A signal delay measurement method, system and terminal

Abstract

The present application belongs to the electronic information, signal processing, communication and radar positioning cross technical field, and relates to a signal delay measurement method, system and terminal. The present application collects the transmitting signal and the receiving signal through the delay system, respectively makes the fast Fourier transform on the two signals and selects the frequency interval according to the spectrum, and then calculates the phase difference change; at the same time, a new phase unwrapping method is proposed to solve the 2pi phase ambiguity problem caused by the calculation of the phase difference, and the phase difference is shifted and corrected to restore it to the phase difference corresponding to the high frequency; finally, the delay in the time domain of the two signals is used, which is priori information that the phase difference is proportional to the frequency in the frequency domain, and the phase difference points of the selected frequency interval are forced to pass through the origin linear fitting, and the delay is calculated through the slope of the straight line. The present application avoids the error accumulation caused by noise or phase mutation, and significantly improves the delay estimation robustness under the condition of low signal-to-noise ratio or frequent phase jump.

Description

Technical Field

[0001] This invention relates to the fields of electronic information, signal processing, communication and radar positioning, and in particular to a signal delay measurement method, system and terminal. Background Technology

[0002] In systems such as radar positioning, communication, high-precision time synchronization, and distributed array signal processing, accurate estimation of signal propagation delay is a core technology for achieving target positioning, synchronization calibration, and coherent signal reception. Traditional delay estimation methods are mainly divided into two categories: time-domain correlation methods and frequency-domain phase difference methods.

[0003] The time-domain correlation method calculates delay by measuring the peak cross-correlation of signals. While intuitive and simple to implement, it is susceptible to noise, multipath interference, and sampling rate limitations, making it difficult to achieve sub-sampling level high-precision measurements. Furthermore, under low signal-to-noise ratio conditions, the correlation peak is prone to shift and distortion, leading to a significant decrease in estimation accuracy. The frequency-domain phase difference method, relying on the physical characteristic that delay exhibits a linear phase change in the frequency domain, estimates delay by linearly fitting the signal phase difference to the frequency. It offers advantages such as high accuracy, strong anti-interference capability, and suitability for broadband signal processing, and has become the mainstream technology for high-precision delay measurement. However, the traditional frequency domain phase difference method still has significant drawbacks in practical engineering applications: First, the 2π periodicity constraint of the signal phase easily leads to phase ambiguity, and the full-band phase expansion process is complex, easily causing error accumulation due to noise or phase abrupt changes. Second, it does not fully utilize the prior information that the phase difference is linearly proportional to the frequency; conventional unconstrained least squares fitting is easily affected by intercept shift, reducing the stability of delay estimation. Third, due to the high cost of high-speed acquisition equipment, signal down-conversion technology is used to down-convert high-frequency signals to facilitate acquisition in order to reduce costs. However, this process also causes a phase shift corresponding to the high frequency. At the same time, under low signal-to-noise ratio conditions, noise will significantly interfere with phase calculation, causing the fitting slope to deviate from the true value, making it difficult to meet the high-precision measurement requirements in complex environments. To solve the above problems, phase expansion, frequency point selection, and weighted fitting are usually used to improve the algorithm, but existing methods still have shortcomings such as insufficient robustness, decreased accuracy under signal down-conversion and low signal-to-noise ratio conditions.

[0004] Therefore, there is an urgent need to propose a signal delay estimation method that can be applied to signal downconversion conditions, effectively suppress phase ambiguity, reduce noise impact, and make full use of physical prior information, so as to improve the accuracy and reliability of delay measurement in complex engineering environments. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a signal delay measurement method, system, and terminal. This invention acquires the transmitted signal and the received signal after a delay system, performs Fast Fourier Transform on both signals, selects a frequency range based on the spectrum, and then calculates the phase difference change. Simultaneously, it proposes a novel phase unwinding method to solve the 2π phase ambiguity problem caused by calculating the phase difference, performing a translation correction on the phase difference to restore it to the phase difference corresponding to the high frequency. Finally, utilizing the prior information that the delay in the time domain of the two signals is linearly proportional to the frequency in the frequency domain, a forced linear fitting is performed on the phase difference points in the selected frequency range, and the delay is calculated from the slope of the straight line. This invention overcomes the limitations of traditional frequency domain phase difference delay measurement methods in down-conversion, low signal-to-noise ratio, or frequent phase jump conditions, significantly improving its stability and practicality in complex measurement environments. It is particularly suitable for precise delay estimation under high-frequency, small-delay, and down-conversion signal conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a signal delay measurement method, comprising the following steps: S1. Acquire the transmitting and receiving signals, and perform Fast Fourier Transform on the transmitting and receiving signals respectively to obtain the signal spectrum; S2. Select the main lobe frequency range in the signal spectrum, calculate the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filter multiple discrete frequency points with amplitudes higher than the preset amplitude threshold based on the spectrum of the main lobe frequency range, determine the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtain the frequency-phase difference data before unwinding. S3. Perform a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay; S4. Calculate the number of integer-cycle phases of the phase difference winding corresponding to the left-value frequency point in the main lobe frequency range based on the initial estimate. ; S5. Based on the integer cycle phase number, the phase difference-frequency curve corresponding to the main lobe frequency range is unwound to obtain the unwound phase difference-frequency curve; S6. Determine the unwinding phase difference corresponding to multiple discrete frequency points in the unwinding phase difference-frequency curve to obtain frequency-unwinding phase difference data. Perform a second linear fitting on the frequency-unwinding phase difference data to obtain the intercept of the fitted line. ; S7. Determine the intercept Is it in If the interval is within the specified range, proceed to step S8; otherwise, calculate the number of phases for the entire cycle. Perform compensation to obtain a new integer cycle phase number, and return to step S5; S8. Move the origin... A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

[0007] As one possible implementation, when the transmitting signal is a high-frequency signal, it is down-converted before acquisition. In this case, the receiving signal is the high-frequency signal from the transmitting end after being delayed by the system and then down-converted. When the transmitting signal is a low-frequency signal, down-conversion is not required before acquisition. In this case, the receiving signal is the low-frequency signal from the transmitting end after being delayed by the system.

[0008] As one possible implementation, the main lobe frequency range is centered on the signal center frequency, and the frequency width is the signal bandwidth; a preset amplitude threshold is used to filter out frequency points with amplitudes higher than the threshold, so as to eliminate low signal-to-noise ratio frequency points.

[0009] As one possible approach, both the first and second linear fittings are implemented using the least squares method.

[0010] As one possible implementation, the phase difference-frequency curve corresponding to the main lobe frequency range is unwrapped using the following method: in, This indicates the unwinding phase difference. This represents the phase difference before unwinding. This represents the number of phases in an entire cycle.

[0011] As one possible implementation, the integer-cycle phase number at each discrete frequency point is calculated using the following method: in, This indicates rounding to the nearest integer. This represents the left value of the main lobe frequency range. This represents the initial estimate of the signal delay.

[0012] As one possible implementation, the following method is used to calculate the number of phases in the integer cycle. Compensation will be provided. Calculate compensation amount : Update the integer cycle phase number: update the integer cycle phase number Updated to + .

[0013] As one possible implementation, the forced linear fitting through the origin is achieved using the least squares method, and the fitting model is as follows: in, This indicates the unwinding phase difference. This represents the final estimated signal delay.

[0014] In a second aspect, the present invention provides a signal delay measurement system, comprising: The signal spectrum acquisition unit collects the transmitting end signal and the receiving end signal, and performs fast Fourier transform on the transmitting end signal and the receiving end signal respectively to obtain the signal spectrum; The phase difference calculation unit before unwinding selects the main lobe frequency range in the signal spectrum, calculates the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filters multiple discrete frequency points with amplitudes higher than a preset amplitude threshold based on the spectrum of the main lobe frequency range, determines the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtains the frequency-phase difference data before unwinding. The initial estimation acquisition unit performs a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay. The integer-cycle phase number calculation unit calculates the integer-cycle phase number of the phase difference winding corresponding to the left-hand frequency point of the main lobe frequency range based on the initial estimate. ; The unwrapping phase difference solving unit unwrappes the phase difference-frequency curve corresponding to the main lobe frequency range based on the integer cycle phase number to obtain the unwrapped phase difference-frequency curve; it then determines the unwrapped phase difference corresponding to multiple discrete frequency points in the unwrapped phase difference-frequency curve to obtain frequency-unwrapped phase difference data. The phase compensation unit performs a second linear fitting on the frequency-unwound phase difference data to obtain the intercept of the fitted line. Determine the intercept Is it in If the interval is within the specified range, then input the currently obtained frequency-unwound phase difference data into the delay estimation unit; otherwise, input the total number of phases for the entire cycle. Compensation is performed to obtain a new integer cycle phase number, and the process is returned to the unwound phase difference solution unit. Delay estimation unit, with origin A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

[0015] Thirdly, the present invention provides a terminal including a processor and a communication interface coupled to the processor, the processor being used to run computer programs or instructions to implement the signal delay measurement method provided in the first aspect.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The signal delay measurement method, system, and terminal proposed in this invention introduce integer phase numbers. The modeling and compensation mechanism first uses a coarse estimate to calculate the number of phase difference windings corresponding to the left-hand frequency point in the selected frequency range, and then uses the intercept obtained by fitting the phase difference after unwinding to... Closed-loop compensation is performed until the intercept falls within the [−π,π] interval. Compared with traditional full-band phase expansion methods, this invention avoids error accumulation caused by noise or phase abrupt changes, can stably and accurately eliminate 2π-bit ambiguity, and significantly improves the robustness of delay estimation under low signal-to-noise ratio or frequent phase jump conditions.

[0017] 2. The signal delay measurement method, system, and terminal proposed in this invention employ a forced linear fitting model passing through the origin in the final estimation stage, performing least-squares fitting on both the origin and the unwound phase difference. This method eliminates the influence of intercept offset on the slope (i.e., delay) in conventional unconstrained fitting, and can significantly improve the accuracy and stability of delay estimation, especially under conditions of phase shift or low signal-to-noise ratio caused by down-conversion.

[0018] 3. This invention proposes a signal delay measurement method, system, and terminal, which does not restrict the frequency type of the transmitting signal: when the signal is high-frequency, it can be down-converted before acquisition, and the receiving end performs corresponding down-conversion before acquisition. This invention introduces integer cycle phase numbers. The intercept judgment and compensation mechanism effectively overcomes the phase shift problem introduced by down-conversion; when the signal is low frequency, it can be directly acquired without down-conversion. Therefore, this method is suitable for both high-frequency systems where expensive high-speed acquisition equipment is limited and conventional low-speed acquisition systems, and has wide engineering adaptability and a low cost threshold for implementation. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of the signal delay measurement method proposed in an embodiment of the present invention; Figure 2 This is a technical schematic diagram of the signal delay measurement method in an embodiment of the present invention; Figure 3This is a schematic diagram of the delay measurement experimental system when the transmitting end is a low-frequency signal in an embodiment of the present invention; Figure 4 This refers to the main lobe frequency region determined in this embodiment of the invention when the transmitting end is a low-frequency signal; Figure 5 This is the unwinding phase difference-frequency curve obtained when the transmitting end is a low-frequency signal in an embodiment of the present invention; Figure 6 In this embodiment of the invention, when the transmitting end is a low-frequency signal, the fitted straight line is obtained by performing a forced linear fitting of the origin and the selected frequency point through the origin; Figure 7 This is an enlarged view of the fitted line obtained by performing a forced linear fitting of the origin and the selected frequency point through the origin in an embodiment of the present invention when the transmitting end is a low-frequency signal; Figure 8 This is a schematic diagram of the delay measurement experimental system when the transmitting end is a high-frequency signal in an embodiment of the present invention; Figure 9 This refers to the main lobe frequency region determined in this embodiment of the invention when the transmitting end is a high-frequency signal; Figure 10 This is the unwinding phase difference-frequency curve obtained when the transmitting end is a high-frequency signal in an embodiment of the present invention; Figure 11 In this embodiment of the invention, when the transmitting end is a high-frequency signal, the fitted straight line is obtained by performing a forced linear fitting of the origin and the selected frequency point through the origin; Figure 12 This is an enlarged view of the fitted line obtained by forcibly fitting the origin and the selected frequency point through the origin when the transmitting end is a high-frequency signal in this embodiment of the invention. Figure 13 This is an error fluctuation diagram calculated by multiple delays when the transmitting end is a high-frequency signal, as shown in this embodiment of the invention.

[0020] Figure Labels 1-Transmitter, 10-Laser, 11-First signal source, 12-Modulator, 13-Beam splitter, 14-Bandpass filter, 15-First mixer, 16-Second signal source; 2-Transmission delay end, 20-Short-distance optical fiber, 21-Long-distance optical fiber, 22-First tunable optical attenuator, 23-Second tunable optical attenuator, 24-Short RF cable, 25-Long RF cable; 3-Receiver, 30-First photodetector, 31-Second photodetector, 32-Oscilloscope, 33-Third mixer, 34-Second mixer, 35-Third signal source, 36-Fourth signal source, 37-First low-pass filter, 38-Second low-pass filter. Detailed Implementation

[0021] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0022] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0023] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c" can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0024] This invention aims to provide a signal delay measurement method, system, and terminal. It acquires the transmitted signal and the received signal after a delay system, performs Fast Fourier Transform on both signals, selects a frequency range based on the spectrum, and then calculates the phase difference change. Simultaneously, it proposes a novel phase unwrapping method to solve the 2π phase ambiguity problem caused by calculating the phase difference, performing a translation correction on the phase difference to restore it to the phase difference corresponding to the high frequency. Finally, utilizing the prior information that the delay in the time domain of the two signals is linearly proportional to the frequency in the frequency domain, it performs a forced linear fitting through the origin on the phase difference points in the selected frequency range, and calculates the delay using the slope of the straight line. This overcomes the limitations of traditional frequency domain phase difference delay measurement methods in situations involving down-conversion, low signal-to-noise ratio, or frequent phase jumps.

[0025] In a first aspect, embodiments of the present invention provide a signal delay measurement method, see [link to previous document]. Figure 1 It includes the following steps: S1. Acquire the transmitting and receiving signals, and perform Fast Fourier Transform on the transmitting and receiving signals respectively to obtain the signal spectrum; As one possible implementation, when the transmitting signal is a high-frequency signal, it is down-converted before acquisition. In this case, the receiving signal is the high-frequency signal from the transmitting end after being delayed by the system and then down-converted. When the transmitting signal is a low-frequency signal, down-conversion is not required before acquisition. In this case, the receiving signal is the low-frequency signal from the transmitting end after being delayed by the system.

[0026] S2. Select the main lobe frequency range in the signal spectrum, calculate the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filter multiple discrete frequency points with amplitudes higher than the preset amplitude threshold based on the spectrum of the main lobe frequency range, determine the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtain the frequency-phase difference data before unwinding. As one possible implementation, the main lobe frequency range is centered on the signal center frequency, and the frequency width is the signal bandwidth; a preset amplitude threshold is used to filter out frequency points with amplitudes higher than the threshold, so as to eliminate low signal-to-noise ratio frequency points.

[0027] S3. Perform a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay; As one possible approach, the first linear fit is achieved using the least squares method.

[0028] S4. Calculate the number of integer-cycle phases of the phase difference winding corresponding to the left-value frequency point in the main lobe frequency range based on the initial estimate. ; As one possible implementation, the integer-cycle phase number at each discrete frequency point is calculated using the following method: in, This indicates rounding to the nearest integer. This represents the left value of the main lobe frequency range. This represents the initial estimate of the signal delay.

[0029] S5. Based on the integer cycle phase number, the phase difference-frequency curve corresponding to the main lobe frequency range is unwound to obtain the unwound phase difference-frequency curve; As one possible implementation, the phase difference-frequency curve corresponding to the main lobe frequency range is unwrapped using the following method: in, This indicates the unwinding phase difference. This represents the phase difference before unwinding. This represents the number of phases in an entire cycle.

[0030] S6. Determine the unwinding phase difference corresponding to multiple discrete frequency points in the unwinding phase difference-frequency curve to obtain frequency-unwinding phase difference data. Perform a second linear fitting on the frequency-unwinding phase difference data to obtain the intercept of the fitted line. ; As one possible implementation, the second linear fitting is achieved using the least squares method.

[0031] S7. Determine the intercept Is it in If the interval is within the specified range, proceed to step S8; otherwise, calculate the number of phases for the entire cycle. Perform compensation to obtain a new integer cycle phase number, and return to step S5; As one possible implementation, the following method is used to calculate the number of phases in the integer cycle. Compensation will be provided. Calculate compensation amount : Update the integer cycle phase number: update the integer cycle phase number Updated to + .

[0032] S8. Move the origin... A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

[0033] As one possible implementation, the forced linear fitting through the origin is achieved using the least squares method, and the fitting model is as follows: in, This indicates the unwinding phase difference. This represents the final estimated signal delay.

[0034] The technical principle of this solution is as follows: In the frequency domain, assume there is a time delay between the two signals. Then its phase response will exhibit a linear change. Assuming... and Two signals respectively and The Fourier transform of, where, Then, in the frequency domain, they will satisfy the following relationship: Then, by comparing the phases of the two signals, the phase difference between them can be obtained as follows: This indicates that, theoretically, there is a linear relationship between phase difference and frequency, with a slope of Therefore, the time delay can be estimated by linearly fitting the relationship between the phase difference and the frequency. : As can be seen from the above formula, the theoretical phase difference-frequency curve should be a straight line passing through the origin. Therefore, in actual measurement, when calculating the slope of the phase difference-frequency straight line, the origin is taken as a key piece of information.

[0035] In actual measurements, only the principal phase can be obtained, i.e., it is limited to... Phase information within the interval. Therefore, the true phase difference can be expressed as: in, An unknown integer represents the phase span. The number of whole weeks; The true phase difference represents the phase information after unwinding, i.e., not confined within... Phase information within the interval; The measured phase difference indicates that it is confined to... Phase information within the interval.

[0036] Traditional methods typically recover continuous phase through phase unwrapping, which is prone to phase ambiguity. Furthermore, the full-band phase unwrapping process is complex and prone to error accumulation due to noise or phase abrupt changes.

[0037] This invention explores integer terms The delay is estimated by relating it to frequency changes. See also Figure 2 As the frequency increases, the phase difference changes in a sawtooth pattern; when the frequency crosses a certain range... Over time, the phase will change cumulatively. Suppose there are two frequency points. and Between them, the phase spans indivual The periodicity is then: Based on the above, the theoretical phase difference-frequency curve should be a straight line passing through the origin, therefore... , Then, the phase magnitude at the frequency point with a high signal-to-noise ratio of the main lobe is combined with... When making corrections, the estimation accuracy can be further improved, and its equivalent form can be expressed as: In the formula, where This is the initial estimate of the signal delay. This is the final estimated signal delay value.

[0038] By introducing integer phase numbers The modeling and compensation mechanism first uses a coarse estimate to calculate the number of phase windings corresponding to the left-hand frequency point in the selected frequency range, and then uses the intercept obtained by fitting the phase difference after unwinding to... Closed-loop compensation is performed until the intercept falls within the [−π,π] interval. Compared with traditional full-band phase expansion methods, this invention avoids error accumulation caused by noise or phase abrupt changes, can stably and accurately eliminate 2π-bit ambiguity, and significantly improves the robustness of delay estimation under low signal-to-noise ratio or frequent phase jump conditions.

[0039] The implementation process and effects of this invention will be further explained below with reference to specific experimental procedures.

[0040] Example 1 This embodiment is applicable to delay estimation after low-frequency signal transmission. See [link / reference] Figure 3 The experimental setup consists of three parts: a transmitter 1, a transmission delay unit 2, and a receiver 3. This embodiment uses a BPSK pulse radar signal based on Barker codes. First, the first signal source 11 transmits a carrier frequency... GHz, symbol rate The 13-bit Barker code radar signal of MHz is modulated by modulator 12 onto the optical carrier generated by laser 10, and split into two paths by beam splitter 13 and enter the transmission delay end 2.

[0041] In the transmission delay end 2, the short-distance optical fiber 20 has a length of 1m, and the long-distance optical fiber 21 has a length of 380m. One signal enters the first tunable optical attenuator 22 after passing through the short-distance optical fiber 20, and the other signal enters the second tunable optical attenuator 23 after passing through the long-distance optical fiber 21.

[0042] The signal emitted from the first adjustable optical attenuator 22 enters the first photodetector 30, and the signal emitted from the second adjustable optical attenuator 23 enters the second photodetector 31. An oscilloscope 32 is used to collect the signals received by the first photodetector 30 and the second photodetector 31.

[0043] Next, the technical solution proposed in this invention is used to perform digital signal processing and delay calculation on the acquired signal. First, based on the center frequency of the Barker code radar signal... and bandwidth Selecting in the frequency domain The main lobe frequency region centered on the center, such as Figure 4 As shown, the analysis frequency band is further limited to avoid interference from low signal-to-noise ratio frequencies in phase estimation. By sampling frequencies at fixed intervals near the center frequency, computational complexity can be reduced while ensuring frequency coverage. Subsequently, the phase difference between the two signals at the selected frequencies is calculated, and local phase expansion is performed only on these frequencies. Unlike traditional methods, this expansion process does not aim for full-frequency continuity, but rather aims to suppress abrupt changes and maintain local linear trends, thereby reducing the impact of noise and outliers.

[0044] Next, a coarse estimate of the delay is obtained by performing a linear fit on the selected frequency point. Then calculate ,in, Then, the phase difference at the selected frequency point is calculated using the formula... Due to the influence of signal-to-noise ratio, a rough estimate of the delay is obtained by performing a translation. There will be errors, which will lead to calculation errors. There are also errors, so it is necessary to... After compensation, the resulting unwrapped phase difference-frequency curve is as follows: Figure 5 As shown. Then, using the origin and the selected frequency point, a least-squares fitting method that forces the transition through the origin is applied to re-estimate the phase difference slope, thus obtaining the final time delay estimation result. See [link to relevant documentation]. Figures 6 to 7 The calculated result differs from the measurement result using a network analyzer (VNA) by only 3.14 ps.

[0045] The results show that the delay measurement results obtained by this method deviate from the actual results measured by the vector network analyzer by only 3.14 ps, achieving picosecond-level measurement accuracy. As a standard instrument for delay parameter measurement in the RF and microwave fields, the vector network analyzer provides highly reliable reference results. The minimal error between the two instruments fully verifies that the measurement accuracy of this method is comparable to that of commercial professional testing equipment. This level of accuracy meets the high-precision detection requirements for delay parameters in fields such as communication and optical transmission, proving the algorithm's reliable application value in precision delay measurement scenarios.

[0046] Example 2 This embodiment is applicable to delay estimation after high-frequency signal transmission. See [link / reference] Figure 8 The experimental setup also includes three parts: a transmitter 1, a transmission delay unit 2, and a receiver 3. This embodiment also uses a BPSK pulse radar signal based on Barker codes. First, the first signal source 11 transmits a carrier frequency... MHz, symbol rate A 13-bit Barker code radar signal of MHz is filtered by a bandpass filter 14 with a frequency bandwidth of [10MHz, 50MHz]. This signal, along with a 9.97GHz single-frequency signal from a second signal source 16, is up-converted to 10GHz in a first mixer 15. Then, it is split into two paths by a beam splitter 13 and enters the transmission delay end 2. The transmission delay end 2 includes a short RF cable 24 and a long RF cable 25. One signal is down-converted in a second mixer 34 with a 9.8GHz single-frequency signal from a third signal source 35, and then filtered by a first low-pass filter 37 to obtain a 200MHz narrowband signal that enters the oscilloscope 32. The other signal is down-converted in a third mixer 33 with a 9.8GHz single-frequency signal from a fourth signal source 36, and then filtered by a second low-pass filter 38 to obtain a 200MHz narrowband signal that enters the oscilloscope 32. Next, the technical solution proposed in this invention is used to perform digital signal processing and delay calculation on the acquired signal. The selected main lobe frequency region is as follows: Figure 9 As shown, for After compensation, the resulting unwrapped phase difference-frequency curve is as follows: Figure 10 As shown, the phase difference slope is finally re-estimated using a least-squares fitting method that forces the point to pass through the origin, based on the origin and the selected frequency points. Figure 11 and Figure 12 As shown. The standard deviation of the delay for multiple measurements is as follows. Figure 13 As shown, the accuracy reaches ±0.5ps.

[0047] In the final estimation stage, this invention employs a linear fitting model that forces the model to pass through the origin, performing least-squares fitting on both the origin and the phase difference points after unwinding. This method eliminates the influence of intercept offset on the slope (i.e., delay) in conventional unconstrained fitting, and can significantly improve the accuracy and stability of delay estimation, especially under conditions of phase shift or low signal-to-noise ratio caused by down-conversion.

[0048] In a second aspect, the present invention provides a signal delay measurement system, comprising: The signal spectrum acquisition unit collects the transmitting end signal and the receiving end signal, and performs fast Fourier transform on the transmitting end signal and the receiving end signal respectively to obtain the signal spectrum; The phase difference calculation unit before unwinding selects the main lobe frequency range in the signal spectrum, calculates the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filters multiple discrete frequency points with amplitudes higher than a preset amplitude threshold based on the spectrum of the main lobe frequency range, determines the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtains the frequency-phase difference data before unwinding. The initial estimation acquisition unit performs a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay. The integer-cycle phase number calculation unit calculates the integer-cycle phase number of the phase difference winding corresponding to the left-hand frequency point of the main lobe frequency range based on the initial estimate. ; The unwrapping phase difference solving unit unwrappes the phase difference-frequency curve corresponding to the main lobe frequency range based on the integer cycle phase number to obtain the unwrapped phase difference-frequency curve; it then determines the unwrapped phase difference corresponding to multiple discrete frequency points in the unwrapped phase difference-frequency curve to obtain frequency-unwrapped phase difference data. The phase compensation unit performs a second linear fitting on the frequency-unwound phase difference data to obtain the intercept of the fitted line. Determine the intercept Is it in If the interval is within the specified range, then input the currently obtained frequency-unwound phase difference data into the delay estimation unit; otherwise, input the total number of phases for the entire cycle. Compensation is performed to obtain a new integer cycle phase number, and the process is returned to the unwound phase difference solution unit. Delay estimation unit, with origin A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

[0049] Thirdly, the present invention provides a terminal including a processor and a communication interface coupled to the processor, the processor being used to run computer programs or instructions to implement the signal delay measurement method provided in the first aspect.

[0050] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the description of the drawings, in carrying out the claimed invention. In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple components. A single processor or other unit can implement several of the functions listed in the specification. While certain measures are described in different embodiments, this does not mean that these measures cannot be combined to produce good results.

[0051] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications fall within the scope of the invention and its equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for measuring signal delay, characterized in that, Includes the following steps: S1. Acquire the transmitting and receiving signals, and perform Fast Fourier Transform on the transmitting and receiving signals respectively to obtain the signal spectrum; S2. Select the main lobe frequency range in the signal spectrum, calculate the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filter multiple discrete frequency points with amplitudes higher than the preset amplitude threshold based on the spectrum of the main lobe frequency range, determine the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtain the frequency-phase difference data before unwinding. S3. Perform a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay; S4. Calculate the number of integer-cycle phases of the phase difference winding corresponding to the left-value frequency point in the main lobe frequency range based on the initial estimate. ; S5. Based on the integer cycle phase number, the phase difference-frequency curve corresponding to the main lobe frequency range is unwound to obtain the unwound phase difference-frequency curve; S6. Determine the unwinding phase difference corresponding to multiple discrete frequency points in the unwinding phase difference-frequency curve to obtain frequency-unwinding phase difference data. Perform a second linear fitting on the frequency-unwinding phase difference data to obtain the intercept of the fitted line. ; S7. Determine the intercept Is it in If the interval is within the specified range, proceed to step S8; otherwise, calculate the number of phases for the entire cycle. Perform compensation to obtain a new integer cycle phase number, and return to step S5; S8. Move the origin... A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

2. The signal delay measurement method according to claim 1, characterized in that, When the transmitting signal is a high-frequency signal, it is down-converted before acquisition. In this case, the receiving signal is the high-frequency signal from the transmitting end after being delayed by the system and then down-converted. When the transmitting signal is a low-frequency signal, it is not necessary to down-convert before acquisition. In this case, the receiving signal is the low-frequency signal from the transmitting end after being delayed by the system.

3. The signal delay measurement method according to claim 1, characterized in that, The main lobe frequency range is centered on the signal center frequency, and the frequency width is the signal bandwidth; the preset amplitude threshold is used to filter out frequency points with amplitudes higher than the threshold, so as to eliminate low signal-to-noise ratio frequency points.

4. The signal delay measurement method according to claim 1, characterized in that, Both the first and second linear fittings were implemented using the least squares method.

5. The signal delay measurement method according to claim 1, characterized in that, The phase difference-frequency curves corresponding to the main lobe frequency range are unwrapped using the following method: in, This indicates the unwinding phase difference. This represents the phase difference before unwinding. This represents the number of phases in an entire cycle.

6. The signal delay measurement method according to claim 1, characterized in that, The number of integer-cycle phases at each discrete frequency point is calculated using the following method: in, This indicates rounding to the nearest integer. This represents the left value of the main lobe frequency range. This represents the initial estimate of the signal delay.

7. The signal delay measurement method according to claim 6, characterized in that, The following method is used to determine the number of phases in the entire cycle. Compensation will be provided. Calculate compensation amount : Update the integer cycle phase number: update the integer cycle phase number Updated to + .

8. The signal delay measurement method according to claim 7, characterized in that, In step S8, the forced linear fitting through the origin is achieved using the least squares method, and the fitting model is as follows: in, This indicates the unwinding phase difference. This represents the final estimated signal delay.

9. A signal delay measurement system, characterized in that, include: The signal spectrum acquisition unit collects the transmitting end signal and the receiving end signal, and performs fast Fourier transform on the transmitting end signal and the receiving end signal respectively to obtain the signal spectrum; The phase difference calculation unit before unwinding selects the main lobe frequency range in the signal spectrum, calculates the phase difference-frequency curves corresponding to the main lobe frequency ranges of the two signals, filters multiple discrete frequency points with amplitudes higher than a preset amplitude threshold based on the spectrum of the main lobe frequency range, determines the phase difference before unwinding corresponding to multiple discrete frequency points in the phase difference-frequency curve, and obtains the frequency-phase difference data before unwinding. The initial estimation acquisition unit performs a first linear fit on the frequency-phase difference data before unwinding to obtain an initial estimate of the signal delay. The integer-cycle phase number calculation unit calculates the integer-cycle phase number of the phase difference winding corresponding to the left-hand frequency point of the main lobe frequency range based on the initial estimate. ; The unwrapping phase difference solving unit unwrappes the phase difference-frequency curve corresponding to the main lobe frequency range based on the integer cycle phase number to obtain the unwrapped phase difference-frequency curve; it then determines the unwrapped phase difference corresponding to multiple discrete frequency points in the unwrapped phase difference-frequency curve to obtain frequency-unwrapped phase difference data. The phase compensation unit performs a second linear fitting on the frequency-unwound phase difference data to obtain the intercept of the fitted line. Determine the intercept Is it in If the interval is within the specified range, then input the currently obtained frequency-unwound phase difference data into the delay estimation unit; otherwise, input the total number of phases for the entire cycle. Compensation is performed to obtain a new integer cycle phase number, and the process is returned to the unwound phase difference solution unit. Delay estimation unit, with origin A forced linear fit is performed between the obtained frequency-unwound phase difference data and the original data to obtain the slope of the fitted line. This slope is then divided by... This is the final estimated signal delay value.

10. A terminal comprising a processor and a communication interface coupled to the processor, the processor being configured to run a computer program or instructions to implement the signal delay measurement method according to any one of claims 1 to 8.

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