KR20000039395A - Receive device and method of gps - Google Patents

Abstract

PURPOSE: A receive device and a method of GPS are provided to assure a line of sight and reduce error due to multiple path by using a time diversity method used in CDMA communication system to measure a position. CONSTITUTION: A receive device of GPS comprises an initial value measurement unit(310), a power value calculation unit and a navigation data process unit(330). The initial value measurement unit(310) measures initial values of time offset values in receive signals having signal strength higher than predetermined threshold value. The power value calculation unit calculates maximum power value of the receive signals in real time by using the initial values. The navigation data process unit(330) receives the maximum power value to calculate the power ratio of the receive signals and searches a present position using the calculated power ratio.

Description

Receiving device and method of positioning system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus and a method of a global positioning system (GPS), and in particular, to use a time diversity technique used in a code division multiple access (CDMA) communication system. The present invention relates to a receiving apparatus capable of measuring a position thereof and a method thereof.

Since the strength of the signal received by a satellite navigation system such as GPS is very weak at about -130 dBm, when the line of sight (LOS) is not secured, the signal itself is not caught and the satellite is relatively low. Since it is caught at a high elevation angle, the visibility is always secured, so there is no problem even if the user is not concerned about the error due to the multipath.

Even when using the same signal system and positioning method as GPS, when constructing a navigation system on the ground, it is required to receive a signal having a lower elevation than the satellite, and the influence of the reflected wave by the ground surface is relatively large, especially in urban areas. In most cases, it is relatively difficult to secure four or more positioning base stations in the visible range in most regions.

Therefore, a technical problem arises that the positioning signals coming from the multipath must be applied to the navigation solution of the navigation algorithm.

There are two methods for obtaining the navigation solution in the conventional GPS, the first is the Least Square Method and the second is Kalman Filtering.

Referring to Figs. 1 and 2, a conventional GPS receiver will be described.

1 is a block diagram of a receiver of a conventional positioning system, which includes a low noise amplifier 110, a signal conversion and sampling unit 120, delay lock loops 131 to 13n, navigation solution calculation, and pseudo distance. Compensation unit 140 is configured.

Referring to the operation of the receiving device of the conventional position measuring system having such a structure as follows.

The low noise amplifier 110 amplifies the signal received through the antenna into a signal of sufficient size and transmits the signal to the signal conversion and sampling unit 120.

The signal conversion and sampling unit 120 down-converts the signal transmitted from the low noise amplifier 110 to a baseband signal, and then samples the down-converted miracle band signal to be processed as a digital signal to delay delay loop (DLL). Ddelay Lock Loops) (131 to 13n).

The delay locked loops 131 to 13n respectively calculate and demodulate the demodulated signal by demodulating the signal transmitted from the signal conversion and sampling unit 120 so that the maximum output of the received signal is obtained by using a pseudo noise code generated therein. And to pass to the pseudo-range correction unit 140.

The navigation solution calculation and pseudo-range correction unit 140 receives the output signals of the delay lock loops 131 to 13n to derive the navigation data and the delay time information, and the signals of the differential global positioning system (DGPS). If present, pseudo range correction is also performed.

In addition, the navigation solution calculation and pseudo-range correction unit 140 obtains the navigation solution by the least square method or the Kalman filter method through the navigation data obtained as described above.

FIG. 2 is a block diagram of the delay lock loop of FIG. 1 and includes a pseudo noise code generator 151, a delay unit 152, a multiplier 153, and an integrator 154.

The operation of the delay locked loop of FIG. 1 having such a structure will now be described.

The delay unit 152 delays the pseudo noise code generated from the pseudo noise code generator 151 to the multiplier 153 for a predetermined time.

The multiplier 153 multiplies the output signal of the signal conversion and sampling unit 120 and the pseudo noise code transmitted through the delay unit 152 to the integrator 154, and then the integrator 154 is a multiplier ( The multiplication value of 153 is integrated and output to the navigation solution calculation and pseudo range correction unit 140.

In general, GPS satellites send signals to Earth with spread spectrum signals, each with an assigned pseudonoise code.

Then, this signal is transmitted to the signal conversion and sampling unit 120 through the antenna and converted to the baseband signal, and then transmitted to the delay locked loops 131 to 13n.

Accordingly, the receiving device tracks four or more satellite signals using delay locked loops 131 to 13n, and measures the propagation delay time therefrom to find the location.

Here, the propagation delay time is basically obtained by the characteristics of autocorrelation and crosscorrelation coefficient of the pseudo noise code.

Basically, if information on the delay time in each of the four or more received satellites is known, it is largely obtained by the least square method and Kalman filter method to find the location of the receiving device itself.

In the satellite method such as GPS using conventional satellites, there is no difficulty in securing the visible distance (LOS) and the loss due to the multipath does not take much weight. It has not been done.

However, since the navigation system using satellite has a disadvantage of enormous development cost and maintenance cost, it is judged that the economical efficiency of the navigation system using the ground network is much higher in a small area such as Korea.

In addition, it has been reported that the secured visibility and the loss due to the multipath have a great influence on the position accuracy in the ground navigation developed up to now.

Currently, GPS satellites utilize polarization diversity to reduce the effects of multipath.

The basic concept is that the direction of rotation of the circularly polarized wave changes every time it is reflected. Since the antenna is designed to receive only one direction of rotation, the multipath signal having a relatively large intensity can be eliminated. .

However, even if the ground network is constructed by the conventional position measuring method alone, there are considerable technical difficulties, so the removal efficiency is considerably lower than that of the satellite network. In order to establish too many positioning base stations in, there was a problem that takes too much cost.

Accordingly, the present invention has been made to solve the above problems, and by measuring the position in GPS using the time diversity technique used in the CDMA communication system, the visible distance which is the biggest error factor in the terrestrial navigation system It is an object of the present invention to provide a receiving apparatus and method thereof capable of securing and reducing errors caused by multipath, and a computer-readable recording medium recording a program for realizing the same.

1 is a block diagram of a receiver of a conventional position measuring system.

2 is a block diagram of the delay locked loop of FIG.

Figure 3 is a configuration diagram of an embodiment of a receiving device of a position measuring system according to the present invention.

Figure 4 is a flow diagram of an embodiment of a receiving method of a position measuring system according to the present invention.

Explanation of symbols on the main parts of the drawings

310: initial value measuring unit 321 to 32n: finger

330: navigation data processing unit

The present invention for achieving the above object, in the receiving apparatus of the position measuring system, the initial value for measuring the initial value information of the time offset (offset) value of the received signal having a signal strength of more than a predetermined threshold of a plurality of received signals Value measuring means; Power value calculating means for calculating in real time the maximum power value of the received signals using initial value information of the time offset values measured by the initial value measuring means; And navigation data processing means for receiving the maximum power values calculated by the power value calculating means, calculating the power ratio of the received signal signals, and obtaining a navigation solution using the calculated power ratio to find the current position.

In addition, the present invention provides a method of receiving a position measuring system, comprising: a first step of measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold among a plurality of received signals; A second step of estimating delay time information of received signals and signal strength information of measured received signals using initial value information of time offset values measured by the initial value measuring means; A third step of obtaining a weighted matrix by summing signal strength information of the first arrived signal and signal strength information of the arrived signals; A fourth step of calculating a weight used to obtain a navigation solution by using the sum of signal signaling information obtained in the third step and a weighted matrix; And a fifth step of measuring a current position based on the weight.

The present invention also provides an information providing system having a processor, comprising: a first function of measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold among a plurality of received signals; A second function of estimating delay time information of received signals and signal strength information of measured received signals using initial value information of measured time offset values; A third function of obtaining a weighted matrix by adding the signal strength information of the first arrived signal and the signal strength information of the subsequently arrived signals; A fourth function of calculating a weight used to calculate a navigation solution by using the sum of signal signaling information obtained in the third function and a weighted matrix; And a computer readable recording medium having recorded thereon a program for realizing a fifth function of measuring the current position by the weight.

In addition, the present invention is based on the time diversity scheme applied in the CDMA communication system, that is, when the delay spread is larger than the chip rate of the pseudo noise code, we can visualize the component of the reached signal. It can be separated into radio signals and signals by multipath.

At this time, by separating the three to five signals with the largest signal strength and then summing the delay time to the same, the signal-to-noise ratio (SNR) is significantly improved compared to conventional receivers. You can.

In addition, in communication, signal-to-noise ratio is an index indicating the main performance and accuracy, but in positioning, an important factor is to eliminate the visibility and multipath signal, that is, the signal entered into the multipath in an area where the visibility is not secured. Because the reception time of the signal that arrives at the earliest is directly entered into the navigation data, there is a problem that it is wrongly judged that it is farther than the actual distance. Judging by this is basically a very important factor.

Therefore, as we know, the intensity distribution of the received signals in the case of the visible distance is known to follow the Rician distribution, and the Rayleigh distribution in the case of the non-visible distance. In this paper, we focus on the difference between the signal strength distribution in the secured and unsecured situations and propose the following method.

First, we will measure the strength of signals separated by 3 to 5 paths.

That is, in the situation where the visible distance is secured, the first signal reached is the visible distance propagation signal, and the strength of the signal is also significantly greater than that of the multipath signals.

However, in a situation where the line of sight is not secured, since only signals reached by multipaths exist, the signal strength does not necessarily mean that the signal reached first is counted, and there is basically no difference in signal strength. will be.

Eventually, the difference between the sum of the signal strengths of the first and second arrived signals will be weighted in the navigation algorithm, and also the strengths of the second and subsequent arrived signals for multipath only signals. Since may be greater than the signal strength reached first, in this case the smallest weight will be applied.

The weights are applied to the two solutions described above, that is, the least squares method and the Kalman filter method, so that the weighted data has a large influence on the calculation and the small weighted data has a small influence on the calculation. This is to reduce the error caused by the path.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

3 is a configuration diagram of an embodiment of a receiving apparatus of a position measuring system according to the present invention.

As shown in FIG. 3, the receiving apparatus of the position measuring system according to the present invention includes an initial value for measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold among a plurality of received signals. Fingers 321 to 32n respectively calculating the maximum power value of the received signals in real time using the initial value information of the time offset values measured by the measurement unit 310 and the initial value measurement unit 310. And a navigation data processor 330 that receives the maximum power values calculated by the fingers 321 to 32n, calculates a power ratio of received signal signals, and obtains a navigation solution using the calculated power ratio to find a current position. do.

Referring to the operation of the receiving device of the position measuring system of the present invention having the structure as described above in detail as follows.

First of all, the receiving device of the present invention is considerably more complicated than the functional block of the conventional GPS receiving device, but this function part has relatively similarities with the RAKE receiver commercially available in the conventional CDMA receiving device. Its basic operation principle is the same, so it can be said that commercialization does not follow a large crowd.

By using the time diversity technique, the initial value measuring unit 310 transmits the initialized delay time information from which a signal equal to or greater than a noise threshold is transmitted to the fingers 321 to 32n for each time period.

Here, n is a natural number, and considering the complexity of the system, it is appropriate to have about 3 to 5 pieces.

In this way, when the number of fingers is about 3 to 5, it is possible to separate the total of n visible signals and multipath signals.

And, the delay time of the first signal received for each received signal is transmitted to the finger 321, where the information of the delay time information (τ ₁ ) and the measured signal strength (p ₁ ) through real-time tracking (tracking) It is delivered to the navigation data processing unit 330 to obtain a navigation solution.

Of course, the method of obtaining the navigation data is the same as described above in FIG.

On the other hand, the other fingers (322 to 32n) transmits only the corresponding signal strength of the signal strength (p _2, ..., p _N ) of the received signal to the navigation data processor 340, respectively.

The navigation data processing unit 330 extracts the navigation data including the time offset value at which the maximum power value is generated and the position information of the positioning base station from the initial time offset initial value of the received signal. do.

Figure 4 is a flow diagram of an embodiment of a receiving method of a position measuring system according to the present invention.

Referring to FIG. 4, the initial value measuring unit 310 measures initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold value among a plurality of received signals (401), and a finger. The navigation data processing units 321 to 32n respectively display the delay time information τ ₁ ,..., Τ _N and the signal strengths p _1, ..., P _N of the measured signals through real-time tracking. Forward to 340 (402).

Next, the process of obtaining the navigation solution by the navigation data processor 340 is as follows.

In general, the signal input to the navigation data processing unit 340 is a finger 322 composed of only the navigation data obtained from the finger 321 and the strength (p ₁ ), the propagation delay time (τ ₁ ) of the fastest transmitted signal, and the multipath. To signal strengths p _1, ..., P _N , respectively.

Once, after obtaining a weighting matrix W from the sum (P _multi) of the intensity (p ₁₎ with the signal intensity _{(p 1, ···, p N} ) of a signal after the arrival of the first arrival signal and calculates the weight (403). Here, the obtained weighting matrix W is a diagonal matrix having only diagonal components, and the diagonal components are defined as relative signal strength differences.

In this way, the current position of the terminal is measured using the obtained navigation solution (405).

In the case of a signal coming only through a multipath, P _multi may occur as p _1. Therefore, if a certain P _crit value is set and the signal strength is less than this, the error is mitigated by applying the smallest weight. It is expected to be possible.

Thus, using the calculated weight as shown in the following [Equation 1] to obtain a navigation solution (404). That is, [Equation 1] is applied to the present invention as a method of obtaining a navigation solution.

Here, matrix A is basically the elements of the linear equation approximated from nonlinear navigation, (·) ^T is the transpose matrix, (·) ^-1 is the inverse matrix, and the matrix component yk of y is c · Δτ _k passed as input. _{, 1} .

The navigation solution used in the present invention is a weighted least square (Weighted Least Square) modified from the least square method.

This method is applied in consideration of the characteristic that, when there is a visible distance in the radio channel characteristic, the signals input by the multipath are basically very small compared to the signals input through the direct visible distance.

And, when there is no direct line of sight, the characteristics of the signal coming into the multipath alone are based on the assumption that the difference in signal strength will not be large.

In some cases, the strength of the first signal among the multipaths is smaller than the strength of the signal reached later. In this case, the signal is determined to be the minimum value of the weight value. In the case of suspicion of a signal transmitted by multipath with a large weighting, a relatively small weighting will be able to considerably alleviate the error in the overall solution.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention can considerably reduce the error by applying the time diversity technique used in the existing CDMA communication terminal to improve the deterioration of the position accuracy due to the multipath, which is a problem in positioning using the ground network. In addition, it is easy to implement because it is a commercialized technique in the existing CDMA communication, and it is expected that even a slight algorithm modification can produce a lot of improvement effects, especially in the process of obtaining the existing navigation solution.

Claims (5)

In the receiving device of the positioning system, Initial value measuring means for measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold value among a plurality of received signals; Power value calculating means for calculating in real time the maximum power value of the received signals using initial value information of the time offset values measured by the initial value measuring means; And Navigation data processing means for receiving the maximum power values calculated by the power value calculation means, calculating the power ratio of the received signal and calculating the navigation solution using the calculated power ratio to find the current position. Receiving device of the positioning system comprising a. The method of claim 1, The navigation data processing means, And a navigation data including a time offset value at which a maximum power value is generated and location information of a positioning base station from a time offset initial value of the first received signal. In the receiving method of the position measuring system, A first step of measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold value among a plurality of received signals; A second step of estimating delay time information of received signals and signal strength information of measured received signals using initial value information of time offset values measured by the initial value measuring means; A third step of obtaining a weighted matrix by summing signal strength information of the first arrived signal and signal strength information of the arrived signals; A fourth step of calculating a weight used to obtain a navigation solution by using the sum of signal signaling information obtained in the third step and a weighted matrix; And A fifth step of measuring a current position based on the weight Receiving method of the position measurement system comprising a. The method of claim 3, wherein The weight matrix, A method of receiving a positioning system, characterized in that it is a diagonal matrix having only diagonal components that are relative signal strength differences. In an information providing system having a processor, A first function of measuring initial value information of time offset values of received signals having a signal strength equal to or greater than a predetermined threshold value among a plurality of received signals; A second function of estimating delay time information of received signals and signal strength information of measured received signals using initial value information of measured time offset values; A third function of obtaining a weighted matrix by adding the signal strength information of the first arrived signal and the signal strength information of the subsequently arrived signals; A fourth function of calculating a weight used to calculate a navigation solution by using the sum of signal signaling information obtained in the third function and a weighted matrix; And A fifth function of measuring a current position based on the weight A computer-readable recording medium having recorded thereon a program for realizing this.