Method and system for measuring signal detection sensitivity of a ground-based gnss-r receiver
By connecting a GNSS simulator with a ground-based GNSS-R receiver and using an iterative algorithm to calculate the signal detection sensitivity, the problem of low cost and high accuracy in measuring the reflected signal detection sensitivity of a ground-based GNSS-R receiver was solved, and accurate sensitivity measurement was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIHANG UNIV
- Filing Date
- 2023-09-19
- Publication Date
- 2026-06-16
Smart Images
Figure CN117055073B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of global navigation satellite system reflected signal measurement technology, and in particular to a method and system for measuring the signal detection sensitivity of a ground-based GNSS-R receiver. Background Technology
[0002] Global Navigation Satellite System Reflectometry (GNSS-R) is a technique that uses GNSS signals reflected from the Earth's surface to remotely sense ground parameters. It has great application potential in areas such as sea surface wind speed detection and soil moisture detection.
[0003] A ground-based GNSS-R receiver is a GNSS reflection signal processing device mounted on a ground-based observation platform. It outputs a time-delay waveform sequence of the reflected signal for the inversion of ground feature parameters. GNSS signals reflected from the ground surface are typically weak. Therefore, the presence of reflected signals needs to be detected during ground feature parameter inversion to ensure the validity of the observation data. Reflection signal detection sensitivity is the minimum input power required to detect the presence of a reflected signal in the time-delay waveform sequence. It is a crucial indicator for ground-based GNSS-R receivers and plays a significant role in reflection signal link budget and the design of reflection signal receiving and processing systems. However, no publicly available reports have yet described methods for measuring the reflection signal detection sensitivity of ground-based GNSS-R receivers.
[0004] Therefore, a method for measuring the sensitivity of ground-based GNSS-R receiver reflected signals is needed to achieve low-cost, high-precision measurement of the sensitivity of ground-based GNSS-R receiver reflected signals. Summary of the Invention
[0005] The purpose of this invention is to provide a method and system for measuring the signal detection sensitivity of a ground-based GNSS-R receiver, which can achieve high-precision measurement of the reflected signal detection sensitivity of a ground-based GNSS-R receiver at low cost.
[0006] To achieve the above objectives, the present invention provides the following solution:
[0007] A method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver, wherein the direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of a GNSS simulator, and the reflected signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator, the method comprising:
[0008] At the current iteration number, obtain the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets of delay power waveforms; each set of delay power waveforms includes multiple delay power samples;
[0009] The average delay power waveform of each visible star at the current iteration number is obtained from the reflection waveform sequence at the current iteration number.
[0010] Peak detection and extraction are performed on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located;
[0011] The noise power of each visible star at the current iteration number is obtained by using the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number.
[0012] The signal power of each visible star at the current iteration number is obtained based on the noise power and peak value of each visible star at the current iteration number.
[0013] The signal-to-noise ratio of each visible star at the current iteration number is obtained based on the signal power and noise power of each visible star at the current iteration number.
[0014] The average signal-to-noise ratio of all the visible stars at the current iteration number is calculated to obtain the average signal-to-noise ratio of the reflected channel signal of the ground-based GNSS-R receiver at the current iteration number;
[0015] Determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number;
[0016] If so, then the insertion loss compensation is performed on the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the sensitivity of the ground-based GNSS-R receiver to detect reflected signals.
[0017] If not, then reduce the signal power output from the second signal output port of the GNSS signal simulator in the next iteration and proceed to the next iteration.
[0018] Optionally, the average delay power waveform of each visible star at the current iteration number is obtained based on the reflection waveform sequence at the current iteration number, specifically including:
[0019] For any visible star, the average delay power waveform of the visible star at the current iteration number is obtained by calculating the average delay power waveform of each group in the signal delay power waveform sequence of the visible star at the current iteration number.
[0020] Optionally, the noise power of each visible star at the current iteration number is obtained based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number. Specifically, this includes:
[0021] For any visible star, according to the formula Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star at the j-th iteration.
[0022] Optionally, the signal power of each visible star at the current iteration number is obtained based on the noise power and peak values of each visible star at the current iteration number, specifically including:
[0023] For any visible star, the signal power of the visible star at the current iteration number is obtained by calculating the difference between the peak value of the visible star at the current iteration number and the noise power of the visible star at the current iteration number.
[0024] Optionally, the insertion loss compensation is applied to the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the reflected signal detection sensitivity of the ground-based GNSS-R receiver, specifically including:
[0025] According to the formula Calculate the sensitivity of the ground-based GNSS-R receiver to detect reflected signals, where, To improve the sensitivity of reflected signals detection for ground-based GNSS-R receivers. L represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, J represents the current iteration number, and L represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration. r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.
[0026] A ground-based GNSS-R receiver signal detection sensitivity measurement system, wherein the direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of a GNSS simulator, and the reflected signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator, the ground-based GNSS-R receiver signal detection sensitivity measurement system comprising:
[0027] The acquisition module is used to acquire the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets of delay power waveforms; each set of delay power waveforms includes multiple delay power samples;
[0028] The average delay power waveform determination module is used to obtain the average delay power waveform of each visible star at the current iteration number based on the reflection waveform sequence at the current iteration number.
[0029] The peak detection and extraction module is used to perform peak detection and extraction on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located.
[0030] The noise power calculation module is used to obtain the noise power of each visible star at the current iteration number based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number.
[0031] The signal power calculation module is used to obtain the signal power of each visible star at the current iteration number based on the noise power of each visible star at the current iteration number and the peak value of each visible star at the current iteration number.
[0032] The signal-to-noise ratio (SNR) calculation module is used to obtain the SNR of each visible star at the current iteration number based on the signal power and noise power of each visible star at the current iteration number.
[0033] The average signal-to-noise ratio (SNR) calculation module is used to calculate the average SNR of all the visible stars under the current iteration number to obtain the average SNR of the ground-based GNSS-R receiver reflection channel signal under the current iteration number;
[0034] The judgment module is used to determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number;
[0035] The detection sensitivity calculation module is used to perform insertion loss compensation on the signal power output by the second signal output port of the GNSS simulator in the previous iteration number to obtain the detection sensitivity of the reflected signal of the ground-based GNSS-R receiver if the condition is met.
[0036] The iteration module is used to reduce the signal power output by the second signal output port of the GNSS signal simulator in the next iteration if the condition is not met, and then proceed to the next iteration.
[0037] Optionally, the average delay power waveform determination module specifically includes:
[0038] The average delay power waveform determination unit is used to calculate the average value of each group of delay power waveforms in the signal delay power waveform sequence of any visible star at the current iteration number, thereby obtaining the average delay power waveform of the visible star at the current iteration number.
[0039] Optionally, the noise power calculation module specifically includes:
[0040] The noise power calculation unit is used to calculate the noise power of any visible star according to the formula. Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star at the j-th iteration.
[0041] Optionally, the signal power calculation module specifically includes:
[0042] The signal power calculation unit is used to calculate the difference between the peak power of the visible star and the noise power of the visible star at the current iteration number for any visible star, thus obtaining the signal power of the visible star at the current iteration number.
[0043] Optionally, the detection sensitivity calculation module specifically includes:
[0044] The detection sensitivity calculation unit is used to calculate the sensitivity according to the formula. Calculate the sensitivity of the ground-based GNSS-R receiver to detect reflected signals, where, To improve the sensitivity of reflected signals detection for ground-based GNSS-R receivers. J represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, and L represents the current iteration number.r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.
[0045] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:
[0046] This invention acquires a reflected waveform sequence at the current iteration number; obtains the average delay power waveform of each visible star based on the reflected waveform sequence; performs peak detection and extraction on the average delay power waveform of each visible star to obtain the peaks and delay indices of each peak; obtains the noise power of each visible star based on the average delay power waveform and delay indices; obtains the signal power of each visible star based on the noise power and peaks of each visible star; obtains the signal-to-noise ratio (SNR) of each visible star based on the signal power and noise power of each visible star; and calculates the average SNR of all visible stars to obtain the ground-based G. The average signal-to-noise ratio (SNR) of the reflected channel signal of the ground-based GNSS-R receiver is determined. If the average SNR is less than the reflected signal detection threshold, insertion loss compensation is applied to the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the reflected signal detection sensitivity of the ground-based GNSS-R receiver. If not, the signal power output from the second signal output port of the GNSS simulator in the next iteration is reduced, and the next iteration begins. This method enables high-precision measurement of the reflected signal detection sensitivity of the ground-based GNSS-R receiver at low cost. Attached Figure Description
[0047] 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.
[0048] Figure 1 A flowchart of a method for measuring the sensitivity of reflected signals from a ground-based GNSS-R receiver, provided in an embodiment of the present invention;
[0049] Figure 2 A schematic diagram of the connection of the ground-based GNSS-R receiver reflected signal detection sensitivity measurement device provided by the present invention;
[0050] Figure 3 The figure shows the average signal-to-noise ratio of the reflected channel signal of the ground-based GNSS-R receiver under different test powers.
[0051] Figure 4This is a flowchart illustrating the steps for obtaining the reflected waveform sequence at the current test power point, as provided in an embodiment of the present invention. Detailed Implementation
[0052] 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.
[0053] 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.
[0054] This invention provides a method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver. The direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of a GNSS simulator via a first RF connection line. The reflected 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 output power of the first and second signal output ports meets a power setting principle. The power setting principle includes: the signal power output from the first signal output port to the direct channel of the ground-based GNSS-R receiver is fixed at the noise power of the direct channel of the ground-based GNSS-R receiver under test conditions; and the initial value of the signal output power of the second signal output port is 10 dB higher than the acquisition sensitivity of the direct channel of the ground-based GNSS-R receiver under test conditions. The method for measuring the signal detection sensitivity of the ground-based GNSS-R receiver includes:
[0055] At the current iteration number, obtain the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets (M) of delay power waveforms, which are obtained at M consecutive sampling times; each set of the delay power waveforms includes multiple (N) delay power samples; M and N are both integers greater than zero.
[0056] The average delay power waveform of each visible star at the current iteration number is obtained from the reflection waveform sequence at the current iteration number.
[0057] Peak detection and extraction are performed on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located.
[0058] The noise power of each visible star at the current iteration number is obtained by using the average delayed power waveform of each visible star at the current iteration number and the delay index of the delayed power sample point where the peak of each visible star is located at the current iteration number; the noise power is the average noise power of the delayed power waveform.
[0059] The signal power of each visible star at the current iteration number is obtained based on the noise power and peak value of each visible star at the current iteration number.
[0060] The signal-to-noise ratio of each visible star at the current iteration number is obtained based on the signal power and noise power of each visible star at the current iteration number.
[0061] The average signal-to-noise ratio (SNR) of all the visible satellites at the current iteration number is calculated to obtain the average SNR of the ground-based GNSS-R receiver's reflection channel signal at the current iteration number; the average SNR is the statistical mean of the SNR of each visible satellite.
[0062] Determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number; the reflection signal detection threshold is the minimum signal-to-noise ratio required to determine the presence of a reflection signal.
[0063] If so, then the insertion loss compensation is performed on the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the sensitivity of the ground-based GNSS-R receiver's reflected signal detection.
[0064] If not, then reduce the signal power output by the second signal output port of the GNSS signal simulator in the next iteration (reducing the signal power output by the second signal output port of the GNSS signal simulator in equal steps of 1dB), and proceed to the next iteration.
[0065] In practical applications, at the j-th iteration, the signal power output by the second signal output port of the GNSS signal simulator is... Through formula (1) Calculate, where, For the direct channel acquisition sensitivity of a ground-based GNSS-R receiver, This is the floor operator.
[0066] In practical applications, the average delay power waveform of each visible star at the current iteration number is obtained from the reflected waveform sequence at the current iteration number, specifically including:
[0067] For any visible star, the average delay power waveform of the visible star at the current iteration number is obtained by calculating the average delay power waveform of each group in the signal delay power waveform sequence of the visible star at the current iteration number.
[0068] The signal delay power waveform sequence of the k-th visible star at the j-th iteration number. for:
[0069]
[0070] Among them, K j Let J be the number of visible stars processed by the reflection channel in the j-th iteration. 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:
[0071] 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 is used. Therefore, in practical applications, the average delay power waveform of the visible star at the current iteration number is obtained by calculating the average value of each group of delay power waveforms in the signal delay power waveform sequence of the visible star at the current iteration number. Specifically, this includes:
[0072] For any visible star, according to the formula Calculate the average delay power waveform of the k-th visible star in the j-th iteration. in, 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.
[0073] In practical applications, the noise power of each visible star at the current iteration number is obtained based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number. Specifically, this includes:
[0074] For any visible star, according to the formula Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star at the j-th iteration.
[0075] In practical applications, the signal power of each visible star at the current iteration number is obtained based on the noise power and peak value of each visible star at the current iteration number. Specifically, this includes:
[0076] For any visible star, the signal power of the visible star at the current iteration number is obtained by calculating the difference between the peak power of the visible star at the current iteration number and the noise power of the visible star at the current iteration number. Specifically, this is done according to the formula... Calculate the signal power of the k-th visible star in the j-th iteration. The peak of the k-th visible star in the j-th iteration is represented by [the peak value]. Let be the noise power of the k-th visible star in the j-th iteration.
[0077] In practical applications, the signal-to-noise ratio (SNR) of each visible star at the current iteration number is obtained based on the signal power and noise power of each visible star at the current iteration number. Specifically, this includes:
[0078] For any visible star, according to the formula Calculate the signal-to-noise ratio of the k-th visible star in the j-th iteration.
[0079] In practical applications, the average signal-to-noise ratio (SNR) of all visible satellites at the current iteration number is calculated to obtain the average SNR of the ground-based GNSS-R receiver's reflection channel signal at the current iteration number. Specifically, this includes:
[0080] According to the formula Calculate the average signal-to-noise ratio of the reflected channel signal of the ground-based GNSS-R receiver at the j-th iteration number.
[0081] In practical applications, the sensitivity of the ground-based GNSS-R receiver's reflected signal detection is obtained by performing insertion loss compensation on the signal power output from the second signal output port of the GNSS simulator in the previous iteration. Specifically, this includes:
[0082] According to the formula Calculate the sensitivity of the ground-based GNSS-R receiver to detect reflected signals, where, To improve the sensitivity of reflected signals detection for ground-based GNSS-R receivers. L represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, J represents the current iteration number (i.e., the number of tests when the average signal-to-noise ratio of the reflection channel first falls below the reflection signal detection threshold), and L represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration. r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.
[0083] This invention utilizes a standard dual-channel GNSS signal simulator to achieve low-cost, high-precision measurement of the sensitivity of reflected signals detected by ground-based GNSS-R receivers.
[0084] This invention provides a more specific method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver. The methods described in the above embodiments are detailed below. See [link to relevant documentation]. Figure 1 The ground-based GNSS-R receiver signal detection sensitivity measurement method of this embodiment includes:
[0085] Step 101: Determine the initial value of the signal output power of the second signal output port of the GNSS simulator.
[0086] The initial value of the signal output power of the second signal output port of the GNSS signal simulator can be obtained by formula... Sure.
[0087] Step 102: For the current test power point, obtain the reflected waveform sequence.
[0088] 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.
[0089] In practical applications, the implementation process of step 102 is as follows: Figure 4 As shown:
[0090] 1. Connect the standard dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.
[0091] See Figure 2 Using a first RF connection line (RF connection line 1) and a second RF connection line (RF connection line 2) with known insertion losses, 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. Let L be the insertion losses of the first RF connection line and the second RF connection line, respectively. d and L r .
[0092] 2. Start, configure, and run the dual-channel GNSS signal simulator
[0093] Turn on the power, start the dual-channel GNSS signal simulator, select the signal to be calibrated, and configure the same ephemeris file, signal simulation start time, and receiver spatial coordinates for both signal output channels. Configure the output power of each channel to the specified power value and run 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 power to be tested.
[0094] 3. Run the ground-based GNSS-R receiver to acquire the delayed power waveform sequence of the reflected channel signal, and obtain the reflected waveform sequence.
[0095] Power on and run the ground-based GNSS-R receiver. The direct channel acquires and tracks the signal, while the reflected channel, with the assistance of the direct channel, performs open-loop tracking of the signal in the reflected channel, calculates and outputs the signal delay power waveform sequence for each satellite.
[0096] 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 as The specific expression is formula (2).
[0097] Step 103: For any visible star, calculate the average delay power waveform of the reflected waveform sequence.
[0098] Specifically, calculate according to formula (4).
[0099] Step 104: For any visible star, extract the average delay power waveform and the corresponding delay index.
[0100] Specifically, for the average delay power waveforms of each visible star signal in the reflection channel obtained in step 103, peak detection and extraction are performed sequentially. The delay index of the peak value of the average delay power waveform of each visible star signal in the reflection channel is denoted as... The corresponding peak size is
[0101] Step 105: For any visible star, calculate the noise power based on the average delay power waveform and the delay index.
[0102] Specifically, calculate according to formula (6).
[0103] Step 106: For any visible star, calculate the signal power based on the peak power and noise power.
[0104] Specifically, calculate according to formula (7).
[0105] Step 107: For any visible star, calculate the signal-to-noise ratio based on the signal power and noise power.
[0106] Specifically, calculate according to formula (8).
[0107] Step 108: Calculate the average signal-to-noise ratio of the reflected channel signal based on the signal-to-noise ratios of all visible star signals.
[0108] Specifically, calculate according to formula (9)
[0109] Step 109: Gradually decrease the signal output power of the second signal output port, repeating steps 102 to 109 until the average signal-to-noise ratio first falls below the reflection signal detection threshold. Finally, calculate the reflection signal detection sensitivity of the ground-based GNSS-R receiver based on the signal power output from the second signal output port and the insertion loss of the RF connection line in the previous test.
[0110] Specifically, if the average signal-to-noise ratio is less than the reflected signal detection threshold for the first time during the Jth test, then the formula for calculating the reflected signal detection sensitivity of the ground-based GNSS-R receiver is formula (10). Through the above steps, the accurate measurement of the reflected signal detection sensitivity of the ground-based GNSS-R receiver is achieved. In practical applications, it can be directly used for the reflected signal detection sensitivity test of the ground-based GNSS-R receiver.
[0111] The above embodiment will be further illustrated below by taking the measurement of the sensitivity of reflected signal detection of a ground-based GNSS-R receiver operating at a frequency of BDS B1 using a standard dual-channel GNSS signal simulator as an example. The reflected signal detection threshold is set to 3dB.
[0112] Specifically, the steps include the following:
[0113] Step 1: Determine the initial values of the signal output power of the first signal output port and the signal output power of the second signal output port of the GNSS signal simulator.
[0114] Under the test conditions, the noise power of the direct-view channel was approximately -140 dBW, and the capture sensitivity of the direct-view channel was... It is approximately -160dBW. Therefore, the signal output power of the first signal output port of the GNSS signal simulator is -140dBW, and the initial value of the signal output power of the second signal output port is -150dBW.
[0115] Step 2: Connect the dual-channel GNSS signal simulator and the ground-based GNSS-R receiver.
[0116] Please see again Figure 2 Using radio frequency connection cable 1 and radio frequency connection cable 2, 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.
[0117] Step 3: Start, configure, and run the dual-channel GNSS signal simulator.
[0118] 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 -150dBW. After configuration, run the dual-channel GNSS signal simulator until the output signal power stabilizes.
[0119] Step 4: Run the ground-based GNSS-R receiver to acquire the waveform sequence of the delayed power of the reflected channel signal.
[0120] Power on and run the ground-based GNSS-R receiver. The direct channel acquires and tracks the signal, while the reflected channel calculates and outputs the delay power waveform sequence for each visible satellite signal, denoted as...
[0121] Step 5: Calculate the average delay power waveform of each visible star signal in the reflection channel.
[0122] According to formula (4), the average delay power waveform of each visible star signal output by the reflection channel is calculated in sequence.
[0123] 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.
[0124] 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
[0125] Step 7: Calculate the average noise power of the waveform sequence of the delay power of each visible star signal in the reflection channel.
[0126] 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 noise power of the delay power waveform sequence of each visible star signal output by the reflection channel is calculated sequentially according to formula (6).
[0127] Step 8: Calculate the signal power of each visible star in the reflection channel.
[0128] 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 signal power of each visible star in the reflection channel is calculated according to formula (7).
[0129] Step 9: Calculate the signal-to-noise ratio of each visible star signal in the reflection channel.
[0130] Using the noise power of each visible star signal in the reflection channel obtained in step 7 and the power of each visible star signal in the reflection channel obtained in step 8, the signal-to-noise ratio of each visible star signal in the reflection channel is calculated according to formula (8).
[0131] Step 10: Calculate the average signal-to-noise ratio.
[0132] Using the signal-to-noise ratios of each visible star signal obtained in step 9, the average signal-to-noise ratio is calculated according to formula (9).
[0133] Step 11: 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 1dB. Repeat steps 4 to 11 until the average signal-to-noise ratio is lower than the reflection signal detection threshold for the first time. Assuming that the average signal-to-noise ratio is lower than the reflection signal detection threshold for the first time in the Jth test, the formula for calculating the reflection signal detection sensitivity is formula (10).
[0134] Through the above steps, accurate measurement of the sensitivity of the ground-based GNSS-R receiver's reflected signal detection was achieved.Figure 3 The average signal-to-noise ratio (SNR) of the reflected channel signal of this ground-based GNSS-R receiver under different test powers is presented. The average SNR falls below the reflected signal detection threshold for the first time in the 7th test. Ignoring the insertion loss of RF connection line 2, the input signal power of the reflected channel is -156 dBW, thus the reflected signal detection sensitivity of this ground-based GNSS-R receiver is -155 dBW.
[0135] The method for measuring the sensitivity of reflected signals in a ground-based GNSS-R receiver provided in this invention uses a standard dual-channel GNSS signal simulator to provide test signals. It measures the sensitivity of reflected signal detection using the signal delay power waveform sequence output by the ground-based GNSS-R receiver's reflected channel under different input powers. Specifically: the dual-channel GNSS signal simulator and the ground-based GNSS-R receiver are connected via an RF cable; the dual-channel GNSS signal simulator is started, configured, and run; the ground-based GNSS-R receiver is run to acquire the delay power waveform sequence of the reflected channel signal output; the average delay power waveform of each visible satellite signal in the reflected channel is calculated; the peak value and delay index of the average delay power waveform of each visible satellite signal in the reflected channel are extracted; the noise power of the delay power waveform sequence of each visible satellite signal in the reflected channel is calculated; the power of each visible satellite signal in the reflected channel is calculated; the signal-to-noise ratio (SNR) of each visible satellite signal in the reflected channel is calculated; the average SNR of the reflected channel signal is calculated; the signal output power of the second signal output port of the dual-channel GNSS signal simulator is gradually reduced, and the acquisition of the reflected channel delay power waveform sequence and the calculation of the average SNR of the reflected channel signal are repeated until the first instance of the average SNR of the reflected channel being less than the reflected signal detection threshold is encountered, ultimately yielding the reflected signal detection sensitivity. This method enables low-cost, high-precision measurement of the sensitivity of reflected signals from ground-based GNSS-R receivers.
[0136] This invention provides a ground-based GNSS-R receiver signal detection sensitivity measurement system, wherein the direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of the GNSS simulator, and the reflected signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator. The ground-based GNSS-R receiver signal detection sensitivity measurement system includes:
[0137] The acquisition module is used to acquire the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets of delay power waveforms; each set of delay power waveforms includes multiple delay power samples.
[0138] The average delay power waveform determination module is used to obtain the average delay power waveform of each visible star at the current iteration number based on the reflection waveform sequence at the current iteration number.
[0139] The peak detection and extraction module is used to perform peak detection and extraction on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located.
[0140] The noise power calculation module is used to obtain the noise power of each visible star at the current iteration number based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number.
[0141] The signal power calculation module is used to obtain the signal power of each visible star at the current iteration number based on the noise power of each visible star at the current iteration number and the peak value of each visible star at the current iteration number.
[0142] The signal-to-noise ratio (SNR) calculation module is used to obtain the SNR of each visible star at the current iteration number based on the signal power and noise power of each visible star at the current iteration number.
[0143] The average signal-to-noise ratio (SNR) calculation module is used to calculate the average SNR of all the visible stars at the current iteration number to obtain the average SNR of the ground-based GNSS-R receiver reflection channel signal at the current iteration number.
[0144] The judgment module is used to determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number.
[0145] The detection sensitivity calculation module is used to perform insertion loss compensation on the signal power output by the second signal output port of the GNSS simulator in the previous iteration to obtain the detection sensitivity of the reflected signal of the ground-based GNSS-R receiver, if the condition is met.
[0146] The iteration module is used to reduce the signal power output by the second signal output port of the GNSS signal simulator in the next iteration if the condition is not met, and then proceed to the next iteration.
[0147] In practical applications, the average delay power waveform determination module specifically includes:
[0148] The average delay power waveform determination unit is used to calculate the average value of each group of delay power waveforms in the signal delay power waveform sequence of any visible star at the current iteration number, thereby obtaining the average delay power waveform of the visible star at the current iteration number.
[0149] In practical applications, the noise power calculation module specifically includes:
[0150] The noise power calculation unit is used to calculate the noise power of any visible star according to the formula. Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star at the j-th iteration.
[0151] In practical applications, the signal power calculation module specifically includes:
[0152] The signal power calculation unit is used to calculate the difference between the peak power of the visible star and the noise power of the visible star at the current iteration number for any visible star, thus obtaining the signal power of the visible star at the current iteration number.
[0153] In practical applications, the detection sensitivity calculation module specifically includes:
[0154] The detection sensitivity calculation unit is used to calculate the sensitivity according to the formula. Calculate the sensitivity of the ground-based GNSS-R receiver to detect reflected signals, where, To improve the sensitivity of reflected signals detection for ground-based GNSS-R receivers. J represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, and L represents the current iteration number. r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.
[0155] This invention enables low-cost, high-precision measurement of the sensitivity of reflected signals from ground-based GNSS-R receivers.
[0156] 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.
[0157] 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 measuring the signal detection sensitivity of a ground-based GNSS-R receiver, characterized in that, The direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of the GNSS simulator, and the reflected signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator. The signal detection sensitivity measurement method of the ground-based GNSS-R receiver includes: At the current iteration number, obtain the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets of delay power waveforms; each set of delay power waveforms includes multiple delay power samples; The average delay power waveform of each visible star at the current iteration number is obtained from the reflection waveform sequence at the current iteration number. Peak detection and extraction are performed on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located; The noise power of each visible star at the current iteration number is obtained by using the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number. The signal power of each visible star at the current iteration number is obtained based on the noise power and peak value of each visible star at the current iteration number. The signal-to-noise ratio of each visible star at the current iteration number is obtained based on the signal power and noise power of each visible star at the current iteration number. The average signal-to-noise ratio of all the visible stars at the current iteration number is calculated to obtain the average signal-to-noise ratio of the reflected channel signal of the ground-based GNSS-R receiver at the current iteration number; Determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number; If so, then the insertion loss compensation is performed on the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the sensitivity of the ground-based GNSS-R receiver to detect reflected signals. If not, then reduce the signal power output from the second signal output port of the GNSS signal simulator in the next iteration and proceed to the next iteration.
2. The method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver according to claim 1, characterized in that, The average delay power waveform of each visible star at the current iteration number is obtained based on the reflection waveform sequence at the current iteration number, specifically including: For any visible star, the average delay power waveform of the visible star at the current iteration number is obtained by calculating the average delay power waveform of each group in the signal delay power waveform sequence of the visible star at the current iteration number.
3. The method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver according to claim 1, characterized in that, The noise power of each visible star at the current iteration number is obtained based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number. Specifically, this includes: For any visible star, according to the formula Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star in the j-th iteration.
4. The method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver according to claim 1, characterized in that, The signal power of each visible star at the current iteration number is obtained based on the noise power and peak value of each visible star at the current iteration number. Specifically, this includes: For any visible star, the signal power of the visible star at the current iteration number is obtained by calculating the difference between the peak value of the visible star at the current iteration number and the noise power of the visible star at the current iteration number.
5. The method for measuring the signal detection sensitivity of a ground-based GNSS-R receiver according to claim 1, characterized in that, The insertion loss compensation is applied to the signal power output from the second signal output port of the GNSS simulator in the previous iteration to obtain the detection sensitivity of the reflected signal of the ground-based GNSS-R receiver, specifically including: According to the formula Calculate the sensitivity of the ground-based GNSS-R receiver for detecting reflected signals, where, For the sensitivity of reflected signals detected by ground-based GNSS-R receivers, J represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, and L represents the current iteration number. r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.
6. A ground-based GNSS-R receiver signal detection sensitivity measurement system, characterized in that, The direct signal input port of the ground-based GNSS-R receiver is connected to the first signal output port of the GNSS simulator, and the reflected signal input port of the ground-based GNSS-R receiver is connected to the second signal output port of the GNSS simulator. The ground-based GNSS-R receiver signal detection sensitivity measurement system includes: The acquisition module is used to acquire the reflection waveform sequence at the current iteration number; the reflection waveform sequence includes the signal delay power waveform sequence of all visible stars output by the reflection channel of the ground-based GNSS-R receiver; the signal delay power waveform sequence includes multiple sets of delay power waveforms; each set of delay power waveforms includes multiple delay power samples; The average delay power waveform determination module is used to obtain the average delay power waveform of each visible star at the current iteration number based on the reflection waveform sequence at the current iteration number. The peak detection and extraction module is used to perform peak detection and extraction on the average delay power waveform of each visible star at the current iteration number to obtain the peak of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star at the current iteration number is located. The noise power calculation module is used to obtain the noise power of each visible star at the current iteration number based on the average delay power waveform of each visible star at the current iteration number and the delay index of the delay power sample point where the peak of each visible star is located at the current iteration number. The signal power calculation module is used to obtain the signal power of each visible star at the current iteration number based on the noise power of each visible star at the current iteration number and the peak value of each visible star at the current iteration number. The signal-to-noise ratio (SNR) calculation module is used to obtain the SNR of each visible star at the current iteration number based on the signal power and noise power of each visible star at the current iteration number. The average signal-to-noise ratio (SNR) calculation module is used to calculate the average SNR of all the visible stars under the current iteration number to obtain the average SNR of the ground-based GNSS-R receiver reflection channel signal under the current iteration number; The judgment module is used to determine whether the average signal-to-noise ratio of the ground-based GNSS-R receiver's reflection channel signal is less than the reflection signal detection threshold at the current iteration number; The detection sensitivity calculation module is used to perform insertion loss compensation on the signal power output by the second signal output port of the GNSS simulator in the previous iteration number to obtain the detection sensitivity of the reflected signal of the ground-based GNSS-R receiver if the condition is met. The iteration module is used to reduce the signal power output by the second signal output port of the GNSS signal simulator in the next iteration if the condition is not met, and then proceed to the next iteration.
7. The ground-based GNSS-R receiver signal detection sensitivity measurement system according to claim 6, characterized in that, The average delay power waveform determination module specifically includes: The average delay power waveform determination unit is used to calculate the average value of each group of delay power waveforms in the signal delay power waveform sequence of any visible star at the current iteration number, thereby obtaining the average delay power waveform of the visible star at the current iteration number.
8. The ground-based GNSS-R receiver signal detection sensitivity measurement system according to claim 6, characterized in that, The noise power calculation module specifically includes: The noise power calculation unit is used to calculate the noise power of any visible star according to the formula. Calculate the noise power of the k-th visible star in the j-th iteration, where, Let be the noise power of the k-th visible star in the j-th iteration. is the delay index of the delay power sample point where the peak of the k-th visible star is located in the j-th iteration, s is the number of delay power samples on the unit pseudocode chip, and [] is the rounding operator; The delay power sample with delay index n is the average delay power waveform of the k-th visible star in the j-th iteration.
9. The ground-based GNSS-R receiver signal detection sensitivity measurement system according to claim 6, characterized in that, The signal power calculation module specifically includes: The signal power calculation unit is used to calculate the difference between the peak power of the visible star and the noise power of the visible star at the current iteration number for any visible star, thus obtaining the signal power of the visible star at the current iteration number.
10. The ground-based GNSS-R receiver signal detection sensitivity measurement system according to claim 6, characterized in that, The detection sensitivity calculation module specifically includes: The detection sensitivity calculation unit is used to calculate the sensitivity according to the formula. Calculate the sensitivity of the ground-based GNSS-R receiver for detecting reflected signals, where, For the sensitivity of reflected signals detected by ground-based GNSS-R receivers, J represents the signal power output from the second signal output port of the GNSS simulator in the previous iteration, and L represents the current iteration number. r The insertion loss of the radio frequency connection line between the second signal output port of the GNSS simulator and the reflected signal input port of the ground-based GNSS-R receiver.