KR100841449B1 - Positioning method using digital audio broadcasting - Google Patents

Abstract

A position tracking method using DAB(Digital Audio Broadcasting) is provided to reduce transmitting power by obtaining information about the position and time offset of peripheral transmitters and to select the position freely. A position tracking method using DAB is composed of the steps of: generating plural DAB signals having continuous transmission frames, respectively, from plural transmitters(T1-T3); transmitting plural DAB signals by adding a pseudo random noise code to the rest transmission frames except for at least one transmission frame in the transmission frames corresponding to plural DAB signals to change the DAB signal including at least one transmission frame, in order according to the progress of the continuous transmission frames; and receiving plural DAB signals through a mobile terminal(M) and calculating each distance(D1-D3) between the mobile terminal and each transmitter, by using a pseudo random noise code.

Description

Location tracking method using digital audio broadcasting {Positioning Method Using Digital Audio Broadcasting}

The present invention relates to a location tracking method, and more particularly, to a indoor location tracking method using a digital audio broadcasting (DAB) and a location tracking system for the same.

Recently, due to the rapid development of information and communication technology, the network infrastructure has been widely spread, and the ubiquitous era based on this is coming as the advanced digital equipment becomes common in daily life. In this ubiquitous era, research related to object recognition and location tracking is needed to meet the needs of various customers.

The existing location tracking system was developed centering around the outdoor environment using GPS, but many user-oriented services proposed by ubiquitous are provided indoors, which is the user's main living space. It is increasing. The location tracking system in the indoor environment can be used in various fields. In case of an emergency, the location tracking system can be rescued from danger by informing its location to the rescue headquarters. It can be useful for providing various services and creating added value, finding friends, and finding directions.

Recognizing the position of an object in a location tracking system requires advanced techniques such as cost and recognition accuracy. However, dynamic movements and static obstacles have a great influence on location recognition. These effects soon lead to errors in recognition accuracy and loss of data. In other words, accurately recognizing and tracking an object is the basis of location tracking technology.

The basics of location tracking techniques include triangulation, scene analysis, and proximity.

Among them, the triangulation method most widely used will be described with reference to the drawings.

1 is a view illustrating a method of determining the position of an object by triangulation, in which triangulation is a method of determining the position of an object (ie, spatial coordinates) by measuring a distance between a plurality of transmitters and an object. .

As shown in FIG. 1, when the object O is located between the first to third servers S1 to S3, each server is measured by measuring a time when the signal transmitted from each server arrives at the object O. The distance between and object O can be calculated.

That is, assuming that a signal that is electromagnetic waves are transmitted at the light flux, the signal arrival time from the first server S1 to the object O is measured and multiplied by the light flux to determine the distance between the first server S1 and the object O. The first distance d1 can be obtained. The second and third distances d2 and d3 between the second and third servers S2 and S3 and the object O may be obtained in a similar manner. Drawing three circles with radiuses of the first to third distances d1 to d3 calculated around each of the first to third servers S1 to S3, respectively, the intersection of the three circles is the intersection of the objects O. Location.

One of the best known systems based on location tracking technology using these methods is the Global Positioning System (GPS). GPS is a principle of obtaining spatial position by receiving radio waves from satellites that know the exact position by tracked orbit and measuring the propagation time from satellite to observation point. However, GPS is widely used for general users, especially car navigation, rather than indoors, because GPS has a wide range of tracking, expensive equipment, and errors due to signal reflection, diffraction, and dispersion in indoor or urban areas. One way to solve this is to install a GPS repeater on the roof of the building to re-broadcast satellite signals from the ground, which adds to the added device and cost.

In addition, it uses the Active Bat System, which uses ultrasonic waves as the indoor positioning system. However, this system requires a high level of technology to be efficient and accurate, and is extremely expensive in terms of cost.

In addition, the indoor location tracking system using the Active Badge System (Active Badge System) using infrared, which receives the infrared signal of the active badge through the network sensor and tracks its location. Infrared signals, however, have the disadvantage of interfering with light and not penetrating even small obstacles. In addition, a relatively large number of readers and gateways are required, and there are limitations in applying them to large factories or amusement parks.

It is an object of the present invention to provide a location tracking method and a location tracking system for minimizing signal loss due to interference.

In addition, in the transmission frame of digital audio broadcasting (DAB) or terrestrial-digital multimedia broadcasting (T-DMB), the present invention transmits by using a signal of a synchronization channel for identifying transmitter position information. Another object is to provide a location tracking method with a minimum number of outputs and transmitters, and a location tracking system for the same.

To achieve the above object, the present invention provides a method comprising the steps of: generating a plurality of digital audio broadcast (DAB) signals, each having a plurality of successive transmission frames, at a plurality of transmitters; A pseudo random noise code is added to the remaining transmission frames except at least one of the corresponding transmission frames of the plurality of DAB signals, wherein the DAB signal including the at least one transmission frame is Transmitting the plurality of DAB signals in such a manner as to be sequentially changed as the consecutive transmission frames elapse; The mobile terminal receives the plurality of DAB signals, and calculates a distance between the mobile terminal and the plurality of transmitters using the pseudo noise code, respectively.

The plurality of transmitters are first to third transmitters, the plurality of DAB signals are first to third DAB signals, and the first to third DAB signals have first to third transmission frames corresponding to each other. Pseudo noise codes are different from each other and independent first to third noise code, the first noise code is added to the first transmission frame of the first DAB signal, the second noise code is the second DAB signal Is added to the second transmission frame, and the third noise code is added to the third transmission frame of the third DAB signal.

Each of the first to third transmission frames includes a synchronization channel, a high speed information channel, and a main information channel, and the first to third noise codes are respectively assigned to the synchronization channels of the first to third transmission frames. Is added.

The calculating of the distance between the mobile terminal and the plurality of transmitters may include transmitting time of the pseudo noise code from the plurality of transmitters, arrival time of the pseudo noise code to the mobile terminal, and Calculating a transmission time of the plurality of pseudo-noise codes from the average time deviation of the mobile terminal and the signal measurement flow time of each transmission frame of the mobile terminal.

In addition, the signal measurement flow time for each transmission frame of the mobile terminal may be a cumulative average value before measurement.

The method may further include determining a location of the mobile terminal from a distance between the mobile terminal and the plurality of transmitters and location information of the plurality of transmitters.

On the other hand, the mobile terminal includes a broadcast signal processor for processing the plurality of DAB signals, and a position calculator for processing the pseudo noise code.

At this time, the position calculating unit of the mobile terminal processes the pseudo noise code by an automatic gain control (AGC) loop, the automatic gain control loop, a) the maximum of the power of the pseudo noise code transmitted from the plurality of transmitters; Determining a first gain rate appropriate for power; b) determining the predicted power of the pseudonoise code sent from the remaining transmitters; c) determining a jump value capable of jumping at a second gain rate corresponding to the predicted power; d) adding the jump value to the first gain and re-entering the position calculator.

Here, the predicted power is determined as a result of subtracting the maximum power from the virtual total power determined by the electromagnetic environment of the systems of the plurality of transmitters and the mobile terminal.

The broadcasting signal processing unit and the position calculating unit of the mobile terminal process the plurality of DAB signals and the pseudo noise code by an automatic frequency control (AFC) loop and a time tracking loop, respectively, and the position calculating unit The automatic frequency control loop and the time tracking loop are operated by using the variables of the automatic frequency control loop and the time tracking loop of the broadcast signal processor.

On the other hand, the mobile terminal is embedded in a mobile phone, the position calculating unit of the mobile terminal processes the pseudo noise code by an automatic frequency control (AFC) loop and a time tracking loop, and the position calculating unit is The AFC loop and the time tracking loop are operated by using variables of an AFC loop and a time tracking loop of the cellular phone.

The mobile terminal includes a broadcast signal processor for processing the plurality of DAB signals, a position calculator for processing the pseudo noise code, and storage means for storing data of the broadcast signal processor or the position calculator, Measuring the pseudo noise code and storing signal variables in a time domain of the pseudo noise code in a storage means; Converting the signal variable in the time domain of the pseudo-noise code stored in the storage means into the signal variable in the frequency domain by using a Fast Fourier Transform; And determining the time at which the pseudo noise code reaches the mobile terminal from the signal variable in the frequency domain.

On the other hand, the present invention provides a method comprising the steps of: generating a plurality of digital audio broadcast (DAB) signals each having a transmission frame; Transmitting and adding a pseudo random noise code to each transmission frame of the plurality of DAB signals; Transmitting a GPS signal from a satellite; Receiving, by the mobile terminal, the plurality of DAB signals and the GPS signals, and calculating the distance between the mobile terminal and the plurality of transmitters by using one of the pseudo noise code and the GPS signal alternately. Provide a location tracking method.

In the present invention, since the position of the object is tracked using the DAB or T-DMB signal, the position tracking can be performed without an additional installation cost, and in particular, the transmission power can be obtained by acquiring position information and time offset information of the peripheral transmitters. Further reduction and autonomous positioning are possible. On the other hand, in the present invention, since the position of the object is tracked by inserting a pseudo random noise code into a DAB or T-DMB signal, accurate position tracking can be performed without an additional installation cost.

The indoor location tracking method according to the present invention uses a digital audio broadcasting (DAB) signal or a terrestrial digital multimedia broadcasting (T-DMB) signal to determine the position (object coordinates) of an object by a triangulation method. Since the terrestrial digital multimedia broadcasting (T-DMB) system basically has the same physical layer as the digital audio broadcasting (DAB) system, the following embodiment uses a digital audio broadcasting (DAB) signal as an example. It will be understood that embodiments of the present invention can be implemented even when using a terrestrial digital multimedia broadcasting (T-DMB) signal.

2 is a conceptual diagram illustrating a location tracking method according to an embodiment of the present invention.

As shown in FIG. 2, the present invention tracks the position of the mobile terminal M by using a digital audio broadcasting (DAB) signal.

That is, when the mobile terminal M is located between the first to third transmitters T1 to T3 of the DAB system, when each transmitter transmits the DAB signal to the mobile terminal M, the mobile terminal M transmits. The information on the arrival time of the received DAB signal is recorded for each transmitter, and information about the arrival time of the DAB signal for each transmitter is transmitted to a location calculation server (not shown) by using other communication means such as a mobile phone. Since the location calculation server secures the information on the timing of the transmission of the DAB signal of each transmitter and the exact position information of each transmitter, the mobile terminal from the first to third transmitters (T1 to T3) is analyzed by analyzing the arrival time and the transmission time. The first to third distances D1 to D3 to (M) are calculated, and the position of the mobile terminal M is determined by triangulation in consideration of accurate position information of the first to third transmitters T1 to T3. do. Then, the location calculation server transmits the calculated location of the mobile terminal M to the mobile terminal M to another communication means, or to other necessary service server.

Since the first to third DAB signals TS1 to TS3 respectively transmitted by the first to third transmitters T1 to T3 can be regarded as being transmitted to the mobile terminal M at the speed of light, the position calculation server is determined from each transmitter. By multiplying the luminous flux by the transmission time of the DAB signal to the mobile terminal M, the first to third distances D1 to D3 between the transmitter and the mobile terminal M can be obtained.

Of course, a time offset, which is the time taken for signal transmission from the transmitter end to the transmitting antenna, must also be considered. That is, the transmission time that the DAB signal is actually transmitted from each transmitter to the mobile terminal (M) can be obtained by subtracting the transmission time from the arrival time and subtracting the simple time difference again. The distance between M) can be found respectively.

In this case, when the first to third transmitters T1 to T3 are synchronized, the first to third transmitters T1 do not require a time monitoring station for determining an absolute time. In the case of the other embodiment to which T3) is not synchronized, an accurate transmission time can be determined by providing a separate visual observation unit.

For example, if the time observer is installed at a predetermined position, the time observer measures the arrival time of the DAB signal transmitted from each transmitter and transmits it to the position calculation server, and already secures the transmission time of each transmitter and the position information of the time observer. The location calculation server calculates the time deviation of each transmitter from the mobile terminal M and uses the location tracking server to track the location of the mobile terminal M or transmits the data to the mobile terminal M through other communication means to use the mobile terminal M where necessary. .

In addition, the first to third DAB signals TS1 to TS3 include identification information of the first to third transmitters T1 to T3, respectively, so that the mobile terminal M includes the first to third DAB signals TS1. To TS3) can identify which of the first to third transmitters T1 to T3 has been transmitted, and position identification information of each transmitter together with the arrival time of the DAB signal from each transmitter as a measurement result. Send to the calculation server.

Since the location calculation server has the transmission time of the DAB signal from all transmitters and the exact position information of all transmitters, the arrival time and the transmission time of the DAB signal sent by the mobile terminal M using the triangulation method and the position information of the transmitter. The location of the mobile terminal (M) can be obtained from, and the location information of the mobile terminal (M) is transmitted to the mobile terminal (M) again so that the mobile terminal (M) can determine its location or transmit it to the corresponding service server. Ensure that appropriate services are provided.

In this case, if the first to third DAB signals TS1 to TS3 each include location information of adjacent transmitters, the mobile terminal M may determine its own location without the help of each transmitter. That is, using the triangulation method, it is possible to calculate the position of the mobile terminal M directly from the first to the third distance (D1 to D3) and the position information of the transmitter, in which case the mobile terminal (M) is autonomous positioning (autonomous positioning) is possible.

In conclusion, in the present invention, the mobile terminal M obtains a transmission time using a time deviation or the like included in the DAB signal, and obtains a distance between the transmitter and the mobile terminal M from the mobile terminal M, and combines it with the transmitter position information. Determine the exact position of the mobile terminal (M) by triangulation.

In particular, in the present invention, even if the mobile terminal (M) is located indoors, the position can be accurately tracked, which is possible by sensing the highest arrival signal of the DAB signal transmitted from each transmitter.

When the mobile terminal M is located in a room, such as a building, the electromagnetic wave DAB signal is transmitted directly to the building, reflected by an object outside the building, or diffracted outside the building and transmitted to the mobile terminal M. The signal reflected or diffracted and transmitted is transmitted to the mobile terminal M later than the signal transmitted directly.

Therefore, the mobile terminal M located indoors receives the DAB signal, which is one transmission signal, several times at a time difference, which causes inaccuracy of the arrival time of the DAB signal.

In the present invention, the transmission signal, the reflection signal, and the diffraction signal, which are transmitted first to the mobile terminal M with a time difference, are regarded as the highest arrival signal, and from each transmitter to the mobile terminal M. Since the transmission time of the DAB signal is determined, it is possible to accurately calculate the distance between each transmitter and the mobile terminal (M).

Meanwhile, in calculating a distance between each transmitter and the mobile terminal, a pseudo random noise code (PRN code) may be added to the synchronization channel SC, which will be described with reference to the accompanying drawings.

3 is a diagram illustrating a part of a transmission frame of a DAB signal according to the first embodiment of the present invention.

As shown in Fig. 3, the null symbol of the synchronization channel SC of the DAB signal to which the transmitter identification information TII is added has a very low bit density for the purpose of transmitter identification. It looks like there are pulses like delta functions.

Therefore, even if a pseudo noise code (PRN code) is inserted into the null symbol section of the synchronization channel (SC), there is a problem in distinguishing the transmitter identification information (TII) and the pseudo noise code (PRN code) if only the power is properly controlled. There is no need to replace the power amplifiers of conventional DAB transmitters with higher output power amplifiers to boost the output of the transmitters.

That is, the DAB signal has a bandwidth of 1.536 MHz, and the PRN code of 1.536 MHz has a spreading gain of about 61.86 dB, so that the energy density per frequency is low enough so that the DAB signal It does not compromise the transmitter identification information (TII) added to the null symbol. In addition, since the density of the transmitter identification information (TII) is very low, the noise floor caused by carriers of the transmitter identification information (TII) during de-spreading is a pseudo noise code (PRN code). It does not affect the perception of the correlation.

Although not shown in the drawings, a distance between each transmitter and a mobile terminal is inserted by inserting a PRN code into not only a synchronization channel (SC) but also a high-speed information channel / main service channel (FIC / MSC). Can be used to calculate.

The output power control of such a pseudo noise code (PRN code) will be described with reference to the drawings.

4 is a schematic diagram showing the structure of a DAB sender according to a first embodiment of the present invention.

As shown in FIG. 4, the DAB transmitter 300 according to the first embodiment of the present invention includes a transmission frame multiplexer 310, a fast information channel / main service channel (FIC / MSC) symbol generator 320, Orthogonal Frequency Division Multiplexing (OFDM) Signal Generator 330, Synchronous Channel (SC) Symbol Generator 340, Transmitter Identification Information (TII) Signal Generator 350, Pseudo Noise (PRN) Code Generator 380 And a third gain block 390.

The transmission frame multiplexer 310 receives the data for the high speed information channel (FIC) and the data for the main service channel (MSC) from the outside and transmits the data to the high speed information channel / main service channel (FIC / MSC) symbol generator 320. The high-speed information channel / main service channel (FIC / MSC) symbol generator 320 generates symbols corresponding to the data for the high-speed information channel (FIC) and the data for the main service channel (MSC) to generate orthogonal frequency division multiplexing ( OFDM) to the signal generator 330.

The sync channel (SC) symbol generator 340 generates a symbol corresponding to the sync channel (SC), transfers the signal to the orthogonal frequency division multiplex (OFDM) signal generator 330, and generates an orthogonal frequency division multiplex (OFDM) signal. The unit 330 generates an orthogonal frequency division multiplex (OFDM) signal using a fast information channel / main service channel (FIC / MSC) symbol and a synchronization channel (SC) symbol, and emitter identification information (TII) signal generator ( The 350 generates a transmitter identification information (TII) signal including information on transmitter recognition, inserts a DAB signal by inserting an orthogonal frequency division multiplex (OFDM) signal into a null symbol of a synchronization channel (SC) of a transmission frame. It serves to complete.

The pseudo noise (PRN) code generator 380 generates a pseudo noise code (PRN code), and the third gain block 390 converts the generated power of the generated pseudo noise code (PRN code) into a third gain rate (G3). It amplifies by as much as it adds to the null symbol of the synchronization channel SC and overlaps the transmitter identification information TII.

Here, the third gain G3 is determined by simulation and experiment within the limit of the efficiency of the DAB.

There are two possible forms of PRN codes used in the first embodiment.

First, as in GPS, each transmitter may use a different PRN code. In this case, the PRN codes used in all transmitters form golden PRN codes with orthogonality, and further, high-speed information channel / main service channel of DAB signal for quick location tracking. In the FIC / MSC, a PRN number used by an adjacent transmitter may be added.

Another form is that each transmitter uses the same PRN code with orthogonality due to different phase offsets, as in Code Division Multiple Access (CDMA). For operation, a suitable PRN phase distance must be found. In addition, for fast location tracking, the information on the PRN phase distance from the absolute time of the adjacent transmitter may be added to the fast information channel / main service channel (FIC / MSC) of the DAB signal. have.

However, in the first embodiment in which the PRN code is added to the synchronization channel SC to calculate the distance between each transmitter and the mobile terminal, the following problem occurs when the mobile terminal is very close to a specific transmitter. May occur.

For example, if the mobile terminal is very close to the first transmitter, the mobile terminal is relatively far from the second and third transmitters, and thus, a PRN code transmitted from the first transmitter to the mobile terminal. Has much greater power than the PRN Code transmitted from the second and third transmitters to the mobile terminal. If the PRN codes transmitted from each transmitter are completely orthogonal to each other, the power difference of the PRN Code will not impede the perception of each PRN Code. Since the PRN code is difficult to have perfect orthogonality, a large power PRN code acts as a noise for recognizing a small power PRN code. Therefore, when the mobile terminal is very close to the first transmitter, a PRN code transmitted from the second or third transmitter to the mobile terminal is caused by the PRN code transmitted from the first transmitter as a noise. ) Can interfere with your perception.

In addition, the mobile terminal includes a plurality of RF elements required for wireless communication such as an amplifier, and these RF elements exhibit saturation when the input signal is large and exhibit non-linear characteristics. This means that the RF device may not output a normal result. A large power PRN code transmitted from the first transmitter is input to the RF device of the mobile terminal, thereby saturating the RF device. This may impede the recognition of the small power PRN code transmitted from the second or third transmitter.

In addition, the mobile terminal has an automatic gain control (AGC) loop so that a signal having a constant magnitude is input to an analog-to-digital converter (ADC) regardless of the magnitude of the input signal. This is to reduce the gain when the signal transmitted to the mobile terminal is large and to increase the gain when the signal transmitted to the mobile terminal is small. When a large power PRN code is transmitted from the first transmitter to the mobile terminal having such an automatic gain control (AGC) loop, the gain is reduced by the automatic gain control (AGC) loop and accordingly a noise figure (noise) figure increases. Thus, the small power PRN code transmitted from the second or third transmitter may be more difficult to recognize.

In addition, the mobile terminal includes an analog-to-digital converter (ADC) for converting the received wireless analog signal to digital, and the resolution of the input signals when the signals input to the analog-to-digital converter (ADC) have a power difference There is a difference, and thus an error occurs in the output value. Therefore, a large power PRN code transmitted from the first transmitter and a small power PRN code transmitted from the second or third transmitter may be input to the analog-to-digital converter (ADC). In this case, an error may occur in the output value, which may impede the recognition of a PRN code transmitted from the second or third transmitter.

In order to solve this problem, in the second embodiment of the present invention, instead of adding and transmitting a PRN code every frame of the DAB signal in each transmitter, a PRN code is given to the transmitter. In addition to the time period (transmission) sequentially. That is, a PRN code is sequentially added to at least one transmission frame, not all transmission frames, among corresponding transmission frames of a plurality of DAB signals of a plurality of transmitters, and a pseudo noise code is not added to the remaining transmission frames. Do not.

5 is a schematic diagram illustrating a location tracking method according to a second embodiment of the present invention, and FIG. 6 is a schematic diagram showing a transmission frame of a DAB signal according to the second embodiment of the present invention.

As shown in FIGS. 5 and 6, the first to third DAB signals DAB1 to DAB3 are transmitted from the first to third transmitters T1 to T3 to the mobile terminal M, respectively. The first to third noise signals PRN1 to PRN3 are added to the null symbol section of each of the synchronization channels SC of the signals DAB1 to DAB3 and transmitted. In this case, the first to third noise signs PRN1 to PRN3 are different from each other and are orthogonal.

The first to third transmitters T1 to T3 simultaneously transmit the first to third pseudonoise codes PRN1 only for a predetermined time period instead of transmitting the first to third pseudonoise codes PRN1 to PRN3 at the same time. By sequentially transmitting the PRN3), a problem caused by simultaneously transmitting a plurality of pseudonoise codes is prevented.

That is, the first transmitter T1 transmits the first pseudo noise code PRN1 during the first time interval TP1, and the second transmitter T2 transmits the second pseudo noise code (T2) during the second time interval TP2. PRN2) is transmitted, and the third transmitter T3 transmits the third pseudo noise code PRN3 during the third time interval TP3. Each of the first to third time periods TP1 to TP3 may have a duration of 1.297 msec corresponding to the null symbol period of the synchronization channel SC of one transmission frame of the DAB signal. Accordingly, the first to third noise signals PRN1 to PRN3 are added to the null symbol period of the synchronization channel SC of the corresponding time interval of the first to third DAB signals DAB1 to DAB3, respectively, to be transmitted for 1.297 msec. Can be.

In conclusion, the first pseudo noise code PRN1 is transmitted during the first time interval TP1 which is a null symbol period of the synchronization channel SC of the first transmission frame of the first DAB signal DAB1 of the first transmitter T1. The second pseudo noise code PRN2 is transmitted during the second time interval TP2, which is a null symbol period of the synchronization channel SC of the second transmission frame of the second DAB signal DAB2 of the second transmitter T2. The third noise signal PRN3 is transmitted during the third time interval TP3, which is a null symbol period of the synchronization channel SC of the third transmission frame of the third DAB signal DAB3 of the third transmitter T3.

Therefore, a pseudo noise code PRN is added only to a null symbol section of a synchronization channel SC of one of the corresponding transmission frames of the first to third DAB signals DAB1 to DAB3.

Here, the number of transmitters is described as 3 for convenience, but in other embodiments, the number of transmitters may vary, and even in this case, each transmitter may occur in simultaneous transmission by sequentially transmitting different pseudo noise codes (PRN3) at different time intervals. Problem can be prevented.

In another embodiment, a pseudo noise code may be added to the DAB signals of two or more transmitters among the remaining transmitters without adding a pseudo noise code to the DAB signals of at least one transmitter among the plurality of transmitters. For example, the first and second pseudo-noise codes PRN1 and PRN2 include the first transmission frame of the first DAB signal DAB1 of the first transmitter T1 and the second DAB signal DAB2 of the second transmitter T2. Is transmitted during the first time interval TP1 of the first transmission frame of the second transmission signal, and the second and third noise signals PRN2 are transmitted to the second transmission frame and the second transmission signal of the second DAB signal DAB2 of the second transmitter T2. The third and first noise codes PRN3 and PRN1 are transmitted during the second time interval TP2 of the transmission frame of the third DAB signal DAB3 of the third transmitter T3, and the third DAB of the third transmitter T3 is transmitted. Since the third transmission frame of the signal DAB3 and the third time period TP3 of the first DAB signal DAB1 of the first transmitter T1 are transmitted, the pseudo noise code is not added to the DAB signal transmitted from the adjacent transmitter. There may be at least one transport frame. In this case, since only a small power pseudo noise code is added to the DAB signal transmitted from the remaining transmitters, the pseudo noise code transmitted from the remaining transmitters can be recognized without a disturbance caused by a large power pseudo noise code.

On the other hand, in order to calculate the location of the mobile terminal, it is necessary to know the transmission time of the PRN code added to the DAB signal transmitted from each transmitter, and the transmission time is the transmission of the pseudo noise code (PRN code) from each transmitter. From the time, the arrival time of the PRN code in the mobile terminal, and the time deviation of the mobile terminal itself. However, since the time deviation of the mobile terminal itself may have time dependence, when receiving each of the pseudo noise codes (PRN codes) in sequence as in the second embodiment, in calculating the distance from each transmitter, the corresponding time interval The time variance of the mobile terminal in U must be taken into account differently. This will be described in more detail with a formula.

The times at which the first to third noise codes PRN1 to PRN3 added to the first to third DAB signals DAB1 to DAB3 are respectively transmitted from the first to third transmitters T1 to T3 are respectively t _T1 and t. _T2 , t _T3 , and the times when the first to third noise signs PRN1 to PRN3 reach the mobile terminal M are called t _M1 , t _M2 and t _M3 , respectively, and the first to third transmitters ( The transmission times of the first to third noise signals PRN1 to PRN3 from T1 to T3 to the mobile terminal M are t1, t2, and t3, respectively, and the mobile terminal M receives the first to third time. interval (TP1 through TP3) time variation with the _{(t offset1, t offset2, t} offset3) the average time drift (AOT) and the flow time of the signal measured in the time interval, respectively _{(drift time: t drift1, t} drift2, t by separating the sum (t + _offset1 = AOT _drift1 t, t + t _offset2 = AOT _{drift2, offset3} t = t + AOT _drift3) of _drift3), their relationship is expressed by the expression below.

t _M1 = t _T1 + t1 + ATO + t _drift1 --- Equation (1)

t _M2 = t _T2 + t2 + ATO + t _drift2 --- equation (2)

t _M3 = t _T3 + t3 + ATO + t _drift3 --- equation (3)

Here, the first to third noise signals PRN1 to PRN3 are transmitted from the first to third transmitters T1 to T3, and the times t _T1 , t _T2 , t _T3 , and the first to third noise codes ( The time t _M1 , t _M2 , t _M3 when PRN1 to PRN3 reaches the mobile terminal M is a value which can be measured and known by the clocks of the transmitter and the mobile terminal, and the average time deviation of the mobile terminal M ( AOT) is high can be seen that value because it is a constant independent of the time intervals by measuring the flow time (drift time: t _drift1, t _drift2, t _drift3) is either a constant independent of the constant to the time interval slowly by time If it is a slow varying time function, its value can be obtained by measurement. In this case, therefore, the transmission times t1, t2, t3 of the first to third noise signs PRN1 to PRN3 can be obtained from the equations (1) to (3), and from each transmitter to the mobile terminal (M). You can find the distance of. In conclusion, the mobile terminal M may calculate the position of the mobile terminal M itself by combining the calculated distance from each transmitter and the location information of each transmitter.

On the other hand, by eliminating the constant term of equations (1) to (3), the transmission times t1, t2, and t3 of the first to third pseudo-noise codes PRN1 to PRN3 can be obtained more simply.

That is, by subtracting equation (1) from equation (2), subtracting equation (2) from equation (3), and subtracting equation (3) from equation (1), the following equations can be obtained.

t _M21 = t _M2 -t _M1 = (t _T2 -t _T1 ) + (t2-t1) + (t _drift2 -t _drift1 ) --- Equation (4)

t _M32 = t _M3 -t _M3 = (t _T3 -t _T3 ) + (t3-t3) + (t _drift3 -t _drift3 ) --- Equation (5)

t _M13 = t _M1 -t _M3 = (t _T1 -t _T3 ) + (t1-t3) + (t _drift1 -t _drift3 ) --- Equation (6)

Here, since each transmitter is synchronized with an absolute time such as GPS, the difference between the transmission times of the first and second pseudonoise codes PRN1 and PRN2 (t _T2 -t _T1 ), the second and third pseudonoise codes ( The difference in the transmission time (T _T3 -t _T2 ) of PRN2, PRN3) and the difference in the transmission time (t _T1 -t _T3 ) of the third and first pseudo noise codes PRN3, PRN1 are shown in the start time between adjacent transmission frames. The difference (transmission frame duration) is 96 msec, and if the flow times t _drift1 and t _drift2 of the signal measurement of the mobile terminal M in the first and second time intervals TP1 and TP2 do not have time dependence. If not always the same, equations (4) to (6) are represented by a simple equation as follows.

t _M21 = 96 msec + (t2-t1) --- Equation (7)

t _M32 = 96 msec + (t3-t2) --- Equation (8)

t _M13 = 96 msec + (t1-t3) --- Equation (9)

Therefore, equations (7) to (9) can be solved by solving the transmission time t1, t2, t3 of the first to third noise codes PRN1 to PRN3.

However, in the actual situation, the flow time t _drift1 , t _drift2 , t _drift3 of the signal measurement of the mobile terminal M in the first to third time intervals TP1 to TP3 has a time dependency, in which case The last term in the formulas (4) to (6) does not become zero.

Therefore, in the second embodiment of the present invention, since the difference in the flow time of the signal measurement in the corresponding time interval has a random Gaussian distribution, the cumulative mean is obtained and the equations (4) to (6) are obtained. We use for solution.

For example, about 10 transmission frames of DAB signals, that is, signals corresponding to 10 time intervals, are transmitted between 1 second before the start of the position tracking, and the difference in the flow time of signal measurement between these time intervals is also 10 Since they exist, they are averaged, substituted into equations (4) to (6), combined, solved, and the transmission times t1, t2, and t3 of the first to third noise signs PRN1 to PRN3 can be obtained.

In conclusion, the mobile terminal M obtains the distance between each transmitter and the mobile terminal M from the transmission times t1, t2, and t3 of the obtained first to third noise codes PRN1 to PRN3, and calculates the distance between each transmitter and the mobile terminal M. The location information may be combined to calculate the location of the mobile terminal M itself.

7 is a schematic diagram showing the structure of a mobile terminal according to a second embodiment of the present invention.

As shown in FIG. 7, the mobile terminal M includes an antenna 410, a first amplifier 420, a broadcast signal processor 430, and a position calculator 440. The broadcast signal processor 430 analyzes the DAB signal transmitted to the mobile terminal and provides a broadcast to the user, and the location calculator 440 analyzes the PRN signal transmitted to the mobile terminal and provides the user with location information.

The broadcast signal processor 430 may include a first local oscillator 431, a second amplifier 432, a first analog digital converter 433, an OFDM demodulator 434, and a DAB signal processor 435. The position calculator 440 includes a second local oscillator 441, a third amplifier 442, a second analog digital converter 443, a PRN demodulator 444, and a PRN signal. It consists of a processing unit 445.

The first amplifier 420 serves to exclude and amplify the noise as much as possible from the signal transmitted as a low noise amplifier, and the second and third amplifiers 432 and 442 are variable gain amplifiers. Amplifier (VGA) serves to amplify by varying the gain ratio so that the power (voltage) of the signals input to the first and second analog digital converters 433 and 443 is constant.

The first and second local oscillators 431 and 441 are voltage controlled oscillators (VCOs) or voltage controlled temperature-compensated crystal oscillators (VCTCXOs), which are used at the frequency of the transmitted signal. It serves to generate the internal reference frequency to mix.

Here, the broadcast signal processing unit 430 and the position calculating unit 440 are each configured by an automatic gain control (AGC) loop, an automatic frequency control (AFC) loop, and a time tracking loop. It works.

The automatic gain control (AGC) loop is for inputting a constant voltage to the analog-to-digital converters (ADCs 433 and 443), and the DAB signal and the PRN signal input to the broadcast signal processor 430 and the position calculator 440. If the power is small, multiply the gain to input it to the analog-to-digital converter (ADC: 433, 443). If the power of the DAB signal and the PRN signal is large, multiply the small gain to input to the analog-to-digital converter (ADC: 433, 443). Irrespective of the magnitude of the DAB signal and the PRN signal, the gain is automatically adjusted so that a signal of a constant power (voltage) is input to the analog-to-digital converters ADCs 433 and 443.

The AFC loop is to compensate for inaccuracies of the local oscillators 431 and 441 inside the mobile terminal M. When the mobile terminal M moves, the frequency of the DAB signal and the PRN signal transmitted by the Doppler effect may change, thereby reducing the accuracy of the local oscillators 431 and 441 inside the mobile terminal M. The AFC loop compensates for the inaccuracies of the local oscillators 431 and 441 by allowing the frequency of the mobile terminal M to follow the changed frequencies of the input DAB and PRN signals.

Also, the time tracking loop is for continuous time synchronization of the input DAB signal and the PRN signal. For example, even when using a single PRN code such as CDMA, even if the frequency is correct, if the time synchronization is not correct, the signal cannot be recovered. Motivation may be less accurate. Accordingly, the mobile terminal M keeps time synchronization by the time tracking loop to prevent the DAB signal and the PRN signal recovery failure due to the time synchronization inaccuracy.

However, in the position tracking method according to the second embodiment of the present invention, the pseudo noise code (PRN code) is set to 1.297 msec corresponding to the null symbol of the synchronization channel (SC) from 96 msec corresponding to one transmission frame of the DAB signal. Therefore, the automatic gain control (AGC) loop, the automatic frequency control (AFC) loop, and the time tracking loop of the mobile terminal (M) are driven by receiving signals only for a time period corresponding to 1.297 msec, which is a fraction of 96 msec. Each loop can be driven incompletely. In addition, since a different DAB signal transmitted from each of the first to third transmitters T1 to T3 is measured for each transmission frame, an error in measurement of a PRN code may be caused.

The third embodiment of the present invention proposes a method for compensating for incomplete driving of an automatic gain control (AGC) loop, and the fourth, fifth, and sixth embodiments of the present invention provide an automatic frequency control (AFC) loop and time tracking. We present a method to compensate for incomplete driving of the loop.

8 is a block diagram of an automatic gain control loop of a mobile terminal according to a third embodiment of the present invention.

As shown in FIG. 8, in the mobile terminal M (see FIG. 7) according to the third embodiment of the present invention comprising a broadcast signal processing section and a position calculating section, an automatic gain control (AGC) operated in the position calculating section. The loop includes a jump block 452 for normal operation of the automatic gain control (AGC) loop when the mobile terminal M is very close to a particular transmitter.

For example, when the mobile terminal M is close to the first transmitter, the mobile terminal M is relatively far from the second and third transmitters, and as a result, the first DAB signal and the first PRN signal are relatively large in power. While the second and second PRN signals, the third DAB signal and the third PRN signal are transmitted with relatively small power.

When the mobile terminal M processes the first PRN signal transmitted from the first transmitter in the first transmission frame, the automatic gain control loop multiplies the large power of the transmitted first PRN signal by a relatively small gain ratio to the analog-to-digital converter. Allow a signal of proper power (voltage) to be input. In the next transmission frame, the power of the second PRN signal transmitted from the second transmitter is multiplied by an appropriate gain ratio so that a signal of an appropriate power (voltage) is input to the analog-to-digital converter. Since the second PRN signal has a low power, it is relatively large. The gain factor should be multiplied. Thus, the proper gain rate between the first and second transmission frames varies very rapidly from small gain rate to large gain rate. Also, since the PRN signal is transmitted only 1.297 msec in each of the 96 msec transmission frame intervals, the automatic gain control loop may not operate normally due to insufficient time to obtain an appropriate gain ratio in the second transmission frame.

In order to solve this problem, the mobile terminal according to the third embodiment of the present invention includes a jump block 452, and guesses the PRN signal transmitted from the transmitter far from the PRN signal transmitted from a specific transmitter in close proximity to obtain an appropriate gain. You can quickly determine the rate.

The automatic gain control loop of the mobile terminal includes a gain block 456 that provides a gain ratio that changes so that the conversion value S output from the analog-digital converter 443 of the mobile terminal becomes a target value A, and an input PRN. A jump block 452 is provided that provides a jump value for estimating the power of the signal and jumping near a corresponding gain ratio.

7 and 8, the operation of the automatic gain control loop in the first and second transmission frames when the mobile terminal is in proximity to the first transmitter.

That is, when the mobile terminal is close to the first transmitter, the first PRN signal having a large power is input to the third amplifier 442 which is a variable gain amplifier in the first transmission frame section, and the amplified signal is the second analog digital converter 443. Is converted into a digital signal. The value of the converted digital signal may be referred to as a conversion value (S) at that time. The gain value provided by the gain block 456 is obtained by subtracting the target value (A) from the conversion value (S). Multiply. When the resultant value is added to the jump value at the corresponding time point provided by the jump block 452 and transferred to the third amplifier 442, the third amplifier amplifies the input signal at the next time point using the received value as a gain ratio. By repeating such a loop, a proper gain ratio is determined in the first transmission frame section. Since the power of the first PRN signal input from the outside will not change significantly, the jump value provided by the jump block 452 is relatively small. Value, and the gain ratio is gradually changed by the automatic gain control loop. The gain value provided by the gain block 456 is a constant that determines the loop time of the automatic gain control loop.

Then, in the second transmission frame section, the second PRN signal having a small power is input to the third amplifier 442, and the resultant value is calculated through the second analog digital converter 443 and the gain block 456. At this time, the jump block 452 predicts the power of the second PRN signal from the power of the first PRN signal to determine the corresponding jump value, and adds the jump value to the result value passed through the gain block 456 to obtain the third amplifier ( In operation 442, the third amplifier 442 amplifies the input signal using the received value as a gain ratio.

At this time, since the power of the second PRN signal is smaller than the power of the first PRN signal, the jump value provided by the jump block 452 at the beginning of the second time interval is very large. After the first loop, since the gain ratio used by the third amplifier 442 to amplify the second PRN signal is already a large value, the jump value becomes smaller again.

Here, since the third amplifier 442 has a relatively fast response time, and the second analog digital converter 443 has a sufficiently wide dynamic range, which is a receivable power range, the second PRN signal after the first PRN signal is processed. In the processing, even if a jump is converted from the small gain value determined in the processing of the first PRN signal having a large power to the proper gain rate of the large value determined in the processing of the second PRN signal having small power, the third amplifier ( 442 and the second analog-to-digital converter 443 operate normally and the automatic gain control loop also operates without problem.

For example, a method of calculating a jump value for estimating an appropriate gain ratio in the second and third transmission frame sections may be described. The powers of the first, second, and third PRN signals are respectively P _PRN1 , P _PRN2 and P _PRN3 In this case, the powers P _PRN2 and P _PRN3 of the second and third PRN signals are calculated from the power of the first PRN signal P _PRN1 and the predetermined virtual total power P as follows.

P _PRN2 = P-P _PRN1 --- Equation (10)

P _PRN3 = P-P _PRN1 --- Equation (11)

Here, the virtual total power (P) is a value determined by the electromagnetic environment of the system such as a mobile terminal and a transmitter can be obtained by measuring in the actual system.

Therefore, when the mobile terminal M is close to the first transmitter, the mobile terminal M is transmitted from the second and third transmitters relatively far from the power of the first PRN signal transmitted from the first transmitter. The power of the 3PRN signal can be predicted, and the appropriate gain ratio to be used in the processing of the second and third PRN signals can also be predicted from the predicted powers of the second and third PRN signals. Therefore, by determining the difference between the proper gain rate in the first transmission frame section and the predicted proper gain rate in the second transmission frame section as a jump value, it is possible to quickly approach the proper gain rate in the second transmission frame section and automatically. The gain control (AGC) loop will operate normally.

The mobile terminal M according to the fourth embodiment of the present invention comprises a broadcast signal processor and a position calculator (see FIG. 7), and the automatic frequency control (AFC) loop and the time tracking loop of the position calculator are OFDM The parameters of the AFC loop and the time tracking loop measured by the demodulator are borrowed. The broadcasting signal processing unit and the position calculating unit of the mobile terminal M operate an automatic frequency control (AFC) loop and a time tracking loop, respectively. The signal is input for the time interval except 1.297msec, which is the null symbol, and the AFC loop and the time tracking loop operate accordingly. Therefore, the automatic frequency control (AFC) loop and the time tracking loop of the broadcast signal processor receive a pseudo noise code (PRN code) for a time period of 1.297 msec corresponding to a null symbol. It works much more reliably than loops and time-tracking loops. In the fourth embodiment of the present invention, the variable of the automatic frequency control (AFC) loop and the time tracking loop of the stable broadcast signal processing unit is used for the automatic frequency control (AFC) loop and the time tracking loop operation of the position calculation unit. AFC loop and time tracking loop can be operated stably early.

In the fifth embodiment of the present invention, the mobile terminal M is incorporated in the cellular phone. In other words, the mobile phone also operates by an automatic frequency control (AFC) loop and a time tracking loop for wireless communication. When the mobile phone has a configuration of a mobile terminal (M) capable of position tracking while receiving DAB broadcasting, The stable AFC loop and time tracking loop parameters of the mobile phone can be used for the AFC loop and time tracking loop operation of the position calculator. Therefore, the automatic frequency control (AFC) loop and the time tracking loop of the position calculation unit can be stably operated at an early stage.

In the sixth embodiment of the present invention, the mobile terminal M is composed of a broadcast signal processor, a position calculator, and a memory. The position calculator includes an analog-to-digital converter (ADC) that converts an analog DAB signal into a digital signal. It is stored in the same storage means and post-processed using the Fast Fourier Transform (FFT).

While the automatic frequency control loop and the time tracking loop stabilize the input signal in the time domain and obtain information about the frequency and time in real time, the ninth embodiment uses post-processing in the frequency domain. By analyzing the input signal, the frequency and time information of the converted signal is obtained from the analog-to-digital converter. The frequency domain and the time domain are substantially the same because the same analysis can be performed by Fourier transform, and the object to be observed in the frequency domain can be obtained from the measurement in the time domain, so there is no need for loop stabilization time as in the time domain analysis. . That is, if there is information on the conversion time of the signal in the analog-to-digital converter, it is possible to determine the arrival time of the mobile terminal of the pseudo noise code by analyzing the frequency or phase of the corresponding conversion signal, and consequently between the mobile terminal and the transmitter. The location of the mobile terminal can be determined by obtaining the distance of.

In the second to sixth embodiments of the present invention, a pseudo noise code (PRN code) is sequentially added to DAB signals transmitted from each transmitter to solve a problem that may occur when the mobile terminal is very close to a specific transmitter. In the seventh embodiment of the present invention, the mobile terminal further includes a GPS receiver in addition to the broadcast signal processor and the position calculator, and when the mobile terminal is very close to a specific transmitter, the GPS signal is received from the satellite and used for location tracking. The problem that occurs when the terminal is very close to a specific transmitter can be solved.

That is, the DAB signal transmitted by each transmitter is added with a pseudo noise code (DAB) in every transmission frame, and when the mobile terminal is very close to a specific transmitter, the position is tracked by using a GPS signal transmitted from a satellite. Overcoming the obstacles caused by power differences, if the mobile terminal is not very close to a specific transmitter, the location is tracked only by the PRN code of the DAB signal transmitted from each transmitter without using the GPS signal transmitted from the satellite.

According to the indoor location tracking method according to the present invention, location tracking is possible without additional installation cost, and the cost can be reduced by reducing the number of transmitters by optimizing the power transmission, which can be immediately implemented.

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the method of grasping the position of an object by triangulation.

Figure 2 is a conceptual diagram for explaining the indoor location tracking method according to an embodiment of the present invention.

3 is a diagram illustrating a part of a transmission frame of a DAB signal according to the first embodiment of the present invention.

4 is a schematic diagram showing the structure of a DAB sender according to a first embodiment of the present invention.

5 is a schematic view for explaining a location tracking method according to a second embodiment of the present invention.

6 is a schematic diagram showing a transmission frame of a DAB signal according to a second embodiment of the present invention.

7 is a schematic diagram showing the structure of a mobile terminal according to a second embodiment of the present invention;

8 is a block diagram of an automatic gain control loop of a mobile terminal according to a third embodiment of the present invention.

Claims (13)

Generating, at the plurality of transmitters, a plurality of digital audio broadcast (DAB) signals, each having consecutive transmission frames; A pseudo random noise code is added to the remaining transmission frames except at least one of the corresponding transmission frames of the plurality of DAB signals, wherein the DAB signal including the at least one transmission frame is Transmitting the plurality of DAB signals in such a manner as to be sequentially changed as the consecutive transmission frames elapse; Receiving, by the mobile terminal, the plurality of DAB signals, and calculating a distance between the mobile terminal and the plurality of transmitters using the pseudo noise code, respectively Location tracking method comprising a. The method of claim 1, The plurality of transmitters are first to third transmitters, the plurality of DAB signals are first to third DAB signals, and each of the first to third DAB signals has first to third transmission frames corresponding to each other. Pseudo noise codes are different from each other and independent first to third noise noise code, The first noise code is added to the first transmission frame of the first DAB signal, the second noise code is added to the second transmission frame of the second DAB signal, and the third noise code is the third DAB. Position tracking method added to the third transmission frame of the signal. The method of claim 2, Each of the first to third transmission frames includes a synchronization channel, a high speed information channel, and a main information channel, and the first to third noise codes are added to the synchronization channels of the first to third transmission frames, respectively. Location tracking method. The method of claim 1, Computing the distance between the mobile terminal and the plurality of transmitters, respectively, the transmission time from the plurality of transmitters of the pseudo noise code, the arrival time of the pseudo noise code to the mobile terminal, and the mobile terminal Calculating a transmission time of the plurality of pseudo-noise codes from an average time deviation of and a signal measurement flow time of each transmission frame of the mobile terminal. The method of claim 4, wherein The signal measurement flow time for each transmission frame of the mobile terminal is a cumulative average value before measurement. The method of claim 1, And determining the position of the mobile terminal from the distance between the mobile terminal and the plurality of transmitters and the location information of the plurality of transmitters. The method of claim 1, The mobile terminal comprises a broadcast signal processor for processing the plurality of DAB signals and a position calculator for processing the pseudo noise code. The method of claim 7, wherein The position calculating unit of the mobile terminal processes the pseudo noise code by an automatic gain control (AGC) loop, The automatic gain control loop may include: a) determining a first gain ratio corresponding to a maximum power among powers of the pseudo noise codes transmitted from the plurality of transmitters; b) determining the predicted power of the pseudonoise code sent from the remaining transmitters; c) determining a jump value capable of jumping at a second gain rate corresponding to the predicted power; d) adding the jump value to the first gain and re-entering the position calculator. The method of claim 8, Wherein the predicted power is determined as a result of subtracting the maximum power from a virtual total power determined by the electromagnetic environment of the system of the plurality of transmitters and the mobile terminal. The method of claim 7, wherein The broadcast signal processor and the location calculator of the mobile terminal process the plurality of DAB signals and the pseudo noise code by an automatic frequency control (AFC) loop and a time tracking loop, respectively, and the location calculator comprises: And a position tracking method of operating the automatic frequency control loop and the time tracking loop by using the parameters of the automatic frequency control loop and the time tracking loop. The method of claim 7, wherein The mobile terminal is embedded in a mobile phone, the position calculating unit of the mobile terminal processes the pseudo noise code by an automatic frequency control (AFC) loop and a time tracking loop, and the position calculating unit is the portable unit. 12. A method of tracking a location using a variable of an AFC loop and a time tracking loop of a telephone to operate the AFC loop and a time tracking loop. The method of claim 1, The mobile terminal comprises a broadcast signal processor for processing the plurality of DAB signals, a position calculator for processing the pseudo noise code, and storage means for storing data of the broadcast signal processor or the position calculator, Measuring the pseudo noise code and storing signal variables in a time domain of the pseudo noise code in a storage means; Converting the signal variable in the time domain of the pseudo-noise code stored in the storage means into the signal variable in the frequency domain by using a Fast Fourier Transform; And determining the time at which the pseudo noise code reaches the mobile terminal from the signal variable in the frequency domain. Generating at the plurality of transmitters a plurality of digital audio broadcast (DAB) signals each having a transmission frame; Transmitting and adding a pseudo random noise code to each transmission frame of the plurality of DAB signals; Transmitting a GPS signal from a satellite; Receiving, by the mobile terminal, the plurality of DAB signals and the GPS signals, and calculating the distance between the mobile terminal and the plurality of transmitters by using one of the pseudo noise code and the GPS signal alternately; Location tracking method comprising a.

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