CN102830410B - Positioning method in combination with Doppler velocity measurement in satellite navigation - Google Patents

Abstract

The invention discloses a positioning method in combination with Doppler velocity measurement in satellite navigation, and relates to the satellite navigation positioning technology. The positioning method comprises: (a) at least two navigational satellites respectively downlink modulate a path of navigation signal; (b) a user terminal receives the path of downlink navigation signal of each navigational satellite and respectively measures the pseudo range of each navigational satellite; (c) at the same time, the user terminal measures Doppler velocity relative to each navigational satellite; and (d) the user terminal realizes navigational positioning by utilizing the observation pseudo range of each navigational satellite and Doppler velocity measurement information obtained in (b) and (c). According to the method, by combination of the Doppler velocity measurement information, the requirement that the quantity of satellites in a satellite navigation system is not less than 4 is reduced, and higher-precision navigational positioning can be realized.

Description

In satellite navigation in conjunction with the localization method of Doppler range rate measurement

Technical field

The present invention relates to satellite navigation positioning technical field, is the localization method in conjunction with Doppler range rate measurement in a kind of satellite navigation, is particularly useful for the little satellite navigation system of number of satellite, has improved the navigator fix performance of system.

Background technology

Under normal circumstances, in satellite navigation and location system, user terminal need to be observed 4 (containing) above satellites simultaneously, could realize three-dimensional localization and clock correction solves.For the less satellite navigation system of number of satellite, if utilize little satellite can realize Position-Solving, can shorten the establishment cycle of system, significantly reduce the cost of establishment system.

Doppler range rate measurement can provide more metrical information for user terminal, in conjunction with the result that tests the speed, can reduce satellite navigation system Navsat is counted to quantitative limitation.

Summary of the invention

The object of the invention is the localization method in conjunction with Doppler range rate measurement in openly a kind of satellite navigation, to improve user's positioning precision, when, number of satellite not good in satellite constellation layout is less, in conjunction with the Doppler range rate measurement of satellite, determine the position of user terminal.

In order to achieve the above object, technical solution of the present invention is:

In satellite navigation, in conjunction with a localization method for Doppler range rate measurement, it comprises step:

A) at least 2 Navsats, respectively Corticofugal Modulation of Somatosensory one road navigation signal;

B) user terminal receives every the descending Yi of Navsat road navigation signal, measures respectively the pseudorange of every Navsat;

C) simultaneously, user terminal measurement is with respect to the doppler velocity of every Navsat;

D) user terminal utilize b), c) observation pseudorange and the Doppler range rate measurement information of every Navsat of step gained, realize navigator fix.

The localization method of described combination Doppler range rate measurement, described in it a) in navigation signal, comprise ranging code and the numeric data code of carrier wave.

The localization method of described combination Doppler range rate measurement, realizes user terminal navigator fix in d) described in it, is to following system of equations:

$v_k^j=l_k^j\mathrm{\δ}{X}_k+m_k^j\mathrm{\δ}{Y}_k+n_k^j{\mathrm{\δZ}}_k-b_k-L_k^j$

$e_u\·e_j=\frac{v_{\mathrm{rel}}}{v_j}$

Utilize least square method to solve unknown parameter vector Δ X, wherein Δ X=[δ X _kδ Y _kδ Z _kb _k] ^t, obtain user coordinates coordinate through iteration repeatedly, more further rectangular space coordinate be converted to the earth longitude and latitude and the geodetic height of user terminal;

Wherein, for the constant term of observational error equation, e _uwith e _jfor unit vector, v _relfor actual measurement speed, v _jfor satellite velocities.

The localization method of described combination Doppler range rate measurement, described in it, the fixed point coordinate of user terminal, is constrained on satellite S _jfor summit, pseudorange on cone face for bus.

The localization method of described combination Doppler range rate measurement, user terminal described in it, is fixed terminal or mobile terminal.

The localization method of described combination Doppler range rate measurement, fixed terminal described in it, is fixed satellite receiving equipment; Mobile terminal is vehicle-mounted, boat-carrying or hand-held receiving equipment.

Method of the present invention is particularly suitable for the satellite navigation system that Doppler range rate measurement precision is very high, when, number of satellite not good in satellite constellation layout is less, can be good at improving the positioning precision of user terminal.

Brief description of the drawings

Fig. 1 is in conjunction with the definite setting circle conical surface schematic diagram of Doppler range rate measurement in the localization method of Doppler range rate measurement in satellite navigation of the present invention.

Embodiment

In satellite navigation of the present invention, relate to Navsat and user terminal in conjunction with the localization method of Doppler range rate measurement.

Navsat: the descending road navigation carrier wave of satellite of satellite navigation system inside, on carrier wave, modulate ranging code and numeric data code.

User terminal: the navigation signal that demodulation of satellite is descending, realize pseudo range measurement and the Doppler range rate measurement of satellite to user terminal.Be described below:

Pseudorange observation equation: demodulation of satellite S _j(j=1,2 ..., n) descending navigation signal, realizes the pseudo range measurement of satellite to user terminal.At t _kin the moment, user's observation obtains satellite S _jpseudorange (j=1,2 ..., n), can obtain pseudorange observation equation:

${\mathrm{\ρ}}_k^j=[{(X^j-X_k)}^2+{(Y^j-Y_k)}^2+{(Z^j-Z_k)}^2{]}^{1/2}+b_k-{\mathrm{c\δt}}^j---\left(1\right)$

$(j=\mathrm{1,2},\·\·\·,n)$

In formula, for observing the pseudorange obtaining; (X _k, Y _k, Z _k) be that user terminal is being measured moment t _kcoordinate; (X ^j, Y ^j, Z ^j) be satellite S _jcoordinate in the time of transmitting navigation signal; b _kfor receiver clock correction equivalent distances; δ t ^jfor satellite clock clock error correction, can in auto-navigation text, try to achieve; C is the light velocity in vacuum.

Consider ionosphere delay tropospheric delay with observation stochastic error there is observational error equation:

${\mathrm{\ρ}}_k^j={[{(X^j-X_k)}^2+{(Y^j-Y_k)}^2+{(Z^j-Z_k)}^2]}^{1/2}$

(2)

$b_k-{\mathrm{c\δt}}^j+{\mathrm{\δ\ρ}}_{k_n}^j+{\mathrm{\δ\ρ}}_{k_P}^j+v_k^j$

In positioning calculation, according to the rough coordinates of user terminal utilize following formula:

$\left\{\begin{array}{c}{X}_k={X_k}^0+{\mathrm{\δX}}_k\\ Y_k={Y_k}^0+{\mathrm{\δY}}_k\\ Z_k={Z_k}^0+{\mathrm{\δZ}}_k\end{array}\right.---\left(3\right)$

(2) formula is carried out to 1 rank Taylor series expansion, obtains its linearization form:

$v_k^j=l_k^j{\mathrm{\δX}}_k+m_k^j{\mathrm{\δY}}_k+n_k^j{\mathrm{\δZ}}_k$

(4)

$-b_k+{\mathrm{\ρ}}_k^j-{\tilde{R}}_k^j+{\mathrm{c\δt}}^j-{\mathrm{\δ\ρ}}_{k_n}^j-{\mathrm{\δ\ρ}}_{k_P}^j$

In formula, for rough coordinates is to satellite S _jdirection cosine:

$l_k^j=\frac{X^j-{X_k}^0}{{\tilde{R}}_k^j},m_k^j=\frac{Y^j-{Y_k}^0}{{\tilde{R}}_k^j},n_k^j=\frac{Z^j-{Z_k}^0}{{\tilde{R}}_k^j}---\left(5\right)$

for rough coordinates is to the distance of satellite Sj:

${\tilde{R}}_k^j={[{(X^j-{X_k}^0)}^2+{(Y^j-Y_k^0)}^2+{(Z^j-{Z_k}^0)}^2]}^{1/2}---\left(6\right)$

Can calculate satellite S by navigation message _jin coordinate and the clock correction of signal x time, can calculate ionosphere and troposphere time delay by correlation formula.

Calculate according to rough coordinates with and the known terms in observation equation (4) is used represent, have:

$v_k^j=l_k^j\mathrm{\δ}{X}_k+m_k^j{\mathrm{\δY}}_k+n_k^j{\mathrm{\δZ}}_k-b_k-L_k^j---\left(7\right)$

In formula, for:

$L_k^j={\tilde{R}}_k^j-{\mathrm{\ρ}}_k^{j,i}-{\mathrm{c\δt}}^j+{\mathrm{\δ\ρ}}_{k_n}^j+{\mathrm{\δ\ρ}}_{k_p}^j---\left(8\right)$

Write formula (7) as matrix form, had:

V＝AΔX-L (9)

In formula, Δ X is undetermined parameter vector:

ΔX＝[δX _k δY _k δZ _k b _k] ^T (10)

A is the matrix of coefficients of unknown parameter:

$A=\left[\begin{array}{cccc}{l}_k^1& m_k^1& n_k^1& -1\\ l_k^2& m_k^2& n_k^2& -1\\ ...& ...& ...& ...\\ l_k^n& m_k^n& n_k^n& -1\end{array}\right]---\left(11\right)$

L is constant term vector:

$L={\left[\begin{array}{cccc}{L}_k^1& L_k^2& \·\·\·& L_k^n\end{array}\right]}^T---\left(12\right)$

V is correction vector:

$V={\left[\begin{array}{cccc}{v}_k^1& v_k^2& \·\·\·& v_k^n\end{array}\right]}^T---\left(13\right)$

Doppler range rate measurement constraint: at t _kin the moment, user terminal records satellite S _j(j=1,2 ..., n) with respect to the speed v of user terminal _rel, have:

v _rel＝v _j-v _u (14)

In formula, v _uv _jrespectively the speed of user and satellite.Can from navigation message, obtain satellite S _jat the position coordinates (X of signal x time ^j, Y ^j, Z ^j) and speed v _j, the coordinate of user terminal is (X _k, Y _k, Z _k), satellite S _jto the unit vector e of this point _ufor:

$e_u=(\frac{X_k-X^j}{r_u},\frac{Y_k-Y^j}{r_u},\frac{Z_k-Z^j}{r_u})---\left(15\right)$

Here, $r_u=\sqrt{{(X_k-X^j)}^2+{(Y_k-{Y^j}_{})}^2+{(Z_k-Z^j)}^2}.$

Satellite S _jspeed unit vector e _jfor:

$e_j=\frac{v_j}{\left|v_j\right|}=(\frac{v_{\mathrm{jx}}}{r_j},\frac{v_{\mathrm{jy}}}{r_j},\frac{v_{\mathrm{jz}}}{r_j})---\left(16\right)$

Here, $r_j=\sqrt{{v_{\mathrm{jx}}}^2+{v_{\mathrm{jy}}}^2+{v_{\mathrm{jz}}}^2}.$

For stationary user, v _u=0, actual measurement speed v _relsatellite velocities v _jarrive user side's projection components upwards at satellite, if accurately recorded v _rel, user is constrained on satellite S _jfor summit, pseudorange on cone face for bus.As shown in Figure 1.

Unit vector e _uwith e _jangle theta meet:

$e_u\·e_j=\frac{v_{\mathrm{rel}}}{v_j}---\left(17\right)$

Above formula is the satisfied Doppler range rate measurement equation of constraint of user terminal.Formula (7) obtains system of equations with formula (17) simultaneous, utilizes least square method to solve unknown parameter vector X, obtains fixed point coordinate.Further rectangular space coordinate can be converted to the earth longitude and latitude and the geodetic height of user terminal.

For mobile terminal, speed is that the position in the unit interval changes, and utilizes double positioning result can obtain speed initial value, in formula (17), and v _reluse v _rel+ v _ureplace and obtain the satisfied Doppler range rate measurement equation of constraint of mobile terminal.Iterative computation can obtain the coordinate of mobile terminal, and then obtains the earth longitude and latitude and the geodetic height of terminal.

Claims (5)

1. In satellite navigation in conjunction with a localization method for Doppler range rate measurement, it is characterized in that, comprise step:

   A) at least 2 Navsats, respectively Corticofugal Modulation of Somatosensory one road navigation signal;

   B) user terminal receives every the descending Yi of Navsat road navigation signal, measures respectively the pseudorange of every Navsat;

   C) simultaneously, user terminal measurement is with respect to the doppler velocity of every Navsat;

   D) user terminal utilize b), c) observation pseudorange and the Doppler range rate measurement information of every Navsat of step gained, realize navigator fix;

   Wherein, describedly realizing user terminal navigator fix in d), is to following system of equations:

   $v_k^j=l_k^j{\mathrm{\δX}}_k+m_k^j{\mathrm{\δY}}_k+n_k^j{\mathrm{\δZ}}_k-b_k-L_k^j$

   $e_u\·e_j=\frac{v_{\mathrm{rel}}}{v_j}$

   Utilize least square method to solve unknown parameter vector Δ X, wherein Δ X=[δ X _kδ y _kδ Z _kb _k] ^t, obtain user coordinates through iteration repeatedly, more further rectangular space coordinate be converted to the earth longitude and latitude and the geodetic height of user terminal;

   Wherein, for the constant term of observational error equation, e _uwith e _jfor unit vector, v _relfor actual measurement speed, v _jfor satellite velocities, b _kfor receiver clock correction equivalent distances, for observation stochastic error, for rough coordinates is to satellite S _jdirection cosine.
2. 2. the localization method of combination Doppler range rate measurement as claimed in claim 1, is characterized in that, described a) in navigation signal, comprise ranging code and the numeric data code of carrier wave.
3. 3. the localization method of combination Doppler range rate measurement as claimed in claim 1, is characterized in that, the fixed point coordinate of described user terminal, is constrained on satellite S _jfor summit, pseudorange on cone face for bus.
4. 4. the localization method of the combination Doppler range rate measurement as described in claim 1 or 3, is characterized in that, described user terminal is fixed terminal or mobile terminal.
5. 5. the localization method of combination Doppler range rate measurement as claimed in claim 4, is characterized in that, described fixed terminal is fixed satellite receiving equipment; Mobile terminal is vehicle-mounted, boat-carrying or hand-held receiving equipment.