CN115001530A - Multipath decision method and device, storage medium and terminal equipment - Google Patents

Multipath decision method and device, storage medium and terminal equipment Download PDF

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CN115001530A
CN115001530A CN202210563936.XA CN202210563936A CN115001530A CN 115001530 A CN115001530 A CN 115001530A CN 202210563936 A CN202210563936 A CN 202210563936A CN 115001530 A CN115001530 A CN 115001530A
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multipath
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师楠
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Beijing Ziguang Zhanrui Communication Technology Co Ltd
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    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
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    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
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    • G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
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    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
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    • G01S19/256—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS relating to timing, e.g. time of week, code phase, timing offset
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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Abstract

The application provides a multipath decision method and device, a storage medium and a terminal device, wherein the multipath decision method comprises the following steps: acquiring accumulation results of a plurality of branches of received signals in an accumulation duration, wherein the phases of spreading codes used by different branches are different; estimating a main path signal according to the accumulation result, and calculating the difference between the main path signal and the accumulation result; and determining whether the received signal has the multipath signal according to the relationship between the difference and a decision threshold, wherein the decision threshold is obtained by simulating simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths. The present application provides a solution for how to easily and accurately determine whether multipath is present in a signal.

Description

Multipath decision method and device, storage medium and terminal equipment
Technical Field
The present application relates to the field of spread spectrum communications technologies, and in particular, to a multipath decision method and apparatus, a storage medium, and a terminal device.
Background
In a spread spectrum communication system, a receiving end determines a delay of a received signal by using an autocorrelation property excellent in a spreading code, and despreads the signal. Taking a Global Navigation Satellite System (GNSS) as an example, a signal is transmitted from a Satellite to the ground, and in an open scene, the signal is approximately directly transmitted to a receiver, and the signal is called a main path or a direct path; in a scene with many obstacles, in addition to direct signals, the signals may arrive at the receiver after being reflected on the surface of the obstacle, and the signals are called multipath or reflection paths. In spread spectrum communication systems, the presence of multipath signals can affect positioning accuracy.
Existing processing methods for multipath signals are classified into three categories: radio frequency antenna based, correlator based phase detector, and data processing based. The principle of the processing method based on the radio frequency antenna is as follows: the signals arriving in the direction above the horizon may contain a main path, the signals arriving in the direction below the horizon are multipath with high probability, and the effect of inhibiting multipath can be achieved by adjusting the gain of the radio frequency antenna in different directions. In the method based on the correlator phase discriminator, the influence of multipath signals on a tracking loop is reduced by adjusting the correlator interval and/or a phase discrimination formula, and the main path position can still be correctly tracked in the scene of the existence of the multipath signals. In the data processing-based method, the accurate reconstruction of the main path signal is realized by estimating the main path and/or the multi-path parameters.
However, the disadvantages of the rf antenna based approach are: the method is high in cost, suitable for application scenes with fixed antenna directions such as surveying and mapping, observation stations and the like, and not suitable for application scenes with variable and flexible antenna directions such as mobile phones, receiver terminals and the like. The disadvantages of the correlator phase detector based approach are: the hardware cost of the narrow correlator is high, the general linear range of a phase discrimination formula for avoiding the influence of multipath signals is small, and the phase discrimination formula is easy to lock in a strong dynamic scene. The data processing method has the disadvantages that the algorithm is complex, iteration is needed, and the calculation amount is large.
Disclosure of Invention
The application provides a multipath judging method and a multipath judging device, and provides a scheme for simply, conveniently and accurately judging whether multipath exists in a signal.
In order to achieve the above object, the present application provides the following technical solutions:
in a first aspect, a multipath decision method is provided, where the multipath decision method includes: acquiring accumulation results of a plurality of branches of received signals in an accumulation duration, wherein the phases of spreading codes used by different branches are different; estimating a main path signal according to the accumulation result, and calculating the difference between the main path signal and the accumulation result; and determining whether the received signal has the multipath signal according to the relationship between the difference and a decision threshold, wherein the decision threshold is obtained by simulating simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths.
Optionally, before determining whether a multipath signal exists in the received signal according to the relationship between the difference and the decision threshold, the method further includes: acquiring a carrier-to-noise ratio of the received signal; the determining whether a multipath signal exists in the received signal according to the relationship between the difference and the decision threshold comprises: when the carrier-to-noise ratio is higher than a preset threshold, directly determining whether a multipath signal exists in the received signal according to the relation between the difference and a decision threshold; and when the carrier-to-noise ratio is lower than a preset threshold, determining whether the received signal has the multipath signal according to the relationship between the difference in a plurality of accumulation time lengths and a decision threshold, wherein the accumulation time lengths are the time lengths required for calculating the accumulation results.
Optionally, the determining whether the multipath signal exists in the received signal according to the relationship between the difference in the plurality of accumulated time durations and the decision threshold includes: if the difference in the continuous first number of accumulated time durations reaches the decision threshold, determining that the multipath signal exists in the received signal; if the difference in the continuous second number of accumulation durations does not reach the decision threshold, determining that the multipath signal does not exist in the received signal; or, if the difference in the consecutive first number of accumulated time durations does not reach the decision threshold, determining that the multipath signal exists in the received signal; determining that the multipath signal is absent from the received signal if the difference over a second number of consecutive accumulation durations reaches the decision threshold.
Optionally, before determining whether a multipath signal exists in the received signal according to the relationship between the difference and the decision threshold, the method further includes: acquiring a carrier-to-noise ratio of the received signal; and determining the decision threshold according to the carrier-to-noise ratio and a preset calculation relationship, wherein the preset calculation relationship represents the calculation relationship between each carrier-to-noise ratio and the corresponding decision threshold, and the preset calculation relationship is obtained by utilizing the simulation of received signals which contain multipath signals and do not contain multipath signals under different signal strengths.
Optionally, the decision threshold is obtained by simulation in the following manner: acquiring a plurality of simulated receiving signals containing multipath signals and not containing multipath signals under different signal strengths and accumulation results of the simulated receiving signals in an accumulation time length; calculating a first difference of each simulated received signal in the presence of multipath signals and a second difference in the absence of multipath signals; and fitting according to the first difference and/or the second difference to obtain a calculation relation between the carrier-to-noise ratio and a decision threshold corresponding to the carrier-to-noise ratio, so that a result determined according to the relation between the decision threshold determined according to the calculation relation and the first difference and/or the second difference is consistent with each simulated received signal.
Optionally, the estimating the main path signal according to the accumulation result includes: estimating the chip delay of the main path signal according to the accumulation result; estimating the amplitude of the main path signal at least according to the chip delay; acquiring the time delay of each branch according to the chip delay and the correlator interval; and reconstructing the main path signal by using at least the function value of the autocorrelation function of the main path signal under the time delay of each branch and the amplitude of the main path signal.
Optionally, the accumulation result is a coherent accumulation result and a non-coherent accumulation result, and the estimating the amplitude of the main path signal at least according to the chip delay is as follows: calculating a first product of a first orthogonal signal of a maximum value of the incoherent accumulation result corresponding to a branch in the coherent accumulation result and a cosine function of a main path phase of the main path signal, and a second product of a second orthogonal signal of the maximum value of the incoherent accumulation result corresponding to a branch in the coherent accumulation result and a sine function of the main path phase of the main path signal; summing the first product and the second product to obtain an intermediate parameter; calculating a difference value between a preset value and chip delay, and calculating a ratio of the intermediate parameter to the difference value to be used as the amplitude of the main path signal; the reconstructing the main path signal at least by using the function value of the autocorrelation function of the main path signal under the time delay of each branch and the amplitude of the main path signal comprises: calculating a function value of an autocorrelation function of the main path signal under the time delay of each branch; and determining an index which takes a natural number as a base number part and an imaginary number as an index part, and calculating the product of the amplitude of the main path signal, the function value of each branch under the time delay and the index to obtain the main path signal, wherein the imaginary number is the main path phase of the main path signal.
Optionally, the accumulation result is a non-coherent accumulation result, and the estimating the amplitude of the main path signal according to at least the chip delay includes: calculating a difference value between a preset value and chip delay, and calculating a ratio of a maximum value of an incoherent accumulation result to the difference value to be used as an amplitude value of the main path signal; the reconstructing the main path signal by using at least the function value of the autocorrelation function of the main path signal under the delay of each branch and the amplitude of the main path signal comprises: calculating a function value of an autocorrelation function of the main path signal under the time delay of each branch; and calculating the amplitude of the main path signal and the function value of each branch under the time delay to obtain the main path signal.
Optionally, the calculating the difference between the main path signal and the accumulation result includes: calculating the difference value between the main path signal and each accumulation result and the ratio of each difference value to the amplitude value of the main path signal; calculating a first average value of each ratio or a second average value of a square value of each ratio; taking the first average, the second average, the inverse of the first average, or the inverse of the second average as the difference.
In a second aspect, the present application further provides a multipath decision device, including: the acquisition module is used for acquiring the accumulation results of the received signals on a plurality of branches within the accumulation duration, and the phases of the spread spectrum codes used by different branches are different; the estimation module is used for estimating a main path signal according to the accumulation result and calculating the difference between the main path signal and the accumulation result; and the judging module is used for determining whether the received signal has the multipath signal according to the relation between the difference and a judging threshold, and the judging threshold is obtained by simulating the simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths.
In a fifth aspect, a computer-readable storage medium is provided, on which a computer program is stored, the computer program being executed by a processor for performing the method provided by the first aspect.
In a sixth aspect, a terminal device is provided, on which a computer program is stored, the computer program being run by a processor to perform the method provided by the first aspect.
In a ninth aspect, a spread spectrum communication system is provided, which includes the terminal device.
Compared with the prior art, the technical scheme of the embodiment of the application has the following beneficial effects:
in the technical scheme of the application, the accumulation results of the received signals on a plurality of branches in the accumulation duration are obtained, and the main path signals are estimated according to the accumulation results; whether the multipath signals exist in the received signals can be determined through the relationship between the estimated main path signals and the decision threshold obtained through simulation. The technical scheme of the invention judges the multipath by the way of the relation between the main path signal and the judgment threshold, thereby avoiding the problem of large calculation amount caused by iteration due to accurate estimation of the main path signal, avoiding iteration and greatly reducing the calculation amount required by judging the multipath; meanwhile, the decision threshold is obtained by simulating the simulated received signals containing the multipath signals and not containing the multipath signals under different signal strengths, so that the accuracy of multipath decision can be ensured. In addition, the technical scheme of the application does not need to newly add hardware resources, and has low cost and strong flexibility; in addition, the phase discrimination formula of the loop has no special requirement, so that the linear range of the phase discrimination formula is large, and the performance is not influenced under strong dynamic property.
Further, when the carrier-to-noise ratio is lower than a preset threshold, if the difference within a first number of continuous accumulated time durations reaches a decision threshold, determining that the multipath signal exists in the received signal; and if the difference in the second number of accumulation time periods does not reach the decision threshold, determining that the multipath signal does not exist in the received signal. According to the technical scheme, the accuracy of multipath judgment under the condition of low carrier-to-noise ratio is enhanced in a multi-judgment mode.
Drawings
Fig. 1 to 3 are schematic diagrams of tracking errors caused by multipath in the prior art;
fig. 4 is a flowchart of a multipath decision method provided in an embodiment of the present application;
fig. 5 is a schematic structural diagram of a receiver according to an embodiment of the present application;
fig. 6 is a schematic diagram of a multipath decision making method using a state machine according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a multipath decision configuration according to an embodiment of the present application.
Detailed Description
Referring to fig. 1, in the prior art, the autocorrelation function of an ideal main path signal is a sharp symmetric triangular peak without considering the influence of noise and bandwidth. The vertical axis of the autocorrelation function is the normalized amplitude of the autocorrelation function, and the horizontal axis is the delay, and the unit is a chip. E, P, L represent the results of the Early (Early), Prompt (Prompt), Late (Late) branch outputs of the correlator, respectively, and d is the correlator interval. The delay interval between the leading branch result E and the immediate branch result P is d1, the delay interval between the immediate branch result P and the delayed branch result L is d2, and d1 and d2 are the same and are d chips. The phase discrimination loop of the receiver can adjust the delay amount of the tracking loop, and when the leading branch result E is equal to the instant branch result P, the P branch is tracked at the accurate position with the delay error of 0.
In the presence of multipath in the received signal, the autocorrelation function shape of the received signal is distorted as shown by the superimposed curves in fig. 2 and 3. Wherein the influence of positive phase multipath on the shape of the autocorrelation function is shown in fig. 2 and the influence of negative phase multipath on the shape of the autocorrelation function is shown in fig. 3. Under the condition of not knowing existence of multipath, the receiving end still adjusts the loop according to the criterion that the leading branch result E is equal to the instant branch result P, and finally the instant branch result P cannot track on the accurate position with the delay error of 0, so that the delay error delta of the spread spectrum code is caused err . Because the delay error between the spreading code and the local spreading code in the received signal can be used as an important observation quantity to perform positioning calculation, the positioning accuracy can be influenced.
As described in the background art, among the various multipath signal processing methods in the prior art, the method based on the rf antenna has the following disadvantages: the method is high in cost, suitable for application scenes with fixed antenna directions such as surveying and mapping, observation stations and the like, and not suitable for application scenes with variable and flexible antenna directions such as mobile phones, receiver terminals and the like. The disadvantages of the correlator phase detector based approach are: the hardware cost of the narrow correlator is high, the general linear range of a phase discrimination formula for avoiding the influence of multipath signals is small, and the phase discrimination formula is easy to lock in a strong dynamic scene. The data processing method has the disadvantages that the algorithm is complex, iteration is needed, and the calculation amount is large.
The application provides a method, which comprises the steps of obtaining accumulation results of a plurality of branches of a received signal in an accumulation duration, and estimating a main path signal according to the accumulation results; whether the multipath signals exist in the received signals can be determined through the relation between the estimated main path signals and the simulated judgment threshold. The technical scheme of the invention judges the multipath by the way of the relation between the main path signal and the judgment threshold, thereby avoiding the problem of large calculation amount caused by iteration due to accurate estimation of the main path signal, avoiding iteration and greatly reducing the calculation amount required by judging the multipath; meanwhile, the judgment threshold is obtained by simulating the simulated received signals containing the multipath signals and not containing the multipath signals under different signal strengths, so that the accuracy of multipath judgment can be ensured. In addition, the technical scheme of the application does not need to newly add hardware resources, and is low in cost and high in flexibility; in addition, the phase discrimination formula of the loop has no special requirement, so that the linear range of the phase discrimination formula is large, and the performance is not influenced under strong dynamic property.
Referring to fig. 4, the method provided by the present application includes:
step 401: acquiring accumulation results of a plurality of branches of received signals in an accumulation duration, wherein the phases of spreading codes used by different branches are different;
step 402: estimating a main path signal according to the accumulation result, and calculating the difference between the main path signal and the accumulation result;
step 403: and determining whether the received signal has the multipath signal according to the relationship between the difference and a decision threshold, wherein the decision threshold is obtained by simulating simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths.
It should be noted that the sequence numbers of the steps in this embodiment do not represent a limitation on the execution sequence of the steps.
The multipath decision method in the present application can be used in a terminal device, and particularly can be used in a receiver, and the receiver has a spread spectrum communication function. The actual application scenario may be a GNSS system, or a communication system using a spread spectrum communication technology, such as a wireless local area network and bluetooth.
It is understood that in a specific implementation, the multipath decision method may be implemented by using a software program running in a processor integrated within a chip or a chip module. The method may also be implemented by combining software and hardware, and the present application is not limited thereto.
The main path in the embodiment of the invention can also be called a direct path; multipath may also be referred to as reflection path; the spreading code may also be referred to as a pseudo code, which is not limited in this application.
In the embodiment of the invention, after the antenna receives the signal, the intermediate frequency data is obtained through the radio frequency front-end processing. The digital front-end part carries out down-conversion and down-sampling processing on the data to obtain baseband data at the frequency of 0. The acquisition module processes the baseband data, carries out three-dimensional search, obtains visible star signs corresponding to pseudo code numbers, corresponding code phases and Doppler, and sends the visible star signs, the corresponding code phases and the Doppler to the tracking module for processing. The tracking module tracks on the basis of the acquired result, and the tracked code phase and Doppler have higher precision.
Referring also to fig. 5, the baseband data is input to the tracking module, and first down-converted to strip carrier doppler. And then, carrying out pseudo code stripping to realize despreading and obtaining a despreading calculation result with 1 spreading code period length. Taking a Global Positioning System (GPS) L1 signal as an example, 1 spreading code period is 1 millisecond (ms). And the de-spread calculation result is divided into IQ two paths, and IQ is two orthogonal signals.
Specifically, the despreading calculation result of 1 spreading code period length can be coherently accumulated to obtain a Coherent accumulation result (COH). The gain of Coherent accumulation may not meet the performance requirement, and at this time, Non-Coherent accumulation may be continued to obtain a Non-Coherent accumulation result (NCS). According to the coherent accumulation result/non-coherent accumulation result obtained by tracking, frequency discrimination and phase discrimination calculation are carried out, and the carrier frequency error (Doppler error) and the spread spectrum code phase error of the current tracking can be estimated. Due to the presence of noise, the estimation error is inaccurate and can jitter around the true value. The error is fed back to the parameters of the tracking loop, specifically to the carrier doppler in the down-conversion process and the code frequency or code phase in the despreading process, and the tracking is continued after the loop is adjusted, and the loop is circulated continuously, so as to ensure that the signal can be locked under the condition that the doppler and the delay of the received signal are changed. A Frequency-Locked Loop (FLL) or a Phase-Locked Loop (PLL) is generally used as a carrier Loop. The code Loop uses a Delay Locked Loop (DLL). The PLL loop uses coherent computation results for phase discrimination, and the DLL loop uses non-coherent computation results for phase discrimination. The FLL loop can use coherent calculation results or non-coherent calculation results for frequency discrimination according to different frequency discrimination formulas.
In one implementation of step 401, the accumulated results of the received signal over multiple branches within the accumulation duration may be obtained. The accumulation result may specifically be a coherent accumulation result and/or a non-coherent accumulation result. The branch here refers to the overall calculation flow from down-conversion to non-coherent accumulation using one spreading code. For example, when the input spreading code phase is only 1, the whole calculation flow from the down-conversion to the non-coherent accumulation is called as 1 branch; when the phase of the input spread spectrum code is multiple, all calculation processes are called as multiple branches, the input data of the multiple branches are the same except the phase difference of the spread spectrum code for despreading, the calculation processes are the same, but the calculation results need to be stored respectively.
In one embodiment of step 402, the main path signal may be estimated according to the accumulation result, and the difference between the main path signal and the accumulation result may be calculated. The difference can indicate whether a multipath signal is present in the received signal.
In one non-limiting embodiment, the main path signal may be represented by the chip delay, phase and amplitude of the main path, that is, estimating the main path signal means estimating the chip delay, phase and amplitude of the main path. The process of estimating the main path signal is as follows: estimating the chip delay of the main path signal according to the accumulation result; estimating the amplitude of the main path signal at least according to the chip delay; acquiring the time delay of each branch according to the chip delay and the correlator interval; and reconstructing the main path signal by using at least the function value of the autocorrelation function of the main path signal under the delay of each branch and the amplitude of the main path signal.
The coherent accumulation result of the plurality of branches is cohaut (k), k is 1,2,.., N, and the non-coherent accumulation result is ncsout (k), k is 1,2,. and N, where k is the index number corresponding to the branch, and N is the number of the branches.
The branch index number peak corresponding to the maximum value in the non-coherent accumulation result NcsOut, that is, NcsOut (peak) ═ max (NcsOut), is determined. Determining coherent accumulation results of branches with maximum values, i.e. cohuut (peak) ═ i (peak) + jq (peak), i (peak) and q (peak) indicate that the maximum value of the incoherent accumulation results corresponds to two orthogonal signals in the coherent accumulation results of the branches.
Specifically, the following formula can be used to estimate the phase of the main path signal:
θ est ＝atan2(I(peak)Q(peak)) (1)
wherein, theta est Represents the phase of the main path signal, and atan2() represents a function defined based on an arctangent function, with particular reference to equation (2).
Figure BDA0003657532230000091
Wherein the function value field is (-pi, pi ].
At the acquisition chip delay delta est Then, the delay Δ is first estimated using any one of the equations (3) to (5). Obtaining the chip delay delta corresponding to the estimated delay delta by looking up the table est In which a plurality of estimated delays delta and their corresponding chip delays delta are recorded est . Alternatively, the chip delay δ may be calculated by equation (6) est 。
Figure BDA0003657532230000092
Figure BDA0003657532230000093
Figure BDA0003657532230000094
Figure BDA0003657532230000095
Wherein, the values of E and L are respectively the non-coherent integration results of the corresponding leading branch and the delaying branch, and d is the interval of the correlator.
The following is a description of estimating the amplitude of the main path signal and reconstructing the main path signal according to the coherent accumulation result and the non-coherent accumulation result, respectively.
Example 1, the amplitude of the main path signal is estimated from the coherent accumulation result using equations (7) and (8), and the main path signal is reconstructed using equation (9). Equation (7) is used to rotate the coherent accumulation result of the branch corresponding to the maximum value of the incoherent accumulation result to the in-phase component.
Coh_real(peak)＝I(peak)×cos(θ est )+Q(peak)×sin(θ est ) (7)
Am est_coh ＝Coh_real(peak)/(1-δ est ) (8)
Figure BDA0003657532230000101
Wherein R _ LOS est_coh Representing the main path signal, R (t) est ) Time delay t of autocorrelation function of representing main path signal in each branch est The following function values. The normalized autocorrelation function R (τ) can be expressed by the formula (10), and the delay t of each branch est Can be expressed by the formula (11).
Figure BDA0003657532230000102
t est ＝(k-peak)×d+δ est ,k＝1,...,N (11)
Wherein peak represents the index number of the branch corresponding to the maximum value of the incoherent accumulation result, k represents the index number of the current branch, d is the interval of the correlator, and delta est Is the chip delay.
Embodiment 2, estimating the amplitude of the main path signal from the incoherent accumulation result using formula (12), and reconstructing the main path signal using formula (13).
Am est_ncs ＝NcsOut(peak)/(1-δ est ) (12)
R_LOS est_coh ＝Am est_coh ×R(t est ) (13)
After the main path signal is estimated, the difference between the main path signal and the accumulated result can be calculated.
In one embodiment, calculating differences between the main path signal and each of the accumulated results, and a ratio of each of the differences to an amplitude of the main path signal; calculating a first average value of each ratio or a second average value of a square value of each ratio; the first average value, the second average value, the inverse of the first average value, or the inverse of the second average value is taken as the difference.
Specifically, the difference Res between the main path signal and each accumulation result may be calculated by using any one of equations (14) and (15).
Res＝CohOut-R_LOS est_coh (14)
Res＝NcsOut-R_LOS est_ncs (15)
Where CohOut represents the coherent accumulation result, R _ LOS est_coh Representing the main path signal estimated from the coherent accumulation result, NcsOut representing the non-coherent accumulation result, R _ LOS est_ncs Representing the main path signal estimated from the non-coherent accumulation result.
Specifically, the difference SRR may be calculated using any one of formulas (16) to (19).
Figure BDA0003657532230000111
Figure BDA0003657532230000112
Figure BDA0003657532230000113
Figure BDA0003657532230000114
Wherein idx represents the branch index number and mean () represents the averaging function.
With continued reference to fig. 4, in a specific implementation of step 403, it is determined whether a multipath signal is present in the received signal based on the relationship of the difference to the decision threshold. The relationship between the difference and the decision threshold depends on a calculation formula of the difference, and the received signal may have a multipath signal when the difference is smaller than the decision threshold, or the received signal may have a multipath signal when the difference is larger than the decision threshold.
Specifically, when the difference SRR is calculated according to the equations (16) and (17), the larger the difference Res, the smaller the difference SRR, that is, when the difference is smaller than the decision threshold, the multipath signal may exist in the received signal. Accordingly, when the difference SRR is calculated according to the equations (18) and (19), the larger the difference Res, the larger the difference SRR, that is, the larger the difference is greater than the decision threshold, the more likely multipath signals are present in the received signal.
The embodiment of the invention judges the multipath by the way of the relation between the main path signal and the judgment threshold, thereby avoiding the problem of large calculation amount caused by iteration due to accurate estimation of the main path signal, avoiding the iteration and greatly reducing the calculation amount required by judging the multipath; meanwhile, the decision threshold is obtained by simulating the simulated received signals containing the multipath signals and not containing the multipath signals under different signal strengths, so that the accuracy of multipath decision can be ensured. In addition, the technical scheme of the application does not need to newly add hardware resources, and is low in cost and high in flexibility; in addition, the phase discrimination formula of the loop has no special requirement, so that the linear range of the phase discrimination formula is large, and the performance is not influenced under strong dynamic property.
In one non-limiting embodiment, different multipath decisions may be employed for received signals having different carrier-to-noise ratios. The Carrier to Noise Ratio (Carrier to Noise Ratio) of the received signal is obtained. When the carrier-to-noise ratio is higher than a preset threshold, directly determining whether a multipath signal exists in a received signal according to the relation between the difference and a judgment threshold; and when the carrier-to-noise ratio is lower than a preset threshold, determining whether the multipath signals exist in the received signals according to the relationship between the difference in the accumulated time lengths and the decision threshold.
In a specific implementation, when the accumulation result is coherent accumulation, the accumulation time length Tacc is CohNum × Tcode, where CohNum represents the number of coherent accumulations and Tcode represents the spreading code period length. When the accumulation result is incoherent accumulation, the accumulation time length Tacc is CohNum × NcsNum × Tcode, where CohNum represents the coherent accumulation frequency, Tcode represents the spreading code period length, and NcsNum represents the incoherent accumulation frequency.
Specifically, when the carrier-to-noise ratio is lower than a preset threshold, if the difference within a first number of continuous accumulated time durations reaches a decision threshold, determining that a multipath signal exists in a received signal; and if the difference in the second number of accumulation time durations does not reach the decision threshold, determining that the multipath signal does not exist in the received signal.
It should be noted that, similar to the decision threshold, the first number and the second number may also be obtained in advance through simulation.
In one specific example, when the carrier-to-noise ratio is higher than a preset threshold, a single decision manner is used. If the difference SRR is calculated according to the formula (16) or (17), when the difference SRR is smaller than the decision threshold Th, it is decided that the received signal contains multipath, otherwise, it does not contain multipath. If the difference SRR is calculated according to the formula (18) or (19), when the difference SRR is greater than the decision threshold Th, it is decided that the received signal contains multipath, otherwise, it does not contain multipath. When the carrier-to-noise ratio is higher than the preset threshold, the closer the correlator output envelope of the received signal is to an ideal triangular peak, the larger the difference between the difference SRR containing multipath and the difference SRR not containing multipath is, the easier it is to distinguish whether the received signal contains multipath, and the better the algorithm performance is.
Under the influence of noise, the output envelope of the correlator is distorted, the lower the carrier-to-noise ratio is, the higher the distortion degree of the envelope is, and at the moment, the difference between the SRR when multipath is contained and the SRR when multipath is not contained is reduced, so that whether the received signal contains multipath is not easy to distinguish. In order to enhance the performance of multipath decision under low carrier-to-noise ratio, a multi-decision strategy can be adopted.
The multiple-decision strategy can be specifically realized by adopting a state machine. Referring to fig. 6, a state of 0 indicates that the received signal does not include multiple paths, and a state of 1 indicates that the received signal includes multiple paths. Specifically, the legend (r) indicates that the initialization state is such that the received signal does not include multipath.
If the difference SRR is calculated according to the formula (16) or (17), the legend indicates that if the difference SRR < the decision threshold Th for n1_ Th (the first number) times in succession, the state is switched from the state in which the received signal does not include multipath to the state in which the received signal includes multipath, the number of times after switching is cleared, and the number of times is cleared if the continuous state is interrupted. The legend (c) indicates that if the continuous n2_ Th (second number) times of differences SRR > is equal to the decision threshold Th, the state is switched from the reception signal including multipath to the reception signal not including multipath, the number of times after switching is cleared, and the number of times is cleared if the continuous state is interrupted.
If the difference SRR is calculated according to the formula (18) or (19), the legend (c) indicates that if the difference SRR > the decision threshold Th for n1_ Th (the first number) times in succession, the state is switched from the state in which the received signal does not include multipath to the state in which the received signal includes multipath, the number of times after switching is cleared, and the number of times is cleared if the continuation state is interrupted. The legend (c) indicates that if the n2_ Th (second number) consecutive differences SRR < > are equal to the decision threshold Th, the state is switched from the reception signal including multipath to the reception signal not including multipath, the number of times after switching is cleared, and the number of times is cleared if the consecutive state is interrupted.
And after each judgment, outputting the current state as a judgment result. In a navigation system, for a satellite whose received signal contains multipath, tracking can be continued, but its observed quantity is not used for positioning solution until its state becomes that the received signal does not contain multipath.
The embodiment of the invention enhances the accuracy of multipath judgment under the condition of low carrier-to-noise ratio by a mode of multiple judgment.
In one non-limiting embodiment, the decision threshold is related to the carrier-to-noise ratio of the received signal. Acquiring a carrier-to-noise ratio of a received signal; and determining a decision threshold according to the carrier-to-noise ratio and a preset calculation relationship, wherein the preset calculation relationship represents the calculation relationship between each carrier-to-noise ratio and the corresponding decision threshold, and is obtained by utilizing the simulation of received signals containing multipath signals and not containing multipath signals under different signal strengths.
In one non-limiting embodiment, the decision threshold is simulated in the following way: acquiring a plurality of simulated receiving signals containing multipath signals and not containing multipath signals under different signal strengths, and accumulating results of the plurality of simulated receiving signals in an accumulating time length; calculating a first difference of each simulated received signal in the presence of multipath signals and a second difference in the absence of multipath signals; and fitting according to the first difference and/or the second difference to obtain a calculation relation between the carrier-to-noise ratio and a decision threshold corresponding to the carrier-to-noise ratio, so that a result determined according to the relation between the decision threshold determined according to the calculation relation and the first difference and/or the second difference is consistent with each simulated received signal.
In specific implementation, during simulation, a simulation scenario that signals contain multipath signals and signals do not contain multipath signals under different signal strengths needs to be set. Specifically, a plurality of simulated received signals containing multipath signals and not containing multipath signals under different signal strengths can be acquired. In a scene containing multipath signals, different multipath delays, phases, amplitudes and numbers can be set according to actual requirements. Note that the difference SRR containing the multipath signal scenario is SRR1 (i.e., the first difference) and the difference SRR not containing the multipath signal is SRR2 (i.e., the second difference).
Different thresholds can be selected according to requirements to make strategies. The false judgment is defined as that the scene without the multipath signal is identified as containing the multipath signal, and the false judgment is defined as that the scene with the multipath signal is identified as not containing the multipath signal.
Taking the example of calculating the difference SRR according to the formula (16) or (17), if the misjudgment rate is low, the decision threshold Th < ═ min (SRR2) may be set; if the rate of the missed judgment is low, the judgment threshold Th > is set to max (SRR 1).
For example, if the required misjudgment rate is low, the decision threshold Th > -max (SRR2) may be set, for example, by calculating the difference SRR according to the formula (18) or (19); if the rate of the missed judgment is low, a judgment threshold Th < ═ min (SRR1) can be set.
Because the signal intensity in the simulation scene is known, an accurate carrier-to-noise ratio can be calculated according to the link gain, the decision thresholds under different carrier-to-noise ratios are counted and subjected to linear fitting, and the calculation relation of the decision thresholds on the carrier-to-noise ratio can be obtained.
The calculation relation is used for carrying out simulation test on other scenes with different signal intensities, the judgment threshold Th is properly adjusted, and a plurality of judgment strategies are used for filtering out single missed judgment or misjudgment. The first number n1_ th and the second number n2_ th are appropriately adjusted. If the misjudgment rate is low (for example, lower than the first threshold), the first number n1_ th > may be set to the second number n2_ th; if the rate of the missed judgment is low (for example, lower than the second threshold), the first number n1_ th may be set to be the second number n2_ th. The above strategy can be used regardless of the SRR calculation method used.
Due to multipath, the carrier-to-noise ratio estimated at the receiving end may not match the signal strength of the main path. Positive multipath will make the estimated carrier-to-noise ratio larger and negative multipath will make the estimated carrier-to-noise ratio smaller. When the calculation relation is used for calculating the judgment threshold Th, the estimated carrier-to-noise ratio is directly used, namely, the threshold calculation value is still applicable under the influence of multipath.
The performance of the multipath decision making of the embodiment of the invention is related to the correlator interval and the carrier-to-noise ratio. In a specific application scenario, when the correlator interval is 1/8 chips and the carrier-to-noise ratio is 35dBHz, an inverse multipath with delay > of 0.1 chips and a positive multipath with delay > of 0.2 chips can be identified. Where a chip refers to a spreading code duration of 1 chip. The decision capability of the embodiment of the invention is improved along with the improvement of the carrier-to-noise ratio and the narrowing of the correlator interval.
For more specific implementation manners of the embodiments of the present application, please refer to the foregoing embodiments, which are not described herein again.
Referring to fig. 7, fig. 7 shows a multipath decision device 70, and the multipath decision device 70 may include:
an obtaining module 701, configured to obtain an accumulation result of a received signal on multiple branches within an accumulation duration, where phases of spreading codes used by different branches are different;
an estimation module 702, configured to estimate a main path signal according to the accumulation result, and calculate a difference between the main path signal and the accumulation result;
a decision module 703, configured to determine whether a multipath signal exists in the received signal according to a relationship between the difference and a decision threshold, where the decision threshold is obtained by simulating a simulated received signal that includes the multipath signal and does not include the multipath signal under different signal strengths.
Further, the multipath decision device 70 may further include an accumulation module, and the accumulation module is configured to calculate an accumulation result. Specifically, the accumulation module calculates a coherent accumulation result cohuut of the received signal in the j-th coherent accumulation period using formula 20 j 。
Figure BDA0003657532230000161
Wherein CohNum represents coherenceNumber of accumulations, I i And Q i Representing two paths of orthogonal signals obtained after despreading the received signals. Specifically, the despreading operation result of the received signal in the ith spreading code period length is I i +jQ i ,i＝0,...,n-1。
The accumulation module calculates the incoherent accumulation result of the received signal in the kth incoherent accumulation period using equations 21 to 23.
Figure BDA0003657532230000162
Figure BDA0003657532230000163
Figure BDA0003657532230000164
Where NcsNum represents the number of incoherent accumulations, the magnitude of the incoherent accumulation result, and
Figure BDA0003657532230000165
and (4) aligning. CohOut _ I j Representing coherent accumulation results cohOut j Real part of, CohOut _ Q j Representing coherent accumulation results cohOut j The imaginary part of (c). That is, the despreading operation results within the period length of the CohNum spreading codes are subjected to coherent accumulation to obtain 1 coherent accumulation result; and carrying out incoherent accumulation on the NcsNum coherent accumulation operation results to obtain 1 incoherent accumulation result.
In a specific implementation, the multipath decision device 70 may correspond to a Chip having a multipath decision function in a receiver, such as a System-On-a-Chip (SOC), a baseband Chip, and the like; or the receiver comprises a chip module with a multipath decision function; or to a chip module having a chip with data processing function, or to a receiver.
For other relevant descriptions of the multipath decision device 70, reference may be made to the relevant descriptions in the foregoing embodiments, and further description is omitted here.
Each module/unit included in each apparatus and product described in the above embodiments may be a software module/unit, or may also be a hardware module/unit, or may also be a part of a software module/unit and a part of a hardware module/unit. For example, for each device or product applied to or integrated into a chip, each module/unit included in the device or product may be implemented by hardware such as a circuit, or at least a part of the module/unit may be implemented by a software program running on a processor integrated within the chip, and the rest (if any) part of the module/unit may be implemented by hardware such as a circuit; for each device or product applied to or integrated with the chip module, each module/unit included in the device or product may be implemented by using hardware such as a circuit, and different modules/units may be located in the same component (e.g., a chip, a circuit module, etc.) or different components of the chip module, or at least some of the modules/units may be implemented by using a software program running on a processor integrated within the chip module, and the rest (if any) of the modules/units may be implemented by using hardware such as a circuit; for each device and product applied to or integrated in the terminal device, each module/unit included in the device and product may be implemented by hardware such as a circuit, and different modules/units may be located in the same component (e.g., a chip, a circuit module, etc.) or different components in the terminal device, or at least a part of the modules/units may be implemented by a software program running on a processor integrated in the terminal device, and the rest (if any) part of the modules/units may be implemented by hardware such as a circuit.
The embodiment of the application also discloses a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium, and when the computer program runs, the steps of the method shown in fig. 1 to 3 can be executed. The storage medium may include a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic or optical disk, and the like. The storage medium may further include a non-volatile (non-volatile) memory or a non-transitory (non-transient) memory, etc.
It should be understood that the term "and/or" herein is merely one type of association relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this document indicates that the former and latter related objects are in an "or" relationship.
The "plurality" appearing in the embodiments of the present application means two or more.
The descriptions of the first, second, etc. appearing in the embodiments of the present application are only for illustrating and differentiating the objects, and do not represent the order or the particular limitation of the number of the devices in the embodiments of the present application, and do not constitute any limitation to the embodiments of the present application.
The term "connect" in the embodiments of the present application refers to various connection manners, such as direct connection or indirect connection, to implement communication between devices, which is not limited in this embodiment of the present application.
The above-described embodiments may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, the above-described embodiments may be implemented in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions or computer programs. The procedures or functions according to the embodiments of the present application are wholly or partially generated when the computer instructions or the computer program are loaded or executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire or wirelessly.
It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
In the several embodiments provided in the present application, it should be understood that the disclosed method, apparatus and system may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative; for example, the division of the cell is only a logic function division, and there may be another division manner in actual implementation; for example, various elements or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be physically included alone, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit 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) to execute some steps of the methods described in the embodiments of the present application.
Although the present application is disclosed above, the present application is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present disclosure, and it is intended that the scope of the present disclosure be defined by the appended claims.

Claims (12)

1. A multipath decision method, comprising:
acquiring accumulation results of a plurality of branches of received signals in an accumulation duration, wherein the phases of spreading codes used by different branches are different;
estimating a main path signal according to the accumulation result, and calculating the difference between the main path signal and the accumulation result;
and determining whether the received signal has a multipath signal according to the relationship between the difference and a decision threshold, wherein the decision threshold is obtained by simulating simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths.
2. The multipath decision method of claim 1, wherein the determining whether a multipath signal is present in the received signal based on the relationship between the difference and the decision threshold further comprises:
acquiring a carrier-to-noise ratio of the received signal;
the determining whether a multipath signal exists in the received signal according to the relationship between the difference and the decision threshold comprises:
when the carrier-to-noise ratio is higher than a preset threshold, directly determining whether a multipath signal exists in the received signal according to the relation between the difference and a decision threshold;
and when the carrier-to-noise ratio is lower than a preset threshold, determining whether the received signal has the multipath signal according to the relationship between the difference in a plurality of accumulation time lengths and a decision threshold, wherein the accumulation time lengths are the time lengths required for calculating the accumulation results.
3. The multipath decision method of claim 2, wherein the determining whether a multipath signal is present in the received signal based on the relationship of the differences in the plurality of accumulated time durations to the decision threshold comprises:
determining that the multipath signal exists in the received signal if the difference within a first number of consecutive accumulated durations reaches the decision threshold;
if the difference in the continuous second number of accumulation durations does not reach the decision threshold, determining that the multipath signal does not exist in the received signal;
or, if the difference in the continuous first number of accumulated time durations does not reach the decision threshold, determining that the multipath signal exists in the received signal;
determining that the multipath signal is absent from the received signal if the difference over a second number of consecutive accumulation periods reaches the decision threshold.
4. The multipath decision method of claim 1, wherein before determining whether a multipath signal is present in the received signal based on the relationship between the difference and the decision threshold, further comprising:
acquiring a carrier-to-noise ratio of the received signal;
and determining the decision threshold according to the carrier-to-noise ratio and a preset calculation relationship, wherein the preset calculation relationship represents the calculation relationship between each carrier-to-noise ratio and the corresponding decision threshold, and the preset calculation relationship is obtained by simulating received signals containing multipath signals and received signals not containing multipath signals under different signal strengths.
5. The multipath decision method according to claim 1, characterized in that the decision threshold is obtained by simulation in the following way:
acquiring a plurality of simulated receiving signals containing multipath signals and not containing multipath signals under different signal strengths and accumulation results of the simulated receiving signals in an accumulation time length;
calculating a first difference of each simulated received signal in the presence of multipath signals and a second difference in the absence of multipath signals;
and fitting according to the first difference and/or the second difference to obtain a calculation relation between the carrier-to-noise ratio and a judgment threshold corresponding to the carrier-to-noise ratio, so that a result determined according to the relation between the judgment threshold determined according to the calculation relation and the first difference and/or the second difference is consistent with each simulated received signal.
6. The multipath decision method of claim 1 wherein the estimating a main path signal based on the accumulated results comprises:
estimating the chip delay of the main path signal according to the accumulation result;
estimating the amplitude of the main path signal at least according to the chip delay;
acquiring the time delay of each branch according to the chip delay and the correlator interval;
and reconstructing the main path signal by using at least the function value of the autocorrelation function of the main path signal under the time delay of each branch and the amplitude of the main path signal.
7. The multi-path decision method of claim 6, wherein the accumulation results are coherent accumulation results and non-coherent accumulation results, and wherein the estimating the amplitude of the main path signal based on at least the chip delay:
calculating a first product of a first orthogonal signal of a maximum value of the incoherent accumulation result corresponding to a branch in the coherent accumulation result and a cosine function of a main path phase of the main path signal, and a second product of a second orthogonal signal of the maximum value of the incoherent accumulation result corresponding to a branch in the coherent accumulation result and a sine function of the main path phase of the main path signal;
summing the first product and the second product to obtain an intermediate parameter;
calculating a difference value between a preset value and chip delay, and calculating a ratio of the intermediate parameter to the difference value to be used as the amplitude of the main path signal;
the reconstructing the main path signal by using at least the function value of the autocorrelation function of the main path signal under the delay of each branch and the amplitude of the main path signal comprises:
calculating a function value of an autocorrelation function of the main path signal under the time delay of each branch;
and determining an index which takes a natural number as a base number part and an imaginary number as an index part, and calculating the product of the amplitude of the main path signal, the function value of each branch under the time delay and the index to obtain the main path signal, wherein the imaginary number is the main path phase of the main path signal.
8. The multipath decision method of claim 6, wherein the estimating the magnitude of the main path signal based at least on the chip delay comprises:
calculating a difference value between a preset value and chip delay, and calculating a ratio of a maximum value of an incoherent accumulation result to the difference value to be used as an amplitude value of the main path signal;
the reconstructing the main path signal at least by using the function value of the autocorrelation function of the main path signal under the time delay of each branch and the amplitude of the main path signal comprises:
calculating a function value of an autocorrelation function of the main path signal under the time delay of each branch;
and calculating the product of the amplitude of the main path signal and the function value of each branch circuit under the time delay to obtain the main path signal.
9. The multipath decision method of claim 1, wherein the calculating the difference between the main path signal and the accumulated result comprises:
calculating the difference value between the main path signal and each accumulation result and the ratio of each difference value to the amplitude value of the main path signal;
calculating a first average value of each ratio or a second average value of a square value of each ratio;
taking the first average, the second average, the inverse of the first average, or the inverse of the second average as the difference.
10. A multipath decision device, comprising:
the acquisition module is used for acquiring the accumulation results of the received signals on a plurality of branches within the accumulation duration, wherein the phases of the spread spectrum codes used by different branches are different;
the estimation module is used for estimating a main path signal according to the accumulation result and calculating the difference between the main path signal and the accumulation result;
and the judging module is used for determining whether the received signal has the multipath signal according to the relation between the difference and a judging threshold, and the judging threshold is obtained by simulating the simulated received signals which contain the multipath signal and do not contain the multipath signal under different signal strengths.
11. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, performs the steps of the multipath decision method of any one of claims 1 to 9.
12. A terminal device comprising a memory and a processor, the memory having stored thereon a computer program operable on the processor, characterized in that the processor, when executing the computer program, performs the steps of the multipath decision method of any one of claims 1 to 9.
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Citations (2)

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CN102891814A (en) * 2012-09-06 2013-01-23 天津市德力电子仪器有限公司 Method for implementing channel multi-path detection based on P1 sign
CN103501187A (en) * 2013-10-10 2014-01-08 中国人民解放军理工大学 Interference cancellation-based short wave multi-path signal synchronization method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102891814A (en) * 2012-09-06 2013-01-23 天津市德力电子仪器有限公司 Method for implementing channel multi-path detection based on P1 sign
CN103501187A (en) * 2013-10-10 2014-01-08 中国人民解放军理工大学 Interference cancellation-based short wave multi-path signal synchronization method

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