JP3390753B2 - GPS positioning method, GPS terminal and GPS positioning system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a GP from a satellite.
A GPS positioning method for receiving an S signal and detecting the reception position,
The present invention relates to a GPS terminal and a GPS positioning system.

[0002]

2. Description of the Related Art Many satellites have been launched around the earth, and each satellite has the same carrier frequency 157.
The radio wave of 5.42 GHz is continuously transmitted. This radio wave is phase-modulated with a pseudo-noise code, and can be separated and received by assigning different code patterns to each satellite. The pseudo noise code is a code pattern called C / A code which is open to the public and can be used, and which changes regularly. In addition, by reversing the polarity of the C / A code, the navigation data as information such as satellite orbit information, satellite correction values, and ionospheric correction coefficients, which are necessary for the user to perform positioning, are converted into the above radio waves. I send it on board.

The above C / A code is as shown in FIG.
1023 bits = 1 msec is one PN frame, and this PN frame is a continuous regular signal. Also,
The navigation data is a signal of 50 BPS, that is, a 1000 PN frame, and C / C depending on the polarity of the navigation data.
The polarity of the A code is also inverted.

FIG. 14 shows, for example, US Pat. No. 5,663,7.
34 is a block diagram showing a configuration of a conventional GPS positioning system and a GPS positioning device described in specification No. 34, in which 101 is a base station, which is provided with a GPS receiving antenna 102 and a transmitting / receiving antenna 103. 104 is a remote unit.

The remote unit 104 includes an RF to IF converter 10 with a GPS receiving antenna 105.
6. An A / D converter 107 for converting an analog signal from the converter 106 into a digital signal.
A memory (digital snapshot memory) 108 for recording the output from the D converter 107, this memory 1
General-purpose programmable digital signal processing circuit (hereinafter abbreviated as DSP circuit) 109 for processing signals from 08
Have.

In addition to this, a program EPROM 110 connected to the DSP circuit 109, a frequency synthesizer 111, a power regulator circuit 112, an address writing circuit 113, a microprocessor 114, and RA.
It has an M (memory) 115, an EEPROM 116, a transmission / reception antenna 117, and a modem 118 connected to the microprocessor 114.

Next, the operation will be described. The base station 101 issues a command to the remote unit 104,
The measurement is performed via the message transmitted by the data communication link 119. The base station 101 transmits Doppler data of satellite information for the target satellite in this message. This Doppler data has the format of frequency information, and the message specifies the target satellite. This message is received by modem 118, which is part of remote unit 104,
Stored in memory 108 coupled to microprocessor 114.

The microprocessor 114 is a DSP circuit 1
09, handles the data information transfer between the address write circuit 113 and the modem 118, and controls the power management function within the remote unit 104.

When remote unit 104 receives instructions for GPS processing (eg, from base station 101) as well as Doppler information, microprocessor 1
Reference numeral 14 gives a function to the RF-to-IF converter 106, the A / D converter 107, and the memory 108 via the battery and the power lines 120a to 120d controlled by the power regulator circuit 112. As a result, the signal from the GPS satellite received via the antenna 105 is down-converted to the IF frequency and then digitized.

This usually corresponds to a time of 100 milliseconds to 1 second (or longer). Such a continuous data set is stored in the memory 108.

The sword range calculation is performed using the DSP circuit 109. In addition, the DSP circuit 109 rapidly performs a number of correlation operations between the locally generated reference and the received signal, thereby enabling a very fast calculation of the sword range, the Fast Fourier Transform (FFT). ) Allows the use of algorithms. The Fast Fourier Transform algorithm simultaneously searches for all such positions in parallel, accelerating the computational process.

When the DSP circuit 109 completes the calculation of the sword range for each of the target satellites, it transmits this information to the microprocessor 114 via the interconnect bus 122. The microprocessor 114 then data links 119 the sword range data for final position calculation.
The modem 118 is used for the purpose of transmitting to the base station 101 via the.

In addition to the sword data, a time lag indicating the elapsed time from the initial data collection in memory 108 to the time of transmission of the data via data communication link 119 can be simultaneously transmitted to base station 101. . This time lag enhances the ability of base station 101 to perform position calculations. This is because this allows GPS satellite position to be taken at the time of data collection.

Modem 118 utilizes separate transmit and receive antennas 117 for sending and receiving messages over data communication link 119. It is understood that modem 118 includes a communication receiver and a communication transmitter, both of which are alternately coupled to transmit / receive antenna 117. Similarly, the base station 101 can use separate antennas 103 to send and receive data link messages, thus continuously transmitting GPS signals via the GPS receiving antenna 102 at the base station 101. Can be received.

The position calculation in the DSP circuit 109 includes the amount of data stored in the memory 108 and the DSP circuit 10.
It is expected that the required time will be less than a few seconds, depending on the speed of 9 or some DSP circuits.

As mentioned above, the memory 108 captures the record of interest for a relatively long time. Effective processing of large blocks of data using the fast convolution method contributes to the performance for processing signals at low reception levels (e.g. when reception levels drop due to significant blockage by buildings, trees, etc.). ).

All sword ranges for visible GPS satellites are calculated using this same buffered data. This is an improvement in performance for continuous tracking GPS receivers under conditions where signal amplitudes change rapidly (such as urban interference conditions).

The signal processing performed by the DSP circuit 109 will be described with reference to FIG. The purpose of the processing is to determine the timing of the received waveform with respect to the locally generated waveform, and for even higher sensitivity the very long part of the waveform is processed, usually from 100 msec to 1 second. To be done.

Received GPS signal (C / A code)
Consists of repetitive sword random (PN frame) of 1023 bits = 1 msec. Therefore, the preceding and following PN frames are added to each other. For example, 10 per second
Since there is a 00PN frame, the first frame is coherently added to the next second frame and the resulting one is added to the third frame. Hereinafter, FIG.
As shown in (E), add sequentially. As a result, 1PN
A signal with a duration of frame = 1023 bits is obtained. By comparing the phase of this sequence with the local reference sequence, the relative timing between the two, or the sword range, can be established.

[0020]

Since the conventional GPS positioning method, GPS terminal, and GPS positioning system are configured as described above, when performing position measurement (hereinafter referred to as positioning) processing, a base is used each time. The Doppler information was obtained from the station, the pseudo-range to each visible satellite was calculated, and the terminal position was detected based on that or the result was sent to the server. Therefore, there has been a problem that communication is always required with the server when positioning is performed, and communication cost is high.

The present invention has been made to solve the above problems, and a GPS positioning method for reducing communication costs by enabling communication with an external device only when reception sensitivity is poor, An object is to obtain a GPS terminal and a GPS positioning system.

[0022]

A GPS positioning method according to the present invention is a GPS positioning method for a GPS terminal receiving a GPS signal.
A PS positioning method, a first step of detecting the intensity of the received electric field by receiving a GPS signal, if the received electric field is strong selects the navigation data obtained by the GPS terminal itself based on the GPS signal If the reception electric field is weak the
The GPS received by an external device different from the GPS terminal
Receives navigation data obtained from the signal from the external device.
A second step of selecting by Shin, containing the GPS signals received by the GPS terminal itself based on the selected navigation data
Specify the boundary of polarity inversion of the data series
Includes a third step of obtaining the position of the GPS terminal using the identified data series . Further, the third step in the GPS positioning method according to the present invention
The fourth obtaining a data series having a polarity from the GPS signal
The fifth step of changing the polarity based on the navigation data obtained from the GPS signal and performing the cumulative addition of the value of the data series at the same bit corresponding position for each C / A code length corresponding portion. The sixth step of calculating the correlation using the C / A code based on the result of the step 5 , the seventh step of obtaining the correlation peak position based on the correlation peak value obtained by this correlation calculation, the correlation including the step of eighth determining a GPS terminal based on the peak position pseudo distance between the C / a code corresponding to a satellite is also <br/> of.

The GPS terminal according to the present invention is a GPS signal
In GPS terminal for receiving, reception field detection unit that detects the intensity of the received electric field by receiving a GPS signal, if the received electric field is strong selects the navigation data obtained by the GPS terminal itself based on the GPS signal the reception when electric field is weak the GPS terminal different from the external device before being received by <br/> Symbol navigation data obtained based on GPS signals the external instrumentation is
The selection unit that receives and selects from the device, and includes the GPS signal received by the GPS terminal itself based on the selected navigation data.
Specify the boundary of polarity inversion of the data series
Includes a position calculation unit that obtains the position of the GPS terminal using the identified data series . The position calculation unit in the GPS terminal according to the present invention is a data sequence acquisition unit that obtains a data sequence having a polarity from the GPS signal , changes the polarity on the basis of navigation data obtained from the GPS signal, and A data processing unit that cumulatively adds values at positions corresponding to the same bit for each C / A code length, a correlation calculation unit that performs correlation calculation using the C / A code based on the processing result, and this correlation calculation unit Based on the obtained correlation peak position, a pseudo distance calculation unit for obtaining a pseudo distance between the GPS terminal and the satellite corresponding to the C / A code.
It includes .

The GPS positioning system according to the present invention is a GPS positioning system comprising an external device for obtaining navigation data from GPS signals and a GPS terminal capable of receiving navigation data from the external device. Is
A reception electric field detection unit that receives a GPS signal and detects the strength of the reception electric field, and if the reception electric field is strong, the GPS
The navigation data obtained by the GPS terminal itself is selected based on the signal, and if the received electric field is weak , the navigation data is received by the external device.
The navigation data obtained based on the GPS signal
A selection unit that receives and selects from an external device , and a GPS received by the GPS terminal itself based on the selected navigation data
Identify the boundary of polarity inversion of the data series included in the signal,
The position calculation unit obtains the position of the GPS terminal using the data series in which the boundary is specified . Also,
Wherein the GPS positioning system according to the present invention GPS
The position calculation unit of the terminal is one of a data sequence acquisition unit that obtains a data sequence having polarity from a GPS signal, and navigation data obtained from the GPS signal or navigation data obtained by the external device based on the GPS signal. And a data processing unit for performing cumulative addition of data series values at the same bit equivalent position for each C / A code length corresponding to the polarity change based on the above, and correlation using the C / A code based on this processing result. shall include a correlation calculation unit for performing calculations and a pseudo distance calculator for determining the pseudorange between the GPS terminal based on correlation peak position obtained by the correlation calculation unit and between satellites corresponding to the C / a code Is.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. FIG. 1 shows a G according to the first embodiment of the present invention.
FIG. 2 is a block diagram for explaining an outline of a usage state of a PS positioning system and a GPS positioning device, in which 1 is a target satellite and 2 is a receiving antenna installed in an environment with a good view for receiving GPS signals from the target satellite 1. Headquarters server 3 provided with 3 as an external device for extracting navigation data and Doppler data from a received GPS signal, and 4 is a terminal connected to headquarters server 2 via a communication medium 5 such as a wireless or wired communication. Reference numeral 4 includes a receiving antenna 6 for receiving GPS signals from the satellite 1.

Next, the outline of the operation will be described. First,
When the headquarter server 2 receives a GPS signal from the receiving antenna 3 installed in an environment with a good view, it determines whether the S / N ratio is good (step ST1) and then calculates Doppler data (step ST2). , GPS navigation data is calculated (step ST3).

On the other hand, the terminal 4 detects the strength of the electric field received through the receiving antenna 6 (step ST4), judges whether the received electric field is good (step ST5), and if YES, the navigation data on the terminal side. And Doppler data are extracted (step ST6), and if NO, necessary navigation data and Doppler data are extracted from the headquarters server 2 (step ST7). Then, the memory section and the calculation section are determined according to the detected received electric field strength, and the received GP is received.
The S signal is stored in the memory (step ST8).

Thereafter, Doppler correction of the received GPS signal is performed (step ST9), this data is divided by navigation data (step ST6, step ST7), and the correlation peak position detection section (step ST10) maximizes the correlation value. This is a pseudo distance by finding a point that The position is calculated based on the pseudo distance and the extracted navigation data (step ST14).

As described above, according to the first embodiment, the quality of the received electric field is judged, and the communication with the headquarter server 2 is performed only when the received electric field is bad. Can be reduced.

FIG. 2 is a block diagram showing a specific configuration of the terminal 4 shown in FIG. 1, wherein 7 is a receiving circuit, 8 and 9 are analog / digital conversion circuits (hereinafter abbreviated as A / D), Reference numeral 11 is a received electric field strength detection unit, 12 is a memory (DR
AM), 13 is an arithmetic processing unit, 14 is an antenna provided in the wireless device 15 for transmitting and receiving data to and from the headquarters server 2 by radio waves, 16 is a modem (or TA) connected to the wireless device 15, An input / output circuit 17 is provided between the modem 16 and the bus 18.

The receiving circuit 7 is a down converter 20 in which band pass filters 19 and 24 are connected to the input and output ends, respectively.
It has a reference oscillator 21, a synthesizer unit 22, a frequency divider 23 that divides the output frequency of the synthesizer unit 22 and outputs a clock signal, and an I / Q converter 25. Further, the arithmetic processing unit 13 includes a CPU 26, a CPU 27, a CPU 28 connected to the bus 18, and a bus 18 respectively.
A memory (RAM) 29 connected to the CPU 27 and a DSP 30 connected to the CPU 27.
Each of them is provided with a memory (ROM) 26a to 28a.

FIG. 3 is a configuration diagram in which FIG. 2 is described in more detail. The same portions as those in FIG. 2 are designated by the same reference numerals and duplicate description will be omitted. The headquarters server 2 includes a GPS reference receiving unit 31, a G
A navigation data extraction unit 32 included in the PS data, a Doppler information calculation unit 33, a signal synthesis unit 36, and a signal transmission / reception unit 37 are included.

The terminal 4 has a memory space based on the output of the received electric field strength detection unit 11, a section determination unit 41 for correlation calculation, a navigation data extraction unit 43 connected to the memory area S, and a switch unit 47 for the communication medium 5. And a Doppler information extraction unit 45 connected to the output of the navigation data extraction unit 43 and the output of the data transmission / reception unit 48.
And a Doppler correction unit 46 connected to the memory area H,
Pseudo distance obtained by detecting the data of the navigation data extraction section 49 connected to the output of the data transmission / reception section 48, the output of the memory area V, and the C / A code generation section 51 by the correlation peak position detection section 52. And a position calculation unit 57 for calculating a position with the navigation data from the memory area V.

The respective units from the navigation data extraction unit 43 to the position calculation unit 57 are not separately provided, but the functions of these units are, for example, CPU26 to CPU28.
And the arithmetic processing unit 13 having the DSP 30. Further, in the illustrated example, three CPUs are shown for the sake of simplification of the description, but in reality, one CPU can be used.

Next, the operation will be described. FIG. 4 is a flow chart for explaining the operation of the headquarters server 2. In the headquarters server 2, first, the GPS reference receiving unit 31 receives a GPS signal (step ST16), and then the Doppler information calculating unit 33 calculates Doppler (step ST16).
17), the navigation data extraction unit 32 extracts the GPS navigation data (step ST18), and then the signal synthesis unit 36.
To synthesize. When the terminal 4 requests data, the signal transmitting / receiving unit 37 transmits the Doppler and navigation data to the terminal 4 side (step ST19).

5 to 7 show a GPS positioning system and GP.
It is a flow chart explaining operation in each CPU of the S positioning device. On the terminal 4 side, first, the CPU 2
On the 6 side, a GPS signal is received via the antenna 6 (step ST21), and the received GPS signal is given a predetermined frequency by the oscillation frequency of the reference oscillator 21 supplied via the synthesizer section 22 in the reception frequency conversion circuit 20. After converting to the frequency, the output of the reception frequency converting circuit 20 is I / Q converted by the I / Q converting section 25 (step ST2).
2), I signal and Q signal are taken out, A / D conversion circuit 8,
A / D conversion is performed at 9.

On the other hand, the received electric field strength at this time is detected by the received electric field strength detector 11, and the electric field level 1 (ultra-weak), the electric field level 2 and the electric field level 3 are selected (steps ST23 to ST23).
In step ST25), the memory section τ1, the memory section τ2, and the memory section τ3 are determined by the memory section / correlation calculation section determination unit 41 according to the selected electric field level (steps ST26 to ST28), and the A / D is performed. The determined section (time) of the GPS signal passing through the conversion circuits 8 and 9
It is stored in the memory area S of the memory 12 and constantly updated (step ST29).

The navigation data extraction unit 43 reads the contents of the memory area S and extracts navigation data. The Doppler information extraction unit 45 extracts Doppler information from the signal from the navigation data extraction unit 43, and also extracts the Doppler information from the signal from the headquarters server 2 via the data transmission / reception unit 48, and stores it in the memory area D29. The Doppler correction unit 46 reads the data in the memory area D29 (step ST30),
The data in the memory area S is Doppler-corrected and the memory area H
(Step ST31).

Next, on the CPU 27 side, the received electric field strength detection unit 11 detects the received electric field levels 1, 2, and 3, and reads the contents of the memory area L storing the electric field strength (step ST32). For example, the data in the memory area V in which the navigation data from the navigation data extraction unit 43 is stored is read (step ST32b). Further, if the electric field level is 1 or 2, the navigation data from the headquarters server 2 is read via the transmission / reception unit 48 and the navigation data extraction unit 49 to read the data in the memory area V (step ST3).
2a). Then, GPS signals are obtained from the memory area H and predetermined navigation data are obtained from the memory area V in the sections corresponding to the specified memory section τ1, memory section τ2, and memory section τ3 (step ST33). In the correlation peak position detection unit 52, the GPS signal from the memory area H is divided by the predetermined navigation data from the memory area V, and the C / A code PN frame 2 is divided within the 1 data section (navigation data).
Corresponding bits of 0 corresponding bits are added, and the correlation calculation between the added C / A code and the C / A code generated by the C / A code generation unit 51 is performed over the above section.
This is memory section τ1, memory section τ2, memory section τ
This is performed over the section of 3 (step ST34).

After that, the navigation data is temporally shifted so that the correlation peak value is maximized, and the correlation peak position obtained by repeating the same correlation calculation is used as the boundary of the polarity inversion of the navigation data and the pseudo. It is a distance. Then, the self-position is calculated and output based on the navigation data and the pseudo distance (step ST35, step ST4).
0).

On the side of the CPU 28, the contents of the memory area L are read (step ST41), and it is judged whether or not the electric field level is 3 or more (step ST42). No connection is made and data is not exchanged (step ST43). If NO, the switch unit 47 is connected to obtain data from the headquarters server 2 (step ST44), the navigation data is stored in the memory area VS, and the Doppler information extraction unit 45 determines the Doppler information according to the electric field level. Section memory area D
(Step ST45).

As described above, according to the first embodiment, the quality of the received electric field is determined, and the communication with the headquarter server 2 is performed only when the received electric field is bad. It is possible to reduce the number of bits, and the correlation peak position detection section allows the regular C consisting of a large number of bits to be reduced.
The values of the same bit position are cumulatively added to the / A code for each cycle, and the C / A code is added with the boundary of increase and decrease of the cumulative addition result as the data addition start position. When integrating (cumulative addition) depending on the polarity of the navigation data as described above, the disadvantages that the signal components cancel each other and are not sufficient for improving the sensitivity (S / N) can be dramatically eliminated, and the C / A buried in noise can be eliminated. The code and the pseudo distance can be detected with certainty, and a highly sensitive GPS positioning system and GPS positioning device can be obtained.

The details of the embodiment of the correlation peak position detector 52 will be described below. In this embodiment, a regular C / A code composed of a large number of bits is divided into navigation data lengths at arbitrary positions, and the divided C / A codes are cumulatively added to the values at the same bit positions. The cumulative addition result is added together with polarities based on the navigation data detected by itself or the navigation data received from the headquarters server, correlation calculation is performed with the addition result and the C / A code, and the obtained correlation peak position Is the data addition start position. FIG. 8 shows the relationship between the number of PN frames and the number of chips when the navigation data length is M. Here, one piece of navigation data consists of 20 PN frames as shown in the figure, and one PN frame consists of 1023 chips. One PN frame (C / A code = PN code) of the GPS signal stored after Doppler correction consists of 1023 chips. The C / A code of the GPS signal is composed of 1023 bits, but it is necessary for the A / D converter to sample at a frequency more than twice in order to faithfully send information according to the sampling theorem when digitizing. Therefore, the number of sampled samples in the memory unit S and the number of signal samples in the memory V are more than double. For example, 1023 chips are 102
It is stored as 3 × 2i (i = 1, 2, 3) sample values. In the following description, C /
Description will be made based on the A code chip unit.

In FIG. 5, the CPU 26 performs Doppler correction for each satellite based on the Doppler information (Doppler frequency shift for each satellite) obtained from the memory D (steps ST30 and ST31). The value is stored in the memory H. With respect to the signal Doppler-corrected by the CPU 27 in FIG. 5, a regular C / A code having a large number of bits is divided into the length of navigation data at an arbitrary position, and the C / A is sequentially divided from the divided start position. Positions scattered in units corresponding to code (= 1023 bits) “Signal sample position (= 1
023 × 2i, i = 1, 2, 3) ”, 1 data (= 20 frames, = 20 × 1) for each sample position.
(023 bits) Primary addition is performed by the amount corresponding to the length. For simplification of description, the following description will be made in units of C / A code chips. The stored GPS data is continuous regular data in which this PN frame repeats. And 20M
The C / A code (P
The phase of the N code is also reversed. The leading portion when the phase of the C / A code reverses coincides with the leading portion of the navigation data when the navigation data changes. FIG. 9 shows a relationship diagram when the length of navigation data is M. In the figure, the j-th PN frame and the i-th PN frame in the K-th navigation data are taken in from an arbitrary portion and stored in a memory corresponding to a predetermined time (in this embodiment, M navigation data). Remember. It is not known from which chip portion of the GPS signal the beginning of the stored data is. FIG. 10 is an explanatory diagram of data processing stored in the memory. GP with external or internal navigation data
The S signal (C / A code) is divided and stored for M navigation data in the memory. A total of M C / A code chips for navigation data imported from an arbitrary part 1023 * 20 * M
Stored in chip memory. At this time, the data in the memory is arranged in a matrix form for one row of 1023 chips (corresponding to the IPN code length), and this is set for the navigation data 20.
A matrix of * M rows fetched 1023 columns and 20 * M columns is shown in FIG. Here, the chip data next to the 1st row and 1023rd column of the data is the 2nd row and 1st column data. Similarly, line 2 1023
Next to the column is the third row and the first column. Repeat this sequence M * 20
Shows up to row 1023 columns. When the GPS signal (navigation data) is arbitrarily divided by the navigation data obtained from the outside or the inside, the beginning portion thereof is the beginning portion where the phase of the GPS signal stored in the memory is reversed (the true portion existing in the GPS signal It does not generally match the beginning part of the navigation data). The correlation peak position detection unit is to match the positions as much as possible by the following method.

Hereinafter, FIG. 11 will be specifically described.
First, 20 divided by navigation data Dk in FIG.
Data in a matrix with rows 1023

[Equation 1] Is calculated by the number 1. S₁ (D₁ ), S₂ (D₁ ),…, S_i (D
₁ ) ,. ． ． S₁₀₂₃(D₁ ) Each and data D1 (=
-1 or +1) and D₁ * S₁ (D₁ ), D₁ * S₂ (D₁ ), ..., D₁ * S_i
 (D₁ ) ,. ． ． , D ₁ * S₁₀₂₃(D₁ ) To get Next, navigation data D₂ With the data divided by

[Equation 2] Is calculated by Equation 2. S₁ (D₂ ), S₂ (D₂ ),…, S_i (D
₂ ) ,. ． ． S₁₀₂₃(D₂ ) Each and data D₂ (=
-1 or +1) and D₂ * S₁ (D₂ ), D₂ * S₂ (D₂ ), ..., D₂ * S_i
 (D₂ ) ,. ． ． , D ₂ * S₁₀₂₃(D₂ ) To get Similarly, navigation data D_M Data divided by
so

[Equation 3] Is calculated by Equation 3. S₁ (D_M ), S₂ (D_M ),…, S_i (D
_M ) ,. ． ． S₁₀₂₃(D_M ) Each and data D_M (=
-1 or +1) and D_M * S₁ (D_M ), D_M * S₂ (D_M ), ..., D_M * S_i
 (D_M ) ,. ． ． , D _M * S₁₀₂₃(D_M ) To get next,

[Equation 4] Here, the correlation calculation between the data group of the sequence of C ₁ , C ₂ , C ₃ , C ₄ , ..., C _{1023 and 1023} C / A codes generated internally is performed (step ST34). The accuracy of the correlation calculation value increases as the number of sampling points increases.
FIG. 12 shows an example in which two sampling points are taken per 1-bit equivalent length as a method of improving the accuracy of the correlation peak position. FIG. 12A shows a case where the true peak is located at the center of the sampling points. (b) is the case where the true peak is slightly off the sampling point, and (c) is the case where the true peak coincides with the sampling point. Peak position Xp (local position from sample point)
Is calculated by Xp = P2 / (P1 + P2) · τ / 2. Here, τ has a length equivalent to 1 bit.

After that, it is judged whether the correlation peak value is a predetermined value or more (step ST51). If the decision result in the step ST51 is YES, the fine adjustment mode is set. That is, the navigation data is slightly shifted by + .DELTA.n chips and -.DELTA.n chips and a convergence point at which the peak value becomes larger is obtained (step ST52).

If it is the convergence point in step 53, the correlation peak position Xp is obtained and the peak maximum position (pseudo distance) is obtained.
Is stored in association with the satellite number (step ST5
4). When step ST53 is NO, slightly + Δ
The position of the navigation data is finely adjusted while shifting by n chips and -Δn chips until the convergence is repeated within a predetermined value until it converges in step ST53.
p is calculated, and the peak maximum position (pseudo distance) is stored in association with the satellite number (step ST54).

On the other hand, if the decision result in the step ST51 is NO, the navigation data is sequentially shifted by one data unit so that the correlation peak position can be detected, and further the correlation peak position is shifted by + Δn chips and −Δn chips. Step ST34, step S until the level exceeds a predetermined level.
T57 is repeated, and YE is determined by the judgment in step ST51.
Repeat until S. If the shift range exceeds the predetermined value in step ST56 in the process of the repeating loop, it is checked in step ST58 whether the Doppler correction value is abnormal. If the Doppler correction value is within the specified value, the Doppler correction value is reloaded, checked and corrected in step ST59, and step ST54 is repeated. As a result, if the Doppler correction value exceeds the default value in step ST58,
It is stored in the satellite together with the satellite number as undetectable,
The pseudo range of another satellite is obtained (step ST60).

Incidentally, the above-mentioned steps ST34 and S
T51 to step ST54 and step ST56 to step ST59 are processing units for clarifying the correlation peak position.

As described above, according to this embodiment,
A regular C / A code in which a PN frame consisting of a large number of bits is continuous is divided into lengths of navigation data at arbitrary positions, and the divided C / A codes are cumulatively added to the values at the same bit positions. , The cumulative addition result is added together with polarities based on the navigation data detected by itself or the navigation data received from the headquarters server, and the addition result and C / A are added.
By performing correlation calculation with the code and using the obtained correlation peak position as the data addition start position, the C / A code can be efficiently cumulatively added without being affected by the polarity change of the navigation data. For example, the C / A code can be reliably received even in a place where reception sensitivity is low, such as in a tunnel or a building.

The GPS positioning system and the GPS positioning device of the present invention described above are mounted on, for example, a mobile phone, and the position detected by the GPS positioning system and the GPS positioning device is displayed on the map data read from the memory. With this configuration, it is possible to obtain a mobile phone equipped with an extremely accurate navigation function that can be reliably used even in a place where reception sensitivity is poor, such as in a tunnel or a building.

As another embodiment, as a matter of course, the correlation calculation may use FFT calculation and IFFT calculation to perform high-speed calculation. As another embodiment, in place of the above correlation calculation, the C generated by the self is generated.
The calculation may be performed by the number of coincidences between the A / A code and the received C / A code or the degree of coincidence.

[0053]

As described above, according to the present invention, the received electric field strength is detected, and only when the received electric field strength is weak,
Since it is configured to communicate with an external device to receive data, there is an effect that the communication cost can be significantly reduced as compared with the conventional case where communication is always performed with the external device.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an outline of a usage state of a GPS positioning system and a GPS positioning device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of the terminal shown in FIG.

FIG. 3 is a block diagram showing the terminal of FIG. 2 in more detail.

FIG. 4 is a flowchart illustrating the operation of the headquarters server.

FIG. 5 C of GPS positioning system and GPS positioning device
6 is a flowchart illustrating an operation of PU26.

FIG. 6 C of GPS positioning system and GPS positioning device
It is a flow chart explaining operation in PU27.

FIG. 7 C of GPS positioning system and GPS positioning device
It is a flow chart explaining operation in PU28.

FIG. 8 is a diagram showing data of a GPS signal (C / A code signal).

FIG. 9 is a diagram illustrating a structure of a GPS signal (C / A code signal).

FIG. 10 is an explanatory diagram of a method of detecting a boundary of polarity reversal of navigation data.

FIG. 11 is a flowchart illustrating a method of detecting a boundary of polarity reversal of navigation data.

FIG. 12 is a detailed explanatory diagram regarding handling of a correlation result (correlation peak data) between the secondary addition result and the C / A code.

FIG. 13 is an explanatory diagram of a C / A code.

FIG. 14 is a block diagram showing a configuration of a conventional GPS positioning system and a GPS positioning device.

FIG. 15 is an explanatory diagram of how to detect a C / A code in a conventional GPS positioning system and GPS positioning device.

[Explanation of symbols]

1 satellite, 2 headquarters server (external device), 4 terminal (G
PS terminal) 5, communication medium, 11 received electric field strength detector, 52 correlation peak position detector.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-6-61979 (JP, A) JP-A-6-148308 (JP, A) JP-A-7-128431 (JP, A) JP-A-8- 146117 (JP, A) JP-A-9-54150 (JP, A) US Patent 5663734 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 5/00-5/14 H04B 7/24-7/26 H04Q 7/00-7/38

Claims (6)

(57) [Claims] 1. In a GPS terminal that receives GPS signals
A first step of receiving a GPS signal and detecting the strength of the received electric field , which is a GPS positioning method according to the above. When the received electric field is strong, the navigation data obtained by the GPS terminal itself based on the GPS signal is selected. and, if the reception electric field is weak
The G received by an external device different from the GPS terminal
Is the navigation data obtained based on the PS signal relevant to the external device?
The second step of receiving and selecting from the GPS signal received by the GPS terminal itself based on the selected navigation data
The polarity inversion boundary of the data series included in
G including a third step of obtaining the position of the GPS terminal using the data series with the specified boundary
PS positioning method. 2. The third step comprises a fourth step of obtaining a polar data sequence from a GPS signal, and the G step.
Fifth step of performing the cumulative addition value of the data sequence at the same bit position corresponding to the C / A code length per equivalent with the polarity change on the basis of navigation data obtained from the PS signal, the fifth step The sixth step of calculating the correlation using the C / A code based on the result, the seventh step of obtaining the correlation peak position based on the correlation peak value obtained by this correlation calculation, and the correlation peak position And G
PS terminal and the GPS positioning method according to claim 1, wherein the eighth step, characterized in containing Mukoto obtaining a pseudo distance between the corresponding satellites in the C / A code. 3. A GPS terminal for receiving a GPS signal
A reception electric field detector for receiving a GPS signal and detecting the strength of the reception electric field;
Select navigation data obtained by GPS terminal itself based on S signal
And, if the reception electric field is weak Unlike the GPS terminal
Obtained based on the GPS signal received by the external device
A selection unit that receives navigation data from the external device and selects the navigation data, and the GPS terminal itself based on the selected navigation data.
Inversion of the data sequence contained in the GPS signal received by
Of the boundary and the data series in which the boundary is identified is used.
A GPS terminal including a position calculation unit for obtaining the position of the GPS terminal. 4. The position calculation unit is a data sequence acquisition unit that obtains a data sequence having polarity from a GPS signal, and the GP.
A data processing unit for changing the polarity based on the navigation data obtained from the S signal and accumulatively adding the values of the data series at positions corresponding to the same bit for each C / A code length
A correlation calculation unit that performs a correlation calculation using the C / A code based on this processing result, and between the GPS terminal and the satellite corresponding to the C / A code based on the correlation peak position obtained by this correlation calculation unit. The GPS terminal according to claim 3, further comprising a pseudo-distance calculation unit that obtains a pseudo-distance with. 5. An external device for obtaining navigation data from a GPS signal and a GPS capable of receiving navigation data from this external device.
A GPS positioning system comprising a terminal, the GP
The S terminal receives a GPS signal and detects the strength of the received electric field, and when the received electric field is strong, selects the navigation data obtained by the GPS terminal itself based on the GPS signal , If the received electric field is weak, the external device
Navigation data obtained based on the GPS signal received by the device.
The selection unit that receives and selects the data from the external device, and the GPS terminal itself receives the navigation data based on the selected navigation data.
Boundary of polarity inversion of data series included in GPS signal
Is specified, and G is determined using the data series in which the boundary is specified.
A GPS positioning system, comprising: a position calculator that determines the position of the PS terminal. 6. The position calculation unit of the GPS terminal is a GPS
A data sequence obtaining unit that obtains a data sequence having a polarity from a signal, and a polarity change based on either navigation data obtained from the GPS signal or navigation data obtained by the external device based on the GPS signal. A data processing unit that cumulatively adds the values of the data series at positions corresponding to the same bit for each C / A code length, and a correlation calculation unit that performs correlation calculation using the C / A code based on this processing result, according to claim 5, characterized in that it comprises a pseudo distance calculator for obtaining pseudoranges correlation peak position obtained by the correlation calculation unit and between satellites corresponding to the C / a code and the GPS terminal based on GPS positioning system.