KR101647946B1 - A positioning apparatus and a positioning method - Google Patents

Abstract

To a positioning apparatus and a positioning method for increasing accuracy of position information by removing noise from the received satellite signal and performing correction on the calculated position coordinates. According to an embodiment of the present invention, there is provided an information processing apparatus including an interference eliminating unit for removing noise of a satellite signal received from a positioning satellite, a position analyzing unit for calculating a user's current position coordinate based on the noise- A direction vector calculating unit for calculating a direction vector with reference to coordinates, and a coordinate correcting unit for performing correction on the current position coordinates based on the direction vector, wherein the interference eliminating unit corrects the received satellite signal by a discrete wavelet transform A wavelet coefficient for each frequency band is calculated, a predetermined threshold value is compared with the wavelet coefficient, the wavelet coefficient is changed according to the comparison result, and inverse discrete wavelet transform is performed on the changed wavelet coefficient, And generates a satellite signal that has been removed .

Description

[0001] The present invention relates to a positioning apparatus and a positioning method,

The present invention relates to a positioning apparatus and method, and more particularly, to a positioning apparatus and a positioning method for improving accuracy of position information by removing noise from a received satellite signal and performing correction on the calculated position coordinates.

As communication and networking technologies are improved, location based services are rapidly evolving. Location-based services refer to all types of services related to the collection, use, and provision of location information, and provide useful functions to users based on location information obtained through a communication network or GPS.

The most important aspect of location-based services is to accurately locate the user or terminal. In recent years, not only satellite signals such as GPS, but also integrated positioning technology using a short distance wireless communication network such as WiFi and Bluetooth have been developed and used to improve the accuracy of location information in shadow areas that positioning satellites can not cover.

On the other hand, the measured position coordinates can contain an error depending on the arrangement state of the positioning satellites, the characteristics of the place where the positioning object exists, and the like. In the case of performing positioning using GPS, the accuracy of the position information can be changed by the number of GPS satellites or the interval between satellites that can smoothly communicate with the positioning target. Especially, when the position information of the positioning object is grasped by the GPS in the urban area, there is a high possibility that the error occurs due to the multipath phenomenon which occurs when the signal is reflected or refracted by the building. Since the satellite signal itself may include various noise in the process of receiving the radio wave, it needs to be prepared. When satellite information and position coordinates containing noise and error are used as they are, there is room for generating various problems in accurate positioning of the positioning object, and additional processing steps are required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an object of providing accurate position coordinates to a user.

According to an aspect of the present invention, there is provided an apparatus for removing interference from a satellite signal received from a positioning satellite. A position analyzer for calculating a current position coordinate of a user based on the noise canceled satellite signal; A direction vector calculating unit for calculating a direction vector with reference to a plurality of previous position coordinates; And a coordinate correcting unit for performing a correction on the current position coordinate based on the direction vector; Wherein the interference elimination unit discrete wavelet transforms the received satellite signal to calculate a wavelet coefficient for each frequency band, compares the predetermined threshold with the wavelet coefficient, The wavelet coefficient is changed, and an inverse discrete wavelet transform is performed on the changed wavelet coefficient to generate a satellite signal from which the noise is removed.

According to another embodiment of the present invention, there is provided a method of detecting a satellite signal, comprising: removing noise of a satellite signal received from a positioning satellite; Calculating a current position coordinate of a user based on the noise canceled satellite signal; Calculating a direction vector with reference to a plurality of previous position coordinates; And performing a correction on the current position coordinate based on the direction vector; Wherein the step of removing the noise includes performing a discrete wavelet transform on the received satellite signal to calculate a wavelet coefficient for each frequency band, comparing the predetermined threshold with the wavelet coefficient, Wherein the step of generating a satellite signal from which noise is removed by performing inverse discrete wavelet transform on the changed wavelet coefficient and calculating the direction vector includes selecting the plurality of previous position coordinates as reference coordinates , A position vector for the remaining reference coordinates is obtained with the oldest coordinate as a reference point among the selected reference coordinates in chronological order, and the direction vector is calculated by combining the position vectors .

According to the present invention, the noise included in the satellite signal can be effectively reduced.

In addition, according to the embodiment of the present invention, accurate position information can be provided to a user by correcting an error of position coordinates.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a state in which a positioning apparatus is located using an integrated positioning system. FIG.
2 is a diagram showing an embodiment of a positioning apparatus according to the present invention.
3 is a diagram illustrating a wavelet transform process.
4 is a diagram illustrating an embodiment of a noise reduction method according to the present invention.
5 is a diagram illustrating a method of selecting reference coordinates among the previously received coordinates.
6 is a diagram showing a method of obtaining a direction vector by combining position vectors and correcting the current coordinates in the direction of a direction vector.
7 is a diagram illustrating a correction method for the current position coordinates according to the present invention.
8 is a diagram showing a positioning method according to the present invention.

The present invention relates to a positioning apparatus and a positioning method for enhancing accuracy of position information by removing noise from a received satellite signal and performing correction on the calculated position coordinates, and more particularly, I will explain.

FIG. 1 is a view showing a state in which the position of the positioning apparatus 100 is grasped using an integrated positioning system.

1, the integrated positioning system 200 may include a positioning satellite 210 and a short-range wireless communication network 220 and other wireless communication networks 230 using WiFi or Bluetooth. Here, the positioning satellite 210 may use at least one of GPS, QZSS, and GLONASS, and the other wireless communication network 230 may include various communication methods such as 3G, 4G, and the like.

The positioning apparatus 100 can receive the position coordinates directly from the positioning satellites 210 of the integrated positioning system 200 and determine the position of the positioning apparatus 100. [ However, when the positioning apparatus 100 exists inside the building, smooth communication with the positioning satellites 210 may not be possible. When information on the actual location of WiFi APs (Access Points) existing in the building is stored in a database, the positioning device 100 transmits the information of the database and the strength of signals transmitted from a plurality of WiFi APs Strength Indicator) can be used to specify the position in the building by coordinates.

However, the coordinate information transmitted from the integrated positioning system 200 basically includes a distance error. In the case of positioning using GPS satellites, multipath problems frequently occur due to reflection of signals by buildings, and the positioning accuracy varies depending on the distance between GPS satellites and GPS satellites capable of smooth communication at the time of positioning. Indoor positioning via WiFi also has multipath problems, and indoor space with limited number of WiFi APs is limited to accurate indoor positioning.

That is, when the coordinate information transmitted from the integrated positioning system 200 is used without correction, the noise included in the satellite signal and the measured positional error contained in the calculated positional coordinates cause accurate positioning of the positioning apparatus 100 This is not easy. However, according to the present invention, it is possible to provide a pre-processing method for satellite signals and a post-processing method for calculated position coordinates to solve the above problems.

2 is a diagram showing an embodiment of a positioning apparatus 100 according to the present invention.

2, the positioning apparatus 100 may include an interference eliminator 110, a position analyzing unit 120, a direction vector calculating unit 130, and a coordinate correcting unit 140. In addition, the positioning apparatus 100 may further include a storage unit 150, a communication unit 160, and an output unit 170. According to the embodiment, the direction vector calculating unit 130 and the coordinate correcting unit 140 may be provided as one component, and some components may be omitted. In this case, each of the components may exist in the form of hardware such as a physical circuit or an electronic component, may exist in the form of software such as a program, or may be configured as a mixture of hardware and software.

The interference canceller 110 may remove the noise of the satellite signal received from the positioning satellite. When noise is included in the satellite signal, the positioning apparatus 100 receiving the signal can calculate the wrong position coordinates, and time and energy may be wasted due to retransmission of the signal. By removing noise from the satellite signal, interference with the positioning data contained in the satellite signal can be mitigated and by improving the bit error rate (BER) performance of the data, the positioning apparatus 100 obtains highly reliable position coordinates .

There are various ways to remove noise from satellite signals. 2, the interference eliminator 110 includes a Discrete Wavelet Transform module 112, a noise cancellation filter module 114, and an Inverse Discrete Wavelet Transform module 116 . The discrete wavelet transform module 112 can perform discrete wavelet transform of the received satellite signals to calculate the wavelet coefficients of each frequency band. The noise removal filter module 114 may change the wavelet coefficient by comparing the wavelet coefficient with a predetermined threshold value. The inverse discrete wavelet transform module 116 may convert the changed wavelet coefficients back into satellite signals. The interference canceller 110 may remove noise from the satellite signal by including each of the modules, but is not limited thereto. Each module constituting the interference eliminator 110 of FIG. 2 is shown for the convenience of illustration and is not limited thereto. Each module of the interference canceller 110 may exist as one component, and each module may exist in the form of at least one of software and hardware. The wavelet transform and the noise cancellation method will be described in detail with reference to FIGS. 3 to 4.

The interference eliminator 110 is not limited to the noise elimination of the satellite signal and may also remove the noise of the location information received from the local area wireless communication network 220 and the wireless communication network 230 of FIG.

The position analyzer 120 may calculate the current position coordinates of the user based on the satellite signal from which the noise is removed. The location analyzer 120 may also use the location information received from the local area wireless communication network 220 and the other wireless communication network 230 of FIG. 1 when calculating the current location coordinates.

Preferably, the position analyzer 120 can calculate the position coordinates based on the carrier phase, pseudorange, satellite orbit information, clock error, and ionospheric error correction parameters included in the satellite signal, but is not limited thereto. The position analyzer 120 can determine the position of the positioning apparatus 100 through a WiFi, a Bluetooth AP position, and a trilateration method using RSSI (Received Signal Strength Indicator).

The direction vector calculation unit 130 may calculate a direction vector with reference to a plurality of previous position coordinates. As described above, the position coordinates calculated from the positional information of various positioning systems may include errors, and therefore need to be corrected. The positioning apparatus 100 according to the present invention can correct the current position coordinates using previously received position coordinates. In particular, the positioning apparatus 100 can estimate the correct position of the current position coordinate using the vector between the previous position coordinates, but is not limited thereto.

The direction vector calculation unit 130 may include a reference coordinate selection module 132, a position vector calculation module 134, and a direction vector calculation module 136. The reference coordinate selection module 132 may select some of the previous position coordinates as reference coordinates. The position vector calculation module 134 may calculate the vector between the reference coordinates and the direction vector calculation module 136 may calculate the direction vector using the vectors calculated in the position vector calculation module 134. [ The selection of reference coordinates, the position vector and the direction vector will be discussed in detail in the description of Figs. 5 to 7.

The coordinate correction unit 140 may perform correction on the current position coordinate based on the direction vector. The specific correction method will be described in detail with reference to FIG.

The storage unit 150 may store the position coordinates received from the positioning satellites, the position information received from the external wireless communication network, and the processing result data of the respective components of the positioning apparatus 100. In particular, the storage unit 150 may store both the position coordinates corrected by the coordinate correction unit 140 and the position coordinates not corrected. The aforementioned reference coordinate selection module 132 may use the previous position coordinates stored in the storage unit 150. [

The communication unit 160 can communicate with positioning satellites, short range wireless communication, and other wireless communication networks and can transmit and receive various information necessary for positioning. The communication unit 160 can evaluate the accuracy of the position coordinates. The communication unit 160 may measure the RSSI of the signal transmitted from the WiFi and the Bluetooth AP, and may determine whether the value of the RSSI is included in the predetermined range and evaluate the accuracy of the signal. Also, the communication unit 160 can derive the accuracy of the satellite signal through DOP (Dilution of Precision). The DOP is a value generated differently according to the positional relationship between a plurality of positioning satellites used in positioning, and can be calculated from information received from each positioning satellite. However, the method for evaluating the accuracy of the position coordinates in the communication unit 160 is not limited to this. In addition, the accuracy evaluation of the position coordinates may be performed in the position analyzer 120, the direction vector calculator 130, and the coordinate corrector 140. [

The output unit 170 can output various information received by the positioning apparatus 100 or generated by the positioning apparatus 100 through light or sound. Preferably, the output unit 170 may output the current position of the user as an image through means such as a display module, but is not limited thereto.

3 is a diagram illustrating a wavelet transform process.

As described above, the discrete wavelet transform module of interference elimination of the positioning apparatus can perform discrete wavelet transform on the received satellite signals, and thereby calculate the wavelet coefficients. Generally, wavelet transform is used when performing time-frequency analysis of a signal. Unlike a short-time Fourier transform (STFT) having a fixed time window length, wavelet transform is performed by performing time-frequency analysis at various scales can do. In other words, unlike Fourier transform and STFT, wavelet transform has multiple decomposition properties for time and frequency domain. Therefore, it is possible to estimate accurate noise generation location by analyzing various interference elements while maintaining the original signal waveform .

The discrete wavelet transform can separate the signal into an approximation signal and a detail signal through the following Equations 1 and 2.

(T) denotes a wavelet function, k denotes a translation parameter in the time axis, N denotes a degree, _ck and _tk (t) denote a scaling function in the equations (1) h _k represents the wavelet coefficient. A wavelet coefficient corresponding to a signal of a specific band can be obtained through a combination of the scaling function and the wavelet function. In particular, the frequency band to be analyzed can be easily selected according to the change of the scaling function. That is, if the scaling function has a large value, it is possible to analyze the approximate signal of the signal, and the overall contour of the signal, that is, the low-frequency component can be analyzed. On the contrary, if the scaling function has a small value, it is possible to analyze the detailed signal of the signal, and it is possible to analyze the detailed change of the signal, that is, the high frequency component. The scaling function can be operated as a bandpass filter. It can be said that the above-mentioned approximate signal corresponds to the low frequency band of the original signal and the detailed signal corresponds to the high frequency band.

In Fig. 3, the original signal is denoted as sig0. The original signal can be divided into a first approximate signal sig1L and a first detailed signal sig1H according to the value of the scaling function. Then, the first approximation signal sig1L can be separated into the second approximation signal sig2L and the second detailed signal sig2H again. Also, the second approximation signal sig2L can be separated into the third approximation signal sig3L and the third detailed signal sig3H again. When each signal is separated into an approximate signal and a detailed signal, the frequency band of the signal is divided into the high frequency band and the low frequency band, and the wavelet coefficient of the corresponding band can be calculated. Generally, when performing discrete wavelet transform, the approximate signal and detailed signal analysis for the original signal are analyzed three times, that is, in three stages. By appropriately using the combination of the scaling function and the wavelet function, the characteristics of the original signal sig0 can be easily grasped with a desired time-frequency resolution.

4 is a diagram illustrating an embodiment of a noise reduction method according to the present invention. In the graph of FIG. 4, the horizontal axis represents the numbering of each subband arranged in the order of low frequency to high frequency, and the vertical axis represents the size of the wavelet coefficient corresponding to each subband. Each subband is divided into vertical dashed lines. In FIG. 4, the lambda (?) Denotes a predetermined threshold value, and the positive threshold value and the negative threshold value are indicated by a dotted line. In the area of each subband, the white square represents the wavelet coefficient value before the change, and the black square adjacent thereto represents the wavelet coefficient value after the change.

The noise cancellation filter module of the interference cancellation according to the embodiment of the present invention may compare the predetermined threshold value with the wavelet coefficient and change the wavelet coefficient according to the comparison result. Preferably, the interference canceller subtracts the threshold value from the wavelet coefficient when the wavelet coefficient is greater than or equal to a predetermined threshold value, replaces the wavelet coefficient with 0 if the absolute value of the wavelet coefficient is less than a predetermined threshold value, And adding the threshold value to the wavelet coefficient when the set threshold value is equal to or less than a value obtained by taking a negative sign. The threshold may be a real number greater than or equal to zero. This can be summarized as the following equation.

은 변화된 후의 웨이블릿 계수이고 ω은 변화되기 전의 웨이블릿 계수이며 λ는 기 설정된 임계값을 나타낸다. 하지만 임계값의 변화 방식은 위의 수학식에 한정되지 않으며 다양한 방식으로 구비될 수 있다.In Equation 3,

Is the wavelet coefficient after the change,? Is the wavelet coefficient before the change, and? Represents the predetermined threshold value. However, the method of changing the threshold value is not limited to the above equation and can be provided in various ways.

In Fig. 4, the wavelet coefficients before the change of the subbands 0, 3, and 5 are replaced with 0 because their absolute values are less than the threshold value. In the case of sub-bands 1, 4, 6, and 7, the wavelet coefficient before the change was changed to a value obtained by subtracting the threshold value from the original wavelet coefficient since the absolute value thereof was larger than the threshold value. In the case of subband 2, the wavelet coefficient before the change is less than the value obtained by subtracting the negative sign from the threshold value, so that the original wavelet coefficient is changed to a value obtained by adding the threshold value. As a result, the absolute value of each wavelet coefficient is reduced by the magnitude corresponding to the absolute value of the threshold value over the entire band, and may be changed to 0, in particular, when the absolute value of the wavelet coefficient is smaller than the absolute value of the threshold value. This may be due to the fact that the noise that may be included in the satellite signal is evenly distributed over a whole frequency band to a value less than a certain size.

The noise cancellation performance of the interference cancellation may be changed according to the predetermined threshold value. Preferably, the predetermined threshold value may be changed according to characteristics of the received satellite signal. That is, the threshold value changes according to the reception environment of the satellite signal, so that the interference can be efficiently mitigated. In particular, the predetermined threshold may be calculated from the estimated standard deviation of the noise included in the received satellite signal corresponding to the length of the sample and the length of the sample used in the discrete wavelet transform of the received satellite signal . This can be expressed as follows.

In Equation (4), lambda is a threshold value, sigma is an estimated standard deviation of noise contained in the satellite signal, and N is the length of a sample used in the discrete wavelet transform. The equation of the threshold value in the above equation (4) is only one embodiment, and the formula for deriving the threshold value is not limited to the above equation.

5 is a diagram illustrating a method of selecting reference coordinates among the previously received coordinates.

The reference coordinates may be used to calculate a position vector between each position coordinate, which is specifically selected among the position coordinates received in the past.

The received position coordinates can be corrected in accordance with the manner described in Fig. 6, wherein the above-mentioned storage unit can store both the corrected position coordinates and the uncorrected position coordinates. The reference coordinate selection module of the direction vector calculation unit may use the previous position coordinates stored in the storage unit, and when the reference coordinates are selected from the previous position coordinates, the previous position coordinates not corrected and the position coordinates You can choose either one.

The reference coordinate selection module can select reference coordinates through various methods. According to one embodiment, the selected reference coordinates may be a certain number of coordinates that are close in time order from the current position coordinates. Fig. 5 (a) shows a method of selecting five reference coordinates close in time order from the current position coordinates. If the G coordinate at the time t ₆ indicated by the black box is the current coordinate, a specific number of coordinates of the current previous coordinates are selected in order to correct the current coordinates. In this case, Is selected. In FIG. 5 (a), the C-coordinate at the time point t ₂ is a coordinate determined to have a very low accuracy according to the above-described accuracy evaluation method. In this case, instead of selecting B, C, D, E, F at t ₆ , the reference coordinate selection module may choose to omit C and choose A instead.

According to another embodiment, the selected reference coordinates may be position coordinates collected during a time period in which the current position coordinate is the end point and the current position coordinate is the time point before the predetermined time from the received time have. In FIG. 5 (b), T is a preset time interval for selecting reference coordinates, and the reference coordinate selection module can use all the position coordinates belonging to the T section as reference coordinates. The interval TA indicated by the one-dot chain line in FIG. 5B is used at the time t ₅ , the interval TB indicated by the two-dot chain line is used at the time t ₆ , and the interval TC indicated by the broken line is used at the time t ₇ Lt; / RTI >

However, the above-described two methods are merely an example of a method of selecting reference coordinates in the reference coordinate selection module and are not limited to the above-described method.

On the other hand, the direction vector used for the coordinate correction is calculated from the combination of the position vectors. When calculating the position vector, by using temporally adjacent coordinates in the current coordinates, the tendency change of the moving direction and the moving distance of the positioning object is reflected Coordinate correction is possible.

In the reference coordinate selection method described above, the number of specific coordinates and the specific time period are not fixed and can be set differently according to the mode of the positioning apparatus. If the positioning apparatus is operated in a mode that emphasizes the directionality of each point in the positioning target, the number of reference coordinates may be reduced or the time interval may be shortened to increase sensitivity to each point of view. In the opposite case, when the positioning device tracks a gentle curved tracking line, the number of reference coordinates can be increased or the time interval can be adjusted to be long.

On the other hand, the reference coordinates may be determined based on the moving speed of the user. The communication unit described above can grasp the position coordinate and the time at which the position information is received. Thus, the positioning apparatus can calculate the traveling speed of the positioning apparatus user from the received position coordinates and position information and each received time. The reference coordinate selection module can easily estimate the position coordinates corresponding to the current situation of the user by adjusting the number of reference coordinates based on the moving speed of the user. Preferably, the number of the reference coordinates to be selected may be determined based on the moving speed of the user. In addition, if the moving speed of the user increases, the number of reference coordinates increases, and when the moving speed of the user decreases, the number of reference coordinates decreases, but the present invention is not limited thereto. In the case where the reference coordinate selection module operates according to the above-described method, by using a smaller number of reference coordinates when the moving speed of the user is decreased, a position vector and a direction vector sensitive to the change of the user's direction are calculated have.

When the reference coordinate selection process for the previous coordinates is completed, the position vector calculation module can calculate the position vector from the selected reference coordinates. Referring back to FIG. 5 (b), is from time t ₇ the five coordinates C, D, E, F, G may be selected as the reference coordinates. In this case, the position vector calculation module can obtain vectors for the remaining D, E, F, and G coordinates based on the C coordinate, which is the oldest coordinate in time order. That is, the position vector at time t ₇ is CD, CE, CF, and CG. The calculated position vectors can be sent to the direction vector calculation module to obtain the direction vector. The direction vector calculation module calculates a direction vector in a direction in which the position coordinates of the current point are estimated to exist from the combination of the received position vectors. 6 is a diagram showing a method of obtaining a direction vector by combining position vectors and correcting the current coordinates in the direction of a direction vector.

In Fig. 6, the position vector is indicated by a solid line arrow, the direction vector is indicated by a dotted line, and a new direction vector calculated from a weighted position vector is indicated by a one-dot chain line.

6 AF1 direction vector of the time t ₅ in (a) is calculated on the basis of the magnitude and direction of the respective position vector AB1, AC1, AD1, AE1. The direction vector AF1 may be obtained by summing the position vectors, but is not limited thereto. When the direction vector AF1 is calculated, a correction for moving the current position coordinate (F) to the direction vector AF1 by the coordinate correcting unit can be performed. There may be various ways of correcting the current position coordinate (F) to AF1. According to a preferred embodiment, the current position coordinates can be shifted to a point F 'closest to the current position coordinate F among the points on the straight line calculated using the oldest reference coordinate A and the direction vector AF1 have.

In this way, it is possible to correct the moving direction of the positioning target through the current position coordinate correction. By using the position vector of the latest coordinate information among the accumulated past coordinate information, the influence of the error included in each coordinate information can be minimized have.

On the other hand, according to the above description, the communication unit can evaluate the accuracy of the received coordinates. The evaluation of the accuracy can also be performed by other components of the positioning apparatus, that is, the interference eliminating unit, the position analyzing unit, the direction vector calculating unit, and the coordinate correcting unit. On the other hand, the direction vector calculator can calculate the weight of each reference coordinate based on the accuracy information of the reference coordinates, and apply the weight of the corresponding reference coordinate to each position vector. When the direction vector is calculated by using the weighted position vector, the influence of the reference coordinate with low accuracy on the calculation of the direction vector can be reduced and the influence of the reference coordinate having high accuracy on the calculation of the direction vector can be increased, The positioning apparatus can more accurately perform correction for the current position coordinates. 6 (b) shows a state in which a direction vector is obtained using a weighted position vector and the current position coordinates are moved in the direction of the direction vector. In Fig. 6 (b), the weighted position vectors that go from the oldest reference coordinate A to the remaining reference coordinate directions are AB2, AC2, AD2, and AE2, respectively. And a new direction vector AF2 can be calculated from the combination of the weighted position vectors. It is possible to perform the correction to which the accuracy of the position coordinates is applied by moving the current position coordinate (F) to F '' above the new direction vector AF2.

7 is a diagram illustrating a correction method for the current position coordinates according to the present invention. The reference coordinates selected with the passage of time are different, so that the position vector and the direction vector can also be changed.

In FIG. 7, the circles on the solid line are the previous position coordinates that have not been corrected, and the circles on the dotted line are the corrected previous position coordinates. Each position coordinate has an alphabetical letter, and position coordinates are received in alphabetical order. In FIG. 7, the current position coordinates are indicated by black circles, and the corrected coordinates of the current position coordinates are indicated by a ring of dotted lines. In FIG. 7, a thin solid arrow indicates a position vector to which a weight is not applied, a thick solid arrow indicates a position vector to which a weight is applied, and a one-dot chain line is a direction vector calculated from a weighted position vector.

According to Fig. 7, the reference coordinates can be selected from the previous position coordinates that are not corrected. When the uncorrected previous position coordinates are selected, the accuracy information of the original position coordinates can be used as it is. However, it is not limited to this, and the corrected previous position coordinates may be used as reference coordinates.

In FIG. 7 (a), the reference coordinates are A, B, C, D, and E, and the oldest reference coordinate is A. Thus, the position vector AB, AC, AD, and AE can be obtained, and the direction vector AF 'can be obtained by using a weighted position vector according to the accuracy of the reference coordinates B, C, D, Since the reference coordinate B has a high accuracy, the position vector AB is increased in size by adding a weight of 1 or more. Since the reference coordinate C has low accuracy, the position vector AC is reduced in size by adding a weight of 1 or less. The position vectors of the remaining reference coordinates may also be changed in size by adding a weight according to the accuracy of each coordinate. If the direction vector is calculated through the above process, correction for moving the current position coordinates over the direction vector can be performed. Accordingly, the current position coordinate F can be corrected to the position of F '.

In FIG. 7 (b), reference coordinates are B, C, D, E and F, and reference coordinates in FIG. 7 (c) are C, D, E, A weighted position vector can be obtained based on each reference coordinate, each direction vector can be calculated from a weighted position vector, and the corrected current position coordinates G 'and H' can be obtained as a result.

8 is a diagram showing a positioning method according to the present invention. 8, a positioning method according to an embodiment of the present invention includes a step of removing a noise of a satellite signal received from a positioning satellite (S110), a step of obtaining a positional information (S130) of calculating a direction vector by referring to a plurality of previous position coordinates, and performing a correction on the current position coordinate based on the direction vector (S140).

The step of removing the noise of the satellite signal (S110) comprises a step of performing discrete wavelet transform on the received satellite signal to calculate wavelet coefficients for each frequency band, comparing the predetermined threshold with the wavelet coefficients, And the inverse discrete wavelet transform is performed on the changed wavelet coefficient to generate a satellite signal from which noise has been removed. At this time, the predetermined threshold value may be changed according to the characteristics of the received satellite signal. Preferably, the predetermined threshold value can be calculated from the estimated standard deviation of the noise contained in the received satellite signal corresponding to the length of the sample and the length of the sample used when wavelet-transforming the received satellite signal .

A method of eliminating noise in a step (S110) of removing noise of a satellite signal, comprising: subtracting the threshold value from the wavelet coefficient when the wavelet coefficient is equal to or greater than the preset threshold value; The wavelet coefficient is replaced with 0 and the threshold value is added to the wavelet coefficient when the wavelet coefficient is less than or equal to the value obtained by subtracting the negative value from the threshold value.

The step of calculating the current position coordinates of the user (S120) can grasp the position of the user based on the position information transmitted from the positioning satellite and the external communication network. At this time, the positioning satellite may be at least one of GPS, QZSS, and GLONASS, and the external communication network may be a short-range wireless communication network including at least one of WiFi and Bluetooth.

The step of calculating a direction vector S130 may include selecting the plurality of previous position coordinates as reference coordinates and obtaining a position vector for the remaining reference coordinates with the oldest coordinate as a reference point in time order among the selected reference coordinates, The direction vectors may be calculated by combining the position vectors. At this time, when selecting the reference coordinates, it is possible to select any of the previous position coordinates that have not been corrected and the position coordinates to which the correction has been performed. In the method of selecting reference coordinates, the selected reference coordinates may be a certain number of coordinates that are close in time order from the current position coordinates. Alternatively, the selected reference coordinates may be position coordinates collected during a time period in which the current position coordinate is the end point and the current position coordinate is a time point before the preset time from the received time. In addition, the number of reference coordinates can be determined based on the moving speed of the user. In this case, when the moving speed of the user increases, the number of reference coordinates increases and the moving speed of the user decreases The number of selected reference coordinates can be reduced.

Meanwhile, the step of calculating the direction vector (S130) may calculate the weights of the respective reference coordinates based on the accuracy information of the reference coordinates, and apply the weights of the corresponding reference coordinates to the respective position vectors.

The step of performing the correction on the current position coordinate (S140) may include moving the current position coordinate to a point closest to the current position coordinate among the points on the straight line calculated using the oldest reference coordinate and the direction vector have.

Through the above process, the noise included in the original satellite signal can be removed, and the error included in the calculated position coordinates can be reduced to provide the user with accurate current position coordinates.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, 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. Accordingly, it is to be understood that within the scope of the appended claims, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

100: Positioning device
110: Interference elimination
120: Position analysis section
130: direction vector calculating unit
140:

Claims (13)

A positioning apparatus for measuring a position of a user,
An interference eliminator for canceling a noise of a satellite signal received from a positioning satellite;
A position analyzer for calculating the current position coordinates of the user based on the satellite signal from which the noise is removed and the position information received from the external communication network;
A direction vector calculating unit for calculating a direction vector with reference to a plurality of previous position coordinates; And
A coordinate correcting unit for performing a correction on the current position coordinate based on the direction vector; Lt; / RTI >
The direction vector calculation unit calculates,
Selecting the plurality of previous position coordinates as reference coordinates, and calculating the direction vector based on the selected reference coordinates,
When the positioning apparatus operates in a first mode in which the directionality of the user is emphasized at each point in time,
Decreasing a predetermined time interval that is a reference when the reference coordinates are selected from the number of reference coordinates and the plurality of previous position coordinates,
When the positioning apparatus is operated in a second mode in which the user's movement tendency is emphasized,
And increases the number of the reference coordinates and the predetermined time interval. The method according to claim 1,
Wherein,
Calculating a wavelet coefficient for each frequency band by performing discrete wavelet transform on the received satellite signal,
Compares the predetermined threshold with the wavelet coefficient, changes the wavelet coefficient according to the comparison result,
Performing inverse discrete wavelet transform on the changed wavelet coefficients to generate a noise-removed satellite signal,
Wherein the predetermined threshold is changed according to a characteristic of the received satellite signal. 3. The method of claim 2,
The predetermined threshold value may be a predetermined threshold value,
And the estimated standard deviation of the noise included in the received satellite signal corresponding to the length of the sample and the length of the sample used in the discrete wavelet transform of the received satellite signal. 3. The method of claim 2,
Wherein,
Subtracting the threshold value from the wavelet coefficient when the wavelet coefficient is greater than or equal to the preset threshold value,
And replacing the wavelet coefficient by 0 when the absolute value of the wavelet coefficient is less than the preset threshold value,
And adds the threshold value to the wavelet coefficient when the wavelet coefficient is equal to or less than a value obtained by subtracting the negative sign from the preset threshold value. The method according to claim 1,
The direction vector calculation unit calculates,
Wherein a position vector of the remaining reference coordinates is obtained with the oldest reference coordinate as a reference point among the selected reference coordinates in chronological order, and the direction vector is calculated by combining the position vectors. 6. The method of claim 5,
The direction vector calculation unit calculates,
Calculating a weight of each of the reference coordinates based on the accuracy information of the reference coordinates,
And applies the weight of the corresponding reference coordinate to each of the position vectors. 6. The method of claim 5,
The correction for the current position coordinate is performed by:
Wherein the current position coordinate is a correction that moves the current position coordinate to a point closest to the current position coordinate among the points on the straight line calculated using the oldest reference coordinate and direction vector. 6. The method of claim 5,
When selecting the reference coordinates,
And selects any one of the previous position coordinates that have not been corrected and the position coordinates that have been corrected. 6. The method of claim 5,
Wherein the selected reference coordinates are a predetermined number of coordinates that are close in time order from the current position coordinates. 6. The method of claim 5,
Wherein the selected reference coordinates are position coordinates collected during a time period in which a time at which a current position coordinate is received is an end point and a time before a preset time from a time at which the current position coordinate is received is a starting point. 6. The method of claim 5,
Wherein the selection number of the reference coordinates is determined based on the moving speed of the user. 12. The method of claim 11,
Wherein the selection number of the reference coordinates increases as the movement speed of the user increases and the selection number of the reference coordinates decreases as the movement speed of the user decreases. Removing noise of a satellite signal received from a positioning satellite;
Calculating coordinates of a user's current position based on the noise-removed satellite signal and position information received from an external communication network;
Calculating a direction vector with reference to a plurality of previous position coordinates; And
Performing a correction on the current position coordinate based on the direction vector; , ≪ / RTI &
Wherein the calculating the direction vector comprises:
Selecting the plurality of previous position coordinates as reference coordinates, and calculating the direction vector based on the selected reference coordinates,
When the positioning apparatus is operated in the first mode in which the directionality of the user is emphasized at each point in time,
Decreasing a predetermined time interval that is a reference when the reference coordinates are selected from the number of reference coordinates and the plurality of previous position coordinates,
When the positioning apparatus is operated in a second mode in which the user's movement tendency is emphasized,
And the number of reference coordinates and the predetermined time interval are increased.

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