Satellite navigation simulator pseudo-range measurement method based on signal synthesis amplitude-phase characteristics

Abstract

The technical scheme of the present application provides a pseudo-range measurement method of a satellite navigation simulator based on signal synthesis amplitude and phase characteristics, changes the pseudo-range of one signal in the double-path satellite synthesis signal, measures the signal amplitude change in the frequency domain, calculates the signal phase difference, and then obtains the signal time delay, finally obtains the actual change value of the pseudo-range, and realizes the pseudo-range measurement. The method changes the time domain measurement into frequency domain measurement, reduces the influence of signal time domain jitter on the measurement result, and measures the relative change of the signal peak value level, so that the inherent noise component in the signal is offset, thereby reducing the noise influence and greatly improving the measurement precision.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation pseudorange testing, and in particular to a pseudorange measurement method for a satellite navigation simulator based on the amplitude and phase characteristics of signal synthesis. Background Technology

[0002] A Global Navigation Satellite System (GNSS) is a system that uses satellite pseudorange signals to measure distances and achieve positioning. GNSS systems offer advantages such as high accuracy, wide coverage, and ease of use, and are widely used in fields such as autonomous driving, intelligent transportation, smart agriculture, and disaster monitoring. Future development of satellite navigation is moving towards higher precision, stronger anti-interference capabilities, and multi-sensor fusion.

[0003] A satellite navigation simulator (or simulator for short) is a standard signal source that simulates a navigation system. It can simulate the state of a carrier at any time and location, and can simulate various error models such as troposphere, ionosphere, clock error, and multipath. It is an indispensable device in the construction, verification, and application of satellite navigation systems. It is also an essential testing, verification, and metrology device in the entire process of satellite navigation terminal design, research and development, production, and maintenance. It is widely used in universities, research institutes, manufacturing enterprises, and the military industry.

[0004] As a core device for verifying and testing navigation systems and terminal products, the performance and accuracy of the simulator are of paramount importance. Pseudorange refers to the distance from a satellite to the carrier, which contains errors. The simulator simulates different satellites through different channels, and the pseudorange is obtained by multiplying the control channel delay by the speed of light. Since pseudorange is directly related to positioning indicators, the pseudorange control accuracy directly reflects the simulator's simulation level. The smaller the pseudorange control resolution of the simulator, the more refined it is; the smaller the pseudorange control error, the more accurate it is.

[0005] Traditional pseudorange control accuracy is tested using a high-speed sampling digital oscilloscope. The oscilloscope measures the waveform delay caused by pseudorange changes in a single-channel satellite signal, multiplies it by the speed of light to obtain the actual pseudorange change, and then calculates the pseudorange control error. Simulated satellite signals can be BPSK modulated signals or single-carrier signals. BPSK modulated signals primarily acquire the delay of the inversion point change, while single-carrier signals acquire the delay of the peak value change. However, regardless of the signal, oscilloscope measurements suffer from waveform jitter and other issues, severely impacting high-precision pseudorange measurements below the centimeter level, resulting in significant uncertainty in the measurement results.

[0006] The existing measurement technique involves using a 1PPS pulse signal output from a simulator as the oscilloscope's reference trigger signal. A single satellite (channel) signal is simulated. The oscilloscope records the initial position of the waveform. The pseudorange Δd (typically the minimum achievable pseudorange control resolution) is changed to horizontally shift the waveform. The termination position of the waveform is recorded. The oscilloscope measures the time delay Δt between these two positions and multiplies it by the speed of light to obtain the actual change in pseudorange. When the satellite signal is a BPSK modulated signal, the position of the zero-crossing reversal point is recorded. However, in actual measurements, the reversal point of the BPSK modulated signal is not a single "point," but rather a zero-crossing curve with fluctuating amplitude, such as... Figure 3 As shown, the modulation signal flips at a time of about 4 ns and the amplitude fluctuates due to interference, making it impossible to accurately locate the waveform position recording point. This results in a measurement delay uncertainty on the order of nanoseconds, making it impossible to measure high-precision pseudorange changes. Furthermore, the measurement signal is limited to BPSK modulation and is not applicable to other modulation methods.

[0007] When the satellite signal is a single carrier, the peak level position of the sine wave is recorded. Due to factors such as crystal oscillator stability and various noise interferences, the waveform displayed on the oscilloscope exhibits jitter. The single-carrier jitter is recorded using the fluorescence function. Figure 4 As shown, the maximum horizontal jitter is 52 ps, which is equivalent to 1.58 cm in pseudorange. Even if the jitter is reduced by averaging, the uncertainty is still large when measuring pseudorange changes of less than 1 cm, making accurate measurement impossible.

[0008] In summary, due to limitations of current pseudorange measurement methods, the minimum pseudorange measurement capability is 1 cm. Domestic simulator manufacturers provide a minimum pseudorange accuracy of 1 cm. While foreign simulator manufacturers can achieve a minimum pseudorange accuracy of 0.3 mm, domestic testing cannot verify whether this technical specification is met. With the deepening application of satellite navigation technology in various industries, navigation and positioning applications require centimeter-level or even millimeter-level accuracy, creating an urgent need for high-precision positioning testing of terminal receivers. Satellite navigation simulators used for testing need to provide a more accurate and stable simulation testing environment, placing higher demands on pseudorange simulation testing. Traditional oscilloscope measurement methods cannot meet the needs of high-precision pseudorange measurement; therefore, providing a high-precision pseudorange measurement method has become a pressing issue. Summary of the Invention

[0009] This invention provides a pseudorange measurement method for satellite navigation simulators based on the amplitude and phase characteristics of signal synthesis, in order to solve the problem of high-precision pseudorange measurement.

[0010] To achieve the above objectives, the present invention provides a method comprising: selecting a single-carrier signal at any frequency point of the simulator navigation system and measuring the single-satellite peak level of a first satellite;

[0011] Measure the signals of the first satellite and the second satellite, and test the combined peak level; compare the combined peak level with the single-satellite peak level, and determine whether the increase in the combined signal amplitude is 6.02dB. If so, the signal amplitude and phase of the two satellites are the same.

[0012] The pseudorange of either satellite in the two satellite signals is changed, and the synthesized peak level is tested a second time. The difference between the synthesized peak level and the single-satellite peak level is obtained. The actual pseudorange between the two satellite signals is obtained based on the difference, thereby obtaining the pseudorange control accuracy of the simulator.

[0013] As a preferred embodiment of the above technical solution, preferably, the difference is obtained by comparing the synthesized peak level with the single-satellite peak level, including:

[0014] After comparing the synthesized peak level obtained from the second measurement with the single-star peak level, the logarithmic change value L(θ) of the synthesized signal amplitude is obtained. The relationship between amplitude and phase is as follows:

[0015]

[0016] The phase difference θ is obtained from the logarithmic change value L(θ) of the synthesized signal amplitude:

[0017]

[0018] As a preferred embodiment of the above technical solution, preferably, after calculating the time delay Δt based on the logarithmic change value of the synthesized signal amplitude, the actual pseudorange Δd is obtained based on the time delay:

[0019]

[0020] Δd = Δt × c.

[0021] As a preferred embodiment of the above technical solution, the pseudorange of the satellite is changed by: directly changing the pseudorange value of the satellite in a single jump, or setting a fixed pseudorange change rate (pseudorange rate) and duration, and calculating the cumulative pseudorange change value after the pseudorange continues to change for a certain period of time.

[0022] This invention provides a pseudorange measurement method for satellite navigation simulators based on the amplitude and phase characteristics of synthesized signals. In the frequency domain, by measuring the amplitude change after signal synthesis, the phase difference is calculated, and the signal delay is obtained, ultimately achieving high-precision pseudorange measurement. This method transforms time-domain measurement into frequency-domain measurement, reducing the impact of signal time-domain jitter on the measurement results. Simultaneously, it measures the relative change in the signal peak level, canceling out inherent noise components in the signal, thereby reducing noise influence and significantly improving measurement accuracy.

[0023] The advantages of this invention are:

[0024] (1) The spectrum analyzer measures the peak power level of a single carrier signal. The signal jitter is small and the measured value is stable.

[0025] (2) The power level difference is used for calculation. When a single measurement is performed, the differences in the influence of noise, parameter settings, etc. cancel each other out. The amplitude change caused by the pseudo-distance change can be accurately measured.

[0026] (3) The measurement is not affected by the frequency point satellite modulation method, and it can measure single carrier signals with a wide range of applications.

[0027] (4) Using the present invention to measure the pseudorange control accuracy of the simulator, the single pseudorange change can reach 3mm, which is 3 times more accurate than the original 1cm; by using pseudorange rate and feature points to measure the cumulative change of pseudorange, the implementation verification can reach 0.3mm, which is 30 times more accurate than the original method. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The system connection diagram is provided for the pseudorange measurement method of satellite navigation simulator based on the amplitude and phase characteristics of signal synthesis provided by the present invention.

[0030] Figure 2 The flowchart below illustrates an embodiment of the pseudorange measurement method for a satellite navigation simulator based on the amplitude and phase characteristics of signal synthesis according to the present invention. Figure 1 .

[0031] Figure 2a The flowchart below illustrates an embodiment of the pseudorange measurement method for a satellite navigation simulator based on the amplitude and phase characteristics of signal synthesis according to the present invention. Figure 2 .

[0032] Figure 3 A magnified view of the zero-crossing point of the satellite BPSK signal measured using existing technology.

[0033] Figure 4 A fluorescence recording of a single satellite and single carrier jitter graph using existing oscilloscope technology.

[0034] Figure 5 This is a diagram showing the peak level of a single satellite signal measured during the implementation of the technical solution of this invention.

[0035] Figure 6 A diagram showing the peak level of a combined signal from two satellites with the same pseudorange.

[0036] Figure 7 To measure the peak level of the synthesized signal after changing the pseudorange of a single satellite by 3 mm.

[0037] Figure 8 The peak level diagram of the synthesized signal after measuring a 3cm pseudorange change of a single star.

[0038] Figure 9 A diagram showing the amplitude level of the synthesized signal after changing the half-cycle pseudorange of a single satellite.

[0039] Figure 10 The amplitude level diagram of the port after disconnecting the simulator output.

[0040] Figure 11 This is a graph showing the original data of the satellite changing at a pseudorange rate of 0.0003 m / s.

[0041] Figure 12 The graph shows the half-cycle curve of the satellite with a pseudorange rate of 0.0003 m / s.

[0042] Figure 13 Create a graph of any 10 points on the pseudorange variation curve. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0044] System connections such as Figure 1 The large signal output terminal of the satellite navigation simulator is connected to the spectrum analyzer, and the external output of the simulator's crystal oscillator is connected to the external input of the spectrum analyzer's crystal oscillator.

[0045] Figure 2 , Figure 2a This is a schematic diagram of a process provided for an embodiment of the present invention, such as... Figure 2 As shown:

[0046] Step 101: Set the initial state of the satellite navigation simulator.

[0047] This includes setting the simulator to select any frequency signal from any navigation system, setting the satellite to a regional geostationary orbit satellite, setting the carrier scene to a static scene, fixing the pseudorange of the satellite and the carrier, and disabling modulation to output a single carrier signal.

[0048] Step 102: Measure the single-satellite peak level P0 of the first satellite.

[0049] Step 103: Measure the peak level P1 of the combined signal from the first and second satellites.

[0050] The second satellite has the same settings as the first satellite. The spectrum analyzer measures the peak level P1 of the synthesized signal. If the initial synthesized signal P1 of the two channels increases by 6.02dB compared to the single signal P0, it means that the amplitude and phase of the two signals are the same and the signal delay is 0; otherwise, the signal is adjusted to make the delay 0.

[0051] Step 104: Adjust the pseudorange of any satellite in the dual-channel signal.

[0052] Specifically, it causes the pseudorange of the first or second satellite to change by a distance d.

[0053] Step 105: Measure the peak level P2 of the combined signal of the two satellites after pseudorange adjustment.

[0054] Step 106: Calculate the difference ΔP between the peak level of the combined pseudorange difference signal of the two satellites and the peak level of the single satellite.

[0055]

[0056] Where L(θ) is the logarithmic change in the amplitude of the synthesized signal after the signals are superimposed.

[0057] The principle of step 106 is explained in detail: a sinusoidal signal with the same frequency and amplitude with a phase difference is superimposed on a sinusoidal signal. The phase difference and amplitude change are related.

[0058] Specifically, an ideal sine wave signal is represented as:

[0059] Two sinusoidal signals of the same frequency and amplitude, with a phase difference of θ, can be synthesized into the following signal:

[0060]

[0061] The frequency of the synthesized signal remains unchanged, and its amplitude is a cosine function of the phase difference θ.

[0062]

[0063] Step 107: Based on the amplitude and phase characteristics of the synthesized signal, obtain the phase difference θ through the amplitude difference.

[0064]

[0065]

[0066]

[0067] Step 108: Obtain the time delay Δt based on the phase difference and get the actual adjusted pseudorange value.

[0068] Specifically, there is a corresponding relationship between the signal phase and the period:

[0069] Where T is the period and Δt is the time delay. This represents the phase difference.

[0070] so

[0071] Δd = Δt × c.

[0072] Where Δt is the time delay between the two signals with pseudo-distance difference, and c is the speed of light, 299792458 m / s.

[0073] The technical solution of this invention can also solve the problem of pseudorange variation measurement below the millimeter level. In specific step 104, pseudorange variation can also be controlled by adjusting the pseudorange variation rate and duration.

[0074] Since pseudorange variation measurement is also limited by the power resolution that can be accurately measured, the smallest pseudorange variation that can be directly measured in a single change is about 3 mm. It is difficult to directly measure pseudorange variations of smaller units in a single measurement (e.g., 0.3 mm). The problem of measuring pseudorange variations at the millimeter level and below can be solved by setting the pseudorange variation rate to accumulate the pseudorange variation over a certain period of time.

[0075] In detail, the pseudorange rate refers to the change in pseudorange per unit time, multiplied by the duration to obtain the cumulative pseudorange change value. If the cumulative pseudorange change value after knowing the duration is accurately measured, it proves that the pseudorange change per second is also accurate. Furthermore, based on the amplitude and phase characteristics analysis of the synthesized two sine wave signals, if one of the signals is continuously varied at a fixed pseudorange rate, the phase difference of the synthesized signal changes from 0° to 360°, and the signal amplitude will experience a process of reaching its maximum, then decreasing to 0, and then reaching its maximum again. When the phase difference changes by 180°, the synthesized signal amplitude is 0, which should be the same as the output state of the disconnected signal. This specific point is selected for convenient and rapid measurement.

[0076] Assume that one of the satellites changes pseudorange by half a period corresponding to the pseudorange rate to be measured. If the measurement signal output is 0 at the end of the operation, it indicates that the signal phase difference is 180°. The specific scheme is as follows:

[0077] Verify that the initial state of the two satellites is the same as the above scheme (equivalent to steps 101-103). Calculate the pseudorange corresponding to half a cycle time based on the navigation frequency signal period. In this embodiment, step 104 is performed as follows: Set one satellite to have a fixed pseudorange rate change signal corresponding to half a cycle of pseudorange. The spectrum analyzer measures the amplitude level P4 of the synthesized signal of the pseudorange difference between the two satellites at this time. Disconnect the simulator simulation output (the output signal should be 0), and the spectrum analyzer measures the amplitude level as P5. If P4 = P5, it indicates that the synthesized signal is 0, and the simulator's pseudorange rate control is accurate. Simultaneously, record the satellite pseudorange values ​​during simulator operation to monitor the pseudorange change process.

[0078] The pseudorange measurement method provided by this invention will now be described in conjunction with specific application scenarios.

[0079] Verification using a single pseudorange control example based on the amplitude and phase characteristics of a synthesized signal:

[0080] like Figure 5 As shown, the GPSL1 frequency point was used as the measurement signal, with a frequency of 1.57542GHz and a period of approximately 0.63475ns. All error models were turned off, and a static scene with fixed pseudoranges between the satellite and the carrier was set. The simulator output a single-satellite single-carrier signal, and the peak signal level P0 was measured to be -58.10dBm using a spectrum analyzer.

[0081] Adding a satellite at frequency L1, the combined single-carrier signals from the two satellites are read using a spectrum analyzer as having a peak signal level P1 of -52.08 dBm. Figure 6 As shown, the level difference is 6.02dB, indicating that the amplitude and phase of the two satellites are the same and the time delay is 0.

[0082] Adjusting the simulator to change the pseudorange of one satellite by 3mm, while keeping others unchanged, the actual measured peak level of the synthesized signal P2 was -52.09dBm. Figure 7 As shown.

[0083] The peak level change of the synthesized signal after a pseudorange change of 3mm is: ΔP2=P2-P0=6.01dB. The increased delay Δt1 calculated using the formula is:

[0084]

[0085] The actual pseudorange change Δd1 is obtained by multiplying the time delay by the speed of light:

[0086] Δd1=Δt1×c=2.992mm

[0087] The results show that when the simulator controls the pseudorange to change by 3 mm, the actual change in pseudorange is calculated to be 2.992 mm by measuring the signal amplitude level change using a spectrum analyzer. The results are consistent with the theoretical derivation.

[0088] To verify the universality of the method, a pseudorange variation of 3cm was performed. The measurement method remained the same, but the pseudorange of one satellite was changed by 3cm, and the peak level of the synthesized signal was measured to be -53.19dBm. Figure 8 As shown.

[0089] The peak level change of the synthesized signal after a pseudorange change of 3 cm is: ΔP3 = P3 - P0 = 4.91 dB.

[0090] Calculate the time delay Δt2:

[0091]

[0092] The actual pseudorange change Δd2 is obtained by multiplying the time delay by the speed of light: Δd2 = Δt2 × c = 2.998 cm.

[0093] The results show that when the simulator controls the pseudorange to change by 3 cm, the change in the measured signal amplitude level is calculated to be 2.998 cm, which further verifies the feasibility of the method.

[0094] The comprehensive implementation results show that it is feasible to measure the pseudorange control change of the satellite navigation simulator using the method of the present invention. The original method measures the minimum pseudorange change to be 1 cm and has a large uncertainty. The method proposed in this invention can directly measure the pseudorange change to be 3 mm, which improves the measurement accuracy by more than 3 times and is stable and reliable.

[0095] Furthermore, this invention provides another example of pseudorange control using pseudorange rate and feature point measurement.

[0096] The initial binary satellite configuration is the same as described above. The experimental measurement frequency is GPS L1, with a signal frequency of 1.57542 GHz, a period of 0.63475 ns, a half-period of 0.31738 ns, and a light speed of 299,792,458 m / s. The pseudorange change corresponding to the half-period of signal movement is:

[0097]

[0098] The spectrum analyzer's sweep width is set to 0Hz, the scan time to 1s, and the simulator is set to measure a pseudorange change of 0.095147m for a single satellite over a duration of 318s, with a pseudorange change rate of 0.0003m / s. Satellite pseudorange data is recorded simultaneously during the operation. Figure 9 As shown, after the operation was completed, the spectrum analyzer measured the signal amplitude level, P4 = -90.95dBm.

[0099] like Figure 10 As shown, with the simulator output disconnected and the spectrum analyzer settings unchanged, the amplitude level P5 at the measurement port is -90.95dBm.

[0100] The results show that when a satellite changes the pseudorange value corresponding to half a cycle at a pseudorange rate of 0.0003 m / s, the power of the synthesized signal is the same as that of the signal after disconnection, P4 = P5 = 0, proving that the 0.0003 m / s pseudorange control is accurate.

[0101] Export the raw satellite pseudorange data recorded by the simulator, such as Figure 11 As shown in the figure, the first column is the serial number, the second column is the pseudorange value, and the third column is the pseudorange change value. Figure 12 The figure shows the change in pseudorange per second as the pseudorange increases continuously. The change is linear, and magnifying any 10 points yields the result. Figure 13 The pseudorange shown changes uniformly at intervals of 0.3 mm per second, indicating that the pseudorange rate is uniform throughout the process.

[0102] Final conclusion: By utilizing the amplitude and phase characteristics of dual-channel signal synthesis and measuring the signal amplitude variation using a spectrum analyzer, the actual pseudorange variation can be calculated. Experimental verification shows that a single pseudorange variation of up to 3 mm can be measured. Furthermore, by accumulating the pseudorange variation through pseudorange rate and duration, a pseudorange variation of 0.3 mm can be measured. Traditional methods have a maximum pseudorange measurement capability of 1 cm. Compared to traditional methods, this method reduces the impact of time-domain signal jitter on the measurement results and is not limited by the modulation method of the measured signal. The pseudorange measurement accuracy is improved by 3 times and 30 times respectively, significantly enhancing the pseudorange measurement capability of the high-performance simulator.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pseudorange measurement method for a satellite navigation simulator based on the amplitude and phase characteristics of signal synthesis, characterized in that, The method includes: Select any frequency point of satellite single carrier signal output by the simulator navigation system, and measure the peak level of the first satellite. Measure the signals of the first satellite and the second satellite, and test the combined peak level; compare the combined peak level with the single-satellite peak level, and determine whether the increase in the combined signal amplitude is 6.02dB. If so, the signal amplitude and phase of the two satellites are the same. The pseudorange of either satellite in the two satellite signals is changed, and the synthesized peak level is tested a second time. The difference between the synthesized peak level and the single-satellite peak level is obtained. The actual adjusted pseudorange value between the two satellite signals is obtained based on the difference, thereby obtaining the pseudorange control accuracy of the simulator. The difference between the synthesized peak level and the single-satellite peak level is obtained by comparing the two values, including: The logarithmic change value of the composite signal amplitude is obtained by comparing the synthesized peak level obtained from the second test with the single-satellite peak level. The relationship between amplitude and phase difference is as follows: ； Based on the logarithmic change value of the synthesized signal amplitude Obtaining phase difference : 。 2. The method according to claim 1, characterized in that, The time delay is calculated based on the logarithmic change value of the synthesized signal amplitude. Then, the actual adjusted pseudorange value is obtained based on the time delay. : ； ,in It is a periodicity.

3. The method according to claim 1, characterized in that, Changing the pseudorange of a satellite can be achieved by: directly changing the pseudorange value in a single jump, or by setting a fixed pseudorange change rate and duration, and calculating the cumulative pseudorange change value after the pseudorange has been continuously changing for a certain period of time.

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