Phase unwrapping method and system based on double-phase signal

Abstract

The invention relates to a phase unwrapping method and system based on double-phase signals, and the method comprises the steps: determining the phase difference between an original signal and an auxiliary signal, and achieving the purpose that in all pixels, when one signal is likely to be wound, the other signal is not likely to be wound; adding an auxiliary signal according to the phase difference between the original signal and the auxiliary signal; setting an upper limit and a lower limit of a winding early-warning phase; and when the original signal and the auxiliary signal exceed the winding early warning phase upper limit or lower limit, updating the value of the current pixel absolute phase through a difference algorithm to realize phase unwrapping. According to the method, due to the fact that an extra signal source is used, the influence of noise interference on winding point judgment is greatly reduced, and a certain recognition capability is achieved for signal mutation; secondly, real-time unwrapping can be realized without storing a large amount of historical data; finally, the algorithm does not need to store a large amount of historical data for judgment, the equation is simple, the requirement for computing power is very small, and the method can be operated in some small equipment.

Description

Technical Field

[0001] This invention relates to the field of phase unwrapping technology, and in particular to a phase unwrapping method and system based on dual-phase signals. Background Technology

[0002] Phase unwrapping is a classic signal processing problem. It refers to the process of restoring a wrapped phase (also known as a truncated phase) to an absolute phase (also known as a continuous phase). Phase wrapping typically occurs when the obtained signal phase is folded within a fixed periodic range. When the signal exceeds this range, phase distortion occurs, necessitating phase unwrapping for restoration. This invention aims to solve this type of problem.

[0003] In practical applications, phase unwrapping can be a very challenging problem due to issues such as severe noise, abrupt phase changes, and phase discontinuities. Current unwrapping methods primarily utilize algorithms. The Shortest Path Method defines a "path cost" to find the globally optimal path to resolve phase entanglement, but its drawback is the inability to unwrap in real-time. Sequential Unwrapping first defines a starting point and then uses the increment of each pixel for unwrapping; however, if subsequent pixels cannot be reset to zero, the unwrapping fails. Other methods include Benders Cut, Least-Squares Method, and Kalman Filtering. Most of these algorithms share a common characteristic: they require significant computational resources, making them unsuitable for scenarios with limited computing power and the need for real-time unwrapping. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a phase unrolling method and system based on dual-phase signals.

[0005] A phase expansion method based on a two-phase signal includes:

[0006] Step 1: Acquire the raw signal output by the target sensor;

[0007] Step 2: Determine the phase difference between the original signal and the auxiliary signal to ensure that, in all pixels, when one signal is likely to become entangled, the other signal is unlikely to become entangled.

[0008] Step 3: Add an auxiliary signal based on the phase difference between the original signal and the auxiliary signal;

[0009] Step 4: Set the upper and lower limits of the entanglement warning phase;

[0010] Step 5: When the original signal and the auxiliary signal exceed the upper or lower limit of the entanglement warning phase, update the value of the absolute phase of the current pixel through the difference algorithm to achieve phase unwrapping.

[0011] Preferably, in step 2, the signal change trend remains consistent when neither the original signal nor the auxiliary signal is phase-entangled; when one of the original signal and the auxiliary signal is phase-entangled, the other signal is not entangled, and the signal change trends are no longer the same, a preset mathematical model is used to determine the phase difference of the auxiliary signal.

[0012] Preferably, in step 3, when the original signal is generated by comparing a variable phase signal with a fixed phase signal, a new fixed phase signal is added, and the phase difference between the new fixed phase signal and the original fixed phase signal is the phase difference calculated in step 2; when the original signal output by the target sensor is a linear system, an excitation signal is added, and the phase difference between the excitation signal and the original excitation signal is the phase difference calculated in step 2.

[0013] Preferably, step 5 includes:

[0014] Step 5.1: Select a pixel as the initial pixel and determine the initial value of the absolute phase;

[0015] Step 5.2: When either the original signal or the auxiliary signal exceeds the limit, the phase change of the corresponding pixel of the other signal is used as the absolute phase change; when both the original signal and the auxiliary signal exceed the limit, the phase change of one of the two signals is selected as the absolute phase change based on the limit exceeding situation of the original signal and the auxiliary signal of the previous pixel.

[0016] Step 5.3: Update the value of the absolute phase of the initial pixel, and calculate the next pixel until all pixels have been traversed.

[0017] The present invention also provides a phase unrolling system based on a dual-phase signal, comprising:

[0018] The raw signal acquisition module is used to acquire the raw signal output by the target sensor;

[0019] The phase difference calculation module is used to determine the phase difference between the original signal and the auxiliary signal, so that in all pixels, when one signal may be entangled, the other signal may not be entangled.

[0020] An auxiliary signal addition module is used to add an auxiliary signal based on the phase difference between the original signal and the auxiliary signal.

[0021] The threshold determination module is used to set the upper and lower limits of the entanglement warning phase;

[0022] The phase unrolling module is used to update the absolute phase value of the current pixel through a difference algorithm when the original signal and the auxiliary signal exceed the upper or lower limit of the winding warning phase, thereby realizing phase unrolling.

[0023] The present invention also provides an electronic device, including a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the transceiver, the memory, and the processor are connected via the bus, characterized in that the computer program, when executed by the processor, implements the steps in the aforementioned phase unrolling method based on a dual-phase signal.

[0024] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps in the phase unrolling method based on a two-phase signal described above.

[0025] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] This invention relates to a phase unwrapping method based on a two-phase signal. Compared with existing technologies, this invention proposes a two-phase signal method with an auxiliary signal for phase unwrapping. The auxiliary signal differs from the original signal only in phase. By adjusting the appropriate phase difference and using the algorithm provided by this invention, the entanglement of the original signal can be identified based on the auxiliary signal, and phase unwrapping can be performed by adjusting the phase based on the auxiliary signal. This invention significantly reduces the impact of noise interference on the determination of entanglement points due to the use of an additional signal source, and also has a certain ability to identify signal abrupt changes. Secondly, it can unwrap in real time without storing a large amount of historical data. Finally, the algorithm of this invention does not require storing a large amount of historical data for judgment, and the equations are simple, requiring very little computing power, and can run on some small devices.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

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

[0029] Figure 1 A flowchart of a phase unrolling method based on a dual-phase signal provided by the present invention;

[0030] Figure 2 The image provided by the present invention shows the change of the winding phase with the absolute phase; wherein, a represents the image of the winding phase changing with the absolute phase in the embodiment (from -4π to 4π), and b represents the image of the absolute phase and the winding phase in the embodiment;

[0031] Figure 3 The present invention provides an image of the intertwined phases of the primary and secondary signals when the phase difference between the primary and secondary signals is one-quarter of a period.

[0032] Figure 4 The phase image of the original signal and the wrapped phase image of the auxiliary signal provided by this invention;

[0033] Figure 5 This is a schematic diagram of the phase over-limit partitioning of the primary and secondary signals winding, provided by the present invention.

[0034] Figure 6 The absolute phase image and restoration error image are obtained by processing the original and auxiliary signal winding phases using an algorithm, as provided in this invention. Detailed Implementation

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] Please see Figure 1 A phase expansion method based on a two-phase signal, comprising:

[0039] Step 1: Acquire the raw signal output by the target sensor;

[0040] Step 2: Determine the phase difference between the original signal and the auxiliary signal to ensure that, in all pixels, when one signal is likely to become entangled, the other signal is unlikely to become entangled.

[0041] Step 3: Add an auxiliary signal based on the phase difference between the original signal and the auxiliary signal;

[0042] Step 4: Set the upper and lower limits of the entanglement warning phase;

[0043] Step 5: When the original signal and the auxiliary signal exceed the upper or lower limit of the entanglement warning phase, update the value of the absolute phase of the current pixel through the difference algorithm to achieve phase unwrapping.

[0044] The phase unfolding method of the present invention will be further described below with reference to specific embodiments:

[0045] A phase-based ultrasonic gas detector product operates on an STM32 microcontroller platform. It requires obtaining the phase difference between the square wave signal output by the onboard sensor and the square wave signal generated by the circuit itself via a clock. The phase of the sensor output signal changes with the measured value, while the phase of the clock-generated square wave signal remains constant. Both signals have the same amplitude and frequency. The method for calculating the phase difference is to calculate the duty cycle of the XOR gate output signal. This method has the advantage of ensuring high accuracy for high-frequency devices, but the disadvantage is that it results in a tangled phase range within [0, π]. Furthermore, whenever the phase is about to cross 0 or π, the output phase changes in the opposite direction, forming a tangled phase. The requirements are to restore the absolute phase, minimize the impact of interference and data fluctuations, and minimize computational power consumption.

[0046] The phase unfolding method based on a dual-phase signal proposed in this invention includes:

[0047] Step 100: Determine the phase difference between the original signal and the auxiliary signal to ensure that, in all pixels, when one signal is likely to become entangled, the other signal is unlikely to become entangled.

[0048] The specific steps of step 100 include:

[0049] Step 101: For a specific example system, construct a mathematical model of how the winding phase changes with the absolute phase. Use Matlab, Python, etc., to construct the mathematical model of how the winding phase changes with the absolute phase, and simulate a specific example, plotting the above-mentioned image. Figure 2 .

[0050] Step 102: Approximately select a suitable auxiliary signal phase difference based on the mathematical model. Achieving this step requires that the trends of change remain consistent when neither the original nor the auxiliary signal is phase-entangled; when one of the original and auxiliary signals is phase-entangled, the other signal is not, and the trends of change of the signals are no longer the same.

[0051] In this case, the image showing the change of the entangled phase with the absolute phase shows that the entangled phase is periodic. Phase entanglement occurs when the phase crosses 0 and π. During this process, the change of the entangled phase is continuous and its change is unidirectional. There is no obvious abrupt change, which renders the phase unwinding method mentioned above basically useless. Therefore, the method proposed in this invention is adopted.

[0052] Theoretically speaking, as long as the difference between the primary and secondary signals is not an integer multiple of π, the requirement for the phase difference between the primary and secondary signals can be met.

[0053] Step 103: Based on the mathematical model and the actual operating requirements of the equipment, further select the phase difference between the primary and secondary signals. This is mainly to improve the tolerance for phase jumps (i.e., how much absolute phase jump per pixel should occur so that phase distortion does not occur after unfolding). It is generally recommended to select a phase difference between the primary and secondary signals such that when one of the primary and secondary signals becomes phase-entangled, the other signal is at the phase point with the lowest probability of phase entanglement. For example, in this case, the phase difference between the primary and secondary signals can be set to one-quarter of a cycle. Figure 3 When the original signal phase is about to become entangled near 0 or π, the corresponding auxiliary signal entanglement phases are all in the least likely position to occur. nearby.

[0054] Step 200: Based on the phase difference between the primary and secondary signals determined in step 100, add an auxiliary signal.

[0055] The specific steps of step 200 include:

[0056] Step 201: Select a suitable method to add an auxiliary signal. For example, assuming the original signal is generated by comparing a variable-phase signal with a fixed-phase signal, a new fixed-phase signal can be added, whose phase differs from the original fixed-phase signal by the phase difference calculated in step 100. This case is similar to the previous one, both generated by comparing two signals. In this case, the microcontroller clock can additionally emit a signal lagging by a quarter cycle, which is then compared again with the sensor output signal to obtain the auxiliary signal, thus achieving... Figure 3 The effect. At this time, the auxiliary signal leads the original signal by a quarter of a cycle, for Figure 1 The example data shown shows the phase of the primary and secondary signals intertwined as follows: Figure 4 .

[0057] Step 300: Perform phase expansion on the original and auxiliary signals obtained in step 200 using an algorithm.

[0058] The specific steps of step 300 include:

[0059] Step 301: Select a pixel as the initial pixel and determine the initial value θ0 of the absolute phase as the initial value of the original signal phase at that pixel.

[0060] In this case, the first pixel of the example phase data is selected as the initial pixel, and the initial value of the absolute phase has been determined.

[0061] Step 302: Set the upper limit L of the entanglement warning phase. max With lower limit L min When the signal phase exceeds the limit, it is considered that phase entanglement may have occurred, and L is adjusted. max and L min This ensures that at least one of the original phase and auxiliary phase signals exceeds the limit at the same pixel. For the initial pixel and the k-th pixel thereafter (k=1, 2, 3...), determine whether the original signal or auxiliary signal exceeds the limit.

[0062] The implementation method for this step obviously needs to be customized according to the specific characteristics of the signal's wrapped phase. In this case, L can be used. min Set to 0.33 L max Set to 0.67 , will a 2 The period is divided into 8 parts according to the over-limit situation of the winding phase of the primary and secondary signals, such as Figure 5 .

[0063] Step 303: Based on the boundary conditions between the current k-th pixel and the (k-1)-th pixel (k=2, 3, 4, ...), use the difference algorithm proposed in this invention to calculate the change in the absolute phase of the current pixel, Δθ. k The design idea of ​​the difference algorithm is as follows: When either the primary or secondary signal exceeds the limit, the phase change of the other signal at that pixel is used as the absolute phase change; when both the primary and secondary signals exceed the limit, the phase change of one of the two signals needs to be selected as the absolute phase change Δθ, taking into account the exceeding conditions of the primary and secondary signals of the previous pixel. k .

[0064] The specific algorithm for this step is as follows:

[0065] First, the cross-limit of the entanglement phase between the original and auxiliary signals of the current k-th pixel and the (k-1)-th pixel is determined. The original signal entanglement phase is defined by eight judgment variables, J. omax_k J omin_k J omax_k-1 Jomin_k-1 J amax_k J amin_k J amax_k-1 J amin_k-1 , respectively representing the phase of the original signal winding around the k-th pixel L. max The original signal of the k-th pixel is wrapped in phase L. min The original signal of the (k-1)th pixel is wrapped in phase L. max The original signal of the (k-1)th pixel is wrapped in phase L. min The phase of the auxiliary signal wrapping around the k-th pixel exceeds L. max The phase of the auxiliary signal wrapping around the k-th pixel exceeds L. min The phase of the auxiliary signal winding of the (k-1)th pixel exceeds L. max The phase of the auxiliary signal winding of the (k-1)th pixel exceeds L. min When an out-of-limit event occurs, the corresponding judgment variable is set to 0, and the rest are set to 1. Clearly, the intertwined phases of the same signal at any given pixel will not simultaneously exceed the limit. max and L min The situation.

[0066] Subsequently combined Figure 5 The difference algorithm equation is given: considering only the case where only one of the original and auxiliary signals exceeds the limit during phase entanglement, the equation is:

[0067] This equation integrates four cases for calculation, assuming the k-th pixel θ a Yue L max All others do not exceed the limit, J amax_k Setting it to 1, the original equation now has only one term remaining, namely:

[0068]

[0069] Furthermore, the phase overlap of the primary and secondary signals may simultaneously exceed the limit, leaving two terms in the original equation. We need to choose which term to compensate for based on the phase overlap situation of the two signals in the (k-1)th pixel. Clearly, if the phase overlap of one of the primary and secondary signals in the (k-1)th pixel has already exceeded the limit, retaining the phase overlap difference term of the other signal will be more effective; if the phase overlap of both the primary and secondary signals in the (k-1)th pixel has exceeded the limit, then either term can be chosen. Integrating this logic into a single equation yields the final equation of the algorithm:

[0070]

[0071] Step 304: Update the absolute phase value of the current pixel. Proceed to the calculation for the next pixel.

[0072] Step 305 repeats steps 303 and 304 to calculate the next pixel until the end.

[0073] The phase of the original and auxiliary signals is recovered after being twisted together by an algorithm, as shown below. Figure 6 .

[0074] The above examples demonstrate the effectiveness of the method of this invention. This invention can also be applied to the field of phase extraction. In the field of phase extraction, Fourier Transform and Phase-Mode Phase matching are both techniques used to extract signal phase information. Both ultimately use the arctangent to calculate the phase, which means that the calculated phase values ​​are distributed in [- , [] or [0,2] Within the range of ], phase unwrapping is a very important step in phase extraction. Therefore, the method of this invention can also be tried for some signal circuits.

[0075] The present invention also provides an electronic device, including a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor. The transceiver, the memory, and the processor are connected via the bus. The computer program, when executed by the processor, implements the steps in the aforementioned phase unwrapping method based on a two-phase signal. Compared with the prior art, the beneficial effects of the electronic device provided by the present invention are the same as those of the phase unwrapping method based on a two-phase signal described in the above technical solution, and will not be repeated here.

[0076] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps in the aforementioned phase unrolling method based on a two-phase signal. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present invention are the same as the beneficial effects of the phase unrolling method based on a two-phase signal described in the above technical solution, and will not be repeated here.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A phase unrolling method based on a two-phase signal, characterized in that, include: Step 1: Acquire the raw signal output by the target sensor; Step 2: Determine the phase difference between the original signal and the auxiliary signal to ensure that, in all pixels, when one signal is likely to become entangled, the other signal is unlikely to become entangled. Step 3: Add an auxiliary signal based on the phase difference between the original signal and the auxiliary signal; Step 4: Set the upper and lower limits of the entanglement warning phase; Step 5: When the original signal and the auxiliary signal exceed the upper or lower limit of the entanglement warning phase, update the value of the absolute phase of the current pixel through the difference algorithm to achieve phase unwrapping.

2. The phase unwrapping method based on a two-phase signal according to claim 1, characterized in that, In step 2, the signal change trends are kept consistent when neither the original signal nor the auxiliary signal is phase-entangled; when one of the original signal and the auxiliary signal is phase-entangled, the other signal is not entangled, and the signal change trends are no longer the same, the phase difference of the auxiliary signal is determined using a preset mathematical model.

3. The phase unrolling method based on a two-phase signal according to claim 2, characterized in that, In step 3, when the original signal is generated by comparing a variable phase signal with a fixed phase signal, a new fixed phase signal is added, and its phase difference from the original fixed phase signal is the phase difference calculated in step 2; when the original signal output by the target sensor is a linear system, an excitation signal is added, and its phase difference from the original excitation signal is the phase difference calculated in step 2.

4. The phase unrolling method based on a two-phase signal according to claim 3, characterized in that, In step 5, Step 5.1: Select a pixel as the initial pixel and determine the initial value of the absolute phase; Step 5.2: When either the original signal or the auxiliary signal exceeds the limit, the phase change of the corresponding pixel of the other signal is used as the absolute phase change; when both the original signal and the auxiliary signal exceed the limit, the phase change of one of the two signals is selected as the absolute phase change based on the limit exceeding situation of the original signal and the auxiliary signal of the previous pixel. Step 5.3: Update the value of the absolute phase of the initial pixel, and calculate the next pixel until all pixels have been traversed.

5. A phase unrolling system based on a dual-phase signal, characterized in that, include: The raw signal acquisition module is used to acquire the raw signal output by the target sensor; The phase difference calculation module is used to determine the phase difference between the original signal and the auxiliary signal, so that in all pixels, when one signal may be entangled, the other signal may not be entangled. An auxiliary signal addition module is used to add an auxiliary signal based on the phase difference between the original signal and the auxiliary signal. The threshold determination module is used to set the upper and lower limits of the entanglement warning phase; The phase unrolling module is used to update the absolute phase value of the current pixel through a difference algorithm when the original signal and the auxiliary signal exceed the upper or lower limit of the winding warning phase, thereby realizing phase unrolling.

6. An electronic device comprising a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the transceiver, the memory, and the processor are connected via the bus, characterized in that, When the computer program is executed by the processor, it implements the steps in the phase unwrapping method based on a two-phase signal as described in any one of claims 1-4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps in the phase unwrapping method based on a dual-phase signal as described in any one of claims 1-4.

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