Carrier Doppler Frequency Measurement Method, Device, Electronic Device and Storage Medium

Abstract

The present invention provides a carrier Doppler frequency measurement method, apparatus, electronic device, and storage medium. The method includes: selecting an intermediate frequency signal obtained by down-converting the radio frequency front-end of a receiver, and a local replica carrier after a tracking loop enters a stable tracking state, performing signal processing on the intermediate frequency signal to confirm that the intermediate frequency signal after signal processing is a received input signal; performing signal processing on the local replica carrier to confirm that the carrier signal after signal processing is a local input signal, calculating the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain a phase fringe, and obtaining the carrier Doppler frequency of the intermediate frequency signal based on the phase fringe. The carrier Doppler frequency measurement method provided by the present invention has good dynamic adaptability, can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite navigation signal processing, and particularly to a method and apparatus for measuring carrier Doppler frequency, an electronic device, and a storage medium. Background Art

[0002] A satellite navigation and positioning system can be used to guide aircraft, ships, vehicles, and individuals along a predefined route to reach the destination safely and accurately. Since the United States successfully established the Global Positioning System (GPS), Europe, Russia, and China have successively launched their own satellite navigation and positioning systems, such as Galileo, GLONSS, and Beidou. However, GPS is still the most widely used satellite navigation and positioning system at present.

[0003] A user uses a satellite navigation receiver to receive and track navigation satellite signals. The purposes of signal tracking are twofold. One is to achieve tracking of the pseudo-code component in the satellite navigation signal, and the other is to achieve tracking of the carrier component. The key to carrier tracking is to recover a coherent carrier that is in the same frequency as the carrier. A typical carrier tracking loop consists of a frequency or phase discriminator, a loop filter, and a carrier numerically controlled oscillator (NCO). Whether it is a frequency-locked loop (FLL) or a phase-locked loop (PLL), their loop bandwidths are fixed and it is impossible to achieve stable frequency tracking when the Doppler dynamic changes greatly. Therefore, scholars at home and abroad have proposed many methods to improve carrier tracking technology, optimizing the discriminator and loop filter in the loop structure to broaden the linear frequency discrimination range and reduce the frequency discrimination error.

[0004] In the prior art, a GPS high-dynamic carrier tracking algorithm based on fuzzy control designs a hybrid carrier tracking loop based on a frequency-locked loop and a phase-locked loop. The loop can automatically switch the working mode according to the change of the noise environment, improving the frequency step problem that appears in the process of loop state conversion; the fine frequency estimation of weak GPS signals based on FFT constructs new coherent accumulation variables by the square method and the differential method respectively as the input of the FFT operation, improving the frequency pulling rate under weak signals; some literatures also introduce adaptive technologies such as Maximum Likelihood Estimation (MLE), Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and Cross-Product Automatic Frequency Control (CPAFC) into the carrier tracking algorithm, enabling the noise bandwidth of the carrier tracking loop to be automatically adjusted according to different dynamic environments, improving the dynamic tracking performance of the loop to varying degrees, but at the same time increasing the complexity of the algorithm. The above methods essentially use mathematical statistical laws on the I and Q branches to perform optimal estimation of state variables under certain conditions, having the inherent disadvantages of high hardware cost and small dynamic adaptation range; although the time-delay estimation method based on frequency compensation gives four methods for measuring the frequency difference between two signals, namely the frequency-domain cross-correlation method, the frequency-domain autocorrelation method, the time-domain cross-correlation method, and the phase construction method, these methods are for the case of single-frequency signals and are not applicable to the direct-sequence spread-spectrum signals used in satellite navigation. Summary of the Invention

[0005] The present invention provides a carrier Doppler frequency measurement method, device, electronic device, and storage medium to solve the technical problems in the prior art that satellite tracking has high hardware cost, small dynamic adaptation range, and cannot achieve precise carrier tracking. The purpose of the present invention is to improve carrier tracking accuracy, expand the dynamic adaptation range, reduce hardware cost, and enhance the user experience.

[0006] In a first aspect, the present invention provides a carrier Doppler frequency measurement method, including:

[0007] Select the intermediate-frequency signal obtained by down-converting the radio frequency front-end of the receiver, and the local replicated carrier after the tracking loop enters the stable tracking state;

[0008] Perform signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal; perform signal processing on the local replicated carrier to confirm that the carrier signal after signal processing is the local input signal;

[0009] Obtain a phase fringe based on the time-domain phase spectrum calculated from the received input signal and the local input signal, and obtain the carrier Doppler frequency of the intermediate-frequency signal based on the phase fringe.

[0010] Further, according to the carrier Doppler frequency measurement method provided by the present invention, the step of obtaining a phase fringe based on the time-domain phase spectrum calculated from the received input signal and the local input signal, and obtaining the carrier Doppler frequency of the intermediate-frequency signal based on the phase fringe includes:

[0011] Perform conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing;

[0012] Determine a time-domain phase spectrum based on the signal after conjugate multiplication processing, and perform Hough transform processing on the time-domain phase spectrum to obtain a phase fringe;

[0013] Obtain a phase fringe slope based on the phase fringe, obtain a frequency difference between the received input signal and the local input signal based on the phase fringe slope, and confirm the carrier Doppler frequency of the intermediate-frequency signal.

[0014] Further, according to the carrier Doppler frequency measurement method provided by the present invention, the step of performing conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing includes:

[0015] The received input signal is:

[0016]

[0017] The local input signal is:

[0018]

[0019] Perform conjugate multiplication processing on the received input signal and the local input signal, and the signal after conjugate multiplication processing is:

[0020]

[0021] Wherein, represents the conjugate signal of the local input signal, f d,k represents the carrier Doppler frequency of satellite k relative to the receiver, f0 represents the center frequency, Ts is the sampling interval; θ k represents the carrier phase difference, and n represents the discretized identifier.

[0022] Further, according to the carrier Doppler frequency measurement method provided by the present invention, determining a time-domain phase spectrum based on the signal after conjugate multiplication processing, and performing a Hough transform on the time-domain phase spectrum to obtain phase fringes, includes:

[0023] Calculating a time-domain phase spectrum based on the signal after conjugate multiplication processing to obtain a time-domain phase spectrum, and performing threshold denoising and Hough transform processing on the time-domain phase spectrum to obtain phase fringes; wherein, the time-domain phase spectrum is:

[0024]

[0025] Further, according to the carrier Doppler frequency measurement method provided by the present invention, obtaining a phase fringe slope based on the phase fringes, obtaining a frequency difference between the received input signal and the local input signal based on the phase fringe slope, and determining the carrier Doppler frequency of the intermediate frequency signal, includes:

[0026] Performing unary linear regression processing on the phase fringes to obtain a phase fringe slope;

[0027] Obtaining a frequency difference between the received input signal and the local input signal based on the phase fringe slope and a preset threshold, and determining the frequency difference as the carrier Doppler frequency of the intermediate frequency signal.

[0028] Further, according to the carrier Doppler frequency measurement method provided by the present invention, performing signal processing on the intermediate frequency signal, and determining that the intermediate frequency signal after signal processing is the received input signal, includes:

[0029] Performing sampling, square detection, DC removal, Hilbert transform, and conjugate processing on the intermediate frequency signal, and determining the obtained signal as the received input signal.

[0030] Further, according to the carrier Doppler frequency measurement method provided by the present invention, performing signal processing on the locally replicated carrier, and determining that the carrier signal after signal processing is the local input signal, includes:

[0031] Performing square detection, DC removal, and Hilbert transform processing on the locally replicated carrier, and determining the obtained signal as the local input signal.

[0032] In a second aspect, the present invention further provides a carrier Doppler frequency measurement device, including:

[0033] A selection module, configured to select an intermediate frequency signal output by a down-conversion of a receiver radio frequency front end, and a locally replicated carrier after a tracking loop enters a stable tracking state;

[0034] A processing module for performing signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal; and performing signal processing on the locally replicated carrier to confirm that the carrier signal after signal processing is the local input signal.

[0035] A calculation module for calculating the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain phase fringes, and obtaining the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes.

[0036] In a third aspect, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of any one of the above carrier Doppler frequency measurement methods are implemented.

[0037] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of any one of the above carrier Doppler frequency measurement methods are implemented.

[0038] In a fifth aspect, the present invention further provides a computer program product, which includes computer-executable instructions that are used to implement the steps of any one of the above carrier Doppler frequency measurement methods when executed.

[0039] The present invention provides a method, device, electronic device, and storage medium for measuring carrier Doppler frequency. The method includes: selecting an intermediate-frequency signal down-converted by a receiver radio frequency front end and a locally replicated carrier after a tracking loop enters a stable tracking state, performing signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal; performing signal processing on the locally replicated carrier to confirm that the carrier signal after signal processing is the local input signal, calculating the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain phase fringes, and obtaining the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes. The carrier Doppler frequency measurement method provided by the present invention has good dynamic adaptability, can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1It is a schematic flow diagram of the carrier Doppler frequency measurement method provided by the present invention;

[0042] Figure 2 It is a schematic principle diagram of the carrier Doppler frequency measurement method provided by the present invention;

[0043] Figure 3 It is the time-domain phase spectrum of two signals provided by the present invention;

[0044] Figure 4 It is a schematic flow diagram of the estimation of the phase fringe slope provided by the present invention;

[0045] Figure 5 It is one of the schematic diagrams of the straight-line parameter estimation of the Hough transform provided by the present invention;

[0046] Figure 6 It is a schematic diagram before denoising without performing the Houg transform in the prior art;

[0047] Figure 7 It is a schematic diagram after denoising by performing the Houg transform provided by the present invention;

[0048] Figure 8 It is a schematic diagram of the time-domain phase spectrum of the simulated GPS provided by the present invention;

[0049] Figure 9 It is a simulation schematic diagram of the Hough transform of the phase fringe provided by the present invention;

[0050] Figure 10 It is a simulation schematic diagram of the unary linear regression of the phase fringe provided by the present invention;

[0051] Figure 11 It is a comparison schematic diagram of the carrier Doppler measurement errors between the phase fringe method and the second-order FLL provided by the present invention;

[0052] Figure 12 It is a schematic diagram of the carrier tracking results of the phase fringe method and the PLL-FLL method for high-dynamic signals provided by the present invention;

[0053] Figure 13 It is a comparison schematic diagram of the carrier tracking errors between the phase fringe method and the PLL-FLL method for high-dynamic signals provided by the present invention;

[0054] Figure 14 It is a schematic structural diagram of the carrier Doppler frequency measurement device provided by the present invention;

[0055] Figure 15 It is a schematic structural diagram of the electronic device provided by the present invention. Detailed implementation manners

[0056] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0057] Figure 1 As shown in the flowchart of the carrier Doppler frequency measurement method provided by the present invention, Figure 1 the carrier Doppler frequency measurement method provided by the present invention specifically includes the following steps:

[0058] Step 101: Select the intermediate-frequency signal after down-conversion of the receiver RF front-end, and the local replica carrier after the tracking loop enters the stable tracking state.

[0059] In this embodiment, it is necessary to select the intermediate-frequency signal after down-conversion of the receiver RF front-end and the local replica carrier after the tracking loop enters the stable tracking state. Among them, the receiver can be a GPS receiver. The tracking of the navigation signal by the GPS receiver is mainly completed through the carrier loop and the code loop. The tracking loop replicates the carrier and the pseudo-code synchronized with the satellite signal, so as to realize carrier stripping and signal despreading, and obtain the data code of the navigation message. While tracking the signal, the receiver obtains the Doppler frequency shift and carrier phase measurement values of the satellite signal according to the parameters of the local replica carrier signal, and obtains the code phase and code pseudo-range measurement values of the satellite signal according to the parameters of the replicated pseudo-code.

[0060] Step 102: Perform signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal; perform signal processing on the local replica carrier to confirm that the carrier signal after signal processing is the local input signal.

[0061] In this embodiment, it is necessary to perform signal processing on the selected intermediate-frequency signal and confirm that the intermediate-frequency signal after signal processing is the received input signal. Among them, the signal processing of the intermediate-frequency signal may include processing such as sampling, DC removal, conjugation, phase extraction, and unary linear regression. Specific details can be seen in the following embodiments and will not be elaborated here.

[0062] In this embodiment, it is necessary to perform signal processing on the local replica carrier and confirm that the carrier signal after signal processing is the local input signal. Among them, the signal processing of the local replica carrier may include processing such as DC removal and Hilbert transform, which will not be elaborated here.

[0063] Step 103: Calculate the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain phase fringes, and obtain the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes.

[0064] In this embodiment, it is necessary to calculate the obtained time-domain phase spectrum based on the received input signal and the local input signal confirmed in step 102, obtain phase fringes according to the time-domain phase spectrum, and then obtain the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes.

[0065] It should be noted that the calculation of the carrier Doppler frequency is based on the Doppler effect. The Doppler effect refers to the fact that when a vibration source such as gamma rays, light, and radio waves moves relative to an observer at a relative speed V, the vibration frequency received by the observer is different from the frequency emitted by the vibration source.

[0066] According to the carrier Doppler frequency measurement method provided by the present invention, the intermediate-frequency signal after down-conversion at the radio frequency front end of the receiver is selected, and the local replicated carrier after the tracking loop enters the stable tracking state. Signal processing is performed on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal. Signal processing is performed on the local replicated carrier to confirm that the carrier signal after signal processing is the local input signal. Calculate the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain phase fringes, and obtain the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes. The carrier Doppler frequency measurement method provided by the present invention has good dynamic adaptability, can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0067] Based on any of the above embodiments, in this embodiment, the calculating the obtained time-domain phase spectrum based on the received input signal and the local input signal to obtain phase fringes, and obtaining the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes includes:

[0068] Perform conjugate multiplication processing on the received input signal and the local input signal to obtain the signal after conjugate multiplication processing;

[0069] Determine the time-domain phase spectrum according to the signal after conjugate multiplication processing, and perform Hough transform processing on the time-domain phase spectrum to obtain phase fringes;

[0070] Obtain the phase fringe slope according to the phase fringes, obtain the frequency difference between the received input signal and the local input signal according to the phase fringe slope, and confirm the carrier Doppler frequency of the intermediate-frequency signal.

[0071] In this embodiment, it is necessary to perform conjugate multiplication on the determined received input signal and the local input signal, determine the time-domain phase spectrum according to the signal after conjugate multiplication processing, perform Hough transform processing on the time-domain phase spectrum to obtain phase fringes, then obtain the slope of the phase fringes according to the obtained phase fringes, obtain the frequency difference between the received input signal and the local input signal according to the slope of the phase fringes, and determine this frequency difference as the carrier Doppler frequency of the intermediate-frequency signal. Among them, the Hough transform is a data processing method that can effectively identify multiple straight lines. The specific content is shown in the following embodiments and will not be introduced in detail here.

[0072] In this embodiment, as Figure 2 shown, the carrier Doppler frequency measurement method based on phase fringes is realized by using time-domain phase parameter estimation. By performing Hilbert transform on the two signals of the input intermediate-frequency signal and the locally generated local replica carrier respectively, then calculating the time-domain cross-correlation power spectrum, and finally measuring the slope of the time-domain phase fringes, the carrier Doppler frequency of the signal is obtained.

[0073] According to the carrier Doppler frequency measurement method provided by the present invention, by performing conjugate multiplication on the received input signal and the local input signal, obtaining the signal after conjugate multiplication processing, then determining the time-domain phase spectrum according to the signal after conjugate multiplication processing, performing Hough transform processing on the time-domain phase spectrum to obtain phase fringes, obtaining the slope of the phase fringes according to the phase fringes, obtaining the frequency difference between the received input signal and the local input signal according to the slope of the phase fringes, and confirming the carrier Doppler frequency of the intermediate-frequency signal, it is possible to improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0074] Based on any of the above embodiments, in this embodiment, the performing conjugate multiplication on the received input signal and the local input signal to obtain the signal after conjugate multiplication processing includes:

[0075] The received input signal is:

[0076]

[0077] The local input signal is:

[0078]

[0079] Performing conjugate multiplication on the received input signal and the local input signal, the signal after conjugate multiplication processing is:

[0080]

[0081] Among them, represents the conjugate signal of the local input signal, f d,kIt represents the carrier Doppler frequency of satellite k relative to the receiver, f0 represents the center frequency, Ts is the sampling interval; θ k represents the carrier phase difference, and n represents the identifier after discretization.

[0082] In this embodiment, it is necessary to perform certain processing on the selected intermediate frequency signal and the local replica carrier signal, conjugate multiply the determined received input signal and the local input signal to obtain the signal after conjugate multiplication processing.

[0083] Among them, the intermediate frequency signal input to the receiver carrier tracking loop is:

[0084]

[0085] In the formula, v is the relative velocity between the satellite and the receiver, c is the speed of light, f0 is the center frequency, Ts is the sampling interval, and θ is the initial phase.

[0086] Since the navigation message D is composed of data with values of ±1, the navigation message can be stripped by using the method of square detection to obtain the carrier square signal as follows:

[0087]

[0088] The signal after filtering out the DC component is:

[0089]

[0090] In the formula, f d,k is the carrier Doppler frequency of satellite k relative to the receiver, and θ k is the carrier phase difference. Now perform Hilbert transform on it and represent it in analytic form, we have:

[0091]

[0092] Similarly, the analytic form of the output signal of the local carrier NCO is obtained as:

[0093]

[0094] The two analytic signals are conjugate multiplied to obtain:

[0095]

[0096] According to the carrier Doppler frequency measurement method provided by the present invention, by conjugate multiplying the received input signal and the local input signal to obtain the signal after conjugate multiplication processing, the accuracy of carrier tracking can be improved, the hardware cost of the tracking loop can be reduced, and the user experience can be enhanced.

[0097] Based on any of the above embodiments, in this embodiment, determining the time-domain phase spectrum according to the signal after conjugate multiplication processing, and performing Hough transform processing on the time-domain phase spectrum to obtain phase fringes, includes:

[0098] Performing time-domain phase spectrum calculation according to the signal after conjugate multiplication processing to obtain a time-domain phase spectrum, and performing threshold denoising and Hough transform processing on the time-domain phase spectrum to obtain phase fringes; wherein, the time-domain phase spectrum is:

[0099]

[0100] In this embodiment, according to the signal after conjugate multiplication processing obtained from the above embodiment, time-domain phase spectrum calculation is performed to obtain the Figure 3 shown time-domain phase spectrum, and then threshold denoising and Hough transform processing are performed on this time-domain phase spectrum to obtain phase fringes.

[0101] It should be noted that in this embodiment, by analyzing and calculating the time-domain phase spectrum of the carrier Doppler frequency, the phase fringe slope can be obtained. Then, dividing the fringe slope by 4π can obtain the carrier Doppler frequency, and dividing the fringe intercept by 2 can obtain the carrier phase difference. Since the time-domain phase spectrum has the characteristic of multi-stripe periodic arrangement, as the Doppler frequency changes, the position of each stripe also changes. Therefore, it is necessary to first identify the position of the clearest straight line in the stripe, and then perform unary linear regression calculation on the slope of a single stripe within the range.

[0102] It should be noted that the Hough transform is a data processing method that can effectively identify multiple straight lines. Its basic principle is to transform the straight line equation expression with x and y as coordinate axes in the data space into the straight line equation expression with slope a and intercept b as coordinate axes. In the rectangular coordinate system xOy, the phase fringe is a straight line, and the equation expression of a straight line is y = a * ×x + b. Taking any point (x0, y0) on the straight line, the straight line equation for this point can be written as b = -x0×a + y0. At this time, a and b are variables, and the aOb coordinate system is defined as the Hough space. If several points (x i , y i ) are selected on the straight line, several straight line equations b = -x i ×a + y i can be obtained in the Hough space. Then, all straight lines will intersect at the point (a * , b * ).

[0103] In this embodiment, as Figure 5 and Figure 6As shown, a point in the data space corresponds to a straight line in the Hough space; several points on a straight line in the data space correspond to several straight lines intersecting at the same point in the Hough space, and the intersection point (a, b) is the slope and intercept parameters of the straight line in the data space.

[0104] Writing the time-domain phase spectrum equation in polar coordinate form gives;

[0105]

[0106] After performing the Hough transform on this data and detecting the peak point (θ0, ρ0) in the Hough space, respectively let to obtain the system of equations

[0107]

[0108] Solve for t a , t b After that, then let

[0109] t min = min{t a , t b} (10)

[0110] t max = max{t a , t b} (11)

[0111] The range where the single straight line is located can be obtained as [t min , t max . Considering that there is an error in the minimum resolution of the Hough space in the rough measurement of the straight line position by the Hough transform, the range of the single straight line may be slightly larger than the actual range, which may cause the data of adjacent straight lines to be mixed into the range of this straight line, resulting in errors in the linear regression. Therefore, 30%-70% of the data within the abscissa range of the straight line is selected, and the areas on both sides that may be confused with other straight lines are discarded. This provides the corresponding phase spectrum data for the subsequent straight line fitting.

[0112] According to the carrier Doppler frequency measurement method provided by the present invention, the time-domain phase spectrum is calculated based on the signal after conjugate multiplication processing, and the time-domain phase spectrum is subjected to threshold denoising and Hough transform processing to obtain phase fringes, which can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0113] Based on any of the above embodiments, in this embodiment, obtaining the slope of the phase fringe according to the phase fringe, obtaining the frequency difference between the received input signal and the local input signal according to the slope of the phase fringe, and determining the carrier Doppler frequency of the intermediate frequency signal includes:

[0114] Perform a univariate linear regression on the phase fringes to obtain the slope of the phase fringes.

[0115] Obtain the frequency difference between the received input signal and the local input signal according to the slope of the phase fringes and a preset threshold, and determine the frequency difference as the carrier Doppler frequency of the intermediate frequency signal.

[0116] In this embodiment, as Figure 4 shown, it is necessary to perform threshold denoising and univariate linear regression on the obtained phase fringes to obtain the slope of the phase fringes, and then obtain the frequency difference between the received input signal and the local input signal according to the slope of the phase fringes and a preset threshold, and determine the frequency difference as the carrier Doppler frequency of the intermediate frequency signal.

[0117] In this embodiment, since the phase spectrum data is in the form of multiple repeated fringes as Figure 3 shown, the slope cannot be directly extracted from the entire sampling time period using univariate linear regression. It is necessary to first determine the time range of a single fringe. In this embodiment, the Hough transform is used to identify the straight line in the data. After determining the position of the straight line, univariate linear regression is performed on a single straight line to extract the carrier Doppler frequency.

[0118] It should be noted that in this embodiment, assuming that the preset threshold is 4π, by analyzing and calculating the time-domain phase spectrum of the carrier Doppler frequency, the slope of the phase fringes can be obtained. Then, dividing the fringe slope by 4π can obtain the carrier Doppler frequency, and dividing the fringe intercept by 2 can obtain the carrier phase difference. Due to the characteristic of the time-domain phase spectrum having a periodic arrangement of multiple fringes, as the carrier Doppler frequency changes, the position of each fringe also changes. It is necessary to first identify the position of the clearest straight line in the fringe, and then perform univariate linear regression on a single fringe in the range to calculate the slope.

[0119] According to the carrier Doppler frequency measurement method provided by the present invention, by performing a univariate linear regression on the phase fringes to obtain the slope of the phase fringes, obtaining the frequency difference between the received input signal and the local input signal according to the slope of the phase fringes and a preset threshold, and determining the frequency difference as the carrier Doppler frequency of the intermediate frequency signal. It can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0120] Based on any of the above embodiments, in this embodiment, the signal processing of the intermediate frequency signal to confirm that the processed intermediate frequency signal is the received input signal includes:

[0121] Perform sampling, square detection, DC removal, Hilbert transform, and conjugate processing on the intermediate frequency signal, and confirm the obtained signal as the received input signal.

[0122] In this embodiment, it is necessary to perform signal processing on the selected intermediate-frequency signal, including sampling, square detection, DC removal, Hilbert transform, and conjugate processing of the intermediate-frequency signal, and the signal obtained after signal processing is confirmed as the received input signal. Among them, the Hilbert transform means that in the fields of mathematics and signal processing, the Hilbert transform (denoted as H here) of a real-valued function is to convolve the signal s(t) with 1 / (πt) to obtain s′(t). The Hilbert transform result s′(t) can be interpreted as the output of a linear time-invariant system whose input is s(t), and the impulse response of this system is 1 / (πt).

[0123] According to the carrier Doppler frequency measurement method provided by the present invention, by sampling, square detection, DC removal, Hilbert transform, and conjugate processing of the intermediate-frequency signal, and confirming the signal obtained after signal processing as the received input signal, the accuracy of carrier tracking can be improved, the hardware cost of the tracking loop can be reduced, and the user experience can be enhanced.

[0124] Based on any of the above embodiments, in this embodiment, the signal processing of the local replicated carrier and the confirmation that the carrier signal after signal processing is the local input signal include:

[0125] Perform square detection, DC removal, and Hilbert transform processing on the local replicated carrier, and confirm the obtained signal as the local input signal.

[0126] In this embodiment, it is necessary to perform signal processing on the local replicated carrier, including square detection, DC removal, and Hilbert transform processing on the local replicated carrier, and confirm the signal obtained after signal processing as the local input signal. It can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0127] Based on any of the above embodiments, in this embodiment, a simulation experiment based on the carrier Doppler frequency measurement method provided by the present invention is provided. Taking the GPS L1 frequency point intermediate-frequency signal generated by simulation as the test object, the static measurement accuracy of the present invention is verified. The carrier frequency of the intermediate-frequency signal of the received signal is set to 6.5 MHz, the sampling rate is 28 MHz, and the Doppler frequency is 200 Hz. The simulation results are as Figures 7 to 10 shown.

[0128] Figure 7 is the time-domain phase spectrum of the received signal and the local replicated carrier signal. It can be seen that the stripes are submerged in the noise, Figure 8 is the phase spectrum after threshold denoising, and the phase stripes are significantly clearer. Figure 9It is the data representation of the time-domain phase spectrum in the Hough space with a resolution of 120×120. Looking along the ρ axis, there are 5 peaks, indicating that there are 5 straight lines in the phase spectrum. Looking along the θ axis, it can be seen that the 5 peaks of ρ basically correspond to the same θ, which means that the 5 straight lines of the phase fringes all have similar slopes. Then, according to the maximum values of θ and ρ, the most reliable section of data is extracted from the phase fringes, and then a unary linear regression is performed on this part of the phase points. As Figure 10 shown, the slope of the regression line divided by 4π is the measurement result of the carrier Doppler.

[0129] 1000 Monte Carlo simulations are carried out respectively under different carrier-to-noise ratios, and the Doppler frequency measurement error is compared with the frequency discrimination error of a second-order FLL with a loop bandwidth of 30 Hz. The simulation results are as Figure 11 shown. It can be seen that the phase fringe method has obvious advantages in frequency discrimination accuracy at low carrier-to-noise ratios. When the carrier-to-noise ratio is 32 dB-Hz, the measurement error of the carrier Doppler frequency is 13.42 Hz, which is about 31% higher than the accuracy of the second-order frequency-locked loop. As the carrier-to-noise ratio increases, the frequency discrimination accuracy of the phase fringe algorithm gradually approaches that of the phase-locked loop.

[0130] In order to verify the dynamic adaptability of the phase fringe method, the relative motion states of the receiver and the satellite are set according to the high-dynamic model of the Jet Propulsion Laboratory (JPL) of the United States. The initial velocity is set to 100 m / s, there is a constant acceleration of -25g from 0 to 0.5 s, and then a jerk of 100 g / s is introduced from 0.5 to 1 s. The carrier-to-noise ratio of the input signal is set to 44 dB-Hz. The measurement results of the carrier Doppler frequency of the traditional PLL-FLL algorithm and the phase fringe method of the present invention for the high-dynamic model are as Figure 12 shown. It can be seen that the phase fringe method can accurately track the carrier Doppler, and its tracking error is as Figure 13 shown. Compared with the traditional PLL-FLL algorithm with a loop bandwidth of 60 Hz, the frequency discrimination error of the phase fringe algorithm is smaller. Especially from 0.5 to 1 s, even with a large jerk, its error will not increase significantly; in addition, it can be seen that the frequency tracking error of the phase fringe method gradually decreases from 0 to 0.4 s and then gradually increases from 0.4 to 0.7 s, showing the characteristic of being proportional to the Doppler frequency.

[0131] According to the carrier Doppler frequency measurement method based on phase fringes provided by the present invention, this method is used to analyze the carrier tracking of a GPS receiver in different motion states. The research results show that:

[0132] 1. The tracking accuracy of the phase fringe algorithm provided by the present invention is high. In the low carrier-to-noise ratio environment of 32 dB-Hz, the tracking accuracy of the carrier Doppler frequency of the static signal is about 31% higher than that of the second-order frequency-locked loop.

[0133] 2. The phase fringe algorithm provided by the present invention has excellent dynamic adaptability. In an environment with a carrier-to-noise ratio of 44 dB-Hz, it can achieve carrier tracking of the JPL high-dynamic model. Moreover, when dealing with jerk, the tracking accuracy has an obvious advantage over the traditional PLL-FLL method, and the error is reduced by about 50%.

[0134] 3. The phase fringe algorithm provided by the present invention can simplify the design of the receiver tracking loop and reduce the hardware cost of the tracking loop.

[0135] Figure 14 For the carrier Doppler frequency measurement method provided by the present invention, as Figure 14 shown, the carrier Doppler frequency measurement device provided by the present invention includes:

[0136] A selection module 1401, configured to select the intermediate-frequency signal after down-conversion of the receiver RF front-end, and the local replica carrier after the tracking loop enters the stable tracking state;

[0137] A processing module 1402, configured to perform signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal; perform signal processing on the local replica carrier to confirm that the carrier signal after signal processing is the local input signal;

[0138] A calculation module 1403, configured to calculate the time-domain phase spectrum obtained according to the received input signal and the local input signal to obtain phase fringes, and obtain the carrier Doppler frequency of the intermediate-frequency signal according to the phase fringes.

[0139] According to the carrier Doppler frequency measurement device provided by the present invention, the intermediate-frequency signal after down-conversion of the receiver RF front-end and the local replica carrier after the tracking loop enters the stable tracking state are selected. Signal processing is performed on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is the received input signal. Signal processing is performed on the local replica carrier to confirm that the carrier signal after signal processing is the local input signal. The time-domain phase spectrum obtained according to the received input signal and the local input signal is calculated to obtain phase fringes, and the carrier Doppler frequency of the intermediate-frequency signal is obtained according to the phase fringes. The carrier Doppler frequency measurement device provided by the present invention has good dynamic adaptability, can improve the accuracy of carrier tracking, reduce the hardware cost of the tracking loop, and enhance the user experience.

[0140] Since the principle of the device described in the embodiments of the present invention is the same as that of the method described in the above embodiments, the more detailed explanation content will not be elaborated here.

[0141] Figure 15 For the schematic diagram of the physical structure of the electronic device provided in the embodiments of the present invention, as Figure 15As shown in the figure, the present invention provides an electronic device, including: a processor 1501, a memory 1502, and a bus 1503;

[0142] Among them, the processor 1501 and the memory 1502 complete communication with each other through the bus 1503;

[0143] The processor 1501 is used to call program instructions in the memory 1502 to execute the methods provided in the above method embodiments, for example, including: selecting the intermediate frequency signal of the down-conversion of the receiver radio frequency front end, and the local replica carrier after the tracking loop enters the stable tracking state; performing signal processing on the intermediate frequency signal to confirm that the intermediate frequency signal after signal processing is the received input signal; performing signal processing on the local replica carrier to confirm that the carrier signal after signal processing is the local input signal; calculating the obtained time-domain phase spectrum according to the received input signal and the local input signal to obtain a phase fringe, and obtaining the carrier Doppler frequency of the intermediate frequency signal according to the phase fringe.

[0144] In addition, when the logical instructions in the above memory 1503 can be implemented in the form of software function units and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. And the foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, etc., which can store program codes.

[0145] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned various methods. The method includes: selecting an intermediate-frequency signal down-converted by a receiver radio frequency front-end, and a locally replicated carrier after a tracking loop enters a stable tracking state; performing signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is a received input signal; performing signal processing on the locally replicated carrier to confirm that the carrier signal after signal processing is a local input signal; calculating a time-domain phase spectrum obtained based on the received input signal and the local input signal to obtain a phase fringe, and obtaining a carrier Doppler frequency of the intermediate-frequency signal based on the phase fringe.

[0146] In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is configured to execute the methods provided by the above-mentioned various methods. The method includes: selecting an intermediate-frequency signal down-converted by a receiver radio frequency front-end, and a locally replicated carrier after a tracking loop enters a stable tracking state; performing signal processing on the intermediate-frequency signal to confirm that the intermediate-frequency signal after signal processing is a received input signal; performing signal processing on the locally replicated carrier to confirm that the carrier signal after signal processing is a local input signal; calculating a time-domain phase spectrum obtained based on the received input signal and the local input signal to obtain a phase fringe, and obtaining a carrier Doppler frequency of the intermediate-frequency signal based on the phase fringe.

[0147] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative labor.

[0148] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring carrier Doppler frequency, characterized in that, Comprising: Selecting an intermediate frequency signal of the down-conversion of the receiver radio frequency front end, and a local replica carrier after the tracking loop enters a stable tracking state; Performing signal processing on the intermediate frequency signal to confirm that the intermediate frequency signal after signal processing is a received input signal; performing signal processing on the local replica carrier to confirm that the carrier signal after signal processing is a local input signal; Calculating a time-domain phase spectrum obtained from the received input signal and the local input signal, obtaining a phase fringe, and obtaining a carrier Doppler frequency of the intermediate frequency signal according to the phase fringe; Wherein, the calculating a time-domain phase spectrum obtained from the received input signal and the local input signal, obtaining a phase fringe, and obtaining a carrier Doppler frequency of the intermediate frequency signal according to the phase fringe includes: Performing conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing; Determining a time-domain phase spectrum according to the signal after conjugate multiplication processing, and performing denoising and Hough transform processing on the time-domain phase spectrum to obtain a phase fringe; Obtaining a phase fringe slope according to the phase fringe, obtaining a frequency difference between the received input signal and the local input signal according to the phase fringe slope, and confirming the carrier Doppler frequency of the intermediate frequency signal.

2. The carrier Doppler frequency measurement method according to claim 1, characterized in that The performing conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing includes: The received input signal is: The local input signal is: Performing conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing as: Among them, represents the conjugate signal of the local input signal, f d,k represents the carrier Doppler frequency of satellite k relative to the receiver, f0 represents the center frequency, and Ts is the sampling interval; θ k represents the carrier phase difference, and n represents the identifier after discretization.

3. The carrier Doppler frequency measurement method according to claim 2, characterized in that, The determining a time-domain phase spectrum according to the signal after conjugate multiplication processing, and performing Hough transform processing on the time-domain phase spectrum to obtain a phase fringe includes: Calculating a time-domain phase spectrum according to the signal after conjugate multiplication processing to obtain a time-domain phase spectrum, and performing threshold denoising and Hough transform processing on the time-domain phase spectrum to obtain a phase fringe; wherein, the time-domain phase spectrum is:

4. The carrier Doppler frequency measurement method according to claim 1, characterized in that The obtaining a phase fringe slope according to the phase fringe, obtaining a frequency difference between the received input signal and the local input signal according to the phase fringe slope, and confirming the carrier Doppler frequency of the intermediate frequency signal includes: Performing unary linear regression processing on the phase fringe to obtain a phase fringe slope; Obtaining a frequency difference between the received input signal and the local input signal according to the phase fringe slope and a preset threshold, and determining the frequency difference as the carrier Doppler frequency of the intermediate frequency signal.

5. The carrier Doppler frequency measurement method according to claim 1, characterized in that The performing signal processing on the intermediate frequency signal to confirm that the intermediate frequency signal after signal processing is a received input signal includes: Performing sampling, square detection, DC removal, Hilbert transform and conjugate taking processing on the intermediate frequency signal, and confirming the obtained signal as a received input signal.

6. The carrier Doppler frequency measurement method according to claim 1, wherein The performing signal processing on the local replica carrier to confirm that the carrier signal after signal processing is a local input signal includes: Performing square detection, DC removal and Hilbert transform processing on the local replica carrier, and confirming the obtained signal as a local input signal.

7. A carrier Doppler frequency measurement device, characterized in that, Comprising: A selection module, configured to select an intermediate frequency signal obtained by down-converting a radio frequency front end of a receiver, and a local replica carrier after a tracking loop enters a stable tracking state; A processing module, configured to perform signal processing on the intermediate frequency signal to confirm that the intermediate frequency signal after signal processing is a received input signal; perform signal processing on the local replica carrier to confirm that the carrier signal after signal processing is a local input signal; A calculation module, configured to calculate a time-domain phase spectrum obtained from the received input signal and the local input signal to obtain phase fringes, and obtain a carrier Doppler frequency of the intermediate frequency signal according to the phase fringes; Wherein, the calculation module is specifically configured to perform conjugate multiplication processing on the received input signal and the local input signal to obtain a signal after conjugate multiplication processing; determine a time-domain phase spectrum according to the signal after conjugate multiplication processing, and perform denoising and Hough transform processing on the time-domain phase spectrum to obtain phase fringes; obtain a phase fringe slope according to the phase fringes, obtain a frequency difference between the received input signal and the local input signal according to the phase fringe slope, and confirm the carrier Doppler frequency of the intermediate frequency signal.

8. An electronic device, characterized in that, Including: A processor, a memory, and a bus, wherein The processor and the memory complete communication with each other through the bus; The memory stores program instructions executable by the processor, and the processor can execute the steps of the carrier Doppler frequency measurement method according to any one of claims 1 to 6 by invoking the program instructions.

9. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of the carrier Doppler frequency measurement method according to any one of claims 1 to 6.

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