CN105572710A - Method for improving positioning precision of second-generation Beidou civil double-frequency positioning receiver - Google Patents

Abstract

The invention provides a method for improving positioning precision of a second-generation Beidou civil double-frequency positioning receiver. The method comprises the steps of: obtaining code phases and carrier phases of B1I and B2I frequency points; calculating current epoch coarse pseudo ranges respectively from the code phases of the double frequency points; according to equivalent range finding errors, assessing noise variances of the double frequency points respectively, then selecting a pseudo range calculation mode, and then calculating a smooth coefficient; according to the pseudo range calculation mode, calculating a current epoch coarse pseudo range linear combined value from the current epoch coarse pseudo ranges of the double frequency points and carrying out ionosphere compensation on the current epoch coarse pseudo range linear combined value, and obtaining a current epoch ionosphere post-compensation pseudo range; calculating a current epoch carrier phase linear combined value from the carrier phases of the double frequency points; calculating a current epoch pseudo range increment from the current epoch carrier phase linear combined value and a last epoch carrier phase linear combined value; calculating a current epoch smooth pseudo range from the current epoch ionosphere post-compensation pseudo range, the current epoch pseudo range increment and the smooth coefficient; and using the current epoch smooth pseudo range to construct a measurement equation, and solving the position of the receiver.

Description

Improve the method for the positioning precision of the civilian double frequency location receiver of Beidou II

Technical field

The present invention relates to Beidou satellite navigation system technical field, be specifically related to a kind of method improving the positioning precision of the civilian double frequency location receiver of Beidou II.

Background technology

Satellite navigation system has become world today's country's overall national strength and the important symbol of scientific technological advance level, and be the important component part on national economy basis, it has entered in daily life, with social development and economic construction closely bound up.China has also dropped into a large amount of funds and manpower, actively carries out the research of Beidou satellite navigation system (BeiDouNavigationSatelliteSystem, BDS).To about the year two thousand twenty, China will build up Beidou satellite navigation system covering the whole world, and it will become another the global round-the-clock satellite navigation system after GPS of America, Russian GLONASS and European Galileo.

Beidou satellite navigation system independently can carry out hi-Fix, avoids the dependence to external positioning system, and this is of great immediate significance to the economic development of China.At present, civilian Big Dipper location adopts B1I single-frequency positioning.But single-frequency measurement and positioning cannot the time delay of Measurement accuracy ionosphere, and measured value also easily fluctuates.In November, 2013, " the formal version 2.0 of dipper system spacing wave interface control document " is issued in China Satecom's navigational system management office.The related content of document definition open service signal B1I and B2I between Beidou satellite navigation system space constellation and user terminal, for civilian double frequency satnav brings opportunity.And the problem of conventional B1I and B2I double frequency localization method ubiquity two aspect: on the one hand, just simply eliminate ionosphere time delay, the measured value of two frequency bins is not combined; On the other hand, in actual environment, owing to affecting by factors such as multipath delay, satellite failure and signal block, receiver may not necessarily receive signal quality good B1I and B2I dual-frequency point signal simultaneously.The problem of these two aspects has had a strong impact on the positioning precision of existing civilian double frequency location receiver.

Summary of the invention

Fundamental purpose of the present invention is to propose a kind of method improving the positioning precision of the civilian double frequency location receiver of Beidou II, the method is while compensation ionosphere time delay, the code phase measuring value of two frequency bins and carrier-phase measurement are combined, improve the reliability of pseudorange after revising; And, pseudorange pattern is selected according to noise variance, further selection B1I single-frequency positioning, B2I single-frequency positioning and double frequency are located, to ensure to utilize measured value as much as possible under reliable prerequisite, thus overcome the technical matters that two of existing in above-mentioned prior art affect positioning precision, make the positioning precision of Beidou II civilian double frequency location receiver be able to larger raising.

The present invention is as follows for solving the problems of the technologies described above proposed technical scheme:

Improve the method for the positioning precision of the civilian double frequency location receiver of Beidou II, comprise the following steps:

The code phase of B1I and the B2I frequency that S1, Real-time Obtaining tracking module export with and carrier phase with

S2, by code phase with calculate the thick pseudorange of current epoch of B1I and B2I frequency respectively with

S3, equivalent range error according to equipment thermonoise, assess the noise variance of B1I and B2I frequency respectively with

S4, according to the noise variance in step S3 with choose its computation of pseudoranges pattern PRMode; Again according to its computation of pseudoranges pattern PRMode, by noise variance with calculate smoothing factor M;

S5, according to its computation of pseudoranges pattern PRMode, by the thick pseudorange of the current epoch in step S2 with calculate current epoch thick pseudorange linear combination value

S6, according to its computation of pseudoranges pattern PRMode, to current epoch thick pseudorange linear combination value carry out ionosphere compensation, obtain current epoch ionosphere and compensate rear pseudorange

S7, by the carrier phase obtained in step S1 with calculate current epoch carrier phase linear combination value

S8, by current epoch carrier phase linear combination value with carrier phase linear combination epoch last time value calculate current epoch pseudorange increment

S9, by current epoch ionosphere compensate after pseudorange current epoch pseudorange increment epoch last time smoothing pseudo range with smoothing factor M, calculate current epoch smoothing pseudo range

S10, use current epoch smoothing pseudo range structure measures equation, resolves the positioning result of receiver.

Compared with prior art, technique scheme provided by the invention at least has following beneficial effect:

1) to the code phase under dual-frequency point B1I and B2I with the thick pseudorange of the current epoch calculated with carry out linear combination, simultaneously also to the carrier phase under dual-frequency point with carry out linear combination, improve the reliability of thick pseudorange and carrier phase, and then improve and finally locate pseudorange, make to utilize pseudorange to resolve the measurement equation of positioning result more stable and accurately, finally improve stability and the precision of receiver positioning result;

2) under dual-frequency point B1I and B2I, to the thick pseudorange of current epoch with current epoch thick pseudorange linear combination value carry out the double frequency ionosphere compensation of delay of pattern switching, take full advantage of the pseudorange under varying environment, the continous-stable of pseudorange is ensure that while accurately eliminating ionosphere time delay, and then improve and finally locate pseudorange, make to utilize pseudorange to resolve the measurement equation of positioning result more stable, finally make positioning result more stable;

3) with the smoothing the phase of carrier wave of linear combination ionosphere compensate after pseudorange, after ionosphere is compensated, pseudorange is more accurate, and then improves and finally locate pseudorange, and the final measurement solution of equation utilizing the pseudorange after improving to construct calculates positioning result accurately;

4) with noise variance dynamic conditioning pseudorange smoothing coefficient, avoid fixed value under various circumstances inadaptable, make level and smooth after pseudorange more level and smooth, and then improve and finally locate pseudorange, utilize the pseudorange structure improved to measure the stability that equation finally improves positioning result;

5) according to noise variance, switch pseudorange pattern, single-frequency pseudorange and double frequency pseudorange are combined, ensure efficiency utilization pseudorange at the signal getting rid of noise larger simultaneously, utilize the pseudorange improved to measure equation last solution by structure and calculate high-precision positioning result.

Technique scheme of the present invention has and realizes simple, and calculated amount is little, only adopts addition and without the need to the multiplication of complexity and division arithmetic, and has excellent performance, advantage that reliability is strong.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of the method for the positioning precision of the civilian double frequency location receiver of raising Beidou II that the specific embodiment of the invention provides;

When Fig. 2 is signal intensity-150dBm, pseudorange and level and smooth rear pseudorange variance before level and smooth;

When Fig. 3 is signal intensity-150dBm, double frequency classic method pseudorange and double frequency linear combination pseudorange variance;

When Fig. 4 is signal intensity-150dBm, double frequency conventional mapping methods error and double frequency linear combination positioning error.

Embodiment

Below in conjunction with accompanying drawing with preferred embodiment the invention will be further described.

The specific embodiment of the present invention provides a kind of method improving the positioning precision of the civilian double frequency location receiver of Beidou II, and the systematic parameter adopted in present embodiment is defined as follows shown in table 1:

The civilian dual-frequency point systematic parameter of table 1 Big Dipper

Index	Value
		B1I frequency of operation (MHz)	1561.098MHz
B2I frequency of operation (MHz)	1207.140MHz

With reference to figure 1, this method comprises the following steps S1 ~ S10:

The code phase of B1I and the B2I frequency that S1, Real-time Obtaining tracking module export with and carrier phase with

S2, by code phase with calculate the thick pseudorange of current epoch respectively with

S3, equivalent range error according to equipment thermonoise, assess the noise variance of B1I and B2I frequency respectively with

S4, according to the noise variance in step S3 with choose its computation of pseudoranges pattern PRMode; Again according to its computation of pseudoranges pattern PRMode, by noise variance with calculate smoothing factor M.Wherein, its computation of pseudoranges pattern PRMode can be obtained by following formula:

$PRMode=\left\{\begin{array}{cc}0,& {\mathrm{\σ}}_{B1}^2\≤T_{B1},{\mathrm{\σ}}_{B2}^2\≤T_{B2}\\ 1,& {\mathrm{\σ}}_{B1}^2>T_{B1},{\mathrm{\σ}}_{B2}^2\≤T_{B2}\\ 2,& {\mathrm{\σ}}_{B1}^2\≤T_{B1},{\mathrm{\σ}}_{B2}^2>T_{B2}\\ 2,& {\mathrm{\σ}}_{B1}^2>T_{B1},{\mathrm{\σ}}_{B2}^2>T_{B2}\end{array}\right.$

Wherein, T _b1and T _b2be respectively the noise gate of B1I and B2I frequency.In this specific embodiment, get T _b1=20 and T _b2=25.

Smoothing factor M can be obtained by following formula:

$M=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\σ}}_{B1}^2,& PRMode=1\\ {\mathrm{\σ}}_{B2}^2,& PRMode=2\\ \frac{{\mathrm{\σ}}_{B1}^2-K\·{\mathrm{\σ}}_{B2}^2}{1-K},& PRMode=3\end{array}\right.$

According to the systematic parameter that table 1 provides, get connector f _b1and F _b2be respectively the carrier frequency of B1I and B2I frequency.K in follow-up formula is identical with the K in this step S4.

S5, according to its computation of pseudoranges pattern PRMode, by the thick pseudorange of the current epoch in step S2 with calculate current epoch thick pseudorange linear combination value can calculate by the following method:

${\mathrm{\ρ}}_C^k=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\σ}}_{C\_B1}^k,& PRMode=1\\ {\mathrm{\σ}}_{C\_B2}^k,& PRMode=2\\ \frac{{\mathrm{\σ}}_{C\_B2}^k-K\·{\mathrm{\σ}}_{C\_B1}^k}{1-K},& PRMode=3\end{array}\right.$

S6, according to its computation of pseudoranges pattern PRMode, to current epoch thick pseudorange linear combination value carry out ionosphere compensation, obtain current epoch ionosphere and compensate rear pseudorange pseudorange after can being compensated by following formulae discovery current epoch ionosphere

${\mathrm{\σ}}_I^k=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\σ}}_{C\_B1}^k+I_{I\_B1}^k,& PRMode=1\\ {\mathrm{\σ}}_{C\_B2}^k+K\·I_{I\_B1}^k,& PRMode=2\\ {\mathrm{\σ}}_C^k-\frac{C\·(T_{GD\_B2}-K\·T_{GD\_B1})}{1-K},& PRMode=3\end{array}\right.$

Wherein, C is the light velocity, gets C=2.99792458 × 10 ⁸m/s; T _{gD_B1}and T _{gD_B2}be respectively the on-board equipment delay inequality of B1I and B2I frequency; with be respectively the thick pseudorange of current epoch of B1I and the B2I frequency in step S2; for utilize epoch last time receiver location and the B1I signal propagation path that calculates of Klobuchar model on ionosphere time delay.

S7, by the carrier phase obtained in step S1 with calculate current epoch carrier phase linear combination value current epoch carrier phase linear combination value can be calculated by following formula:

S8, by current epoch carrier phase linear combination value with carrier phase linear combination epoch last time value calculate current epoch pseudorange increment wherein C is the light velocity.

S9, by current epoch ionosphere compensate after pseudorange current epoch pseudorange increment epoch last time smoothing pseudo range with smoothing factor M, calculate current epoch smoothing pseudo range ${\mathrm{\ρ}}_S^k=\frac{1}{M}\·{\mathrm{\ρ}}_I^k+\frac{(M-1)}{M}\·({\mathrm{\ρ}}_S^{k-1}+{\mathrm{\ρ}}_D^k)$

S10, use current epoch smoothing pseudo range structure measures equation, resolves the positioning result of receiver.

Positioning performance when the preceding method modeling and simulating that provides by specific embodiment of the invention satellite-signal intensity is-150dBm.As can be seen from Figure 2, the pseudorange after carrier smoothing obviously fluctuates reduction, and it acts on important in location.Employ method of the present invention as can be seen from Figure 3 obvious relative to the smoothing effect of classic method to pseudorange.As can be seen from Figure 4 the final positioning precision of method of the present invention is adopted to improve about 10m.More than prove, the method putting forward the positioning precision of Beidou II civilian double frequency location receiver provided by the invention has larger help to raising positioning precision under weak signal.And the present invention has and realizes simple, calculated amount is little, only adopts addition and without the need to the multiplication of complexity and division arithmetic, and excellent performance, advantage that reliability is strong.

Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For those skilled in the art, without departing from the inventive concept of the premise, some equivalent to substitute or obvious modification can also be made, and performance or purposes identical, all should be considered as belonging to protection scope of the present invention.

Claims (8)

1. improve the method for the positioning precision of the civilian double frequency location receiver of Beidou II, it is characterized in that: comprise the following steps:

The code phase of B1I and the B2I frequency that S1, Real-time Obtaining tracking module export with and carrier phase with

S2, by code phase with calculate the thick pseudorange of current epoch of B1I and B2I frequency respectively with

S3, equivalent range error according to equipment thermonoise, assess the noise variance of B1I and B2I frequency respectively with

S4, according to the noise variance in step S3 with choose its computation of pseudoranges pattern PRMode; Again according to its computation of pseudoranges pattern PRMode, by noise variance with calculate smoothing factor M;

S5, according to its computation of pseudoranges pattern PRMode, by the thick pseudorange of the current epoch in step S2 with calculate current epoch thick pseudorange linear combination value

S6, according to its computation of pseudoranges pattern PRMode, to current epoch thick pseudorange linear combination value carry out ionosphere compensation, obtain current epoch ionosphere and compensate rear pseudorange

S7, by the carrier phase obtained in step S1 with calculate current epoch carrier phase linear combination value

S8, by current epoch carrier phase linear combination value with carrier phase linear combination epoch last time value calculate current epoch pseudorange increment

S9, by current epoch ionosphere compensate after pseudorange current epoch pseudorange increment epoch last time smoothing pseudo range with smoothing factor M, calculate current epoch smoothing pseudo range

S10, use current epoch smoothing pseudo range structure measures equation, resolves the positioning result of receiver.

2. the method for claim 1, is characterized in that: in step S4, the choosing method of its computation of pseudoranges pattern PRMode is as follows:

$PRMode=\left\{\begin{array}{cc}0,& {\mathrm{\σ}}_{B1}^2\≤T_{B1},{\mathrm{\σ}}_{B2}^2\≤T_{B2}\\ 1,& {\mathrm{\σ}}_{B1}^2>T_{B1},{\mathrm{\σ}}_{B2}^2\≤T_{B2}\\ 2,& {\mathrm{\σ}}_{B1}^2\≤T_{B1},{\mathrm{\σ}}_{B2}^2>T_{B2}\\ 3,& {\mathrm{\σ}}_{B1}^2>T_{B1},{\mathrm{\σ}}_{B2}^2>T_{B2}\end{array}\right.$

Wherein, T _b1and T _b2be respectively the noise gate of B1I and B2I frequency.

3. the method for claim 1, is characterized in that: in step S4, the computing method of smoothing factor M are as follows:

$M=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\σ}}_{B1}^2,& PRMode=1\\ {\mathrm{\σ}}_{B2}^2,& PRMode=2\\ \frac{{\mathrm{\σ}}_{B1}^2-K\·{\mathrm{\σ}}_{B2}^2}{1-K},& PRMode=3\end{array}\right.$

Wherein, connector f _b1and F _b2be respectively the carrier frequency of B1I and B2I frequency.

4. the method for claim 1, is characterized in that: calculate current epoch thick pseudorange linear combination value in step S5 method as follows:

${\mathrm{\ρ}}_C^k=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\ρ}}_{C\_B1}^k,& PRMode=1\\ {\mathrm{\ρ}}_{C\_B2}^K,& PRMode=2\\ \frac{{\mathrm{\ρ}}_{C\_B2}^K-K\·{\mathrm{\ρ}}_{C\_B1}^k}{1-K},& PRMode=3\end{array}\right.$

Wherein, connector f _b1and F _b2be respectively the carrier frequency of B1I and B2I frequency.

5. the method for claim 1, is characterized in that: calculate current epoch ionosphere in step S6 and compensate rear pseudorange method as follows:

${\mathrm{\ρ}}_I^k=\left\{\begin{array}{cc}Null,& PRMode=0\\ {\mathrm{\ρ}}_{C\_B1}^k+I_{I\_B1}^k,& PRMode=1\\ {\mathrm{\ρ}}_{C\_B2}^k+K\·I_{I\_B1}^k,& PRMode=2\\ {\mathrm{\ρ}}_C^k-\frac{C\·(T_{GD\_B2}-K\·T_{GD\_B1})}{1-K},& PRMode=3\end{array}\right.$

Wherein, C is the light velocity; Connector f _b1and F _b2be respectively the carrier frequency of B1I and B2I frequency; T _{gD_B1}and T _{gD_B2}be respectively the on-board equipment delay inequality of B1I and B2I frequency; with be respectively the thick pseudorange of current epoch of B1I and the B2I frequency in step S2; for utilize epoch last time receiver location and the B1I signal propagation path that calculates of Klobuchar model on ionosphere time delay.

6. the method for claim 1, is characterized in that: in step S7, calculates current epoch carrier phase linear combination value method as follows:

Wherein, connector f _b1and F _b2be respectively the carrier frequency of B1I and B2I frequency.

7. the method for claim 1, is characterized in that: calculate current epoch pseudorange increment in step S8 concrete grammar be: wherein C is the light velocity.

8. the method for claim 1, is characterized in that: calculate current epoch smoothing pseudo range in step S9 concrete grammar as follows: ${\mathrm{\ρ}}_S^k=\frac{1}{M}\·{\mathrm{\ρ}}_I^k+\frac{(M-1)}{M}\·({\mathrm{\ρ}}_S^{k-1}+{\mathrm{\ρ}}_D^k).$