CN103645485A - Pseudorange differential method based on dual-satellite time difference and frequency difference passive positioning - Google Patents

Abstract

The invention provides a pseudorange differential method based on dual-satellite time difference and frequency difference passive positioning. According to the method, the pseudorange difference between two satellites and a reference station is measured successively, the pseudorange correction of the satellites is calculated, the pseudorange difference of an unknown radiation source is corrected through the pseudorange correction to obtain an arrival time difference which is close to the true value, the arrival frequency difference between the reference station and the two satellites is measured, the arrival frequency difference between the reference station and the two satellite which is close to the true value is calculated, the arrival frequency difference between the unknown radiation source and the two satellites is corrected through the frequency correction of the satellites to obtain an arrival frequency difference which is close to the true value, and the high-accuracy positioning of the unknown radiation source is realized through an earth ellipsoid equation and the arrival time difference and the arrival frequency difference which are close to the true value. According to the invention, system positioning errors can be corrected, so that the accuracy of a dual-satellite passive positioning system can be improved.

Description

A kind of pseudo range difference method based on the frequency difference passive location of the double star time difference

Technical field

The invention belongs to the technical field of passive location, be particularly applied in the Correction of Errors technology of double star passive location, pseudo range difference method.

Background technology

GPS pseudo range difference is current widely used a kind of technology, its ultimate principle is that the receiver of base station records it to the distance of satellite, because the existence of ephemeris error and star clock error, the pseudorange of measuring is also not equal to the pseudorange obtaining according to ephemeris computation, think the measured value that contains error, using the pseudorange obtaining according to ephemeris computation as true value, true pseudorange is compared with the measured value that contains error, utilize a wave filter by this differential filtering and obtain pseudorange correction, then by the pseudorange correction broadcast of all satellites in view to user, user utilizes this correction to correct corresponding pseudo range observed quantity.Finally, user utilizes the pseudorange after correction to solve the position coordinates of self, with regard to cancellation base station and user's common error, has reached the object that improves positioning precision.Double star passive location system is that to take two satellites be platform, adopt to arrive mistiming and the poor co-located technology of arrival rate, by measuring radiation source radiation signal, arrive that time of arrival between 2 observation platforms is poor and arrival rate is poor and earth ellipsoid equation is determined the position of radiation source.Therefore measuring error and the earth ellipsoid error in equation of its positioning precision and TDOA, FDOA are relevant.At present, it is international and domestic that mainly to concentrate on the research that the positioning calculation of measurement equation is improved one's methods more, and positioning precision can only reach 10～20km, if do not adopt the Correction of Errors method of science to be corrected various positioning errors, be just difficult to realize the hi-Fix to radiation source.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides a kind of pseudo range difference method based on the frequency difference passive location of the double star time difference, can improve the positioning precision of double star passive location.

The technical solution adopted for the present invention to solve the technical problems comprises the following steps:

1) two satellites of measurement are poor to the pseudorange of reference station

${\mathrm{\ρ}}_0^{s2}-{\mathrm{\ρ}}_0^{s1}=r_0^{s2}-r_0^{s1}+\mathrm{\Δ}{\mathrm{\ρ}}_0^s+\mathrm{\Δ}{\mathrm{\ρ}}_0---\left(1\right)$

In formula be respectively two satellites to the pseudorange of reference station,

be respectively two satellites to the geometric distance of reference station, can obtain according to the position at known reference station and satellite broadcasting ephemeris computation, that is:

$r_0^{s2}=\sqrt{{(x_{s2}-x_0)}^2+{(y_{s2}-y_0)}^2+{(z_{s2}-z_0)}^2}---\left(2\right)$

$r_0^{s1}=\sqrt{{(x_{s1}-x_0)}^2+{(y_{s1}-y_0)}^2+{(z_{s1}-z_0)}^2}---\left(3\right)$

(x in formula ₀, y ₀, z ₀) be the coordinate of reference station, (x _si, y _si, z _si), i=1,2 is positions of two satellites,

represent the range error relevant with satellite position with ground reference station location, Δ ρ ₀represent the range error relevant with receiver;

2) calculate the pseudorange correction of satellite:

$\mathrm{\Δ\ρ}=(r_0^{s1}-r_0^{s2})-({\mathrm{\ρ}}_0^{s1}-{\mathrm{\ρ}}_0^{s2})---\left(4\right)$

3) utilize pseudorange correction Δ ρ to correct the pseudorange of unknown radiation source poor, obtain approaching poor Δ t' time of arrival of true value:

${\mathrm{c\Δt}}^{\′}={\mathrm{\ρ}}^{s2}-{\mathrm{\ρ}}^{s1}+\mathrm{\Δ\ρ}=\sqrt{{(x_{s1}-x)}^2+{(y_{s1}-y)}^2+{(z_{s1}-z)}^2}-\sqrt{{(x_{s2}-x)}^2+{(y_{s2}-y)}^2+{(z_{s2}-z)}^2}---\left(5\right)$

In formula, (x, y, z) represents the position of unknown radiation source, and c is the light velocity;

4) arrival rate of witness mark station to two satellite is poor is Δ f _r;

5) the poor Δ f of the arrival rate that approaches true value of computing reference station to two satellite ₀,

$\frac{{\mathrm{c\Δf}}_0}{f_0}=\frac{x_{s2}-x_0}{r_2}{v}_{x2}+\frac{y_{s2}-y_0}{r_2}{v}_{y2}+\frac{z_{s2}-z_0}{r_2}{v}_{z2}-\frac{x_{s1}-x_0}{r_1}{v}_{x1}-\frac{y_{s1}-y_0}{r_1}{v}_{y1}-\frac{z_{s1}-z_0}{r_1}{v}_{z1}---\left(6\right)$

(v in formula _xi, v _yi, v _zi), i=1, the 2nd, the speed of satellite;

6) calculate the frequency correction number of satellite:

ΔF＝Δf ₀-Δf _r （7）

7) arrival rate of unknown radiation source to two satellite is poor is Δ f, and utilizing frequency correction to count Δ F, to correct the arrival rate of unknown radiation source poor, obtains approaching the poor Δ f' of arrival rate of true value:

$\frac{{\mathrm{c\Δf}}^{\′}}{f_0}=\frac{c(\mathrm{\Δf}+\mathrm{\ΔF})}{f_0}=\frac{x_{s2}-x}{r_2}{v}_{x2}+\frac{y_{s2}-y}{r_2}{v}_{y2}+\frac{z_{s2}-z}{r_2}{v}_{z2}-\frac{x_{s1}-x}{r_1}{v}_{x1}-\frac{y_{s1}-y}{r_1}{v}_{y1}-\frac{z_{s1}-z}{r_1}{v}_{z1}---\left(8\right)$

8) utilize earth ellipsoid equation:

$\frac{x^2}{a^2}+\frac{y^2}{a^2}+\frac{z^2}{b^2}=1---\left(9\right)$

In formula, a is earth semi-major axis, and b is earth semi-minor axis;

9) by formula (5), (8) and (9), resolve the position of unknown radiation source, and then realize hi-Fix.

The invention has the beneficial effects as follows: by utilizing the known radiation source of location aware, utilize the pseudo range difference method of GPS to correct the positioning error of unknown radiation source, improved the positioning precision of double star passive location system, and precision can be better than 5km.

Embodiment

Below in conjunction with embodiment, the present invention is further described, the present invention includes but be not limited only to following embodiment.

Difference measurements precision time of arrival that the present embodiment adopts is 30ns, and arrival rate difference measurements precision is 10Hz, and between star, distance accuracy is 0.3m, and between star, Relative position determination precision is 1m, and satellite orbit is low orbit satellite data, and satellite altitude is 800km.In this embodiment with the carrier frequency f of reference station ₀=10GHz, the initial coordinate of unknown radiation source is that [100 35 0] are example, on this basis unknown radiation source is chosen at random, and reference station coordinates is [105 35 0], and the pseudo range difference method based on the frequency difference passive location of the double star time difference specifically comprises the following steps:

1, instrumented satellite 1 and satellite 2 are poor to the pseudorange of reference station

rice, wherein

${\mathrm{\ρ}}_0^{s2}-{\mathrm{\ρ}}_0^{s1}=r_0^{s2}-r_0^{s1}+\mathrm{\Δ}{\mathrm{\ρ}}_0^s+\mathrm{\Δ}{\mathrm{\ρ}}_0---\left(1\right)$

In formula

be respectively satellite 1 and satellite 2 to the pseudorange of reference station,

be respectively satellite 1 and satellite 2 to the geometric distance of reference station, can obtain according to the position at known reference station and satellite broadcasting ephemeris computation, that is:

$r_0^{s2}=\sqrt{{(x_{s2}-x_0)}^2+{(y_{s2}-y_0)}^2+{(z_{s2}-z_0)}^2}---\left(2\right)$

$r_0^{s1}=\sqrt{{(x_{s1}-x_0)}^2+{(y_{s1}-y_0)}^2+{(z_{s1}-z_0)}^2}---\left(3\right)$

(x in formula ₀, y ₀, z ₀) be the coordinate of reference station, (x _si, y _si, z _si), i=1, the 2nd, satellite position,

represent the range error relevant with satellite position with ground reference station location, Δ ρ ₀represent the range error relevant with receiver;

2, calculate the pseudorange correction of satellite, wherein

therefore:

$\mathrm{\Δ\ρ}=(r_0^{s1}-r_0^{s2})-({\mathrm{\ρ}}_0^{s1}-{\mathrm{\ρ}}_0^{s2})=9m$

3, utilize pseudorange correction Δ ρ to correct the pseudorange of unknown radiation source poor, obtain approaching poor Δ t' time of arrival of true value:

$\begin{array}{c}{\mathrm{c\Δt}}^{\′}=\sqrt{{(x_{s1}-x)}^2+{(y_{s1}-y)}^2+{(z_{s1}-z)}^2}-\sqrt{{(x_{s2}-x)}^2+{(y_{s2}-y)}^2+{(z_{s2}-z)}^2}\\ ={\mathrm{\ρ}}^{s2}-{\mathrm{\ρ}}^{s1}+\mathrm{\Δ\ρ}=18.839\×{10}^3+7=18.846\×{10}^3\end{array}---\left(5\right)$

In formula, (x, y, z) represents the position of unknown radiation source;

4, witness mark station is poor to the arrival rate of satellite 1 and satellite 2 is Δ f _r=1.884 * 10 ³hz;

5, computing reference station is to the poor Δ f of the arrival rate that approaches true value of satellite 1 and satellite 2 ₀=1.886 * 10 ³hz,

$\frac{{\mathrm{c\Δf}}_0}{f_0}=\frac{x_{s2}-x_0}{r_2}{v}_{x2}+\frac{y_{s2}-y_0}{r_2}{v}_{y2}+\frac{z_{s2}-z_0}{r_2}{v}_{z2}-\frac{x_{s1}-x_0}{r_1}{v}_{x1}-\frac{y_{s1}-y_0}{r_1}{v}_{y1}-\frac{z_{s1}-z_0}{r_1}{v}_{z1}---\left(6\right)$

(v in formula _xi, v _yi, v _zi), i=1, the 2nd, the speed of satellite;

6, calculate the frequency correction number of satellite:

ΔF＝Δf ₀-Δf _r＝2Hz

7, unknown radiation source is poor to the arrival rate of satellite 1 and satellite 2 is Δ f, and utilizing frequency correction to count Δ F, to correct the arrival rate of unknown radiation source poor, obtains approaching the poor Δ f' of arrival rate of true value:

$\begin{array}{c}\frac{{\mathrm{c\Δf}}^{\′}}{f_0}=\frac{x_{s2}-x}{r_2}{v}_{x2}+\frac{y_{s2}-y}{r_2}{v}_{y2}+\frac{z_{s2}-z}{r_2}{v}_{z2}-\frac{x_{s1}-x}{r_1}{v}_{x1}-\frac{y_{s1}-y}{r_1}{v}_{y1}-\frac{z_{s1}-z}{r_1}{v}_{z1}\\ =\frac{c(\mathrm{\Δf}+\mathrm{\ΔF})}{f_0}=\frac{c(5.388\×{10}^3+2)}{f_0}=161.7\end{array}---\left(8\right)$

8, utilize earth ellipsoid equation:

$\frac{x^2}{a^2}+\frac{y^2}{a^2}+\frac{z^2}{b^2}=1---\left(9\right)$

In formula, a is earth semi-major axis, and b is earth semi-minor axis;

9, by formula (5), (8) and (9), resolving the solution of unknown radiation source after difference is

U_A=[5947320.5,2092654.4,961549.4], and the solution of unknown radiation source is U_B=[5946669.3 before difference, 2092401.4,966086.1], the initial solution of emulation is U_O=[5948414.5,2089750.9,961099.3], the positioning precision before difference is | U_B-U_O|=5.91 * 10 ³m, differentiated positioning precision is | U_A-U_O|=3.14 * 10 ³m, therefore differentiated positioning precision is better than 5km.

As can be seen from the above embodiments, when unknown radiation source is positioned, to observed quantity difference time of arrival and the poor pseudo range difference method of utilizing of arrival rate, can eliminate some public errors, make positioning precision bring up to and be better than 5km by 10 current～20km, improved the positioning precision of passive location.

Claims (1)

1. the pseudo range difference method based on the frequency difference passive location of the double star time difference, is characterized in that comprising the steps:

1) two satellites of measurement are poor to the pseudorange of reference station

In formula

be respectively two satellites to the pseudorange of reference station,

be respectively two satellites to the geometric distance of reference station, can obtain according to the position at known reference station and satellite broadcasting ephemeris computation, that is:

(x in formula ₀, y ₀, z ₀) be the coordinate of reference station, (x _si, y _si, z _si), i=1,2 is positions of two satellites,

represent the range error relevant with satellite position with ground reference station location, Δ ρ ₀represent the range error relevant with receiver;

2) calculate the pseudorange correction of satellite:

3) utilize pseudorange correction Δ ρ to correct the pseudorange of unknown radiation source poor, obtain approaching poor Δ t' time of arrival of true value:

In formula, (x, y, z) represents the position of unknown radiation source, and c is the light velocity;

4) arrival rate of witness mark station to two satellite is poor is Δ f _r;

5) the poor Δ f of the arrival rate that approaches true value of computing reference station to two satellite ₀,

(v in formula _xi, v _yi, v _zi), i=1, the 2nd, the speed of satellite;

6) calculate the frequency correction number of satellite:

ΔF＝Δf ₀-Δf _r （7）

7) arrival rate of unknown radiation source to two satellite is poor is Δ f, and utilizing frequency correction to count Δ F, to correct the arrival rate of unknown radiation source poor, obtains approaching the poor Δ f' of arrival rate of true value:

8) utilize earth ellipsoid equation:

in formula, a is earth semi-major axis, and b is earth semi-minor axis;

9) by formula (5), (8) and (9), resolve the position of unknown radiation source, and then realize hi-Fix.