star signal in the reflection channel is calculated according to formula (16), which is the second average waveform.

[0147] Step 204: For any visible star at any input power point, perform peak detection and peak extraction on the second average waveform to obtain the second peak and the second delay index.

[0148] Specifically, for the average delay power waveforms of each visible star signal in the reflection channel obtained in step 204, peak detection and extraction are performed sequentially. The delay index (i.e., the second delay index) where the peak of the average delay power waveform of each visible star signal in the reflection channel is located is denoted as... The corresponding peak value (the value of the second peak) is:

[0149] Step 205: For any visible star at any input power point, calculate the second noise power based on the second average waveform and the second delay index.

[0150] Specifically, the average noise power of the delayed power waveform sequence of each visible star signal in the reflection channel is calculated according to formula (18), which is the second noise power.

[0151] Step 206: For any visible star at any input power point, calculate the output power of the reflection channel based on the second peak and the second noise power.

[0152] Specifically, the output power of the reflection channel is calculated according to formula (19).

[0153] Step 207: Construct the reflection channel output power sequence based on the reflection channel output power at all input power points.

[0154] The output power sequence of the reflection channel is the set of output powers corresponding to all input power points, and the element arrangement order is the same as that of the input power sequence, denoted as formula (20).

[0155] Step 208: Based on the input power sequence and the output power sequence, establish the input-output power relationship model of the ground-based GNSS-R receiver reflection channel.

[0156] The ground-based GNSS-R receiver input-output power relationship calibration method of this embodiment does not require the installation of a blackbody radiation calibration component for the ground-based GNSS-R receiver, which can reduce the complexity, size, weight and manufacturing cost of the ground-based GNSS-R receiver.

[0157] This invention provides an example of calibrating the input-output power relationship of a ground-based GNSS-R receiver operating at GPS L1 and BDSB1 using a standard dual-channel GNSS signal simulator. Specifically, the calibration of the input-output power relationship for the direct channel uses GPS L1 as an example, while the calibration of the input-output power relationship for the reflected channel uses BDS B1 as an example.

[0158] I. Calibration of input-output power relationship of direct channel of ground-based GNSS-R receiver.

[0159] Specifically, the steps include the following:

[0160] Step 1: Construct the input power sequence for the direct channel of the ground-based GNSS-R receiver

[0161] Under the given test conditions, the noise power of the direct-view channel -140dBW, direct-channel capture sensitivity Approximately -160dBW. The direct-view channel calibration power adjustment step is set to Δp. d With a value of 2dBW and ignoring RF connection insertion loss, the direct channel input power sequence length I is determined to be 11. The direct channel input power sequence for the ground-based GNSS-R receiver is constructed as follows:

[0162]

[0163] Step 2: Connect the dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.

[0164] Referring to Figure 2, use RF connection cable 1 and RF connection cable 2 to connect the signal output port 1 and output port 2 of the dual-channel GNSS simulator to the direct signal input port and reflected signal input port of the ground-based GNSS-R receiver, respectively.

[0165] Step 3: Start, configure, and run the dual-channel GNSS signal simulator.

[0166] Connect the power supply and start the dual-channel GNSS signal simulator. Select the GPS L1C / A signal to be calibrated. Configure the ephemeris file, signal simulation start time, and receiver spatial coordinates for output port 1. Set the output power to -140dBW. After configuration, run the dual-channel GNSS signal simulator until the output signal power stabilizes.

[0167] Step 4: Run the ground-based GNSS-R receiver to acquire the direct channel signal delay power waveform sequence.

[0168] Turn on the power and run the ground-based GNSS-R receiver. The direct channel completes the acquisition and tracking of the signal, calculates and outputs the delay power waveform sequence of each visible star signal, denoted as formula (4).

[0169] Step 5: Calculate the average delay power waveform of each visible star signal in the direct channel.

[0170] The average delay power waveform (first average waveform) of each visible star signal output by the direct channel is calculated sequentially according to formulas (6) and (7).

[0171] Step 6: Extract the peak value of the average delay power waveform and its delay index of each visible star signal in the direct channel.

[0172] For the average delay power waveforms of each visible star signal in the direct-view channel obtained in step 5, peak detection and extraction are performed sequentially. Let the delay index of the peak value of the average delay power waveform of each visible star signal in the direct-view channel be denoted as . The corresponding peak size is

[0173] Step 7: Calculate the average noise power (first noise power) of the waveform sequence of the delayed power of each visible star signal in the direct channel.

[0174] Using the average delay power waveform of each visible star signal in the direct channel obtained in step 5 and the delay index of the peak value of the average delay power waveform obtained in step 6, the average noise power of the delay power waveform sequence of each visible star signal output by the direct channel is calculated in sequence according to formula (8), which is the first noise power.

[0175] Step 8: Calculate the output power of the direct-view channel.

[0176] Using the peak value of the average delay power waveform of each satellite obtained in step 6 and the average noise power of the delay power waveform sequence of each satellite obtained in step 7, the output power of the direct channel is calculated according to formula (9).

[0177] Step 9: Adjust the output power setting of the dual-channel GNSS signal simulator to reduce the output signal power of its first signal output port by 2dB. Repeat steps 4 to 9 to calculate the output power at the input power point until the output power at all input power points is obtained. Finally, the direct channel calibration output power sequence is obtained as shown in formula (10).

[0178] Step 10: Establish a model showing the relationship between the input power sequence and the output power sequence of the direct-fire channel.

[0179] The following second-order polynomial model is used to fit the relationship between the input power sequence constructed in step 1 and the output power sequence obtained in step 9. Among them, a d b d and c d The fitting coefficients are to be determined.

[0180] The fitting coefficients are solved based on the least squares criterion to obtain the input-output power relationship model of the direct-fire channel. This model can be used to calibrate the input-output power of the direct-fire channel. Figure 3 shows a scatter plot of the output power sequence corresponding to the input power sequence and a second-order polynomial model of the input-output power relationship of the direct-fire channel constructed based on the least squares criterion.

[0181] II. Calibration of the input-output power relationship of the reflection channel of the ground-based GNSS-R receiver.

[0182] Specifically, the steps include the following:

[0183] Step 1: Construct the input power sequence for the reflection channel of the ground-based GNSS-R receiver.

[0184] Under the given test conditions, the noise power of the reflection channel The sensitivity of the reflected channel detection signal is -140dBW. Approximately -160dBW. Set the reflection channel calibration power adjustment step to Δp. r With a power factor of 2 dBW and ignoring RF connection insertion loss, the input power sequence length J of the reflection channel is determined to be 11. The input power sequence of the ground-based GNSS-R receiver's reflection channel is constructed as follows:

[0185]

[0186] Step 2: Connect the dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.

[0187] Referring to Figure 2, use RF connection cable 1 and RF connection cable 2 to connect the signal output port 1 and output port 2 of the dual-channel GNSS simulator to the direct signal input port and reflected signal input port of the ground-based GNSS-R receiver, respectively.

[0188] Step 3: Start, configure, and run the dual-channel GNSS signal simulator.

[0189] Connect the power supply and start the dual-channel GNSS signal simulator. Select the BDS B1I signal as the signal to be calibrated. Configure the same ephemeris file, signal simulation start time, and receiver spatial coordinates for output port 1 and output port 2. Set the signal output power of output port 1 to -140dBW and the signal output power of output port 2 to -140dBW. After configuration, run the dual-channel GNSS signal simulator until the output signal power stabilizes.

[0190] Step 4: Run the ground-based GNSS-R receiver to acquire the waveform sequence of the delayed power of the reflected channel signal.

[0191] Turn on the power and run the ground-based GNSS-R receiver. The direct channel completes the acquisition and tracking of the signal, and the reflection channel calculates and outputs the delay power waveform sequence of each visible star signal, denoted as formula (14).

[0192] Step 5: Calculate the average delay power waveform of each visible star signal in the reflection channel.

[0193] Based on formulas (16) and (17), the average delay power waveform (second average waveform) of each visible star signal output by the reflection channel is calculated in sequence.

[0194] Step 6: Extract the peak value of the average delay power waveform of each visible star signal in the reflection channel and its delay index.

[0195] For the average delay power waveforms of each visible star signal in the reflection channel obtained in step 5, peak detection and extraction are performed sequentially. Let the delay index of the peak value of the average delay power waveform of each visible star signal in the reflection channel be denoted as . The corresponding peak size is

[0196] Step 7: Calculate the average noise power (second noise power) of the waveform sequence of the delayed power of each visible star signal in the reflection channel.

[0197] Using the average delay power waveform of each visible star signal obtained in step 5 and the delay index of the peak value of the average delay power waveform obtained in step 6, the average noise power of each visible star signal delay power waveform sequence output by the reflection channel is calculated sequentially according to formula (18), which is the second noise power.

[0198] Step 8: Calculate the output power of the reflection channel.

[0199] Using the peak value of the average delay power waveform of each satellite obtained in step 6 and the average noise power of the delay power waveform sequence of each satellite obtained in step 7, the output power of the reflection channel is calculated according to formula (19).

[0200] Step 9: Adjust the output power setting of the dual-channel GNSS signal simulator to reduce the output signal power of its second signal output port by 2dB. Repeat steps 4 to 9 to calculate the output power at the input power point until the output power at all input power points is obtained. Finally, the output power sequence of the reflection channel calibration is obtained as shown in formula (20).

[0201] Step 10: Establish a model showing the relationship between the input power sequence and the output power sequence of the reflection channel.

[0202] Establish a model relating the input power sequence and the output power sequence of the reflection channel.

[0203] The following second-order polynomial model is used to fit the relationship between the input power sequence constructed in step 1 and the output power sequence obtained in step 9: Among them, a r b r and c r The fitting coefficients are to be determined. Figure 4 shows a scatter plot of the output power sequence corresponding to the input power sequence and a second-order polynomial model of the input-output power relationship of the reflection channel constructed based on the least squares criterion.

[0204] In view of the above method, this embodiment of the invention provides a GNSS-R receiver input-output power relationship calibration system, including:

[0205] A construction module is used to construct the input power sequence of a ground-based GNSS-R receiver; the input power sequence is either a direct channel input power sequence including multiple input power points or a reflection channel input power sequence including multiple input power points.

[0206] The waveform sequence acquisition module is used to acquire the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver; the waveform sequence is the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver.

[0207] The signal power calculation module is used to determine the signal power of each visible star in the waveform sequence corresponding to any input power point in the input power sequence, based on the waveform sequence corresponding to the input power point.

[0208] The channel output power calculation module is used to obtain the channel output power corresponding to the input power point based on the signal power of all visible stars in the waveform sequence corresponding to the input power point.

[0209] The output power sequence calculation module is used to obtain the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in the input power sequence.

[0210] The calibration module is used to obtain an input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The input-output power relationship model of the ground-based GNSS-R receiver is used to calibrate the relationship between the input power and the output power of the ground-based GNSS-R receiver.

[0211] As an optional implementation, the signal power calculation module specifically includes:

[0212] The average delay power waveform calculation unit is used to obtain the average delay power waveform of each visible star in the waveform sequence corresponding to any input power point in the input power sequence, based on the waveform sequence corresponding to the input power point.

[0213] The peak detection unit is used to perform peak detection and extraction on the average delay power waveform of each visible star to obtain the peak of each visible star and the delay index of the delay power sample point where the peak of each visible star is located.

[0214] The noise power calculation unit is used to obtain the noise power of each visible star based on the average delay power waveform of each visible star and the delay index of the delay power sample point where the peak of each visible star is located.

[0215] The signal power calculation unit is used to obtain the signal power of each visible star in the waveform sequence corresponding to the input power point based on the noise power of each visible star and the peak of each visible star.

[0216] As an optional implementation, the building module specifically includes:

[0217] The construction unit is used to construct the input power sequence of the ground-based GNSS-R receiver based on the channel acquisition sensitivity, the set power adjustment step, and the sequence number of each input power point.

[0218] As an optional implementation, the channel output power calculation module specifically includes:

[0219] The channel output power calculation unit is used to calculate the average signal power of all visible stars in the waveform sequence corresponding to the input power point to obtain the channel output power corresponding to the input power point.

[0220] This invention uses a standard dual-channel GNSS signal simulator to provide test signals and calibrates the input-output power relationship using the signal delay power waveform sequences output by a ground-based GNSS-R receiver under different input powers: Constructing an input power sequence; connecting the dual-channel GNSS signal simulator and the ground-based GNSS-R receiver; starting, configuring, and running the dual-channel GNSS signal simulator; running the ground-based GNSS-R receiver and obtaining its output delay power waveform sequences under different input powers; calculating the average delay power waveforms of each visible satellite signal under different input powers; extracting the peak values ​​and delay indices of the average delay power waveforms of each visible satellite signal under different input powers; calculating the average noise power of the delay power waveform sequences of each visible satellite signal under different input powers; calculating the output power under different input powers and constructing a calibration output power sequence; and establishing an input-output power relationship model. This method achieves low-cost, high-precision calibration of the input-output power relationship of a ground-based GNSS-R receiver.

[0221] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0222] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for calibrating the input-output power relationship of a GNSS-R receiver, characterized in that, include: Construct the input power sequence for a ground-based GNSS-R receiver; the input power sequence is either a direct channel input power sequence including multiple input power points or a reflective channel input power sequence including multiple input power points; Obtain the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver; the waveform sequence is either the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver; for any waveform sequence corresponding to an input power point in the input power sequence, determine the signal power of each visible star in the waveform sequence corresponding to the input power point; obtain the channel output power corresponding to the input power point based on the signal power of all visible stars in the waveform sequence corresponding to the input power point; obtain the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in the input power sequence; obtain the input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The receiver's input-output power relationship model is used to calibrate the input power and output power relationship of the ground-based GNSS-R receiver. For any waveform sequence corresponding to an input power point in the input power sequence, the signal power of each visible star in the waveform sequence corresponding to the input power point is determined based on the waveform sequence corresponding to the input power point. Specifically, this includes: for any waveform sequence corresponding to an input power point in the input power sequence, obtaining the average delay power waveform of each visible star in the waveform sequence corresponding to the input power point; performing peak detection and extraction on the average delay power waveform of each visible star to obtain the peak of each visible star and the delay index of the delay power sample point where the peak of each visible star is located; obtaining the noise power of each visible star based on the average delay power waveform of each visible star and the delay index of the delay power sample point where the peak of each visible star is located; and obtaining the signal power of each visible star in the waveform sequence corresponding to the input power point based on the noise power of each visible star and the peak of each visible star.

2. The GNSS-R receiver input-output power relationship calibration method according to claim 1, characterized in that, Constructing the input power sequence of a ground-based GNSS-R receiver specifically includes: constructing the input power sequence of the ground-based GNSS-R receiver based on channel acquisition sensitivity, setting power adjustment steps, and the sequence number of each input power point.

3. The GNSS-R receiver input-output power relationship calibration method according to claim 1, characterized in that, The channel output power corresponding to the input power point is obtained based on the signal power of all visible stars in the waveform sequence corresponding to the input power point. Specifically, this includes: calculating the average value of the signal power of all visible stars in the waveform sequence corresponding to the input power point to obtain the channel output power corresponding to the input power point.

4. A GNSS-R receiver input-output power relationship calibration system, characterized in that, include: The system includes a construction module for constructing the input power sequence of a ground-based GNSS-R receiver; the input power sequence is either a direct channel input power sequence including multiple input power points or a reflection channel input power sequence including multiple input power points; a waveform sequence acquisition module for acquiring the waveform sequence corresponding to each input power point in the input power sequence of the ground-based GNSS-R receiver; the waveform sequence is either the signal delay power waveform sequence of each visible star tracked by the direct channel of the ground-based GNSS-R receiver or the signal delay power waveform sequence of each visible star output by the reflection channel of the ground-based GNSS-R receiver; a signal power calculation module for determining the signal power of each visible star in the waveform sequence corresponding to any input power point in the input power sequence based on the waveform sequence corresponding to the input power point; a channel output power calculation module for obtaining the channel output power corresponding to the input power point based on the signal power of all visible stars in the waveform sequence corresponding to the input power point; and an output power sequence calculation module for obtaining the output power sequence of the ground-based GNSS-R receiver based on the channel output power corresponding to all input power points in the input power sequence. The calibration module is used to obtain the input-output power relationship model of the ground-based GNSS-R receiver based on the input power sequence and the output power sequence of the ground-based GNSS-R receiver. The input-output power relationship model of the ground-based GNSS-R receiver is used to calibrate the relationship between the input power and the output power of the ground-based GNSS-R receiver. The signal power calculation module specifically includes: an average delay power waveform calculation unit, used to obtain the average delay power waveform of each visible star in the waveform sequence corresponding to any input power point in the input power sequence, based on the waveform sequence corresponding to the input power point. The peak detection unit is used to detect and extract the peaks of the average delayed power waveforms of each visible star to obtain the peaks of each visible star and the delay index of the delayed power sample points where the peaks of each visible star are located; the noise power calculation unit is used to obtain the noise power of each visible star based on the average delayed power waveforms of each visible star and the delay index of the delayed power sample points where the peaks of each visible star are located; the signal power calculation unit is used to obtain the signal power of each visible star in the waveform sequence corresponding to the input power point based on the noise power of each visible star and the peaks of each visible star.

5. The GNSS-R receiver input-output power relationship calibration system according to claim 4, characterized in that, The construction module specifically includes: a construction unit, used to construct the input power sequence of the ground-based GNSS-R receiver based on the channel acquisition sensitivity, the set power adjustment step, and the sequence number of each input power point.

6. The GNSS-R receiver input-output power relationship calibration system according to claim 4, characterized in that, The channel output power calculation module specifically includes: a channel output power calculation unit, used to calculate the average signal power of all visible stars in the waveform sequence corresponding to the input power point to obtain the channel output power corresponding to the input power point.

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