CN104914427B - The distance-finding method and system of the adaptive time delay stimation based on received signal strength - Google Patents
The distance-finding method and system of the adaptive time delay stimation based on received signal strength Download PDFInfo
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Abstract
The present invention provides the distance-finding method and system of a kind of adaptive time delay stimation based on received signal strength, is favorably improved range accuracy.Methods described includes：S1：Electric field signal and magnetic field signal are obtained, and eliminates the noise in the electric field signal and magnetic field signal；S2：It is determined that eliminating the intensity of electric field signal and magnetic field signal after noise, and primarily determine that electromagnetic field time delay estimate；S3：Electromagnetic field time delay estimate according to primarily determining that determines electromagnetic field time delay initial value, and to being processed except the electric field signal after denoising and the carrying out of magnetic field signal, determines the communication distance between measuring distance of target.The system includes：The present invention is applied to the communications field.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a ranging method and system based on adaptive delay estimation of received signal strength.
Background
Currently, in near-field electromagnetic field ranging, an adaptive time delay estimation algorithm is used to estimate time delay between electromagnetic fields, and a communication distance between ranging targets is measured according to a relationship between the estimated time delay between the electromagnetic fields and the communication distance between the ranging targets. The adaptive delay estimation algorithm comprises the following steps: traditional adaptive delay estimation algorithms and variable step size adaptive delay estimation algorithms. Although the conventional adaptive time delay estimation algorithm can accurately estimate the time delay between two paths of received signals (an electric field signal and a magnetic field signal), the conventional adaptive time delay estimation algorithm has a certain time delay under the condition that the time delay is changed continuously, and meanwhile, if the target needing distance measurement is changed continuously, the conventional adaptive time delay estimation algorithm cannot measure the distance between the targets needing distance measurement quickly and accurately.
Compared with the traditional adaptive time delay estimation algorithm, the variable-step adaptive time delay estimation algorithm can effectively improve the convergence speed of the adaptive algorithm and improve the tracking performance of the algorithm on a variable system, but the variable-step adaptive time delay estimation algorithm adopts a larger step length to improve the convergence speed in the convergence stage, so that a larger convergence error is introduced, the electromagnetic field time delay estimation error in the stage is larger, and if the position of a ranging target is changed all the time, the ranging error is always larger. In addition, due to the influence of noise, when a cost function of the adaptive delay estimation algorithm has a local optimal value and a global optimal value, if an initial delay estimation value is improperly set, the algorithm converges to the local optimal value, so that delay estimation is wrong.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a distance measurement method and a distance measurement system based on self-adaptive time delay estimation of received signal strength, so as to solve the problems of large electromagnetic field time delay estimation error and large distance measurement error in the prior art.
To solve the foregoing technical problem, an embodiment of the present invention provides a ranging method based on adaptive delay estimation of received signal strength, including:
s1: acquiring an electric field signal and a magnetic field signal, and eliminating noise in the electric field signal and the magnetic field signal;
s2: determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated, and preliminarily determining an electromagnetic field time delay estimation value;
s3: and determining an initial electromagnetic field time delay value according to the preliminarily determined estimated electromagnetic field time delay value, processing the electric field signal and the magnetic field signal after removing the noise, and determining the communication distance between the ranging targets.
Optionally, the S1 includes before:
setting an initial value of electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The S1 includes:
transmitting the low-frequency signal through a transmitting terminal;
acquiring an electric field signal in the transmitting signal through an electric field receiving antenna and acquiring a magnetic field signal in the transmitting signal through a magnetic field receiving antenna;
eliminating noise in the electric field signal and the magnetic field signal by an adaptive threshold noise blanker;
and respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces.
Optionally, the eliminating noise in the electric field signal and the magnetic field signal by the adaptive threshold noise blanker comprises:
determining the strength of the acquired electric field signal and magnetic field signal;
according to the determined strength of the electric field signal and the magnetic field signal and the set peak-to-average power ratio R of the emission signalTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: the noise-free magnetic field signal comprises an electric field signal and a magnetic field signal, wherein the electric field signal and the magnetic field signal contain noise, N is the sampling number, and the value range of k is 1,2, … … and N.
Optionally, the S2 includes:
determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
preliminarily determining an electromagnetic field time delay estimated value according to the relation between the communication distance between the ranging targets and the electromagnetic field time delay
Optionally, the S3 includes:
when in useUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
According to determined initial value of electromagnetic field time delayAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the electromagnetismInitial value of field delay
If the electromagnetic field time delay estimates the final valueWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayDetermining a communication distance between ranging targets;
if the electromagnetic field time delay estimates the final valueAnd returning to the step S1 to continue the execution when the change is not constant.
The embodiment of the invention also provides a ranging system based on the self-adaptive time delay estimation of the received signal strength, which comprises the following steps:
the noise elimination unit is used for acquiring an electric field signal and a magnetic field signal and eliminating noise in the electric field signal and the magnetic field signal;
the time delay preliminary determination unit is used for determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated and preliminarily determining an electromagnetic field time delay estimation value;
and the communication distance determining unit is used for determining an initial electromagnetic field time delay value according to the preliminarily determined estimated electromagnetic field time delay value, processing the electric field signal and the magnetic field signal after the noise is removed, and determining the communication distance between the ranging targets.
Optionally, the system further comprises:
an initialization unit for setting an initial value of the electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The noise canceling unit includes:
the signal transmitting module is used for transmitting the low-frequency signal through the transmitting end;
the electric field signal receiving module is used for acquiring an electric field signal in the transmitting signal through an electric field receiving antenna;
the magnetic field signal receiving module is used for acquiring a magnetic field signal in the transmitting signal through the magnetic field receiving antenna;
a noise elimination module for eliminating noise in the electric field signal and the magnetic field signal through an adaptive threshold noise blanker;
and the signal storage module is used for respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces.
Optionally, the noise cancellation module comprises:
the received signal strength determining submodule is used for determining the strength of the acquired electric field signal and magnetic field signal;
a blanker threshold determination submodule for determining the peak-to-average power ratio R of the transmission signal based on the determined strengths of the electric field signal and the magnetic field signal and the settingTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: electric field signal and magnetic field signal, the electric fieldThe signal and the magnetic field signal contain noise, N is the number of samples, and the value range of k is 1,2, … … and N.
Optionally, the preliminary delay determining unit includes:
the received signal strength determining module is used for determining the strength of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
the communication distance preliminary determination module is used for preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
a time delay preliminary determination module for preliminarily determining an electromagnetic field time delay estimation value according to a relationship between a communication distance between ranging targets and an electromagnetic field time delay
Optionally, the communication distance determining unit includes:
a delay initial value determining module for determining whenUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
A time delay final value determining module for determining the initial value of the time delay according to the determined electromagnetic fieldAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delay
A communication distance determining module for estimating a final value if the electromagnetic field time delayWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayDetermining a communication distance between ranging targets;
a return execution module for estimating the final value if the electromagnetic field time delayAnd returning to the noise elimination unit to continue executing when the change is continuous.
The technical scheme of the invention has the following beneficial effects:
in the scheme, the strength of the electric field signal and the magnetic field signal after the noise is eliminated is used for preliminarily estimating the electromagnetic field time delay estimated value, the initial value of the electromagnetic field time delay is determined according to the preliminarily estimated electromagnetic field time delay estimated value, and the electric field signal and the magnetic field signal after the noise is eliminated are processed, so that the communication distance between ranging targets is determined. Therefore, an electromagnetic field time delay initial value is determined according to the preliminarily estimated electromagnetic field time delay estimated value, the influence of the local optimal value of the cost function on the electromagnetic field time delay estimation can be avoided within a certain signal-to-noise ratio range, and when the ranging target moves rapidly, the electromagnetic field time delay initial value of the adaptive time delay estimation algorithm can be continuously updated according to the acquired strength of the electric field signal and the magnetic field signal, so that the convergence speed of the adaptive time delay estimation algorithm, the electromagnetic field time delay estimation precision and the ranging precision can be effectively improved.
Drawings
Fig. 1 is a flowchart of a method for ranging based on adaptive delay estimation of received signal strength according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a transmitting end and a receiving end according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a relationship between a delay and a communication distance, and a path loss and a communication distance according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an adaptive delay estimation module based on received signal strength according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a basic adaptive delay estimation module according to an embodiment of the present invention;
fig. 6 is a schematic diagram of an optimization result of the SETDE algorithm by the adaptive delay estimation module based on received signal strength according to the embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a self-adaptive time delay estimation distance measurement method and system based on received signal strength, aiming at the problems of large time delay estimation error and large distance measurement error of the existing electromagnetic field.
Example one
Referring to fig. 1, an embodiment of the present invention provides a ranging method based on adaptive delay estimation of received signal strength, including:
s1: acquiring an electric field signal and a magnetic field signal, and eliminating noise in the electric field signal and the magnetic field signal;
s2: determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated, and preliminarily determining an electromagnetic field time delay estimation value;
s3: and determining an initial electromagnetic field time delay value according to the preliminarily determined estimated electromagnetic field time delay value, processing the electric field signal and the magnetic field signal after removing the noise, and determining the communication distance between the ranging targets.
According to the self-adaptive time delay estimation distance measurement method based on Received Signal Strength (RSS), the Strength of an electric field Signal and a magnetic field Signal after noise is eliminated is used for preliminarily estimating the electromagnetic field time delay estimation value, an electromagnetic field time delay initial value is determined according to the preliminarily estimated electromagnetic field time delay estimation value, and the electric field Signal and the magnetic field Signal after the noise is eliminated are processed, so that the communication distance between distance measurement targets is determined. Therefore, an electromagnetic field time delay initial value is determined according to the preliminarily estimated electromagnetic field time delay estimated value, the influence of the local optimal value of the cost function on the electromagnetic field time delay estimation can be avoided within a certain signal-to-noise ratio range, and when the ranging target moves rapidly, the electromagnetic field time delay initial value of the adaptive time delay estimation algorithm can be continuously updated according to the acquired strength of the electric field signal and the magnetic field signal, so that the convergence speed of the adaptive time delay estimation algorithm, the electromagnetic field time delay estimation precision and the ranging precision can be effectively improved.
In the embodiment of the present invention, receiving a signal includes: an electric field signal and a magnetic field signal.
In the foregoing specific implementation of the ranging method based on adaptive time delay estimation of received signal strength, optionally, the S1 includes:
setting an initial value of electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The S1 includes:
transmitting the low-frequency signal through a transmitting terminal;
acquiring an electric field signal in the transmitting signal through an electric field receiving antenna and acquiring a magnetic field signal in the transmitting signal through a magnetic field receiving antenna;
eliminating noise in the electric field signal and the magnetic field signal by an adaptive threshold noise blanker;
and respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces.
In the embodiment of the invention, the communication distance between the ranging targets can be determined according to the received signal strength or the time delay of the electromagnetic field respectively. However, in a complex environment, due to reasons such as building shielding, attenuation of a received signal is not only related to a communication distance, and meanwhile, when a receiving end has a low signal-to-noise ratio, an error occurs in received signal strength calculation, so that a ranging method based on the received signal strength is not accurate enough, but a low-frequency signal can better penetrate through a building, and delay information can be effectively extracted under the conditions of non-line-of-sight and low signal-to-noise ratio, so that the method is more suitable for indoor ranging.
In the embodiment of the present invention, for example, the low frequency signal may be transmitted through the transmitting antenna of the transmitting terminal, the receiving antenna is then used to receive the electric field signal and the magnetic field signal in the transmitted signal, after the electric field signal and the magnetic field signal are received, the sampling number N of the receiver 211 needs to be set for sampling the electric field signal and the magnetic field signal, and the electric field signal and the magnetic field signal after sampling are adaptively processed by the adaptive delay estimation module 213. Referring to fig. 2, the transmitting antenna at the transmitting end may be an electric field antenna, and the transmitter 201 at the transmitting end transmits a low-frequency signal 203, which is a low-frequency narrow-band signal, through the electric field antenna 202, where the frequency of the low-frequency signal is adjustable, the modulation mode is selectable, and the transmission power is adjustable. The distance between the receiver 211 and the transmitter 201 at the receiving end is r204, and the receiving antenna comprises: the magnetic field receiving antenna 205 and the electric field receiving antenna 206 receive the magnetic field signal and the electric field signal, respectively, of the transmission signal. In order to reduce the influence of noise on the intensity of a received signal, the received magnetic field signal and electric field signal are filtered by an AGC \ filter module 208 and an AGC \ filter module 207 respectively, the AGC amplification factor is adjustable, a filter is selected according to the characteristics of a transmitted signal, the magnetic field signal and the electric field signal conditioned by the AGC \ filter module are sampled by an AD sampler 210 and an AD sampler 209 respectively, and the sampling frequency is adjustable according to the signal frequency and the requirement of distance measurement precision. In the embodiment of the present invention, the transmitting antenna may be various electric field antennas, and the receiving antenna may be various electric field receiving antennas and magnetic field receiving antennas, for example, the electric field antenna and the electric field receiving antenna may employ a monopole antenna, and the magnetic field antenna and the magnetic field receiving antenna may employ a loop antenna.
In the embodiment of the present invention, in order to reduce the calculation load when calculating the RSS value in S2, the electric field signal and the magnetic field signal sampled in S1 are stored in N storage spaces, respectively, so as to be reused in S2.
In the foregoing specific embodiment of the ranging method based on adaptive time delay estimation of received signal strength, optionally, the eliminating noise in the electric field signal and the magnetic field signal by an adaptive threshold noise blanker includes:
determining the strength of the acquired electric field signal and magnetic field signal;
according to the determined strength of the electric field signal and the magnetic field signal and the set peak-to-average power ratio R of the emission signalTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: the noise-free magnetic field signal comprises an electric field signal and a magnetic field signal, wherein the electric field signal and the magnetic field signal contain noise, N is the sampling number, and the value range of k is 1,2, … … and N.
In the embodiment of the present invention, the received signal strength RSS is expressed by an average power equation (1) of the received signal:
in the formula (1), s (k) is a signal received by a receiving end, s (k) includes an electric field signal, a magnetic field signal and noise, N is the number of samples, and the value range of k is 1,2, … … and N. Therefore, when the electromagnetic field time delay estimation value is preliminarily calculated by RSS, the calculation error is derived from the RSS value including the electric field signal strength, the magnetic field signal strength, and the noise strength at the same time. In order to minimize the estimation error of the electromagnetic field time delay, the influence of noise must be removed as much as possible when calculating the RSS value, the noise with the amplitude exceeding the threshold is filtered by an adaptive threshold noise blanker, and the received signal s' (k) after the noise is filtered is expressed as formula (2):
in the formula (2), B is the threshold value of the self-adaptive threshold noise blanker, when the threshold value B is set to be too small, most target signals (including electric field signals and magnetic field signals) are filtered, and the calculation error of the RSS value is increased; when the threshold B is set too large, the blanking effect on noise is limited. In an indoor ranging environment, the threshold B changes with the movement of a ranging target, so that the threshold B needs to be adaptively changed according to the strength change of a target signal at a receiving end, and when the threshold B of the adaptive noise blanker is equal to the peak value of the target signal, the blanking effect is optimal.
In the embodiment of the present invention, the Peak value of the target signal may be calculated by a Peak-to-Average power ratio (PAPR). The peak-to-average power ratio is defined by formula (3):
in the embodiment of the invention, the peak-to-average power ratio of the target signal at the transmitting end is assumed to be RTXAnd the signal containing noise at the receiving end is s (k), the threshold B of the adaptive noise blanker can be represented by equation (4):
in the foregoing specific implementation of the ranging method based on adaptive time delay estimation of received signal strength, optionally, the S2 includes:
determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
preliminarily determining an electromagnetic field time delay estimated value according to the relation between the communication distance between the ranging targets and the electromagnetic field time delay
In the embodiment of the invention, the communication distance between the ranging targets and the estimated value of the electromagnetic field time delay are preliminarily determined according to the stored RSS (received signal strength) after sampling and the relationship between the low-frequency signal propagation model, the electromagnetic field time delay and the communication distance between the ranging targetsWherein the electromagnetic field time delay deltatThe relationship with the communication distance r between the ranging targets is expressed by equation (5):
in equation (5), ω is the center angular frequency of the transmission signal, and λ is the wavelength of the transmission signal.
In the embodiment of the present invention, referring to fig. 3, a relationship between an electromagnetic field time delay between an electric field signal and a magnetic field signal and a communication distance between ranging targets, and a relationship between a path loss and a communication distance are shown, where T is a maximum time delay between the electric field signal and the magnetic field signal, λ is a signal wavelength, and the communication distance is (0-0.6) λ.
In the embodiment of the present invention, the electromagnetic field intensity of the transmission signal attenuates with the increase of the communication distance, and when the transmission signal is received by the electric field receiving antenna and the magnetic field receiving antenna, respectively, the propagation formula of the low-frequency signal is expressed as formula (6) and formula (7):
in the formula (6), "like" indicates that both the transmitting antenna and the receiving antenna are electric field antennas or magnetic field antennas; in the formula (7), "ulike" denotes a transmitting antenna and a receiving antennaOne of the receiving antennas is an electric field antenna, the other is a magnetic field antenna, PTXIs the input power of the transmitting antenna, PRXIs the output power of the receiving antenna, ATXIs the effective area of the transmitting antenna, ARXIs the effective area of the receiving antenna, r is the communication distance between ranging targets, k 2 pi/λ is the wavenumber, and λ is the transmitted signal wavelength.
In the foregoing specific implementation of the ranging method based on adaptive time delay estimation of received signal strength, optionally, the S3 includes:
when in useUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
According to determined initial value of electromagnetic field time delayAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delay
If the electromagnetic field time delay estimates the final valueWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayDetermining a communication distance between ranging targets;
if the electromagnetic field time delay estimates the final valueAnd returning to the step S1 to continue the execution when the change is not constant.
In the embodiment of the present invention, referring to fig. 2, the sampled digital signal 212 is passed through the adaptive delay estimation module 213 based on the received signal strength to obtain the electromagnetic field delay Δ between the magnetic field signal and the electric field signalt214, obtaining a communication distance r215 between the ranging targets according to a relationship between the communication distance between the ranging targets and the electromagnetic field delay, wherein a schematic structural diagram of the adaptive delay estimation module based on the received signal strength is shown in fig. 4.
In the embodiment of the present invention, the initial value of the electromagnetic field delay in the adaptive delay estimation module 213 based on the received signal strength is set firstTime delay difference delta of electromagnetic fieldDWherein the electromagnetic field time delay difference value deltaDBased on the time delay estimate of the electromagnetic fieldIs determined by the error range of (c). When in useUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation moduleAccording to determined initial value of electromagnetic field time delayAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delayIf the electromagnetic field time delay estimates the final valueWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayThe communication distance between ranging targets is determined.
In the embodiment of the invention, the final value is estimated if the electromagnetic field time delayAnd when the RSS value changes continuously, returning to the step S1 to continue the execution, thereby realizing accurate tracking ranging on the ranging target moving quickly. When the signal-to-noise ratio is within a certain range, the error between the electromagnetic field time delay value calculated according to the RSS and the real electromagnetic field time delay is within a certain range, and the convergence speed of the self-adaptive time delay estimation algorithm can be effectively improved. Meanwhile, because the error is within a certain range, the electromagnetic field time delay is initialThe value is closer to the real time delay, the influence of the local optimal value of the cost function on the time delay estimation can be effectively avoided, the self-adaptive time delay estimation algorithm is finally converged to the real time delay, the real communication distance between the self-adaptive time delay estimation algorithm and the ranging target is obtained, and the ranging precision is improved.
In the embodiment of the invention, the lookup table is established for the relation between the RSS value and the communication distance between the ranging targets and the relation between the communication distance between the ranging targets and the electromagnetic field time delay, so that the calculation time can be saved, and the ranging speed can be improved.
The self-adaptive time delay estimation algorithm based on the received signal strength provided by the embodiment of the invention is suitable for various self-adaptive time delay estimation algorithms. Referring to fig. 5, which is a schematic structural diagram of the basic adaptive Delay estimation module, in practical applications, the adaptive Delay estimation module may use adaptive Delay estimation algorithms based on different methods and derived algorithms, such as Least Mean Square (LMS)/Least Mean P-norm (LMP), for different noise environments and different signal-to-noise ratios, such as Least Mean Square Time Delay Estimation (LMSTDE), Constrained Time Delay Estimation (CTDE), Explicit Time Delay Estimation (ETDE), Simple Explicit Time Delay Estimation (SETDE), Explicit Time Delay estimation (and Gain estimation).
In the embodiment of the present invention, referring to fig. 6, which is a result of optimizing the SETDE algorithm by the adaptive delay estimation module based on received signal strength provided by the present invention, it can be seen from fig. 6 that the electromagnetic field delay step Dsstep＝2.5TsAnd varies in a sinusoidal manner, wherein TsIs the time interval between sampling points, the traditional SETDE algorithm can not track the time delay change, and the improved RSSI-SETDE algorithm based on the Received Signal Strength Indication (RSSI) can still track the time delay change rapidly, thereby being capable of rapidly movingThe distance measurement target realizes accurate tracking distance measurement.
Example two
The present invention further provides a specific embodiment of a ranging system based on adaptive delay estimation of received signal strength, and since the ranging system based on adaptive delay estimation of received signal strength provided by the present invention corresponds to the specific embodiment of the ranging method based on adaptive delay estimation of received signal strength, and the ranging system based on adaptive delay estimation of received signal strength can achieve the object of the present invention by executing the process steps in the specific embodiment of the method, the explanation in the specific embodiment of the ranging method based on adaptive delay estimation of received signal strength is also applicable to the specific embodiment of the ranging system based on adaptive delay estimation of received signal strength provided by the present invention, and will not be repeated in the following specific embodiments of the present invention.
The embodiment of the invention also provides a ranging system based on the self-adaptive time delay estimation of the received signal strength, which comprises the following steps:
the noise elimination unit is used for acquiring an electric field signal and a magnetic field signal and eliminating noise in the electric field signal and the magnetic field signal;
the time delay preliminary determination unit is used for determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated and preliminarily determining an electromagnetic field time delay estimation value;
and the communication distance determining unit is used for determining an initial electromagnetic field time delay value according to the preliminarily determined estimated electromagnetic field time delay value, processing the electric field signal and the magnetic field signal after the noise is removed, and determining the communication distance between the ranging targets.
The distance measurement system based on the self-adaptive time delay estimation of the received signal strength preliminarily estimates the electromagnetic field time delay estimated value through the strength of the electric field signal and the magnetic field signal after noise elimination, determines the initial value of the electromagnetic field time delay according to the preliminarily estimated electromagnetic field time delay estimated value, and then processes the electric field signal and the magnetic field signal after the noise elimination, thereby determining the communication distance between the distance measurement targets. Therefore, an electromagnetic field time delay initial value is determined according to the preliminarily estimated electromagnetic field time delay estimated value, the influence of the local optimal value of the cost function on the electromagnetic field time delay estimation can be avoided within a certain signal-to-noise ratio range, and when the ranging target moves rapidly, the electromagnetic field time delay initial value of the adaptive time delay estimation algorithm can be continuously updated according to the acquired strength of the electric field signal and the magnetic field signal, so that the convergence speed of the adaptive time delay estimation algorithm, the electromagnetic field time delay estimation precision and the ranging precision can be effectively improved.
In the foregoing specific implementation of the ranging system based on adaptive time delay estimation of received signal strength, optionally, the system further includes:
an initialization unit for setting an initial value of the electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The noise canceling unit includes:
the signal transmitting module is used for transmitting the low-frequency signal through the transmitting end;
the electric field signal receiving module is used for acquiring an electric field signal in the transmitting signal through an electric field receiving antenna;
the magnetic field signal receiving module is used for acquiring a magnetic field signal in the transmitting signal through the magnetic field receiving antenna;
a noise elimination module for eliminating noise in the electric field signal and the magnetic field signal through an adaptive threshold noise blanker;
and the signal storage module is used for respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces.
In the foregoing specific embodiment of the ranging system based on adaptive delay estimation of received signal strength, optionally, the noise cancellation module includes:
the received signal strength determining submodule is used for determining the strength of the acquired electric field signal and magnetic field signal;
a blanker threshold determination submodule for determining the peak-to-average power ratio R of the transmission signal based on the determined strengths of the electric field signal and the magnetic field signal and the settingTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: the noise-free magnetic field signal comprises an electric field signal and a magnetic field signal, wherein the electric field signal and the magnetic field signal contain noise, N is the sampling number, and the value range of k is 1,2, … … and N.
In the foregoing specific implementation of the ranging system based on adaptive delay estimation of received signal strength, optionally, the preliminary delay determination unit includes:
the received signal strength determining module is used for determining the strength of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
the communication distance preliminary determination module is used for preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
time delayA preliminary determination module for preliminarily determining an electromagnetic field time delay estimation value according to a relationship between a communication distance between ranging targets and an electromagnetic field time delay
In the foregoing specific implementation manner of the ranging system based on adaptive time delay estimation of received signal strength, optionally, the communication distance determining unit includes:
a delay initial value determining module for determining whenUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
A time delay final value determining module for determining the initial value of the time delay according to the determined electromagnetic fieldAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delay
A communication distance determining module for estimating a final value if the electromagnetic field time delayWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayDetermining a communication distance between ranging targets;
a return execution module for estimating the final value if the electromagnetic field time delayAnd returning to the noise elimination unit to continue executing when the change is continuous.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A ranging method based on adaptive time delay estimation of received signal strength is characterized by comprising the following steps:
s1: acquiring an electric field signal and a magnetic field signal, and eliminating noise in the electric field signal and the magnetic field signal;
s2: determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated, and preliminarily determining an electromagnetic field time delay estimation value;
s3: determining an initial electromagnetic field time delay value according to the preliminarily determined estimated electromagnetic field time delay value, processing the electric field signal and the magnetic field signal after removing the noise, and determining the communication distance between ranging targets; wherein,
said S1 previously comprising:
setting an initial value of electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The S1 includes:
transmitting the low-frequency signal through a transmitting terminal;
acquiring an electric field signal in the transmitting signal through an electric field receiving antenna and acquiring a magnetic field signal in the transmitting signal through a magnetic field receiving antenna;
eliminating noise in the electric field signal and the magnetic field signal by an adaptive threshold noise blanker;
respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces;
the eliminating noise in the electric field signal and the magnetic field signal by the adaptive threshold noise blanker comprises:
determining the strength of the acquired electric field signal and magnetic field signal;
according to the determined strength of the electric field signal and the magnetic field signal and the set peak-to-average power ratio R of the emission signalTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: the noise-free magnetic field signal comprises an electric field signal and a magnetic field signal, wherein the electric field signal and the magnetic field signal contain noise, N is the sampling number, and the value range of k is 1,2, … … and N.
2. The method according to claim 1, wherein the S2 includes:
determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
preliminarily determining an electromagnetic field time delay estimated value according to the relation between the communication distance between the ranging targets and the electromagnetic field time delay
3. The method according to claim 2, wherein the S3 includes:
when in useUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
According to determined initial value of electromagnetic field time delayAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delay
If the electromagnetic field time delay estimates the final valueWhen the constant value or the error is within a preset range, estimating a final value according to the electromagnetic field time delayDetermining a communication distance between ranging targets;
if the electromagnetic field time delay estimates the final valueAnd returning to the step S1 to continue the execution when the change is not constant.
4. A ranging system for adaptive delay estimation based on received signal strength, comprising:
the noise elimination unit is used for acquiring an electric field signal and a magnetic field signal and eliminating noise in the electric field signal and the magnetic field signal;
the time delay preliminary determination unit is used for determining the intensity of the electric field signal and the magnetic field signal after the noise is eliminated and preliminarily determining an electromagnetic field time delay estimation value;
the communication distance determining unit is used for determining an initial electromagnetic field time delay value according to the preliminarily determined electromagnetic field time delay estimated value, processing the electric field signal and the magnetic field signal after the noise is removed, and determining the communication distance between ranging targets; wherein,
the system further comprises:
an initialization unit for setting an initial value of the electromagnetic field time delayTime delay difference delta of electromagnetic fieldDNumber of samples N, peak-to-average power ratio R of transmitted signalTX；
The noise canceling unit includes:
the signal transmitting module is used for transmitting the low-frequency signal through the transmitting end;
the electric field signal receiving module is used for acquiring an electric field signal in the transmitting signal through an electric field receiving antenna;
the magnetic field signal receiving module is used for acquiring a magnetic field signal in the transmitting signal through the magnetic field receiving antenna;
a noise elimination module for eliminating noise in the electric field signal and the magnetic field signal through an adaptive threshold noise blanker;
the signal storage module is used for respectively storing the electric field signal and the magnetic field signal after the noise is eliminated into N storage spaces;
the noise canceling module includes:
the received signal strength determining submodule is used for determining the strength of the acquired electric field signal and magnetic field signal;
a blanker threshold determination submodule for determining the peak-to-average power ratio R of the transmission signal based on the determined strengths of the electric field signal and the magnetic field signal and the settingTXDetermining a threshold value B of the adaptive threshold noise blanker:
wherein E (| s (k) & gtY2) Which is indicative of the strength of the received signal,s (k) is a signal received by a receiving end, and s (k) includes: the noise-free magnetic field signal comprises an electric field signal and a magnetic field signal, wherein the electric field signal and the magnetic field signal contain noise, N is the sampling number, and the value range of k is 1,2, … … and N.
5. The system according to claim 4, wherein the preliminary delay determining unit comprises:
the received signal strength determining module is used for determining the strength of the electric field signal and the magnetic field signal after the noise is eliminated according to the stored electric field signal and the magnetic field signal;
the communication distance preliminary determination module is used for preliminarily determining the communication distance between ranging targets according to the propagation formula of the low-frequency signals and the strength of the electric field signals and the magnetic field signals after the noise is eliminated;
a time delay preliminary determination module for preliminarily determining an electromagnetic field time delay estimation value according to a relationship between a communication distance between ranging targets and an electromagnetic field time delay
6. The system according to claim 5, wherein the communication distance determining unit includes:
a delay initial value determining module for determining whenUpdating the initial value of the electromagnetic field time delay of the self-adaptive time delay estimation moduleWhen in useElectromagnetic field time delay initial value of non-updating self-adaptive time delay estimation module
A time delay final value determining module for determining the initial value of the time delay according to the determined electromagnetic fieldAnd processing the electric field signal and the magnetic field signal after the noise is eliminated by using a self-adaptive time delay estimation module to determine an electromagnetic field time delay estimation final valueAnd updating the initial value of the electromagnetic field time delay
A communication distance determining module for estimating a final value if the electromagnetic field time delayWhen the constant value or the error is within the preset range, the value is determined according to the valueThe estimated final value of electromagnetic field time delayDetermining a communication distance between ranging targets;
a return execution module for estimating the final value if the electromagnetic field time delayAnd returning to the noise elimination unit to continue executing when the change is continuous.
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