JP2005321301A - Gps positioning system and gps positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high sensitivity of positioning by producing a navigation data series by itself without acquiring it from a outside, and by executing coherent integration to correspond to a conventional art. <P>SOLUTION: A reception means 3 amplifies a GPS signal received from an antenna 2, and further A/D-converts it by an A/D-converting means 4. A multiplication means 8 modulates a spectral dispersion code generated by a spectral dispersion code generating means 7 with all the combinations of code series generated by a code generating means 6. The A/D-converted GPS signal and a delayed signal are correlation-processed by a correlation-processing means 10 while the spectral dispersion code modulated by the multiplication means 8 is sequentially delayed with a prescribed time unit by a delay means 9. A delay time estimation means 11 selects the maximum delayed time in a result of the correlation-processing, as τ<SB>1</SB>. A positioning calculation means 12 calculates a distance between a GPS satellite and a GPS positioning device, based on the τ<SB>1</SB>, calculates similar calculation for a plurality of satellites, and calculates the present position based thereon. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a GPS positioning apparatus and a GPS positioning method that receive a GPS signal from a satellite and accurately detect a reception position.

  In a conventional GPS positioning apparatus and GPS positioning method, a GPS signal from a satellite is a headquarter server in which a receiving antenna is installed in an environment with a good view, and a GPS terminal connected to the headquarter server via a wired or wireless communication medium Received by. The headquarter server calculates GPS navigation data from the GPS signal. On the other hand, the GPS terminal itself extracts navigation data from the GPS signal if the received electric field of the GPS signal is good, and receives necessary navigation data from the headquarter server if the received electric field is not good. Then, the GPS terminal divides the GPS signal series (C / A code) by the length of the navigation data at an arbitrary position, and cumulatively adds the value of the same bit position to each divided C / A code. The results are accumulated by matching the polarities based on the navigation data detected by itself or the navigation data received from the headquarters server (hereinafter, this calculation operation is called coherent integration). Further, the GPS terminal calculates the correlation between the addition result and the C / A code of all the satellites of the GPS terminal itself, obtains the point where the correlation value is maximum as the addition start position, and adds the C / A code. To calculate the pseudo distance. The position is calculated based on this pseudo distance and the extracted navigation data.

Thus, in the conventional high-sensitivity GPS positioning device, when the received electric field is weak, the navigation data is acquired from the outside and the coherent integration is performed. As a result, positioning is possible even in an indoor environment where only weak GPS signals can be received. (For example, see Patent Document 1)
Japanese Patent Laid-Open No. 2001-349935 (Page 7, left column, FIG. 1)

  In the conventional high-sensitivity GPS positioning device, in order to achieve high sensitivity, it is necessary to receive navigation data from the external infrastructure side through a separate wireless data link or the like. For this reason, there has been a problem that high-sensitivity positioning can be realized only within a range in which the wireless data link can be reliably received.

  In addition, there is a problem that additional cost is required for the data link, the infrastructure construction for navigation data observation, or the use of the infrastructure service. Furthermore, it is necessary to attach a wireless data link receiver and antenna separately to the GPS positioning device, which makes the positioning device large and heavy, making it inconvenient to carry, increasing device cost, and battery replacement frequency due to increased power consumption There was a problem such as increased.

The GPS positioning device according to the present invention is
Receiving means for receiving and amplifying and demodulating GPS signals from satellites;
A / D conversion means for A / D converting the signal demodulated by the receiving means;
Code generation means for generating all combinations of code sequences;
Spread spectrum code generating means for generating a spread spectrum code corresponding to the satellite;
Multiplying means for modulating the first spread spectrum code with the code sequence;
Delay means for sequentially delaying the spread spectrum code modulated by the multiplication means from a time length of 0 to a time length corresponding to 1 bit of the code sequence in a predetermined time unit;
Correlation processing means for performing correlation processing between the delayed signal generated by the delay means and the signal A / D converted by the A / D conversion means;
A delay time estimating means for outputting a delay time corresponding to a maximum correlation value among the results of the correlation processing;
A positioning calculation means for calculating the distance between the corresponding satellite and itself based on the delay time output from the delay time estimation means, and calculating the current position based on this distance;
It is equipped with.

  According to the present invention, the GPS positioning device and the GPS positioning method are provided with means for automatically generating all combinations of the navigation data series and means for executing coherent integration according to the conventional method. GPS positioning can be realized with high sensitivity without acquiring navigation data from the outside, even in a room with low sensitivity. In addition, since an antenna and a receiving device for acquiring navigation data from the outside are not required, there is an effect that it is possible to reduce the weight of the device and the cost of the product.

An embodiment of the present invention will be described below.
Embodiment 1.
FIG. 1 is a block diagram illustrating a configuration of a GPS positioning device according to Embodiment 1 of the present invention. In FIG. 1, a GPS positioning apparatus 1 performs positioning using a GPS satellite. The GPS antenna 2 receives a GPS signal from a GPS satellite, and the receiving means 3 amplifies the GPS signal received by the GPS antenna 2. The A / D conversion means 4 converts the analog data from the reception means 3 into digital data, and the data storage means 5 records the A / D converted data. The code generation means 6 generates all combination patterns of code sequences. The spread spectrum code generating means 7 generates a spread spectrum code for each satellite. The multiplication means 8 multiplies the code sequence generated by the code generation means 6 and the spread spectrum code generated by the spread spectrum code generation means 7. The delay means 9 delays the spread spectrum code processed by the multiplication means 8 by a delay time τ. The correlation processing means 10 performs a correlation process between the GPS reception signal held in the data storage means 5 and the spread spectrum code processed by the delay means 9. The delay time estimating means 11 holds the result of the correlation processing sent from the correlation processing means 10 and the delay time τ, and calculates the delay time τmax that maximizes the result of the correlation processing. The positioning calculation means 12 calculates the distance from the satellite from τmax sent from the delay time estimation means 11, and calculates the current position based on this distance. The display means 13 displays the current location from the current position calculated by the positioning calculation means 12.

  Although not shown in FIG. 1, there is a control means for controlling the GPS positioning apparatus 1 as a whole. The data storage means 5, the code generation means 6, the spread spectrum code generation means 7, the multiplication means 8, the delay It is connected to the means 9, the correlation processing means 10, the delay time estimation means 11, the positioning calculation means 12, and the display means 13 through a system bus or the like, and controls each of these means. As an example of this control means, the CPU or DSP of the computer may be operated by a control program stored in a ROM, EEPROM, or the like. However, in the following, in order to simplify the description, it is assumed that the data storage means 5, the code generation means 6 and the like execute data processing themselves.

  The display means 13 is, for example, a liquid crystal panel, but may be an output to an external storage device, another signal processing device, an arithmetic device, or the like.

Next, the overall operation will be described.
FIG. 2 is a schematic flowchart showing a processing program executed by control means (not shown) of the GPS positioning device. This program may be stored in advance in a memory such as a ROM of the control means, but the program itself exists independently of the device, and is an external storage medium such as a floppy (registered trademark) disk or CD, or the Internet. It may be installed in a writable memory via the communication line. In this case, the invention of the program of the GPS positioning device is established.

  In the GPS positioning device 1, first, a GPS signal is received by the GPS antenna 2, and processing such as amplification and frequency conversion is performed by the receiving unit 3, and then A / D conversion is performed by the A / D conversion unit 4 to perform digital processing. Convert to data (step ST1). The A / D converted data is recorded in the data storage means 5 (step ST2).

  When data of a predetermined length is recorded in the data storage means 5, the code generation means 6 generates a code sequence of a predetermined length and sends it to the multiplication means 8 (step ST3). The multiplying unit 8 acquires the spread spectrum code for each satellite from the spread spectrum code generating unit 7, modulates it with the code sequence sent from the code generating unit 6, and sends the modulated spread spectrum code to the delay unit 9 ( Step ST4).

  The delay means 9 delays the spread spectrum code modulated by the multiplication means 8 by the time τ and sends it to the correlation processing means 10 (step ST5). The correlation processing means 10 reads the GPS received signal from the data storage means 5, performs correlation processing with the spread spectrum code delayed by the time τ sent from the delay means 9, and sends the calculation result to the delay time estimation means 11. send. The delay time estimation means 11 internally retains the delay time τ corresponding to the sent correlation processing result (step ST6).

  The delay means 9 spreads the modulated spread spectrum code delayed by time τ until the correlation calculation is performed on the delayed signal having the maximum time length corresponding to 1 bit of the code sequence from the time length 0. Are sequentially generated (step ST7). Further, the code generation means 6 sequentially generates code sequences until the correlation calculation for all combinations of code sequences is processed (step ST8). For all these combinations, the correlation processing means 10 performs correlation calculation processing.

  The delay time estimation means 11 selects the maximum value from all the calculated correlation processing results, and sends the delay time τ corresponding to that value to the positioning calculation means 12 as τmax (step ST9). The positioning calculation means 12 calculates the distance between the corresponding GPS satellite and the GPS positioning device from τmax. By repeatedly performing the same processing as described above, the distances from a plurality of GPS satellites to the GPS positioning device are obtained. From these distance information, the current position of the GPS positioning device is calculated (step ST10).

The current position calculated by the positioning calculation means 12 is output to the display means 13, and the current position is displayed (step ST11).
The GPS positioning device performs position measurement using a GPS satellite by the above operation.

Next, operations of the code generation unit 6, the spread spectrum code generation unit 7, the multiplication unit 8, the delay unit 9, the correlation processing unit 10, and the delay time estimation unit 11 will be described.
FIG. 3 shows a GPS signal format.
As shown in FIG. 3, the GPS signal is a code with a period of 1 millisecond, which is spread spectrum modulated with 1023 chips for an arbitrary information bit Bi (i = 1, 2, 3,..., N). Bi of information modulation 1 bit is formed in units of 20 (referred to as spread spectrum codes) (C (i, 1) to C (i, 20)). Accordingly, the spread spectrum codes (C (i, 1) to C (i, 20)) are either all 1s or all 0s. Also, the symbols 1 and 0 of Bi, C (i, 1) to C (i, 20) in FIG. 3 mean that they are π or 0 phase modulated, respectively. Navigation messages such as GPS satellite positions are written in the bit strings B1 to Bn. Further, in the spread spectrum code of 1 millisecond = 1 period, there is 1023 chip data, and one chip is a signal of “1” or “0”. In actual GPS signal processing, data is sampled at a sampling frequency more than doubled according to the sampling theorem when data of 1023 chips is acquired. In the following, for simplification, description will be made on the basis of a chip unit, and it is assumed that 1 chip = 1 bit (“0” or “1”).

  Here, a case where coherent integration with a data size of 80 milliseconds (for 80 spread spectrum codes) is performed will be described. FIG. 4 shows this. The data storage means 5 stores a GPS signal. At this time, the correlation calculation process is started when an 81-millisecond GPS signal, which is longer by 1 msec than the data size to be processed, is recorded. Here, 81 milliseconds is used, as will be described later, even if any delay is assumed, it will be within 81 milliseconds.

  The code generation means 6 generates an 80-bit code sequence such as C1 to C80 in FIG. At this time, from the 80-bit code “000 ... 00” where all bits are “0”, the first bit is “0” and all others are “1” “011 ... 11” 80-bit codes Generate any code up to. Further, the code generation means 6 does not generate codes from “100... 00” to “111... 11”. This is because the result of coherent integration obtained from these codes is completely equivalent to the result of coherent integration performed by bit-inverted codes of these codes, with the opposite polarity, so it is not necessary for correlation processing. is there. Thereby, the operation to process can be halved.

  Next, the multiplication means 8 takes out the spread spectrum code having a length of 1 millisecond from the spread spectrum code generation means 7 and performs phase modulation with the code sequences C1 to C80 generated by the code generation means 6. When the value of Cn is 1, π phase modulation is performed, and when it is 0, 0 phase modulation is performed. In this way, a spread spectrum code having a length of 80 milliseconds is created.

  Next, the delay means 9 shifts the spread spectrum code created by the multiplication means 8 by the delay time τ. Here, the delay time τ is simply a length of one chip (= 1/1023 milliseconds), and is a value from 0 seconds to 1022/1023 milliseconds. At this time, the delay means 9 shifts 1022 times for each chip.

  The correlation processing means 10 takes out 81 ms-long GPS reception data recorded in the data storage means 5. Next, a correlation process between the 80-millisecond spread spectrum code sequentially sent from the delay means 9 and the GPS reception signal region corresponding to this spread-spectrum code is performed. The delay time estimation means 11 records the result of the correlation processing means 10 and the corresponding delay time τ.

  Correlation processing means 10 performs correlation processing for all combinations of code sequences, delay time τ of 0 to 1022/1023 milliseconds, and all combinations thereof. The delay time estimation means 11 sends to the positioning calculation means 12 τ, which has the maximum correlation among them, as τmax.

As described above, according to the first embodiment, the code generation means 6 performs the correlation calculation processing on the spread spectrum codes generated from the code sequences of all combinations, thereby increasing the maximum value of the GPS signal correlation processing. Therefore, even in a room where the GPS signal reception sensitivity is low, the GPS positioning can be performed without acquiring navigation data from the outside.
Further, since an antenna, a receiving device, and the like for acquiring navigation data from the outside are not required, it is possible to reduce the weight of the device and reduce the cost of the product.

  In the present embodiment, correlation processing is performed on a GPS reception signal having a length of 80 milliseconds. However, in an apparatus that requires higher reception sensitivity, a signal having a length longer than that is used. Correlation processing may be performed on. On the other hand, in an apparatus with a sufficient reception sensitivity lower than in the case of this example, the correlation calculation process may be performed with a signal having a small length.

Embodiment 2.
In Embodiment 1 described above, correlation calculation processing is performed for all combinations of code sequences. However, 200 times of coherent integration is required to achieve a high sensitivity of 23 dB, for example. As in the first embodiment described above, when a code sequence pattern is generated brute-force, the total number of patterns reaches 2 to the 199th power. It is not realistic to perform correlation processing for all the patterns from the viewpoint of calculation load. Therefore, a method of simplifying the pattern generation of the code sequence and reducing the calculation load can be considered.

  FIG. 5 is a block diagram showing the configuration of the GPS positioning device according to Embodiment 2 of the present invention. In FIG. 5, 14 is navigation data generating means for generating all combinations of navigation data, and 15 is code boundary data generating means for creating a code sequence by truncating a part of the navigation data generated by the navigation data generating means 14. is there. Other means are the same as those in the first embodiment.

Next, the overall operation will be described.
FIG. 6 is a schematic flowchart showing a processing program executed by control means (not shown) of the GPS positioning device. The processing up to step ST1 and step ST2 is the same as the operation in the first embodiment.

  Next, when A / D converted data having a predetermined length is recorded in the data storage means 5, the navigation data generating means 14 generates navigation data having a predetermined length to generate code boundary data. The data is sent to the means 15 (step ST21). The code boundary data generation means 15 extends each bit of the navigation data sent from the navigation data generation means 14 by a prescribed number so as to match the format of the A / D converted data, The extension data of the first bit is sequentially truncated to generate a code sequence (step ST22). The subsequent processing from step ST4 to step ST8 is the same as the operation of the first embodiment.

After the processing up to step ST8 is performed, the navigation data generating means 14 sequentially generates navigation data until correlation calculation is processed for all combinations of navigation data (step ST23). For all these combinations, the correlation processing means 10 performs a correlation calculation process. The subsequent processing from step ST9 to step ST11 is the same as the operation of the first embodiment.
The GPS positioning device of the second embodiment performs position measurement using a GPS satellite by the above operation.

Next, operations of the navigation data generation unit 14 and the code boundary data generation unit 15 will be described.
Here, as in the case of the first embodiment, a case will be described in which coherent integration is performed with a data size of 80 milliseconds (for 80 spread spectrum codes). FIG. 7 shows this. The data storage means 5 stores a GPS signal. At this time, the correlation calculation process is started when an 81-millisecond GPS signal, which is longer by 1 msec than the data size to be processed, is recorded.

  The navigation data generation means 14 generates navigation data that is one bit larger than the size of the navigation data to be processed. In the example of FIG. 7, if the size of the navigation data to be processed is 4 bits, 5 bits of navigation data such as B1 to B5 are generated. At this time, all codes from a 5-bit code “00000” in which all bits are “0” to a code “01111” in which only the first bit is “0” and all others are “1” are generated. The navigation data generation means 14 does not generate codes from “10000” to “11111”.

  The code boundary data generation means 15 receives the navigation data generated by the navigation data generation means 14, and 20 bits from B1 to B5 are consecutively arranged so as to match the format of the A / D converted data as shown in FIG. Create the data. Next, the code boundary data generation unit 15 rounds down the generated data by the number of values of the code boundary D, and generates data of code sequences C1 to C80. For each navigation data, D is a multiple of L. Here, it is assumed that L = 4 and D takes a value that is a multiple of 4 of 0, 4, 8, 12, and 16. The example of FIG. 7 shows a case where D is 16. In this way, the navigation data generation unit 14 and the code boundary data generation unit 15 create code sequences for all possible combinations of the navigation data and all the values of the code boundary D, and perform correlation processing.

  It is unclear to the positioning device where the code sequence whose navigation data polarity changes will be. In the case of the processing by the code boundary data generation means 15 described above, for example, when the code sequence is truncated by 4 units, the location shifted by two worst code sequences (in this case, C2 and C3 in FIG. 7). There may be a point of change in navigation data. This is shown in the bit pattern of the received signal at the bottom of FIG. In this case, the mismatch of the bits of the code sequence is at most 2 bits, and the expected value of the mismatch is 1 bit.

Furthermore, this loss does not occur unless the navigation data bits are adjacent to the received data. That is, the combination of Bn-1 and Bn navigation data bits is
[Bn-1, Bn] = [0, 0], [0, 1], [1, 0], [1, 1]
However, in the case of [0,0] and [1,1], there is no loss even if the continuous bit breaks. Since the probability of changing the information and bits of adjacent navigation data is 1/2, the expected value of mismatch is 0.5 bits, which is half of 1 bit.

  That is, even if the number of truncation of consecutive bits is set every 4 bits, 19.5 bits out of 20 bits can be expected to be added as coherent integration. Therefore, the loss of coherent integration is 0.5 / 20. On the other hand, since the total number of bit patterns of the code sequence Cn is set for every 4 bits of bit pattern breaks, the computation load is reduced to one-fourth that when 20 consecutive bit breaks are divided.

  As described above, according to the second embodiment, in addition to the effects of the first embodiment, the navigation data generating means 14 generates a navigation data bit pattern in a brute force and forms 20 navigation data bits. The bit pattern truncation number of minutes is set for each L bit to generate a code sequence bit pattern. As a result, the calculation load can be reduced to 1 / L, even though the loss of coherent integration is small. As a result, the hardware scale of the coherent integration calculation means can be reduced, so that it is possible to save power and reduce the weight of the apparatus. In addition, it is possible to shorten the time from receiving the GPS signal to positioning.

Embodiment 3.
In Embodiment 1 described above, all combinations of code sequences and all combinations of delay times sequentially generated for each delay time τ (hereinafter, this may also be referred to as all possible values of delay time τ). Correlation processing was performed with round robin. However, in the correlation process when the delay time τ is the same, if the correlation process is performed in the first spread spectrum code unit (1 millisecond) and the result of this correlation process is stored in the storage means, the correlation after the second time is performed. By using the correlation processing result stored in the storage means in the process, it is possible to generate other code sequence patterns simply by changing the polarity, so correlation processing with this pattern makes it easy to perform correlation processing. Yes. As a result, a method of reducing the load of correlation processing can be considered.

  FIG. 8 is a block diagram showing the configuration of the GPS positioning device according to Embodiment 3 of the present invention. In FIG. 8, reference numeral 16 denotes code unit correlation processing result storage means for storing the result of correlation processing in spread spectrum code units (1 millisecond) calculated by the correlation processing means 10. Other means are the same as those in the first embodiment.

Next, the overall operation will be described.
FIG. 9 is a schematic flowchart showing a processing program executed by control means (not shown) of the GPS positioning device. The processing from step ST1 to step ST5 is the same as the operation in the first embodiment.

  Next, the correlation processing means 10 determines whether or not correlation processing relating to the delay time τ is performed for the first time (step ST31). When the correlation processing related to the delay time τ is performed for the first time, the correlation processing means 10 performs the correlation processing for each spread spectrum code (in units of 1 millisecond), and the correlation processing result for each spread spectrum code unit is displayed as the spread spectrum code. Stored in the unit correlation processing result storage means 16 (step ST32). When the correlation processing related to the delay time τ is not the first time, the correlation processing means 10 reads the result of the correlation processing for each code unit related to the delay time τ from the spread spectrum code unit correlation processing result storage means 16 (step ST33). The correlation processing means 10 performs correlation processing using these values and sends the calculation result to the delay time estimation means 11. The delay time estimation means 11 internally retains the delay time τ corresponding to the sent correlation processing result (step ST34).

The subsequent processing from step ST7 to step ST11 is the same as the operation in the first embodiment.
The GPS positioning apparatus of the third embodiment performs position measurement using a GPS satellite by the above operation.

Next, operations of the correlation processing means 10 and the code unit correlation processing result storage means 16 will be described.
Here, as in the case of the first embodiment, a case will be described in which coherent integration is performed with a data size of 80 milliseconds (for 80 spread spectrum codes). FIG. 10 shows this. First, an 80-bit code sequence “0000... 00” and a spread spectrum code delayed by a delay time τ are sent to the correlation processing means 10. The correlation processing means 10 performs a correlation process between the spread spectrum code and the GPS reception signal in each spread spectrum code unit (1 millisecond unit). The obtained correlation processing results for each code unit are recorded in the code unit correlation processing result storage means 16 as E1 (τ) to E80 (τ).

  Here, for simplification, in the correlation processing in the correlation processing means 10, “1” of the signal of one chip (each bit) is set to “+1” and “0” is set to “−1”. All the multiplication results are added. This is shown in FIG. When the correlation between the spread spectrum code and the GPS received signal matches, the correlation result is 1023. When the spread spectrum code is π-phase modulated, the correlation result is −1023. If the correlation does not match, the correlation result is -1 or +1. These values are recorded in the code unit correlation processing result storage means 16 as E1 (τ) to E80 (τ) for each delay time τ.

  Next, the correlation processing means 10 calculates the result of correlation processing for the spread spectrum code of 80 milliseconds from E1 (τ) to E80 (τ). In this case, since the code sequence is “0000... 00”, a value obtained by adding all E1 (τ) to E80 (τ) is calculated as a result of the correlation process. The correlation processing means 10 passes this result and the delay time τ to the delay time estimation means 11. Similar processing is performed for all possible values of the delay time τ.

  Next, an 80-bit code sequence “0000... 001” generated by the code generator 6 and a spread spectrum code delayed by a delay time τ are sent to the correlation processor 10. The correlation processing means 10 reads E1 (τ) to E80 (τ) from the code unit correlation processing result storage means 16 as a result of the correlation processing for each code unit corresponding to the delay time τ. Using these values of E1 (τ) to E80 (τ), the correlation processing means 10 calculates the result of the correlation processing for the 80 ms spread spectrum code. This is shown in FIG. Since C1 to C79 of the code sequence are 0, E1 (τ) to E79 (τ) are multiplied by “+1”, and since C80 of the code sequence is 1, E80 (τ) is set to “−1”. Multiplication is performed, and a value obtained by adding these is used as a result of the correlation processing. The correlation processing means 10 passes this result and the delay time τ to the delay time estimation means 11. Similar processing is performed for all possible values of the delay time τ.

  Similarly, the correlation processing unit 10 reads E1 (τ) to E80 (τ) from the code unit correlation processing result storage unit 16 as a result of the correlation processing of each code unit corresponding to the delay time τ, and generates a code to this. When the 80-bit code sequence generated by the means 6 is “0”, it is multiplied by “+1”, and when it is “1”, it is multiplied by “−1” to calculate the correlation processing result. This can be expressed in the following formula.

  As described above, according to the third embodiment, in addition to the effects of the first embodiment, the correlation calculation processing means 10 performs correlation processing for each code unit, and these results are stored as code unit correlation processing result storage means. 16 is used to perform correlation processing calculations. As a result, if correlation processing is performed for all possible values of the delay time τ related to the first code sequence, there is no need to perform correlation processing for each spread spectrum code unit in correlation processing of other combinations of code sequences, By reading the value from the spread spectrum code unit correlation processing result storage means 16, it is possible to perform the final correlation processing calculation, and the effect of greatly reducing the calculation load can be obtained. As a result, the hardware scale of the coherent integration calculation means can be reduced, so that it is possible to save power and reduce the weight of the apparatus. In addition, it is possible to shorten the time from receiving the GPS signal to positioning.

  In the above embodiment, there is a processing loop related to the code sequence outside the processing loop related to the delay time τ. However, there is no problem in the processing even if the processing loop related to the delay time τ is outside the processing loop related to the code sequence. In this case, correlation processing for all combinations of code sequences is performed for each delay time τ, and the data of E1 (τ) to E80 (τ) is not retained when processing the delay time τ + 1. Get better. Thereby, the effect that the data amount stored in the code unit correlation processing result storage means 16 can be greatly reduced is obtained, and the hardware scale can be suppressed. Therefore, it is possible to save power and reduce the weight of the apparatus. The effect is obtained.

Embodiment 4.
In the above-described third embodiment, in the correlation process with the same delay time τ, after performing the correlation process in the spread spectrum code unit (1 millisecond), another code sequence pattern is generated simply by changing the polarity, Since this code sequence can be correlated, the load of the correlation processing using the code sequence has been reduced. However, in the correlation processing with the same delay time τ, a method of further reducing the calculation load by using the difference regarding the correlation processing results of different code sequences can be considered.

  FIG. 13 is a block diagram showing the configuration of the GPS positioning device according to Embodiment 4 of the present invention. In FIG. 13, reference numeral 17 denotes correlation processing result temporary storage means for storing the previous correlation processing result related to the delay time τ calculated by the correlation processing means 10. Other means are the same as those in the third embodiment.

Next, the overall operation will be described.
FIG. 14 is a schematic flowchart showing a processing program executed by control means (not shown) of the GPS positioning device. The processing from Step ST1 to Step ST5, Step 31, and Step 32 and Step 33 after branching from Step 31 is the same as the operation of the third embodiment.

  When the correlation processing related to the delay time τ is performed for the first time in the branch of step 31, after the processing of step 32 is performed, the correlation processing means 10 obtains the result of the correlation processing for each spread spectrum code (in units of 1 millisecond). Is used to perform the summation process (step 41).

  If the correlation processing related to the delay time τ is not the first time in the branch of step 31, after the processing of step 33 is performed, the correlation processing means 10 performs the correlation processing calculated in the correlation processing related to the previous delay time τ. The result is read from the correlation processing result temporary storage means 17. After that, the difference between the correlation processing is calculated from the code sequence in the correlation processing related to the previous delay time τ and the currently processed code sequence, and is added to or subtracted from the correlation processing result read from the correlation processing result temporary storage means 17. Then, the result of the correlation process is calculated (step 42).

  The result of the correlation processing calculated by the correlation processing means 10 is sent to the delay time estimation means 11. Further, the correlation processing result, the corresponding delay time τ, and the set of code sequences are recorded in the correlation processing result temporary storage means 17. The delay time estimation means 11 internally retains the delay time τ corresponding to the sent correlation processing result (step ST43).

The subsequent processing from step ST7 to step ST11 is the same as the operation of the third embodiment.
The GPS positioning apparatus of the fourth embodiment performs position measurement using a GPS satellite by the above operation.

Next, operations of the correlation processing means 10 and the correlation processing result temporary storage means 17 will be described.
Here, as in the case of the third embodiment, a case will be described in which coherent integration is performed with a data size of 80 milliseconds (for 80 spread spectrum codes). FIG. 15 shows this. First, an 80-bit code sequence “0000... 00” and a spread spectrum code delayed by a delay time τ are sent to the correlation processing means 10. The correlation processing means 10 performs a correlation process between the spread spectrum code and the GPS reception signal in each code unit (1 millisecond unit). The obtained correlation processing results for each code unit are recorded in the code unit correlation processing result storage means 16 as E1 (τ) to E80 (τ). Next, the correlation processing means 10 calculates the result of correlation processing for the spread spectrum code of 80 milliseconds from E1 (τ) to E80 (τ). In this case, since the code sequence is “0000... 00”, assuming that the processing result is S1 (τ), the following equation is obtained.

S1 (τ) = E1 (τ) + E2 (τ) + E3 (τ) + ・ ・ ・ + E79 (τ) + E80 (τ) ……… (2)

  The correlation processing means 10 passes 80-bit data “0000... 00”, which is a set of the result, the delay time τ, and the code sequence in this case, to the correlation processing result temporary storage means 17. Similar processing is performed for all possible values of the delay time τ.

  Next, the code generation means 6 sends an 80-bit code sequence “0000... 001” and a spread spectrum code delayed by a delay time τ to the correlation processing means 10. The correlation processing means 10 reads E1 (τ) to E80 (τ) from the code unit correlation processing result storage means 16 as a result of the correlation processing for each code unit corresponding to the delay time τ. Further, S1 (τ), which is the result of the previous correlation process recorded in the correlation process result temporary storage means 17, is read. If the code sequence to be processed at this time is “0000... 001” and the processing result is S2 (τ), the following equation is obtained.

S2 (τ) = E1 (τ) + E2 (τ) + E3 (τ) + ... + E79 (τ) − E80 (τ)
= S1 (τ) −2 × E80 (τ) ……………………………………………… (3)

  As shown in Equation (3), the correlation processing means 10 calculates S2 (τ) only from the data of S1 (τ) and E80 (τ). This doubles the value of the correlation processing result E80 (τ) of the 80th code unit, which is a bit changing from the code sequence “0000... 000” to the code sequence “0000... 001”, This is exactly the same as subtracting from the previous correlation processing value S1 (τ). The correlation processing means 10 performs the same processing for all possible values of the delay time τ and records the result in the correlation processing result temporary storage means 17.

  Similarly, as shown in FIG. 15, the correlation processing result corresponding to the code sequence “0000... 010” is represented by S3 (τ) and the correlation processing corresponding to the code sequence “0000. When the result is S4 (τ), the mathematical expression of the operation to be processed is as follows.

S3 (τ) = E1 (τ) + E2 (τ) + E3 (τ) + ・ ・ ・ −E79 (τ) + E80 (τ)
= S2 (τ) −2 × E79 (τ) + 2 × E80 (τ) ………………………………… (4)

S4 (τ) = E1 (τ) + E2 (τ) + E3 (τ) + ・ ・ ・ −E79 (τ) − E80 (τ)
= S3 (τ) −2 × E80 (τ) ………………………………………………… (5)

  Similarly, the correlation processing means 10 calculates S3 (τ) and S4 (τ) using the previously calculated S2 (τ) and S3 (τ), and the result is stored in the correlation processing result temporary storage means 17. Record. In this way, the correlation processing means 10 doubles the correlation processing result En (τ) of the spread spectrum code unit corresponding to the bit changing from the previous code sequence, and adds or subtracts it from the value of the previous correlation processing. Thus, the value of the correlation process is calculated.

  As described above, by performing the calculation, it is possible to calculate the correlation processing result simply by taking the past calculation result and its difference, and the calculation can be reduced compared to the case of the third embodiment. The order of processing of the code sequence in FIG. 15 is the same as the sequence called binary code when C1 to C80 are considered as binary digits. For this reason, it is possible to easily determine how the code sequence from C1 to C80 changes, and it is easy to perform a difference operation such as Equation (3) and Equation (4). Further, in Equation (3), Equation (4), etc., E79 (τ) and E80 (τ) are multiplied by 2, but such an operation can be performed by a 1-bit shift in a binary number. For this reason, operations such as Equation (3) and Equation (4) can be processed as shifts and simple addition / subtraction in processing such as hardware, which leads to simplification and reduction of the apparatus.

  In addition, the order of processing of the code sequence in FIG. 15 is the same as the order called binary code, but the calculation load can be further reduced by making the order of processing of the code series the same as the order called gray code. it can. This is shown in FIG.

  FIG. 16 is the same as the above-described processing except that the processing sequence of the code sequence is different. In FIG. 16, S′1 (τ), which is the result of the correlation processing of the code sequence “000... 0000”, and S′2 (τ, which is the result of the correlation processing of the code sequence “000. ) Is obtained by the same equation as S2 (τ) in Equation (2) and S2 (τ) in Equation (3). Next, the correlation processing means 10 obtains S′3 (τ), which is the result of the correlation processing of the code sequence “000... 0011”. This is expressed in the following formula.

S'3 (τ) = E1 (τ) + E2 (τ) + E3 (τ) + ・ ・ ・ −E79 (τ) − E80 (τ)
= S'2 (τ) −2 × E79 (τ) ………………………………………………… (6)

In the same manner, the correlation processing results are calculated in the order shown in FIG. The feature of the Gray code is that it is configured so that the difference from the previous code is always only one bit. Even in the processing in FIG. 16, there is always one difference from the previous code sequence. It is lined up to become only. For this reason, the result of the correlation process can be calculated by only performing addition / subtraction once from the result of the previous correlation process. For this reason, the number of operations can be reduced to about half compared to the processing in the case where the code sequences are arranged in the order of binary codes as shown in FIG. In addition, when such processing is performed by hardware, since the calculation processed in one correlation process is one addition / subtraction, the memory and the calculator need only be accessed once. It becomes easy to simplify and downsize the transfer bus, processing device, and the like.

  As described above, according to the fourth embodiment, the past correlation processing result is stored in the correlation processing result temporary storage means 17, and the correlation processing is calculated using the difference from the past correlation processing result. Execute. Thereby, the effect that calculation load can be suppressed significantly is acquired. As a result, the hardware scale of the coherent integration calculation means can be reduced, and thus the effects of saving power, reducing the weight of the apparatus, and the like can be obtained. In addition, it is possible to shorten the time from receiving the GPS signal to positioning.

  In the above-described embodiment, there is a processing loop related to the code sequence outside the processing loop related to the delay time τ. However, there is no problem in the processing even if the processing loop related to the delay time τ is outside the processing loop related to the code sequence. In this case, correlation processing for all combinations of code sequences is performed for each delay time τ, and data such as S1 (τ) and S′1 (τ) is processed when processing the delay time τ + 1. You don't have to hold it. As a result, an effect that the amount of data stored in the correlation processing result temporary storage means 17 can be greatly reduced is obtained, and the hardware scale can be suppressed, so that it is possible to save power and reduce the weight of the apparatus. An effect is obtained.

  As described above, since the present invention can realize high-sensitivity GPS positioning by executing coherent integration, a GPS positioning device and a GPS positioning method for accurately measuring a reception position by receiving a GPS signal from a satellite Applies to the field of

1 is a block diagram showing a configuration of a GPS positioning device in Embodiment 1 of the present invention. 5 is a flowchart showing a GPS positioning signal processing program according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing a format of a GPS reception signal in Embodiment 1 of the present invention. 6 is a diagram showing a method of correlation processing between a GPS reception signal and a generated code in Embodiment 1 of the present invention. FIG. FIG. 5 is a block diagram showing a configuration of a GPS positioning device in Embodiment 2 of the present invention. 7 is a flowchart showing a GPS positioning signal processing program according to Embodiment 2 of the present invention. FIG. 10 is a diagram showing a method for generating a code sequence from navigation data in Embodiment 2 of the present invention. FIG. 6 is a block diagram showing a configuration of a GPS positioning device in Embodiment 3 of the present invention. 10 is a flowchart showing a GPS positioning signal processing program according to Embodiment 3 of the present invention. It is a figure which shows the method of the correlation process of a spread spectrum code and a GPS received signal in Embodiment 3 of this invention. FIG. 10 is a diagram illustrating a result of correlation processing between a spread spectrum code in 1-millisecond units and a GPS reception signal in Embodiment 3 of the present invention. It is a figure which shows the method of calculating the value of a correlation process from the result of the correlation process in a code unit in Embodiment 3 of this invention. FIG. 9 is a block diagram showing a configuration of a GPS positioning device in Embodiment 4 of the present invention. 14 is a flowchart showing a GPS positioning signal processing program according to Embodiment 4 of the present invention. FIG. 10 is a diagram showing a method for calculating a correlation processing value from a difference between a code sequence generated in the order of binary codes and the correlation processing in the fourth embodiment of the present invention. It is a figure which shows the method of calculating the value of a correlation process from the difference of a code sequence and the correlation process produced | generated in the order of the Gray code in Embodiment 4 of this invention.

Explanation of symbols

1 GPS positioning device, 2 GPS antenna, 3 receiving means, 4 A / D conversion means, 5 data storage means, 6 code generation means, 7 spread spectrum code generation means, 8 multiplication means, 9 delay means, 10 correlation processing means, 11 delay time estimation means, 12 positioning calculation means, 13 display means, 14 navigation data generation means, 15 code boundary data generation means, 16 code unit correlation processing result storage means, 17 correlation processing result temporary means.

Claims (8)

Receiving means for receiving and amplifying and demodulating GPS signals from satellites;
A / D conversion means for A / D converting the signal demodulated by the receiving means;
Code generation means for generating all combinations of code sequences;
Spread spectrum code generating means for generating a spread spectrum code corresponding to the satellite;
Multiplying means for modulating the spread spectrum code with the code sequence;
Delay means for sequentially delaying the spread spectrum code modulated by the multiplication means from a time length of 0 to a time length corresponding to 1 bit of the code sequence in a predetermined time unit;
Correlation processing means for performing correlation processing between the delayed signal generated by the delay means and the signal A / D converted by the A / D conversion means;
A delay time estimating means for outputting a delay time corresponding to a maximum correlation value among the results of the correlation processing;
A positioning calculation means for calculating the distance between the corresponding satellite and itself based on the delay time output from the delay time estimation means, and calculating the current position based on this distance;
GPS positioning device characterized by comprising. Instead of the code generation means,
Navigation data generating means for generating all combinations of the first navigation data of J + 1 bits (J is a positive integer);
Each bit of the first navigation data is extended by K pieces (K is a positive integer) to generate second navigation data, and K pieces corresponding to the first bit of the second navigation data are generated. The extended data is sequentially rounded down in units of L (L is a positive integer different from J and K). Each time the rounded down data, J × K of the remaining data after the second navigation data is rounded down. Code boundary data generating means for outputting as a code sequence;
The GPS positioning device according to claim 1, further comprising: Spread spectrum code unit correlation processing result storage means for storing the result of correlation processing in spread spectrum code units,
The correlation processing means performs code correlation processing using a correlation processing result stored in the spread spectrum code unit correlation result storage means in correlation processing in the case where the delay time is the same. The GPS positioning device according to claim 1. Correlation processing result temporary storage means for storing the previous correlation processing result;
Correlation processing means for calculating a correlation processing result from a difference from the previous correlation processing result;
The GPS positioning device according to claim 3, further comprising: The code generation means includes
5. The GPS positioning device according to claim 4, wherein the code sequence code is generated in the same order as the Gray code. The code generation means includes
The GPS positioning apparatus according to claim 1, wherein a code sequence in which the bit-inverted codes match is not generated. A / D conversion step to receive GPS signal from satellite and A / D convert,
A code generation step for generating all combinations of code sequences;
A spread spectrum code generating step for generating a first spread spectrum code corresponding to the satellite;
A multiplication step of modulating the first spread spectrum code by the code sequence;
A delay step for generating a delayed signal obtained by sequentially delaying the spread spectrum code modulated by the multiplication means step from a time length of 0 to a time length corresponding to 1 bit of the code sequence in a predetermined time unit;
A correlation processing step for performing correlation processing between the delayed signal generated by the delay step and the signal A / D converted by the A / D conversion step;
A delay time estimating step of outputting a delay time corresponding to a maximum correlation value among the results of the correlation processing;
Calculating a distance between the corresponding satellite and itself based on the delay time output from the delay time estimating step, and calculating a current position based on the distance;
A GPS positioning method characterized by comprising: Instead of the code generation step,
A navigation data generation step for generating all combinations of J + 1 bit (J is a positive integer) first navigation data;
Each bit of the first navigation data is extended by K pieces (K is a positive integer) to generate second navigation data, and K pieces corresponding to the first bit of the second navigation data are generated. The extended data is sequentially rounded down in units of L (L is a positive integer different from J and K). Each time the rounded down data, J × K of the remaining data after the second navigation data is rounded down. Code boundary data generation step for outputting as a code sequence;
The GPS positioning method according to claim 7, further comprising:

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