JP2003262667A - Reception apparatus and location calculation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently and quickly calculate a location, without the need for an initial value. <P>SOLUTION: Signals, transmitted from a plurality of GPS satellites constituting a global positioning system, are received by an antenna 14. In n number of simultaneous quadratic equations having constants for three-dimensional locations of the GPS satellites and pseudo-distances to the satellites contained in received signals and unknown variables as own three-dimensional locations and clocking errors between the satellites and themselves, the constants corresponding to one of the satellites are subtracted from the unknown variables and converted, and a CPU 26 implements a process for calculating their own locations by solving obtained one quadratic equation and at least three linear equations. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a Global Navigation Satellites System (GNSS).
The present invention relates to a receiving device and a position calculating method for receiving a signal transmitted from a plurality of satellites constituting m) and calculating its own position.

[0002]

2. Description of the Related Art In recent years, Global Navigation Satellites S (GNSS) has been used to measure the position of a moving body on the ground using artificial satellites that orbit the earth.
ystem) is becoming popular. As such a global positioning system, the GPS (Glob
al Positioning System), GLONASS constructed by the former Soviet Union, and GALILEO being constructed mainly by European countries.

In this global positioning system, a receiving device that receives a signal transmitted from a satellite and calculates its own position receives a signal from at least four or more satellites, and based on the received signal, the receiving device receives the signal. It has a function of calculating the position of and notifying the user. The receiving device demodulates the signal transmitted from each satellite to obtain the orbit information of each satellite, and based on the orbit information and time information of each satellite and the delay time of the received signal, the reception device simultaneously coordinates its three-dimensional position. Calculate by equation.

It is to be noted that the global positioning system requires at least four satellites to obtain received signals for the following reason. That is, there is an error between the internal time of the clock included in the receiving device and the time based on the atomic clock included in each satellite, and four unknown parameters of the three-dimensional position and the accurate time, which eliminate the influence of the error, are calculated. In order to require pseudoranges from at least four satellites.

Here, an example of a method used in the conventional global positioning system when the receiving device calculates its own position will be described.

The receiving device calculates the three-dimensional position of each satellite from the orbit information and time information contained in each signal transmitted from four or more satellites, and at the same time calculates the pseudo range from the phase of the spread code contained in the received signal. To calculate. Then, the self three-dimensional position is calculated by solving at least four simultaneous equations in which the three-dimensional position of the receiving device and the clock error between each satellite and the receiving device are unknowns. At this time, since each equation is a quadratic equation that does not have a multiplication term of different unknowns, conventionally, by giving an appropriate initial value close to the solution and applying Newton's method, it is possible to perform simultaneous calculations. Solve

The Newton's method is to locally perform linear approximation at a point close to the solution, first obtain a solution of the linear simultaneous equations using an appropriate initial value, and then obtain the obtained solution as the next initial value. This is a calculation method for obtaining a final solution by substituting it as a value and obtaining the next solution, and recursively performing iterative calculation until the solution converges within a predetermined error.

Here, the conventional method for calculating the position of the receiving device by the Newton method will be specifically described.
Assuming that the three-dimensional position of the i-th satellite obtained from the signal received by the receiving device is (X _i , Y _i , Z _i ) and the pseudo range is ρ _i , the three-dimensional position (X ₀ , Y ₀ , Z
₀ ) and the clock error δ _τ inside the receiver as unknowns, the following simultaneous equation 1 is obtained.

[Equation 1] In Expression 1, ρ _i = c × τ _i , τ _i is the signal arrival time from the satellite detected by the receiving device to the receiving device, and c is the speed of light. In addition, the three-dimensional position (X _i , Y _i , Z _i ) of each satellite is calculated from the orbit information and time information in the navigation message included in the received signal. In the receiving device, the unknowns in Expression 1 are X ₀ , Y ₀ , Z _0, δτ.
Therefore, these unknowns can be obtained by receiving signals from at least four satellites and solving four simultaneous equations.

When applying the Newton's method in solving these simultaneous equations, first, an appropriate three-dimensional position (X ₀₀ , Y ₀₀ , Z) expected as the current position of the receiving device is obtained.
₀₀ ), X ₀ = X ₀₀ + δX, Y ₀ = Y ₀₀ +
δY, Z ₀ = Z ₀₀ + δZ, and new δX, δY, δ
Let Z be the unknown. Then, Equation 1 is transformed to the following Equation 2
To get In Expression 2, δρ = cδτ.

[Equation 2] Here, approximation is performed as in the following Equation 3, and simultaneous equation 1 in Equation 2 is performed.
The following equation [delta] X, [delta] Y, .delta.Z, solved [delta] _tau like Gaussian elimination and sweep method, Yuku by solving the following equation 4 as iteratively _{X 00, Y 00, Z 00} .

[Equation 3]

[Equation 4] Then, [delta] X, [delta] Y, .delta.Z, the value of [delta] _tau Yuku converges to 0, these values are the calculation ends when it becomes a sufficiently small value. Then, the coordinate value (X
₀₀ , Y ₀₀ , Z ₀₀ ) is regarded as (X ₀ , Y ₀ , Z ₀ ) to calculate the three-dimensional position of the receiving device.

[0010]

The conventional receiving apparatus is configured to calculate the three-dimensional position by iterative calculation as described above. For example, when the position is continuously obtained, the current position and the previous position are calculated. Since there is little change from the calculated position, the previously calculated position is set to the initial value (X ₀₀ , Y ₀₀ , Z
_The current position can be sequentially updated by solving the equation 2 as ₀₀ ).

However, when the current position is calculated immediately after the receiving device is powered on, for example, the previous position stored in the receiving device is used as the initial value. At this time, as the deviation between the position where the power is turned on to the receiving device and the previous position increases, the amount of calculation in the above-described iterative calculation increases, and the time required to calculate the current position and the consumed power increase. There was a problem that it would end up.

Further, the method of calculating the current position by the above-described iterative calculation is based on the previous time stored in the receiving device, such as when the receiving device is powered on after moving a long distance by an aircraft or the like. If the difference between the position and the current position is too large, the previous position cannot be used as the initial value. Further, even if the previous position stored in the receiver is cleared for some reason, the previous position cannot be used as the initial value.

Therefore, in the conventional receiving apparatus, when many positions on the earth are registered in advance inside the receiver and the previous position cannot be used as the initial value, each position is sequentially substituted as the initial value. A method of attempting to calculate the current position is adopted. However, in this case, inefficient iterative calculation with a large amount of calculation is repeated for each of a large number of registered positions, which dramatically increases the time required to calculate the current position and the power consumption. There was a problem that it would increase.

The present invention has been made in view of the above-mentioned conventional circumstances, and when receiving the signals transmitted from a plurality of satellites constituting the global positioning system and calculating its own position, an initial value is set. It is an object of the present invention to provide a receiving device and a position calculation method capable of calculating a position efficiently and quickly without the need for.

[0015]

A receiving device according to claim 1 of the present invention is a receiving device which receives signals transmitted from a plurality of satellites constituting a global positioning system and calculates its own position. And a position calculating means for calculating the position of the self based on the signal received by the receiving means, the position calculating means receiving the signal by the receiving means. The three-dimensional position of each of the n satellites (n is a natural number of 4 or more) and the pseudo distance to each satellite are constants, and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables. For n simultaneous quadratic equations, the unknown variables are converted into those obtained by subtracting the constants corresponding to any of the satellites,
The position of the self is calculated by solving the obtained one quadratic equation and at least three linear equations.

A receiving device according to a second aspect of the present invention is a receiving device for receiving a signal transmitted from a plurality of satellites constituting a global positioning system and calculating its own position,
The receiver includes a receiving unit that receives a signal transmitted from the satellite, and a position calculating unit that calculates a position of itself based on the signal received by the receiving unit, and the position calculating unit receives the n received by the receiving unit. N (n is a natural number of 5 or more) each of which has a constant three-dimensional position of each satellite and a pseudo distance to each satellite, and n which has its own three-dimensional position and the clock error between each satellite and itself as unknown variables Of the simultaneous quadratic equation of 1 is obtained by performing variable conversion into one obtained by subtracting the unknown variable by the constant corresponding to one of the satellites, and
The position of the self is calculated by solving four linear equations out of the following equations and at least four linear equations.

A receiving device according to claim 3 of the present invention is a receiving device for receiving signals transmitted from a plurality of satellites constituting a global positioning system and calculating its own position,
The receiver includes a receiving unit that receives a signal transmitted from the satellite, and a position calculating unit that calculates a position of itself based on the signal received by the receiving unit, and the position calculating unit receives the n received by the receiving unit. N (n is a natural number of 6 or more), each of which has a constant three-dimensional position and a pseudorange to each satellite, and n which has its own three-dimensional position and the clock error between each satellite and itself as unknown variables Of the simultaneous quadratic equation of 1 is obtained by performing variable conversion into one obtained by subtracting the unknown variable by the constant corresponding to one of the satellites, and
Among the following equations and at least five linear equations, the least square method is applied to at least five linear equations to calculate the position of the self.

A position calculating method according to claim 4 of the present invention is
A position calculating method for calculating one's own position on the basis of signals transmitted from a plurality of satellites constituting the global positioning system, which is a three-dimensional position of each of n (n is a natural number of 4 or more) of the satellites. For n simultaneous quadratic equations in which the pseudo-distance to each satellite is a constant and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, the unknown variable is set to one of the satellites. The position of the self is calculated by performing variable conversion to a value obtained by subtraction by the corresponding constant and solving the obtained one quadratic equation and at least three linear equations.

A position calculating method according to claim 5 of the present invention is
A position calculating method for calculating one's own position based on signals transmitted from a plurality of satellites constituting the global positioning system, which is a three-dimensional position of each of n (n is a natural number of 5 or more) of the satellites. For n simultaneous quadratic equations in which the pseudo-distance to each satellite is a constant and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, the unknown variable is set to one of the satellites. Characteristically, the position of the self is calculated by performing variable conversion to the one obtained by subtraction by the corresponding constant and solving four linear equations out of the obtained one quadratic equation and at least four linear equations. It is what

A position calculating method according to claim 6 of the present invention is
A position calculating method for calculating one's own position based on signals transmitted from a plurality of satellites constituting the global positioning system, which is a three-dimensional position of each of n (n is a natural number of 6 or more) of the satellites. For n simultaneous quadratic equations in which the pseudo-distance to each satellite is a constant and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, the unknown variable is set to one of the satellites. Position of the self by applying the least squares method to at least 5 linear equations out of the obtained 1 quadratic equations and at least 5 linear equations Is calculated.

In the present invention configured as described above, the self position is calculated by solving the linear equation obtained after the variable conversion. Therefore, it is not necessary to perform the iterative calculation that requires a large amount of calculation, and the initial value substitution is not necessary. Therefore, the position can be calculated efficiently and quickly.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below in detail with reference to the drawings. Below, the Global Positioning System (GNSS: Global)
A case will be described in which the present invention is applied to a receiving device that receives signals transmitted from at least four satellites that make up the Navigation Satellites System) and calculates its own position based on these received signals. In this example, a GPS (Global Positioning System) widely used in Japan is assumed as a global positioning system, and a GPS receiving device will be described as a receiving device compatible with this GPS.

This GPS receiver is for L1 band, C / A
This is to receive a spread spectrum signal radio wave called a (Clear and Acquisition) code as a received signal. As shown in FIG. 1, when demodulating a received received signal, pseudo random noise (Pseudo- rando
(m Noise; PN) sequence spreading code and the spread code in the received signal are synchronized by separating the function and the spread code and carrier wave (hereinafter referred to as carrier) synchronization function is separated. It is configured to speed up the synchronization acquisition based on the circuit scale. However, the present invention is not limited to the application to such a GPS receiving device, and a receiving device that receives signals transmitted from a plurality of satellites constituting the global positioning system and calculates its own position. Of course, it can be widely applied to the position calculation method.

As shown in FIG. 1, the GPS receiver 10 has a crystal oscillator (X'tal Oscillator; hereinafter referred to as XO) which generates a transmission signal D1 having a predetermined transmission frequency.
11 and a predetermined oscillation frequency F different from this XO11
Temperature Compensated X'tal Oscillator for Generating Oscillation Signal D2 with _OSC ;
Hereinafter referred to as TCXO. ) 12 and a multiplier / divider 13 for multiplying and / or dividing the oscillation signal D2 supplied from the TCXO 12.

The XO 11 generates an oscillation signal D1 having a predetermined oscillation frequency of, for example, 32.768 kHz. The XO 11 uses the generated oscillation signal D1 for RT described later.
Supply to C (Real Time Clock) 27.

The TCXO12 is different from the XO11 in that it has a predetermined oscillation frequency F _OSC of, for example, about 18.414 MHz.
Generate an oscillating signal D2. The TCXO 12 supplies the generated oscillation signal D2 to the multiplier / divider 13 and the frequency synthesizer 18 described later.

The multiplier / divider 13 is a CPU (Ce
The oscillation signal D2 supplied from the TCXO 12 is multiplied by a predetermined multiplication rate and / or divided by a predetermined division ratio based on the control signal D3 supplied from the ntral processing unit 26. The multiplication / frequency divider 13 includes a synchronization acquisition unit 24, which will be described later, a synchronization holding unit 25, which will be described later, a CPU 26, a timer 28 which will be described later, and an oscillation signal D3 which has been multiplied and / or divided.
And to a memory 29 described later.

The GPS receiver 10 also includes an antenna 14 for receiving an RF (Radio Frequency) signal transmitted from a GPS satellite and a low noise amplifier (Low) for amplifying a received RF signal D5 received by the antenna 14. Noise Amplifier; hereinafter referred to as LNA.) 15
And the amplified RF signal D amplified by this LNA 15.
Band pass filter (hereinafter, referred to as BPF) 16 that passes a predetermined frequency band component out of 6
And the amplified RF signal D passed by this BPF 16
7, a frequency synthesizer 18 for generating a local oscillation signal D10 having a predetermined frequency F _LO based on the oscillation signal D2 supplied from the TCXO 12, and a predetermined frequency F _RF amplified by the amplifier 17. A multiplier 19 for multiplying the amplified RF signal D8 having the local oscillation signal D10 supplied from the frequency synthesizer 18, and a predetermined frequency F _IF down-converted by being multiplied by the multiplier 19.
Intermediate Frequency;
It is called IF. ) An amplifier 20 that amplifies the signal D11, and a low pass filter (hereinafter referred to as LPF) 21 that passes a predetermined frequency band component of the amplified IF signal D12 amplified by the amplifier 20.
The analog-type amplified IF signal D13 passed by the LPF 21 is converted to the digital-type amplified IF signal D14.
Analog / digital converter (Analog / Digit)
al Converter; hereinafter referred to as A / D. ) 22 and.

The antenna 14 spreads a carrier R having a frequency of 1575.42 MHz transmitted from a satellite (hereinafter, referred to as a GPS satellite) constituting GPS.
Receive the F signal. The received RF signal D5 received by the antenna 14 is supplied to the LNA 15.

The LNA 15 amplifies the received RF signal D5 received by the antenna 14. The LNA 15 supplies the amplified amplified RF signal D6 to the BPF 16.

The BPF 16 is a so-called SAW (Surface).
Acoustic wave) filter, and passes a predetermined frequency band component of the amplified RF signal D6 amplified by the LNA 15. The amplified RF signal D7 passed by the BPF 16 is supplied to the amplifier 17.

The amplifier 17 further amplifies the amplified RF signal D7 passed by the BPF 16. Amplifier 17
Is the amplified predetermined frequency F _RF , that is, 157
The amplified RF signal D8 of 5.42 MHz is supplied to the multiplier 19.

The frequency synthesizer 18 controls the TCX under the control of the control signal D9 supplied from the CPU 26.
A local oscillation signal D10 having a predetermined frequency F _LO is generated based on the oscillation signal D2 supplied from O12. The frequency synthesizer 18 uses the generated local oscillation signal D10.
Is supplied to the multiplier 19.

The multiplier 19 multiplies the amplified RF signal D8 having a predetermined frequency F _RF amplified by the amplifier 17 by the local oscillation signal D10 supplied from the frequency synthesizer 18 to reduce the amplified RF signal D8. The IF signal D11 having the predetermined frequency F _IF of about 1.023 MHz is generated by conversion. The IF signal D11 is supplied to the amplifier 20.

The amplifier 20 amplifies the IF signal D11 down-converted by the multiplier 19. Amplifier 2
0 supplies the amplified amplified IF signal D12 to the LPF 21. The LPF 21 passes a lower band component than the predetermined frequency of the amplified IF signal D12 amplified by the amplifier 20. The amplified IF signal D13 passed by the LPF 21 is supplied to the A / D 22.

The A / D 22 converts the analog amplified IF signal D13 passed by the LPF 21 into a digital amplified IF signal D14. The amplified IF signal D14 converted by the A / D 22 is supplied to the synchronization acquisition unit 24 and the synchronization holding unit 25 bit by bit.

In the GPS receiver 10, among these units, the LNA 15, 17, 20, BPF 1
6, frequency synthesizer 18, multiplier 19, LPF2
1, and the A / D 22 is a reception RF having a high frequency of 1575.42 MHz received by the antenna 14.
To facilitate the digital signal processing of the signal D5,
For example, the frequency conversion unit 23 down-converts to the amplified IF signal D14 having a low frequency F _{IF of} about 1.023 MHz.

Further, the GPS receiving apparatus 10 performs synchronous acquisition of the spread code generated by itself and the expanded code in the amplified IF signal D14 supplied from the A / D 22 and synchronous acquisition for detecting the carrier frequency in the amplified IF signal D14. The amplified IF signal D1 supplied from the unit 24 and the A / D 22
4, a synchronization holding unit 25 for holding the synchronization between the spread code and the carrier and demodulating the message, a CPU 26 for collectively controlling each unit to perform various arithmetic processing, and a time based on the oscillation signal D1 supplied from the XO11. RT to measure
C27 and a timer 28 as an internal clock of the CPU 26
RAM (Random Access Memory) and ROM (Read O
nly Memory) and the like.

The synchronization acquisition unit 24, under the control of the CPU 26, amplifies the signal supplied from the A / D 22 based on the multiplied and / or frequency-divided oscillation signal D3 supplied from the frequency multiplier / frequency divider 13. The spread code in the IF signal D14 is synchronously captured, and the carrier frequency in the amplified IF signal D14 is detected. At this time, the synchronization acquisition unit 24
Performs synchronization acquisition with coarse accuracy. The synchronization acquisition unit 24 stores the satellite number for identifying the detected GPS satellite, the phase of the spread code, and the carrier frequency in the synchronization holding unit 25 and the CPU.
26.

Under the control of the CPU 26, the synchronization holding unit 25, based on the frequency-multiplied and / or frequency-divided oscillation signal D3 supplied from the frequency multiplier / frequency divider 13, the amplification supplied from the A / D 22. The spread code and the carrier in the IF signal D14 are held in synchronization, and the navigation message included in the amplified IF signal D14 is demodulated. At this time, the synchronization holding unit 25 starts the operation with the satellite number, the phase of the spread code, and the carrier frequency supplied from the synchronization acquisition unit 24 as initial values, as described later. The synchronization holding unit 25
The amplified IF signals D14 from a plurality of GPS satellites are held in parallel in parallel, and the detected spread code phase, carrier frequency, and navigation message are supplied to the CPU 26.

The CPU 26 acquires the phase of the spreading code, the carrier frequency, and the navigation message supplied from the synchronization holding unit 25, and based on these various information, its own 3
Various calculation processes such as a process of calculating the dimensional position and a process of correcting the time information of the GPS receiving apparatus 10 are performed. Further, the CPU 26 inputs / outputs each unit of the GPS receiving apparatus 10 and various peripherals, and input / output with the outside.
ut) controls overall.

The RTC 27 measures time based on the oscillation signal D1 supplied from the XO 11. This RTC2
7 is the time information measured by 27, which is used until the accurate time information of the GPS satellite is obtained, and the CPU 26 which has obtained the accurate time information of the position satellite of the GPS receiving device XO11 It is corrected as appropriate by controlling.

The timer 28 functions as an internal clock of the CPU 26, and is used for generating various timing signals necessary for the operation of each section and for time reference. For example, in the GPS receiving apparatus 10, the synchronization holding unit 25 is synchronized with the phase of the spread code captured by the synchronization capturing unit 24.
The timer 28 refers to the timing for starting the operation of the spreading code generator described later.

The memory 29 is composed of RAM, ROM and the like. In the memory 29, a RAM is used as a work area when various processes are performed by the CPU 26 and the like, when buffering various input data, and when storing intermediate data and calculation result data generated in the calculation process. Also RAM is used. Further, in the memory 29, a ROM is used as a means for storing various programs and fixed data.

In the GPS receiver 10, these synchronization acquisition unit 24, synchronization holding unit 25, CPU 26,
The RTC 27, the timer 28, and the memory 29 are configured as a baseband processing unit.

A GPS receiver 10 having such units
In the above, at least each of the units except the XO 11, the TCXO 12, the antenna 14, the LNA 15, and the BPF 16 can be configured as a demodulation circuit 30 that is formed of one integrated chip.

The GPS receiver 10 receives RF signals from at least four GPS satellites, converts the RF signals into IF signals by the frequency conversion unit 23, and then acquires synchronization of spread codes by the synchronization acquisition unit 24. Also, the carrier frequency is detected, and the synchronization holding unit 25 holds the synchronization between the spreading code and the carrier and demodulates the navigation message. Then, the GPS receiver 10 detects the phase of the spread code,
CP based on carrier frequency and navigation message
U26 calculates its own three-dimensional position.

Here, in the GPS receiver 10, the CP
The position calculation process performed in U26 will be described. GP
In the S reception device 10, any one of three position calculation processes described below may be performed according to the number of GPS satellites that have received signals or the number of received signals used in the position calculation process. Good.

<First Position Calculation Processing: Using Four Received Signals> First, when signals from at least four GPS satellites are received, the position is calculated using four received signals. The outline of the first position calculation processing that can be adopted for the following will be described.

The three-dimensional position of the i-th GPS satellite
(X_i, Y_i, Z_i), And the pseudo distance is ρ _iThen,
Three-dimensional position of the GPS receiver 10 (Xo, Yo, Zo)
And the clock error δ inside the GPS receiver 10_τAnd are unknowns
The following simultaneous equations are obtained.

[Equation 5] In Equation 1, ρ _i = c × τ _i , and τ _i is
The signal arrival time from each GPS satellite to the GPS receiver 10, and c is the speed of light. Note that τ _i is the CPU 26
Calculated by

By substituting the relational expressions of Expression 6, Expression 7, Expression 8, and Expression 9 into Expression 5 shown below, the Expression 1 is changed to Expression 10 and Expression 11 below. One quadratic equation and three linear equations will be derived.

[Equation 6] However, in Expression 10 and Expression 11, Xo ′ = Xo−X
₀ , Yo ′ = Yo−Y ₀ , Zo ′ = Zo−Z ₀ , ρo ′ =
δρ + ρ ₀ , X _i ′ = X _i −X ₀ , Y _i ′ = Y _i −Y ₀ Z
_i ′ = Z _i −Z ₀ , ρ _i ′ = ρ _i −ρ ₀ , a _i = (X _i ′
^{_{2 + Y i '2 + Z}} i' 2 -ρ i '2) / 2 to. That is, the coordinates (Xo ', Yo', Zo ') are 0th (i =
0) represents the relative coordinates of the GPS receiver 10 with respect to the GPS satellite, and the coordinate position (X _i ′, Y _i ′, Z _i ′) represents the relative coordinates of the other GPS satellites with respect to the 0th GPS satellite. Further, the unknown number in Expression 10 and Expression 11 is X
They are o ', Yo', Zo ', and ρo'.

Equation 11 is 3 for four unknowns.
Since ρo ′ is a parameter, Xo ′, Yo ′, and Zo ′ are respectively expressed by the following equation 1
2, can be expressed as in Equation 13 and Equation 14.

[Equation 7] Substituting the above equation 12, equation 13, and equation 14 into equation 10,
The unknown ρo ′ is obtained as in the following Expression 15.

[Equation 8] As a result, the relational expression ρo ′ = δρ + ρ ₀ , and δρ
= Cδτ, the internal clock error δτ of the GPS receiving apparatus 10 can be obtained.

Next, Equation 15 is transformed into Equation 12, Equation 13, and Equation 14
By substituting for Xo ′, Yo ′, Zo ′, unknowns Xo ′ = Xo−X ₀ , Yo ′ = Yo−Y ₀ , Z
o '= Xo from _{Zo-Z 0} of the equation, Yo, is Zo obtained. That is, the three-dimensional position (X
o, Yo, Zo) can be calculated.

Since equation 15 is a quadratic equation,
Although there are two solutions, as ρo ′, ρo ′> 0 and a solution that is appropriate for calculating the three-dimensional position of the GPS receiver 10 may be selected.

When the GPS receiving apparatus 10 calculates its own position based on the above-mentioned first position calculating process,
It operates as shown in the flow chart of FIG.

When the position calculation process for calculating its own position is started, the GPS receiver 10 receives the signal transmitted from the GPS satellite in step S10 shown in FIG. At this time, it is assumed that the signals from at least four GPS satellites are normally received. Then, in the GPS receiving apparatus 10, the synchronization acquisition unit 24 and the synchronization holding unit 25 function as described above, so that the received signal from each GPS satellite includes the satellite number included in, the phase of the spread code, the carrier frequency, and Navigation message is CPU26
Is supplied to.

Next, in step S11, the CPU 26
Calculates the three-dimensional position (X _i , Y _i , Z _i ) of each GPS satellite based on the orbit information included in the navigation message. Further, in step S12, the CPU 26 calculates the pseudo distance ρ _i based on the phase of the spread code.

Next, in step S13, the CPU 26
Is the relative position (X _i ′, Y _i ′, Z _i ′) of the other GPS satellites to the 0th GPS satellite and the deviation amount ρ of the time information.
_{i 'and} calculated. At this time, as in the above description, X _i '
= X _i −X ₀ , Y _i ′ = Y _i −Y ₀ , Z _i ′ = Z _i −
The relational expression of Z ₀ , ρ _i ′ = ρ _i −ρ ₀ is used.

Next, in step S14, the CPU 26
Using the value calculated in step S13, a _i = (X
The value of a _i is calculated from the relational expression _i ′ ² + Y _i ′ ² + Z _i ′ ² −ρ _i ′ ² ) / 2.

Next, in step S15, the CPU 26
Is a determinant A for calculating Expression 12, Expression 13, and Expression 14.
To calculate. Next, in step S16, the CPU 26
Calculates the determinant b. Next, in step S17, the CPU 26 calculates determinants d ₁ and d ₂ for calculating Expression 15.

Next, in step S18, the CPU 26
Calculates the value of ρo ′ based on Equation 15. Next, in step S19, the CPU 26 calculates the calculated ρo ′.
Value and α ₁ , α derived from determinant A and determinant b
Equations 12, 13, and 14 are calculated using the values of ₂ , β ₁ , β ₂ , γ ₁ , and γ ₂ . As a result, the 0th G
Relative coordinates of the GPS receiver 10 with respect to the PS satellite (X
o ', Yo', Zo ') is obtained. Next, in step S20, the CPU 26 sets Xo ′ = Xo−X ₀ , Yo ′ = Y.
o-Y ₀ , Zo ′ = Zo-Z ₀
The values of o, Yo, Zo are calculated.

It should be noted that the GPS receiving apparatus 10 is assumed to perform the above-described processing from step S18 to step S20 for each of the two values of ρo 'calculated by equation 15.

Next, in step S21, the CPU 26
Determines the validity with respect to the two coordinates (Xo, Yo, Zo) obtained by using the two values of ρo ′ calculated by Expression 15, and determines one of them as the three-dimensional position of the GPS receiver 10. select. As a result, the three-dimensional position of the GPS receiver 10 is obtained.

In this step S21, the CP
U26 uses the relational expression ρo ′ = δρ + ρ _{0 and the} relational expression δρ = cδτ for ρo ′ for which the solution selected as the three-dimensional position is obtained, and uses the GPS receiver 10
It is also possible to calculate the internal clock error δτ and to control the RTC 27 or the timer 28 based on this clock error δτ to perform the process of correcting the current time.
As a result, the GPS receiver 10 can always keep accurate time inside.

Next, in step S22, the CPU 26
Is 3 of the GPS receiver 10 obtained as described above.
The dimensional position is output in response to a request from another system.

Since the GPS receiving apparatus 10 calculates its own three-dimensional position by the series of position calculating processes described above, it does not need the initial value required in the conventional position calculating method. Further, iterative calculation as in the case of calculating the position by the Newton method is not performed. Therefore, the self-three-dimensional position can be calculated quickly and reliably with a relatively small amount of calculation.

Further, since the GPS receiver 10 can perform the position calculation processing without requiring the initial value,
For example, it is not necessary to register a large number of positions on the earth inside the receiver in advance for the purpose of responding to the case where the power is turned on after moving for a long distance in an airplane or the like. Therefore, it is not necessary to secure a storage area for registering these positions.

In FIG. 2, the position calculation process is
It shows the flow of processing when it is performed once.
When performing the position calculation process continuously, the S reception device 10 performs step S1 after the process in step S22.
The processes after 0 may be repeated.

Further, in the first position calculation processing, it is necessary that the signals (received signals) from at least four GPS satellites can be normally received. For example, five or more received signals are normally received. Even if it is possible, for example, DOP (Dilution O
A reception signal having a good f Precision value may be selected and used in the position calculation process. This also applies to the second position calculation process and the third position calculation process described later.

<Second Position Calculation Processing: Using Five Received Signals> Next, when signals from at least five GPS satellites can be received, the position is calculated using five received signals. The second position calculation process that can be used in this case will be described.

In the first position calculation process described above, the simultaneous equations shown in equation 1 are converted into one quadratic equation (equation 1).
0) and three linear equations (Equation 11),
Solves the system of equations by eliminating the three unknowns. However, when the position calculation is performed using five received signals, Equation 11 is i = 0, 1, 2, 3,
There are four linear equations of four.

Even when five received signals are used,
The unknowns remain four (Xo ′, Yo ′, Zo ′, ρo ′), and the four equations of Equation 11 are themselves simultaneous linear equations. From this fact, when position calculation is performed using five received signals, four unknowns (Xo ′, Yo ′, Zo ′, ρ) are obtained by solving the four simultaneous linear equations of Expression 11.
o ') is uniquely obtained.

Therefore, the unknown number X on the left side in Expression 11 is
Let B be the coefficient matrix of o ′, Yo ′, Zo ′, ρo ′, and the right side be the vertical vector e, and f = (Xo ′, Yo ′, Zo ′, ρ.
o ′) ^T , Equation 11 can be expressed as Equation 16 below.

[Equation 9] Therefore, the unknowns Xo ′, Yo ′, Zo ′, ρo ′ can be directly obtained by solving the determinant of Equation 16.

When the GPS receiver 10 calculates its own position based on the above-mentioned second position calculation processing,
It operates as shown in the flowchart of FIG.

The GPS receiving apparatus 10 is as shown in FIG.
In addition, the processing from step S10 to step S14 is
The same processing as the first position calculation processing described above is performed.
As a result, it is possible to connect five GPS satellites from i = 0 to 4
X_i', Y_i', Z_i', Ρ _i'Value is calculated and a_i
The value of is obtained.

Next, in step S30, the CPU 26
Is the unknowns Xo ', Yo', Z on the left side of Equation 11.
Let B be the coefficient matrix of o'and ρo ', and the vertical vector e on the right side,
And f = (Xo ′, Yo ′, Zo ′, ρo ′) ^T. Next, in step S31, the values of Xo ', Yo', Zo ', and ρo' are calculated by solving the determinant of Expression 16. Next, in step S20, the CPU 26
_{Xo '= Xo-X 0,} Yo' = Yo-Y 0, Zo '= Zo
The values of Xo, Yo, and Zo are calculated using the relational expression −Z ₀ . Thereby, the three-dimensional position (Xo, Yo, Zo) of the GPS receiver 10 is obtained.

Next, in step S22, the CPU 26
Is 3 of the GPS receiver 10 obtained as described above.
The dimensional position is output in response to a request from another system.

In step S20, the CPU2
6 uses the relational expression of ρo ′ = δρ + ρ _{0 and the} relational expression of δρ = cδτ for the obtained ρo ′, and
The clock error δτ inside the receiving apparatus 10 may be calculated, and the RTC 27, the timer 28, or the like may be controlled based on the clock error δτ to perform the process of correcting the current time. As a result, the GPS receiver 10 can always keep accurate time inside.

By operating as described above, the GPS receiving device 10 can calculate its own position based on the second position calculating process. This second position calculation process does not require the initial value required in the conventional position calculation method. In addition, complicated iterative calculation as in the case of calculating the position by the Newton method is not performed. Therefore, the self-three-dimensional position can be calculated quickly and reliably with a relatively small amount of calculation. That is, the GPS receiving device 10 achieves the same effect as the first position calculation process by performing the position calculation by the second position calculation process.

In this second position calculating process, it is necessary that at least five signals from GPS satellites can be normally received, and the calculation process from step S10 to step S14 is more than that in the first position calculating process. Will also increase. However, as compared with the first position calculation process that requires solving the quadratic equation and that the validity of the two obtained solutions must be finally determined, the second position calculation process is There is an advantage that the three-dimensional position of the GPS receiving apparatus 10 can be directly obtained with a smaller calculation amount of solving a linear equation.

<Third Position Calculation Processing: Using Six or More Received Signals> Next, when signals from at least six GPS satellites can be received, at least six received signals are used to determine the position. The third position calculation process that can be adopted when the calculation is performed will be described.

In the first position calculation process described above, the simultaneous equations shown in equation 1 are converted into one quadratic equation (equation 1).
0) and three linear equations (Equation 11),
Solves the system of equations by eliminating the three unknowns. However, when position calculation is performed using five received signals, equation 11 is i = 0, 1, 2, ...
·, N and at least five linear equations.

Also in this case, there are four unknowns (X
o ′, Yo ′, Zo ′, ρo ′) and five or more equations 11 are themselves simultaneous linear equations.
From this, when position calculation is performed using six received signals, the least squares method is applied to five or more equations 11 that exist, and four unknowns (Xo ′, Yo ′,
Zo ′, ρo ′) will be uniquely obtained.

That is, in this case, the determinant f can be obtained by modifying the above-described expression 16 to obtain the following expression 17. Then, from the obtained determinant f, the three-dimensional position (Xo, Yo, Zo) of the GPS receiver 10 can be easily calculated in the same manner as the second position calculation process.

[Equation 10] The GPS receiving apparatus 10 operates as shown in the flowchart of FIG. 4 when calculating its own position based on the above-described third position calculating process.

As shown in FIG. 4, the GPS receiving apparatus 10 performs the processing from step S10 to step S14 as follows.
The same processing as the first position calculation processing described above is performed.
This allows at least 6 GPSs from i = 0 to N
For the satellite, the values of X _i ′, Y _i ′, Z _i ′, ρ _i ′ are calculated, and the value of a _i is obtained.

Next, in step S30, the CPU 26
Is the unknowns Xo ', Yo', Z on the left side of Equation 11.
Let B be the coefficient matrix of o'and ρo ', and the vertical vector e on the right side,
And f = (Xo ′, Yo ′, Zo ′, ρo ′) ^T. Next, in step S40, the values of Xo ', Yo', Zo ', and ρo' are calculated by solving the determinant of Expression 17. Next, in step S20, the CPU 26
_{Xo '= Xo-X 0,} Yo' = Yo-Y 0, Zo '= Zo
The values of Xo, Yo, and Zo are calculated using the relational expression −Z ₀ . Thereby, the three-dimensional position (Xo, Yo, Zo) of the GPS receiver 10 is obtained.

Next, in step S22, the CPU 26
Is 3 of the GPS receiver 10 obtained as described above.
The dimensional position is output in response to a request from another system.

In step S20, the CPU 2
6 uses the relational expression of ρo ′ = δρ + ρ _{0 and the} relational expression of δρ = cδτ for the obtained ρo ′, and
The clock error δτ inside the receiving apparatus 10 may be calculated, and the RTC 27, the timer 28, or the like may be controlled based on the clock error δτ to perform the process of correcting the current time. As a result, the GPS receiver 10 can always keep accurate time inside.

By operating as described above, the GPS receiving device 10 can calculate its own position based on the third position calculating process. The third position calculation process does not require the initial value required in the conventional position calculation method. In addition, complicated iterative calculation as in the case of calculating the position by the Newton method is not performed. Therefore, the self-three-dimensional position can be calculated quickly and reliably with a relatively small amount of calculation. That is, the GPS receiving device 10 achieves the same effect as the first position calculation process by performing the position calculation by the third position calculation process.

By the way, in the third position calculation process,
The 0th (i = 0) GPS satellite is not subject to error minimization, but is 2 for other GPS satellites.
Since the multiplication error is minimized, the error of the obtained solution, that is, G is compared with the second position calculation process described above.
This has the advantage that the error in the three-dimensional position of the PS receiver 10 can be reduced.

The GPS receiving apparatus 10 performs one of the first to third position calculating processes described above according to the number of GPS satellites that have received signals or the number of received signals used in the position calculating process. Is configured to perform processing. Therefore, the GPS receiving apparatus 10 can calculate the position quickly and efficiently without substituting the initial value and repetitive calculation when calculating the position of itself.

Note that the GPS receiving apparatus 10 determines whether the first signal is received according to the state of the received signal or the number of GPS satellites that can receive the signal.
It may be possible to appropriately switch which one of the first to third position calculating processes is performed, and it is set in advance to perform any one of the first to third position calculating processes. May be.

Further, a software program for causing a desired electronic device to execute a procedure corresponding to the position calculation processing executed by the CPU 26 as described above may be stored in various recording media and provided.

As described above, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

[0095]

According to the present invention, the self position is calculated by solving the linear equation obtained after the variable conversion. For this reason, it is not necessary to perform iterative calculation that requires a large amount of calculation, and it is not necessary to substitute an initial value, so that the position can be calculated efficiently and quickly. Therefore,
According to the present invention, the time required to calculate the current position can be greatly reduced, and the convenience for the user can be greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a GPS receiving device shown as an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of position calculation processing executed by the GPS receiving apparatus.

FIG. 3 is a flowchart showing another example of position calculation processing executed by the GPS receiving apparatus.

FIG. 4 is a flowchart showing yet another example of position calculation processing executed by the GPS receiving apparatus.

[Explanation of symbols]

10 GPS receiver, 11 XO, 12 TCX
O, 13 multiplier / divider, 14 antenna, 1
5, 17, 20 LNA, 16 BPF, 18 frequency synthesizer, 19 multiplier, 21 LPF,
22 A / D, 23 Frequency conversion unit, 24 Synchronization acquisition unit, 25 Synchronization holding unit, 26 CPU, 27
RTC, 28 timer, 29 memory, 30 demodulation circuit

Claims (6)

[Claims] 1. A receiving device for receiving a signal transmitted from a plurality of satellites constituting a global positioning system to calculate its own position, and a receiving means for receiving a signal transmitted from the satellite, A position calculating means for calculating its own position based on the signal received by the receiving means, wherein the position calculating means includes three satellites for each of n satellites (n is a natural number of 4 or more) received by the receiving means. For the n simultaneous quadratic equations in which the dimensional position and the pseudo distance to each satellite are constants and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, Convert the variable to the one obtained by subtracting the above constant corresponding to either,
A receiving device characterized in that the position of itself is calculated by solving the obtained one quadratic equation and at least three linear equations. 2. A receiving device for receiving the signals transmitted from a plurality of satellites constituting the global positioning system to calculate its own position, and a receiving means for receiving the signals transmitted from the satellites. A position calculating means for calculating its own position based on the signal received by the receiving means, wherein the position calculating means includes three satellites for each of the n (n is a natural number of 5 or more) satellites received by the receiving means. For the n simultaneous quadratic equations in which the dimensional position and the pseudo distance to each satellite are constants and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, Convert the variable to the one obtained by subtracting the above constant corresponding to either,
A receiving device, characterized in that it calculates its own position by solving four linear equations among the obtained one quadratic equation and at least four linear equations. 3. A receiving device for receiving the signals transmitted from a plurality of satellites constituting the global positioning system to calculate its own position, and receiving means for receiving the signals transmitted from the satellites. A position calculating means for calculating its own position based on the signal received by the receiving means, wherein the position calculating means includes three satellites for each of n satellites (n is a natural number of 6 or more) received by the receiving means. For the n simultaneous quadratic equations in which the dimensional position and the pseudo distance to each satellite are constants, and the three-dimensional position of itself and the clock error between each satellite and itself are unknown variables, Convert the variable to the one obtained by subtracting the above constant corresponding to either,
A receiving apparatus, characterized in that the position of itself is calculated by applying the least squares method to at least five linear equations among the obtained one quadratic equation and at least five linear equations. 4. A position calculation method for calculating the position of the self based on signals transmitted from a plurality of satellites constituting a global positioning system, each of which is n (n is a natural number of 4 or more) of the satellites. Is a constant and the pseudo-distance to each satellite is a constant, and the unknown variable is the above for n simultaneous quadratic equations in which the three-dimensional position of the self and the clock error between each satellite and the self are unknown variables. Position that is calculated by performing variable conversion to the one obtained by subtracting the above constant corresponding to one of the satellites, and solving the obtained one quadratic equation and at least three linear equations to calculate its own position Calculation method. 5. A position calculating method for calculating one's own position based on signals transmitted from a plurality of satellites constituting a global positioning system, wherein each of n (n is a natural number of 5 or more) of said satellites. Is a constant and the pseudo-distance to each satellite is a constant, and the unknown variable is the above for n simultaneous quadratic equations in which the three-dimensional position of the self and the clock error between each satellite and the self are unknown variables. The position of one's own position is calculated by performing variable conversion to the one obtained by subtracting the above constant corresponding to one of the satellites and solving four linear equations out of the obtained one quadratic equation and at least four linear equations. A position calculating method characterized by calculating. 6. A position calculating method for calculating one's own position based on signals transmitted from a plurality of satellites constituting a global positioning system, wherein each of n (n is a natural number of 6 or more) of said satellites. Is a constant and the pseudo-distance to each satellite is a constant, and the unknown variable is the above for n simultaneous quadratic equations in which the three-dimensional position of the self and the clock error between each satellite and the self are unknown variables. Variable conversion to the one obtained by subtracting the above constant corresponding to one of the satellites, and applying the least squares method to at least five linear equations among the obtained one quadratic equation and at least five linear equations A position calculation method characterized in that the position of the self is calculated thereby.