CN101315423A - Method for computing code phase pseudo range between locating terminal and satellite in auxiliary global satellite positioning system - Google Patents

Abstract

The invention provides a method for calculating the code phase pseudorange between a locating terminal and a satellite in an A-GPS. An A-GPS locating terminal captures the distance measuring signals of satellite and gets the measuring information according to the assistant information received from the network rapidly; an A-GPS algoritic module makes use of the initial position provided by the A-GPS locating terminal and the satellite navigation teletext information provided by the other locating devices to work out the pseudorange from the initial position to the satellite; then the A-GPS algoritic module makes use of the measuring information of terminal to work out the corrected range between the initial position and the actual terminal position; and then the actual pseudorange between the A-GPS locating terminal and the satellite is further worked out. The method inherits the method that the traditional GPS locating system conducts the location through code phase pseudorange; the locating process that the A-GPS locating terminal does not need to download directly, the satellite navigation teletext is obtained indirectly through a network, and the A-GPS locating terminal completes the fast capture of the satellite signals and calculation of the pseudorange information is realized.

Description

Calculate the method for code phase pseudo range between locating terminal and the satellite in a kind of auxiliary global satellite positioning system

Technical field

The present invention relates to technical fields such as global positioning satellite and mobile communication, be particularly related to and a kind of mobile data net (as GSM/GPRS, WCDMA and CDMA2000) and Global Positioning System (GPS) (as gps system) combined, realize the auxiliary method of down finishing location of the latter at the former.

Background technology

The main pseudo range measurement method that adopts in tradition GPS (Global Positioning System GPS) single-point location, this method are based on following formula:

$\left\{\begin{array}{c}{\mathrm{\ρ}}_1=\sqrt{{(x_1-x_u)}^2+{(y_1-y_u)}^2+{(z_1-z_u)}^2}+{\mathrm{ct}}_u\\ {\mathrm{\ρ}}_2=\sqrt{{(x_2-x_u)}^2+{(y_2-y_u)}^2+{(z_2-z_u)}^2}+{\mathrm{ct}}_u\\ {\mathrm{\ρ}}_3=\sqrt{{(x_3-x_u)}^2+{(y_3-y_u)}^2+{(z_3-z_u)}^2}+{\mathrm{ct}}_u\\ {\mathrm{\ρ}}_4=\sqrt{{(x_4-x_u)}^2+{(y_4-y_u)}^2+{(z_4-z_u)}^2}+{\mathrm{ct}}_u\end{array}---\left(1\right)\right.$

Wherein, (x ₁, y ₁, z ₁), (x ₂, y ₂, z ₂), (x ₃, y ₃, z ₃), (x ₄, y ₄, z ₄) being respectively observation t constantly, the locus coordinate of visible four satellites of terminal can be calculated by the navigation message of satellite broadcasting; (x _u, y _u, z _u) be the position coordinates of waiting to ask locating terminal; ρ ₁, ρ ₂, ρ ₃, ρ ₄Be respectively the distance of terminal to four satellite that t records constantly, be called pseudorange, can draw by the navigation message of satellite broadcasting; t _uBeing the clock correction of terminal and satellite clock, also is to treat evaluation; C is the light velocity.

Traditional GPS location, the GPS locating terminal need obtain pseudorange value by downloading satellite navigation message, thereby has following shortcoming:

(1) primary positioning time is long.Must pass through to download satellite navigation message (D sign indicating number) owing to will obtain pseudorange value, so locating terminal also need with two track loop circuit tracings and separate to translate satellite navigation message, so the positioning time that needs is longer after catching ranging code (C/A sign indicating number).

(2) under the situation of satellite environment condition difference, be difficult to the location.Because the GPS locating terminal needs ownly to download satellite navigation message, if the GPS receiver is in moving or obtain in the satellite-signal and have no progeny, satellite navigation message is difficult to continuous the biography, needs to download again, therefore locatees if signal receives discontinuous then being difficult to.

Summary of the invention

The present invention is directed in the above and traditional GPS location terminal and obtain the problem that pseudorange brings voluntarily, proposed to calculate in a kind of auxiliary global satellite positioning system (A-GPS) method of pseudorange between A-GPS locating terminal and the satellite, in this method, the A-GPS locating terminal only need be caught the satellite ranging coded signal, calculates pseudorange between satellite and the terminal thereby obtain satellite navigation message indirectly by other positioning equipments.This method has shortened the primary positioning time of locating terminal greatly, has reduced the complexity of positioning terminal equipment, has improved the actual effect and the reliability of location.

Technical scheme provided by the present invention may further comprise the steps:

A, A-GPS server according to the terminal initial position, calculate the supplementary that accessory terminal accelerates to catch satellite-signal after terminal is sent location request, this supplementary is issued the A-GPS locating terminal;

B, A-GPS locating terminal are caught the gps satellite distance measuring signal rapidly according to supplementary and are carried out locator data and measure, and this metrical information is transferred to A-GPS location algorithm module;

C, A-GPS location algorithm module are according to going out pseudorange value between A-GPS locating terminal and the satellite from the location measurement information of receiving terminal with from the satellite navigation message information calculations of other positioning equipment.

Step C specifically also comprises following link:

D, A-GPS location algorithm module be according to the satellite navigation message information that other positioning equipments provide, and calculates the capture terminal satellite-signal position coordinates of satellite constantly, and according to the initial position coordinate of terminal, calculate the pseudorange of satellite to the terminal initial position;

E, A-GPS location algorithm module calculate the range difference of terminal physical location with respect to initial position according to the metrical information that the A-GPS locating terminal provides;

F, A-GPS location algorithm module according to the satellite that calculates to the pseudorange of terminal initial position and terminal physical location with respect to the range difference of initial position, calculate the pseudorange that satellite arrives the terminal physical location.

The present invention is described in further detail below in conjunction with accompanying drawing.

Brief Description Of Drawings

Fig. 1 is an A-GPS system schematic under the MSA mode.

Fig. 2 is each module information interaction diagrams of A-GPS.

Fig. 3 is its computation of pseudoranges process flow diagram.

Embodiment

Because gps satellite signal with light velocity propagation, therefore, requires pseudorange P, be exactly in fact the time τ that asks signal to propagate.In the present invention, estimate out earlier the initial position of A-GPS locating terminal, calculate the pseudorange of this initial position, thereby obtain corresponding signal propagation time to satellite; Catching the satellite ranging signal by the A-GPS locating terminal by supplementary again, to obtain the equivalent time that the terminal physical location propagates with respect to the signal of initial position poor, promptly whole chip and broken chip value; The time splicing is carried out to the signal propagation time of satellite and the chip information of A-GPS terminal in the base station, obtain the signal propagation time of A-GPS locating terminal to satellite; This time is carried out integer ambiguity handle, multiply by the light velocity again, can obtain the pseudorange of A-GPS locating terminal to satellite.

In the present invention, take out the A-GPS algoritic module and carried out the calculating of pseudorange, this functional module can be placed on and realize (MSA mode) in the A-GPS server, also can be placed on and realize (MSB mode) in the A-GPS locating terminal, Fig. 1 is an A-GPS system schematic under the MSA mode, wherein, the initial position point can be base station location or other aided location of mobile cellular sub-district, terminal place, can pass through the GSM/GPRS network alternately between A-GPS locating terminal and the A-GPS server, also can be CDMA/CDMA 1x network or wireless station etc.

Describe the present invention in detail below in conjunction with Fig. 1 and Fig. 2.

Step 1, A-GPS server calculate the satellite situation in the A-GPS locating terminal sky according to the initial position message that the A-GPS locating terminal transmits, and supplementary is passed to the A-GPS locating terminal;

Step 2, the A-GPS locating terminal is caught the satellite ranging signal rapidly according to the supplementary of A-GPS server transmission, obtain the phase pushing figure of ranging code signal, be the ranging code (C/A sign indicating number) and the local C/A sign indicating number that produces chip offset relatively that the A-GPS locating terminal receives, this side-play amount is defined as whole chip and broken chip.

And definition: 1 C/A sign indicating number width is called 1 whole chip, and each C/A sign indicating number cycle is 1023 whole chips, because a C/A sign indicating number cycle is 1ms, therefore, the width of each whole chip is 1/1023ms; Each whole chip is divided into 1024 broken chips again, and therefore, the width of each broken chip is 1/1024/1023ms.

Step 3, A-GPS locating terminal will put in order chip and broken chip information passes to A-GPS location algorithm module.

Step 4, the method of algoritic module employing time splicing, travel-time and A-GPS the locating terminal whole chip and the broken chip value that measure of the signal that cell base station is measured from the satellite to the base station is combined, obtains the travel-time of signal from satellite to the A-GPS locating terminal.Calculation process as shown in Figure 3, concrete grammar is as follows:

Can obtain the three-dimensional location coordinates (X of A-GPS locating terminal place cell base station by the A-GPS server _b, Y _b, Z _b) and observing the three-dimensional location coordinates (X of satellite constantly _s, Y _s, Z _s), thereby can calculate the station star distance of cell base station to satellite:

$R_b=\sqrt{{(X_s-X_b)}^2+{(Y_s-Y_b)}^2+{(Z_s-Z_b)}^2}---\left(2\right)$

Satellite to the theoretical value of the signal propagation time of cell base station is:

τ _db＝R _b/C (3)

Add the influence of satellite clock deviation and ionosphere and tropospheric, satellite to the actual value of the signal propagation time of cell base station is:

τ _b＝R _b/C+dt _u+d _ion/C+d _trop/C (4)

Wherein, d _IonBe the equivalent distances error that produces owing to the ionosphere influence; d _TropBe the equivalent distances error that produces owing to the troposphere influence; t _uClock correction for terminal and satellite clock; C is the light velocity.

Because the radius of each cellular cell generally between 0.1km-20km, can get as calculated, if the propagation distance of gps signal from the A-GPS locating terminal to cell base station is 20km, the corresponding time is | τ-τ _b|＜0.06667ms.Therefore, A-GPS locating terminal and base station receive satellite-signal, and the difference of corresponding signal propagation time should be far smaller than 1ms, therefore, can get τ _bInteger ms part, as the integer ms part of asking signal propagation time τ, that is:

τ′＝(modτ _b)ms (5)

Utilize code phase measuring by the A-GPS locating terminal, resulting whole chip and broken chip value can calculate the decimal ms part of τ.Computing formula is as follows:

${\mathrm{\τ}}^{\′\′}=(\frac{\mathrm{Wchip}}{1023}+\frac{\mathrm{Fchip}}{{1023}^2})\mathrm{ms}---\left(6\right)$

Wherein, Wchip is whole chip value, and Fchip is broken chip value.

By above calculating, can get

τ＝[τ′+τ″]ms (7)

Also there is the problem of an integer ambiguity in the A-GPS locating terminal that calculates so to the signal propagation time of satellite.Several class values of hypothesis are analyzed below:

As following table 1, τ _bBe the actual propagation time of signal from the satellite to the base station; τ ₀The actual propagation time for signal from satellite to the A-GPS locating terminal; τ is the travel-time of signal from satellite to the A-GPS locating terminal that calculates.

	τ b	τ 0	τ
				1	70.5	70.6	70+0.6＝70.6
2	69.9	70.1	69+0.1＝69.1
				3	70.1	69.9	70+0.9＝70.9

The integer ambiguity problem of table 1 signal propagation time

By last table the 1 row, as can be known, get the τ that the base station obtains _bIntegral part 70 and the time decimal part 0.6 that obtains of the chip information of A-GPS locating terminal, both additions can obtain τ=70+0.6=70.6, this and actual value τ ₀The=70.6th, match.

Come the 2nd row of analytical table again, get the τ that the base station obtains equally _bIntegral part 69 and the time decimal part 0.1 that obtains of the chip information of A-GPS locating terminal, both additions can obtain τ=69+0.1=69.1, this and actual value τ ₀=70.1 do not match, and difference just in time is 1ms.This is because locate saltus step has taken place at whole millisecond at the signal propagation time of base station and A-GPS locating terminal, therefore, need handle this situation.

There is the similar situation of the 2nd row equally in the 3rd of analytical table the row again.

Result of calculation is carried out following calculation process:

If (τ-τ _b＜-0.5), τ=τ+1 then

If (τ-τ _b＞0.5), τ=τ-1 (8) then

Like this, several groups of data of his-and-hers watches 3-1 are handled, and the result who obtains is as table 3-2.

	τ b	τ 0	τ before revising	Revised τ
					1	70.5	70.6	70+0.6＝70.6	70.6
2	69.9	70.1	69+0.1＝69.1	69.1+1＝70.1
					3	70.1	69.9	70+0.9＝70.9	70.9-1＝69.9

The integer ambiguity of table 2 signal propagation time is handled

The 2nd row of table is because τ-τ _b=69.1-70.1=-1＜-0.5 is so add 1 operation, revised τ=69.1+1=70.1=τ ₀

Equally, the 3rd row of table is because τ-τ _b=70.9-69.9=1＞0.5 is so subtract 1 operation, revised τ=70.9-1=69.9=τ ₀

Through after the correction of integer ambiguity, the signal propagation time that calculates is identical with actual value.

Step 5 is calculated the actual distance of A-GPS locating terminal to gps satellite;

Gps satellite signal is with light velocity propagation, and therefore, the A-GPS locating terminal to the pseudorange of GPS star is:

P＝Cτ (9)

In sum, although the present invention has been done briefly bright in conjunction with the foregoing description, yet this only is in order to be used for illustrative purposes, the foregoing description is not interpreted as the restriction to scope of the present invention, under the prerequisite that does not break away from spirit of the present invention and the defined scope of accessory claim, those of ordinary skills can make various modifications and replacement.

Claims (3)

1, calculate the method for pseudorange between locating terminal and the satellite in a kind of auxiliary global satellite positioning system (A-GPS), may further comprise the steps:

A, A-GPS server according to the terminal initial position, calculate the supplementary that accessory terminal accelerates to catch satellite-signal after terminal is sent location request, this supplementary is issued the A-GPS locating terminal;

B, A-GPS locating terminal are caught the gps satellite distance measuring signal rapidly according to supplementary and are carried out locator data and measure, and this metrical information is transferred to A-GPS location algorithm module;

C, A-GPS location algorithm module are according to going out pseudorange value between A-GPS locating terminal and the satellite from the location measurement information of receiving terminal with from the satellite navigation message information calculations of other positioning equipment.

2, localization method step C as claimed in claim 1, further comprising the steps of:

D, A-GPS location algorithm module be according to the satellite navigation message information that other positioning equipments provide, and calculates the capture terminal satellite-signal position coordinates of satellite constantly, and according to the initial position coordinate of terminal, calculate the pseudorange of satellite to the terminal initial position;

E, A-GPS location algorithm module calculate the range difference of terminal physical location with respect to initial position according to the metrical information that the A-GPS locating terminal provides;

F, A-GPS location algorithm module according to the satellite that calculates to the pseudorange of terminal initial position and terminal physical location with respect to the range difference of initial position, calculate the pseudorange that satellite arrives the terminal physical location.

3, localization method as claimed in claim 1 or 2 is characterized in that: as long as adopt the positioning system similar to the GPS principle of work to use, for example: the Galileo system in GLONASS system, Europe and Chinese dipper system etc.

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