JP3270407B2 - GPS positioning method, GPS terminal and GPS positioning system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a GPS positioning method, a GPS terminal, and a GPS positioning system that receive an S signal and accurately detect a reception position.

[0002]

2. Description of the Related Art A number of satellites are launched around the earth, and each satellite has the same carrier frequency 157.
Radio waves of 5.42 GHz are continuously transmitted. This radio wave is phase-modulated by a pseudo-noise code, and can be separately received by assigning a different code pattern to each satellite. The pseudo-noise code is a regularly changing code pattern called a publicly available C / A code. In addition, the navigation data necessary for the user to perform positioning, such as satellite orbit information, correction values on the satellite, and ionospheric correction coefficients, is inverted into the radio waves by inverting the polarity of the C / A code. I'm sending it.

[0003] As shown in FIG.
1023 bits = 1 msec is defined as 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 signal of 1000 PN frame.
The polarity of the A code is also inverted.

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

[0005] This remote unit 104 comprises 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 a DSP circuit) 109 for processing the signal from step 08
Having.

In addition, a program EPROM 110 connected to a DSP circuit 109, a frequency synthesizer 111, a power regulator circuit 112, an address writing circuit 113, a microprocessor 114, an RA
M (memory) 115, EEPROM 116, and a modem 118 having a transmitting / receiving antenna 117 and connected to a 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 a 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. The Doppler data has a format of frequency information, and the message specifies a target satellite. This message is received by the modem 118 that is part of the remote unit 104,
Stored in memory 108 coupled to microprocessor 114.

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

When remote unit 104 receives instructions for GPS processing and Doppler information (eg, from base station 101), microprocessor 1
Reference numeral 14 gives functions 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. Thus, 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 quickly performs a number of correlation operations between the locally generated reference and the received signal, thereby enabling a very fast computation of the sword range (FFT). ) Enable the use of the algorithm. The Fast Fourier Transform algorithm searches all such positions simultaneously in parallel, accelerating the computation 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. Next, the microprocessor 114 transmits the sword range data to the data link 119 for the final position calculation.
The modem 118 is used for the purpose of transmission to the base station 101 via the.

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

The modem 118 utilizes a separate transmit / receive antenna 117 for transmitting and receiving messages over the 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 transmit and receive data link messages, and thus continuously transmit GPS signals via the GPS receive antenna 102 at the base station 101. Can be received.

For the position calculation in the DSP circuit 109, the amount of data stored in the memory 108 and the DSP circuit 10
Depending on the speed of nine or several DSP circuits, the time required is expected to be less than a few seconds.

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

All sword ranges for visible GPS satellites are calculated using this same buffered data. This results in improved performance for continuous tracking GPS receivers in situations where the amplitude of the signal changes rapidly (such as urban fault 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 occurring waveform, and to obtain a higher sensitivity, the extremely long part of the waveform, typically over 100 ms to 1 second, is processed Is done.

GPS signal (C / A code) to be received
Consists of a repetitive sword random (PN frame) of 1023 bits = 1 msec. Therefore, the preceding and succeeding 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.
(E) is sequentially added. 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, ie, the sword range (pseudorange), can be determined.

[0020]

Since the conventional GPS positioning system and the conventional GPS positioning device are configured as described above, in order to realize high sensitivity, a pre-correlation calculation called a pre-integration of a received GPS signal is performed. In the course of the signal processing, the preliminary integration is performed for 5 to 10 PN frames in order to avoid the influence of the reduction of the integration effect due to the polarity inversion of the navigation data. In the phase of the C / A code included in the GPS reception signal, the polarity of the section phase of the navigation data is inverted according to the content of the navigation data. Therefore, in such processing, since the polarity of the C / A code is changed by the navigation data, when integration (accumulation addition) is performed based on the polarity of the C / A code, the signal components cancel each other out and the sensitivity (S / N) is obtained. There was a drawback that it was not enough for improvement. That is, the boundary of the polarity reversal of the navigation data was not detected. For this reason, there is a problem that the number of integrals is theoretically limited and the improvement of sensitivity (S / N) is insufficient.

In addition, each time a remote unit as a terminal performs position measurement (hereinafter, referred to as positioning) processing, it obtains Doppler information from the base station, calculates a pseudo distance to each visible satellite, and calculates the pseudo distance. Based on the result or sending the result to the server, the terminal position was detected. Therefore, there is a problem that communication with a server is always required when positioning, and communication costs are high.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and communication with an external device can be performed only when reception sensitivity is poor, thereby reducing communication costs and reducing the cost of home use. High-sensitivity GPS positioning system and GPS that can receive signals stably even indoors and behind buildings
The purpose is to obtain a positioning device.

[0023]

A GPS positioning method according to the present invention comprises: a first step of obtaining a data series having a polarity from a GPS signal; a step of changing a polarity based on navigation data obtained from the GPS signal; The value of C
A second step of performing cumulative addition at a position corresponding to the same bit for each / A code length, a third step of calculating a correlation using a C / A code based on the result of the second step, A fourth step of obtaining a correlation peak position based on the correlation peak value obtained by the calculation, and a fifth step of obtaining a pseudo distance between the GPS terminal and a satellite corresponding to the C / A code based on the correlation peak position. It includes steps.

[0024]

The GPS terminal according to the present invention is a GPS terminal.
A data sequence obtaining unit for obtaining a data sequence having a polarity from a signal, performing a polarity change based on navigation data obtained from a GPS signal, and accumulating the data sequence value at a position corresponding to the same bit for each C / A code length A data processing unit for performing a correlation calculation using a C / A code based on the processing result; and a GPS terminal and a C / A code based on a correlation peak position obtained by the correlation calculation unit. It is provided with a pseudo distance calculation unit for obtaining a pseudo distance between corresponding satellites.

[0026]

[0027] The GPS positioning system according to the present invention is a GPS positioning system comprising an external device for obtaining navigation data from a GPS signal and a GPS terminal for calculating using navigation data from the external device. ,
A data sequence obtaining unit for obtaining a data sequence having a polarity from a GPS signal, and performing a polarity change based on navigation data obtained from an external device, and changing a value of the data sequence at a position corresponding to the same bit for each C / A code length. A data processing unit for accumulative addition, a correlation calculation unit for performing a correlation calculation using a C / A code based on the processing result, and a GPS terminal and a C / A based on a correlation peak position obtained by the correlation calculation unit And a pseudo-distance calculator for calculating a pseudo-distance between satellites corresponding to the / A code. In addition, the GPS positioning according to the present invention
The system is an external device that obtains navigation data from GPS signals
And a GPS terminal capable of receiving navigation data from this external device
A GPS positioning system comprising: a GPS terminal;
Receives the GPS signal and detects the strength of the received electric field.
Receiving electric field detector and GPS when this electric field is strong
When you select the navigation data obtained by the GPS terminal based on the signal
If the received electric field is weak, an external device based on the GPS signal
A selection unit for selecting the navigation data obtained in
Position calculation to find GPS terminal position based on navigation data
And a GPS terminal, and a GPS terminal
Data sequence obtaining unit for obtaining a data sequence having a characteristic, GP
Based on navigation data obtained from S signal or GPS signal
Based on one of the navigation data obtained by the external device
To change the polarity and change the value of the data series to C / A code.
Data to be cumulatively added at the position corresponding to the same bit for each
And a C / A code based on the processing result
Calculation unit that performs correlation calculation by
GPS terminal and C / A code based on the determined correlation peak position
Distance calculation to find the pseudo distance between satellites corresponding to the distance
Unit.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram for explaining 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. In the figure, reference numeral 1 denotes a target satellite, and 2 denotes a GPS signal received from a target satellite 1. Headquarters server as an external device for extracting navigation data and Doppler data from a received GPS signal, and a headquarters server 4 via a communication medium 5 such as a wireless or wired network. The terminal 4 is provided with a receiving antenna 6 for receiving a GPS signal from the satellite 1.

Next, an outline of the operation will be described. First,
When the headquarters server 2 receives the 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 the 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 via the receiving antenna 6 (step ST4) and determines whether the received electric field is good (step ST5). And Doppler data are extracted (step ST6). If NO, necessary navigation data and Doppler data are extracted from the headquarters server 2 (step ST7). Then, a memory section and a calculation section are determined according to the detected received electric field strength, and the received GP
The S signal is stored in the memory (step ST8).

Thereafter, the received GPS signal is subjected to Doppler correction (step ST9), this data is divided by the navigation data (steps ST6 and ST7), and the correlation peak position detector (step ST10) maximizes the correlation value. By obtaining such a point, this is regarded as a pseudo distance. 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 determined, and communication is performed with the head office server 2 only when the received electric field is defective. 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, 9 are analog / digital conversion circuits (hereinafter abbreviated as A / D), 11 is a reception field strength detection unit, 12 is a memory (DR
AM), 13 is an arithmetic processing unit, 14 is an antenna provided in the radio 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 radio 15, Reference numeral 17 denotes an input / output circuit provided between the modem 16 and the bus 18.

The receiving circuit 7 comprises a down converter 20 having band-pass filters 19 and 24 connected to input and output terminals, respectively.
, A reference oscillator 21, a synthesizer 22, a frequency divider 23 for dividing the output frequency of the synthesizer 22, and outputting a clock signal, and an I / Q converter 25. The arithmetic processing unit 13 includes a CPU 26, a CPU 27, and a CPU 28 connected to the bus 18, respectively.
And a DSP 30 connected to the CPU 27. Each of the CPUs 26 to 28
Are provided with memories (ROM) 26a to 28a, respectively.

FIG. 3 is a block diagram showing FIG. 2 in further detail. The same parts as those in FIG. The headquarters server 2 has a GPS reference receiving unit 31 and a G
It includes 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.

The terminal 4 determines a memory space and a section for correlation calculation based on the output of the received electric field strength detector 11, a navigation data extractor 43 connected to the memory area S, and a switch 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.
A Doppler correction unit 46 connected to the memory area H;
A pseudo-distance obtained by detecting the data of the navigation data extraction unit 49 connected to the output of the data transmission / reception unit 48, the output of the memory area V, and the C / A code generation unit 51 by the correlation peak position detection unit 52. And a position calculating unit 57 for calculating a position based on the navigation data from the memory area V.

The components of the navigation data extraction unit 43 to the position calculation unit 57 are not provided independently of each other, but the functions of these units are, for example, CPU 26 to CPU 28.
And the arithmetic processing unit 13 having the DSP 30. Although the illustrated example shows three CPUs for the sake of simplicity of explanation, it can actually be performed by one CPU.

Next, the operation will be described. FIG. 4 is a flowchart illustrating the operation of the head office server 2. In the headquarters server 2, first, the GPS reference receiving unit 31 receives the GPS signal (step ST16), and then the Doppler information calculating unit 33 calculates the Doppler (step ST16).
17) The GPS navigation data is extracted by the navigation data extraction unit 32 (step ST18), and thereafter, the signal synthesis unit 36
To synthesize. When there is a data request from the terminal 4, the Doppler and navigation data are transmitted from the signal transmitting / receiving unit 37 to the terminal 4 (step ST19).

FIGS. 5 to 7 show the GPS positioning system and the GP.
It is a flowchart explaining operation | movement in each CPU of 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 converted into a predetermined signal by the reception frequency conversion circuit 20 according to the oscillation frequency of the reference oscillator 21 supplied via the synthesizer unit 22. After the frequency conversion, the output of the reception frequency conversion circuit 20 is subjected to I / Q conversion by the I / Q converter 25 (step ST2).
2), extract the I signal and the Q signal, and
In step 9, A / D conversion is performed.

On the other hand, the reception electric field intensity at this time is detected by the reception electric field intensity detection section 11, and an electric field level 1 (very weak), an electric field level 2, and an electric field level 3 are selected (steps ST23 to ST23).
Step ST25), the memory section τ1, the memory section τ2, and the memory section τ3 are determined by the memory section and the section 41 for correlation calculation in accordance with the selected electric field level (step ST26 to step ST28), and the A / D is determined. Section (time) in which the GPS signal passed through the conversion circuits 8 and 9 was determined
It is stored in the memory area S of the memory 12 and is constantly updated (step ST29).

The navigation data extracting section 43 reads the contents of the memory area S and extracts navigation data. The Doppler information extracting unit 45 extracts Doppler information from the signal from the navigation data extracting unit 43, and extracts Doppler information from the signal from the head office server 2 via the data transmitting / receiving 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),
Doppler correction of the data in the memory area S
(Step ST31).

Next, on the CPU 27 side, the received electric field strength detecting section 11 detects the received electric field levels 1, 2, 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 where the navigation data is stored is read from the navigation data extraction unit 43 (step ST32b). If the electric field level is 1 or 2, the navigation data from the headquarters server 2 is read from the stored memory area V via the transmission / reception unit 48 and the navigation data extraction unit 49 (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 sections corresponding to the specified memory sections τ1, τ2, and τ3 (step ST33). In the correlation peak position detecting section 52, the GPS signal from the memory area H is divided by predetermined navigation data from the memory area V, and within one data (navigation data) section, the C / A code PN frame 2
Corresponding bits corresponding to 0 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 called memory section τ1, memory section τ2, memory section τ
This is performed over section 3 (step ST34).

Thereafter, the navigation data is temporally shifted so that the correlation peak value becomes maximum, and the correlation peak position obtained by repeating the same correlation calculation is used as a boundary between the polarity inversion of the navigation data and a pseudo-point. It is a distance. Then, it calculates and outputs its own position based on the navigation data and the pseudo distance (step ST35, step ST4).
0).

The CPU 28 reads the contents of the memory area L (step ST41) and judges whether the electric field level is 3 or more (step ST42). No connection is made and no data is exchanged (step ST43). If NO, the switch unit 47 is connected to acquire data from the headquarters server 2 (step ST44), the navigation data is stored in the memory area VS, and the Doppler information is extracted by the Doppler information extraction unit 45 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 head office server 2 is performed only when the received electric field is bad. The correlation peak position detection unit can reduce the number of bits in a regular C
Since the / A code is configured so that the value at the same bit position is cumulatively added for each cycle and the boundary of increase or decrease of the cumulative addition result is used as the data addition start position, the C / A code is added. When integration (cumulative addition) is performed according to the polarity of navigation data, the disadvantage that signal components cancel each other out and are not enough to improve sensitivity (S / N) can be dramatically removed, and C / A buried in noise can be removed. The code and the pseudo distance can be reliably detected, and a highly sensitive GPS positioning system and GPS positioning device can be obtained.

An embodiment of the correlation peak position detecting section 52 will be described in detail below. In this embodiment, a regular C / A code consisting of a large number of bits is divided into navigation data lengths at arbitrary positions, and each divided C / A code is cumulatively added to the value of the same bit position. Based on the navigation data detected by itself or the navigation data received from the headquarters server, the cumulative addition result is added with matching polarities, a correlation calculation is performed with the addition result and the C / A code, and the obtained correlation peak position is obtained. 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 is composed of 20 PN frames as shown in the figure, and one PN frame is composed of 1023 chips. One PN frame (C / A code = PN code) of the GPS signal stored after Doppler correction is equivalent to 1023 chips. The C / A code of the GPS signal is made up of 1023 bits, but it is necessary to sample at an A / D converter at twice or more frequency in order to faithfully transmit information by the sampling theorem when digitizing. Therefore, the number of sampled samples in the memory section S and the number of signal samples in the memory V are twice or more. For example, 1023 chips are 102
It is stored as 3 × 2i (i = 1, 2, 3) sample values. In the following description, C /
The 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 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 subjected to the Doppler correction by the CPU 27 in FIG. 5, a regular C / A code having a large number of bits is divided into navigation data lengths at an arbitrary position, and the C / A code is sequentially arranged from the divided leading position. The jump position in units of code (= 1023 bits) "signal sample position (= 1
023 × 2i, i = 1, 2, 3) ”, one data (= 20 frames, = 20 × 1) for each sample position.
(023 bits) The primary addition is performed for the length. For the sake of simplicity, the following description will be given for each C / A code chip. The stored GPS data is continuous regular data in which the PN frame is repeated. And 20M
The C / A code (P
N code) is also inverted in phase. The leading portion when the phase of the C / A code is reversed coincides with the leading portion of the navigation data when the navigation data changes. FIG. 9 shows a relationship diagram when the navigation data length is M pieces. In the figure, the PN frame j-th chip and the PN frame i-th chip in the K-th navigation data are fetched from an arbitrary part and are stored in a memory corresponding to a predetermined time (M navigation data in this embodiment). 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 in the memory for M pieces of navigation data. C / A code chip total 1023 * 20 * M for M navigation data taken in from any part
It is stored in the chip memory. The arrangement of the data stored in the memory at this time is taken in a matrix format for one row for 1023 chips (corresponding to the IPN code length), and this is used for the navigation data for 20 bits.
FIG. 10 shows a matrix of * M rows taken out, 1023 columns, and 20 * M columns. Here, the next chip data in the first row and 1023 column of the data is the data in the second row and first column. Similarly, two rows 1023
Next to the column is the third row and first column. M * 20
Represents up to row 1023. If the GPS signal (navigation data) is arbitrarily divided by the navigation data obtained from the outside or the inside, the leading part is the leading part where the phase of the GPS signal stored in the memory is reversed (the true part existing in the GPS signal). (The first part of the navigation data). The correlation peak position detecting section performs the following infinitely matching by the following method.

FIG. 11 is specifically described below.
First, in FIG. 10, the 20 divided by the navigation data Dk is used.
The data in the row 1023 matrix

(Equation 1) Is calculated by Equation 1. S ₁ (D ₁ ), S ₂ (D ₁ ),..., S _i (D
₁ ),. . . S ₁₀₂₃ (D ₁ ) and data D 1 (=
-1 or +1), and D ₁ * S ₁ (D ₁ ),
D ₁ * S ₂ (D ₁ ),..., D ₁ * S _i (D ₁ ),. . . ,
D ₁ * S ₁₀₂₃ (D ₁ ) is obtained. Next, the data divided by the navigation data D ₂

(Equation 2) Is calculated by Equation 2. S ₁ (D ₂ ), S ₂ (D ₂ ),..., S _i (D
₂ ),. . . S ₁₀₂₃ (D ₂ ) and data D ₂ (=
-1 or +1), and D ₂ * S ₁ (D ₂ ),
D ₂ * S ₂ (D ₂ ),..., D ₂ * S _i (D ₂ ),. . . ,
D ₂ * S ₁₀₂₃ (D ₂ ) is obtained. Similarly, the navigation data D _M
With the data divided by

(Equation 3) Is calculated by Equation 3. S ₁ (D _M ), S ₂ (D _M ), ..., S _i (D
_M ),. . . S ₁₀₂₃ (D _M ) and data D _M (=
-1 or +1), and D _M * S ₁ (D _M ),
D _M * S ₂ (D _M ), ..., D _M * S _i (D _M ),. . . ,
D _M * S ₁₀₂₃ (D _M ) is obtained. next,

(Equation 4) Here, a correlation calculation is performed between the data group arranged in the order of C ₁ , C ₂ , C ₃ , C ₄ ,..., C _{1023 and 1023} C / A codes generated internally (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 one bit equivalent length as a method for 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 point. (b) shows the case where the true peak is slightly off the sampling point, and (c) shows the case where the true peak coincides with the sampling point. Note that the peak position Xp (local position from the sample point)
Is determined by Xp = P2 / (P1 + P2) · τ / 2. Here, τ is a length equivalent to 1 bit.

Thereafter, it is determined whether the correlation peak value is equal to or greater than a predetermined value (step ST51). If the decision result in the step ST51 is YES, a fine adjustment mode is set. In other words, a convergence point at which the peak value becomes larger is obtained while slightly shifting the navigation data by + Δn chips and −Δn chips (step ST52).

If it is a 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). If step ST53 is NO, slightly + Δ
The position of the navigation data is finely adjusted while shifting by n chips and -Δn chips.
p is determined, 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 every data so that the correlation peak position can be detected, and further, the correlation peak position is shifted by + Δn chip and −Δn chip. Step ST34, Step S
T57 is repeated, and YE is determined in step ST51.
Repeat until S. If the shift range exceeds the predetermined value in step ST56 in the process of the repetitive loop, it is checked in step ST58 whether the Doppler correction value is normal. If the Doppler correction value is within the specified value, the Doppler correction value is reread and checked and corrected in step ST59, and step ST54 is repeated. As a result, if the Doppler correction value exceeds the predetermined value in step ST58,
The satellite stores it as undetectable along with the satellite number,
A pseudo distance of another satellite is obtained (step ST60).

Note that the above steps ST34 and S
Steps T51 to ST54 and steps ST56 to 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 navigation data lengths at an arbitrary position, and each divided C / A code is cumulatively added to the value of the same bit position. Based on the navigation data detected by itself or the navigation data received from the headquarters server, the cumulative addition result is added with matching polarities, and the addition result and C / A
By calculating the correlation 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, it is possible to reliably receive the C / A code even in a place where reception sensitivity is poor such as in a tunnel or a building.

The above-described GPS positioning system and GPS positioning device of the present invention are mounted on, for example, a portable telephone, and the positions detected by the GPS positioning system and the GPS positioning device are 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 places with poor reception sensitivity, such as in tunnels and buildings.

In another embodiment, the correlation calculation is
However, the use of FFT and IFFT calculations
Thus, a high-speed operation may be performed. In another embodiment,
Therefore, instead of the above solid correlation calculation, C
/ A code matches the received C / A code
It may be calculated by a number or a degree of coincidence.

[0056]

As described above, according to the present invention, a regular C / C frame in which PN frames each having a large number of bits are continuous.
A code is divided into navigation data lengths at arbitrary positions,
The value of the same bit position is cumulatively added to each of the divided C / A codes, and the result of the cumulative addition is added based on the navigation data detected by itself or the navigation data received from the headquarters server, and adds the results. And the C / A code are calculated, and the obtained correlation peak position is used as the data addition start position. Therefore, the C / A code is added without being affected by the polarity change of the navigation data. With such a configuration, the C / A code buried in the noise can be reliably detected, and the S / N ratio can be improved. Therefore, when applied to a mobile phone or the like, there is an effect that the C / A code can be reliably received even in a place where reception sensitivity is low, such as in a building or a subway platform. In addition, since the addition section is configured to be variable according to the state of the reception electric field, there is an effect that the C / A code can be more reliably received in combination with the above points.

[0057]

[Brief description of the 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 a terminal shown in FIG.

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

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

FIG. 5 shows C of the GPS positioning system and the GPS positioning device.
5 is a flowchart illustrating an operation in a PU 26.

FIG. 6 shows C of the GPS positioning system and the GPS positioning device.
6 is a flowchart illustrating an operation in a PU 27.

FIG. 7 shows C of the GPS positioning system and the GPS positioning device.
5 is a flowchart illustrating an operation in a PU.

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

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

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

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

FIG. 12 is a detailed explanatory diagram regarding handling of a correlation result (correlation peak data) between a secondary addition result and a 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 terminals (G
PS terminal), 5 communication medium, 11 reception electric field strength detection section, 52 correlation peak position detection section.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S 5/00-5/14 H03L 1/00-7/26 H04B 1/69-1/713 H04B 7 / 14-7/195 H04B 7/22

Claims (11)

(57) [Claims] 1. A first step of obtaining a data sequence having a polarity from a GPS signal, wherein the polarity is changed based on navigation data obtained from the GPS signal and the value of the data sequence is changed every C / A code length. A second step of performing cumulative addition at the same bit equivalent position, a third step of calculating a correlation using a C / A code based on the result of the second step, and a correlation peak obtained by the correlation calculation. A fourth step of determining a correlation peak position based on the value,
A GPS positioning method comprising: a fifth step of calculating a pseudo distance between a GPS terminal and a satellite corresponding to the C / A code based on the correlation peak position. 2. The method according to claim 1, further comprising the step of shifting the navigation data when the desired correlation peak value cannot be obtained, and changing the polarity based on the shifted navigation data. 2. The GPS positioning method according to 1. 3. The GPS according to claim 2, wherein the shift is performed in a direction in which a correlation peak value is maximized.
Positioning method. 4. The GPS positioning method according to claim 2, wherein the shift amount is a predetermined value. 5. The GPS positioning method according to claim 4, wherein the shift amount has a different value and changes from a large value to a small value. 6. The GPS according to claim 1, further comprising a seventh step of performing Doppler correction on the GPS signal using Doppler information obtained from the GPS signal.
Positioning method. 7. An eighth step of receiving a GPS signal, detecting the strength of the received electric field, and changing the length of the data sequence in accordance with the strength of the received electric field. The GPS positioning method according to claim 1. 8. A data sequence having a polarity from a GPS signal.
Data series obtaining unit for obtaining the GPS signal
Change the polarity based on the navigation data and
The value of the data sequence is equivalent to the same bit for each C / A code length
The data processing unit for accumulating the summing in position, based on the processing result
A correlation calculator for performing a correlation calculation using a C / A code,
GP based on the correlation peak position obtained by the correlation calculator
Pseudo distance between S terminal and satellite corresponding to the C / A code
G provided with a pseudo-distance calculation unit for determining the separation
PS terminal. 9. An external device for obtaining navigation data from a GPS signal.
G that calculates using the navigation data from the device and this external device
A GPS positioning system comprising a PS terminal,
The GPS terminal is a data series having a polarity from a GPS signal.
And a navigation system obtained from the external device.
The polarity is changed based on the data and the data system is changed.
The column value is the same bit equivalent position for each C / A code length equivalent
And a data processing unit that performs cumulative addition at
A correlation calculator for performing a correlation calculation using the C / A code;
GP based on the correlation peak position obtained by the correlation calculator
Pseudo distance between S terminal and satellite corresponding to the C / A code
A pseudo-distance calculator for determining the separation
GPS positioning system. 10. The data processing unit is a correlation calculation unit.
The correlation peak value obtained by the correlation calculation is
To shift the navigation data when the threshold value is not reached.
Work and change polarity based on shifted navigation data
10. The GPS positioning system according to claim 9, wherein
Stem. 11. An external device for obtaining navigation data from a GPS signal.
Device and GP that can receive navigation data from this external device
A GPS positioning system comprising an S terminal,
The PS terminal receives the GPS signal and receives the received electric field.
Electric field detection unit that detects
Is the navigation data obtained by the GPS terminal based on the GPS signal.
When the receiving electric field is weak, the G
Select navigation data obtained by the external device based on PS signal
And a GP based on the selected navigation data.
A position calculating unit for determining the position of the S terminal, wherein the GPS terminal has a polarity data from a GPS signal.
A data sequence obtaining unit for obtaining a sequence;
Based on the navigation data or the GPS signal
Based on one of the navigation data obtained by the
Change the data sequence value and change the C / A code length
Data processing for cumulative addition at the same bit equivalent position for each minute
And the C / A code based on this processing result.
The correlation calculation unit that performs the related calculation, and the correlation calculation unit
GPS terminal and the C / A code
Distance calculation to find the pseudo distance between satellites corresponding to the distance
GPS positioning system, further comprising:
M