CN102565818A - Method and system for starting navigation system - Google Patents

Abstract

The invention is suitable for the technical field of multi-media data processing and provides a method and system for starting a navigation system. The method comprises the following steps: capturing transmission signals of at least four satellites under control; finding to acquire same bits output by the transmission signals of at least four satellites; performing bit synchronization on the same bits, and computing the relative time T of transmission; computing pseudorange rho from each satellite to a receiver according to the worked-out relative time T of the signal transmission of each satellite; computing user coordinates according to the worked-out pseudorange rho; positioning the position of a user; and controlling the navigation system to be started. In the embodiment of the invention, the bit synchronization is performed on the same bits in the captured transmission signals of the satellites, and the relative time T of the signal transmission of the satellites is computed; the pseudorange rho from each satellite to the receiver is computed; the user coordinates are computed according to the worked-out pseudorange rho; the position of the user is positioned; and the navigation system is controlled to be started, thereby, the starting time is shortened, and meanwhile, the hardware cost does not need to be additionally increased.

Description

A kind of startup method and system of navigational system

Technical field

The invention belongs to field of navigation technology, relate in particular to a kind of startup method and system of navigational system.

Background technology

(G1obal Positioning System GPS) through about 30 years progressively development, has become perfect round-the-clock, the electric location of a high precision wireless time dissemination system towards the whole world to GPS, has won users' trust.GPS is mainly used in military affairs at first, along with the cancellation of selecting availability (SA) policy, has also expanded greatly in the effect of civil area.On performance, the satellite navigation consumer products develops towards directions such as quick location, high sensitivity, high precision, miniaturization, low-power consumption, integrated navigations.The quick station-keeping ability of navigation neceiver is mainly by primary positioning time (Time To First Fix, TTFF) this index decision; Improve this performance of primary positioning time; No matter for civil areas such as vehicle mounted guidance markets, or military field such as guided missile navigation, all particularly important.

Primary positioning time TTFF is divided into cold start-up (Cold start), warm startup (Warm start), warm start (Hot start), and following table is the definition of three kinds of patterns:

Data type	Cold?start	Warm?start	Hot?start
				Previous position	X	√	√
Time	X	√	√
				Almanac	X	√	√
Ephemeris	X	X	√

Wherein, √: expression has X: expression does not have;

Almanac data (Almanac) comprises the orbit information of satellite, can be used for calculating current visible satellite, accelerates acquisition speed.Almanac data transfer cycles 12.5 minutes is so it is consuming time longer to download complete Almanac data;

Almanac data (Ephemeris) comprises the accurate correction to the Almanac data, is necessary when calculating accurate position.The transmission cycle of Ephemeris data is 30 seconds, and be 2 hours general effective time.

For warm start; Owing to almanac data has been arranged; Realize locating the temporal information that only needs to confirm again GPS, usual method is all inside counting information of utilizing in each subframe stem handing-over word (HOW), and the length of a frame is 6 seconds in the GPS navigation data; Seek the subframe head and add work consumed time such as acquiring satellite and bit synchronous, the TTFF of warm start generally will be more than 6 seconds.

Current; The method that has had some to reduce warm start TTFF can be with being controlled at start-up time in 2 seconds, and implementation method is: from the RTC of receiver, read the current time; Calculate co-ordinates of satellite and estimate transmission time of satellite-signal; Utilize these two temporal informations can calculate data represented time of navigation bit of current output, complicated but the method realizes, and require to be equipped with in the GPS receiver RTC of degree of precision.

Summary of the invention

The purpose of the embodiment of the invention is to provide a kind of startup method of navigational system, and that the hot start method that is intended to solve the navigational system that prior art provides is realized is complicated, elapsed time is long, and requires to be equipped with in the GPS receiver problem of the RTC of degree of precision.

The embodiment of the invention is achieved in that a kind of startup method of navigational system, and said method comprises the steps:

System powers on, and the transmission signals of at least 4 satellites is caught in control;

Search the same bits of the transmission signals output of obtaining said at least 4 satellites;

Same bits to said at least 4 satellite transmission signal that get access to are exported is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity;

According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts.

Another purpose of the embodiment of the invention is to provide a kind of start-up system of navigational system, and said system comprises:

The transmission signals trapping module is used for system and powers on, and the transmission signals of at least 4 satellites is caught in control;

Same bits is searched acquisition module, is used to search the same bits of the transmission signals output of obtaining at least 4 satellites that said transmission signals trapping module captures;

The relative time computing module, the same bits that is used for said same bits is searched said at least 4 satellite transmission signal output that acquisition module gets access to is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

Its computation of pseudoranges module is used for according to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, and wherein, said pseudorange ρ=T*C, C are the light velocity; And

Locating module is used for calculating user coordinates according to the pseudorange ρ that calculates, and customer location is positioned, and the control navigational system starts.

In embodiments of the present invention, the same bits in the transmission signals of the satellite-signal that captures is carried out bit synchronous, calculate the relative time T of satellite-signal transmission; According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity; According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts, and has shortened start-up time, does not also need extra increase hardware cost simultaneously.

Description of drawings

Fig. 1 is the realization flow figure of the startup method of the navigational system that provides of the embodiment of the invention;

Fig. 2 is the structural representation of the navigation message that provides of the embodiment of the invention;

Fig. 3 is the synoptic diagram of the bit synchronous that provides of the embodiment of the invention;

Fig. 4 is the word verification synoptic diagram that the embodiment of the invention provides;

Fig. 5 is the structured flowchart of the start-up system of the navigational system that provides of the embodiment of the invention.

Embodiment

In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

In embodiments of the present invention; The startup method of the navigational system that the embodiment of the invention proposes need not accomplished the frame synchronization of GPS navigation data, does not rely on the RTC whether degree of precision is housed in the GPS receiver yet, and realizes simple; Start consuming time fewly, can realize at lower cost simultaneously.

The purpose of the embodiment of the invention is to provide a kind of startup method of navigational system, and said method comprises the steps:

System powers on, and the transmission signals of at least 4 satellites is caught in control;

Search the same bits of the transmission signals output of obtaining said at least 4 satellites;

Same bits to said at least 4 satellite transmission signal that get access to are exported is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity;

According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts.

Another purpose of the embodiment of the invention is to provide a kind of start-up system of navigational system, and said system comprises:

The transmission signals trapping module is used for system and powers on, and the transmission signals of at least 4 satellites is caught in control;

Same bits is searched acquisition module, is used to search the same bits of the transmission signals output of obtaining at least 4 satellites that said transmission signals trapping module captures;

The relative time computing module, the same bits that is used for said same bits is searched said at least 4 satellite transmission signal output that acquisition module gets access to is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

Its computation of pseudoranges module is used for according to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, and wherein, said pseudorange ρ=T*C, C are the light velocity; And

Locating module is used for calculating user coordinates according to the pseudorange ρ that calculates, and customer location is positioned, and the control navigational system starts.

In embodiments of the present invention, the same bits in the transmission signals of satellite-signal output is carried out bit synchronous, calculate the relative time T of satellite-signal transmission; According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity; According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts.

Fig. 1 shows the realization flow of the startup method of the navigational system that the embodiment of the invention provides, and its concrete step is described below:

In step S101, system powers on, and the transmission signals of at least 4 satellites is caught in control.

In step S102, search the same bits of the transmission signals output of obtaining said at least 4 satellites.

In step S103, the same bits that said at least 4 satellite transmission signal that get access to are exported is carried out bit synchronous, calculate the relative time T of satellite-signal transmission.

In embodiments of the present invention, the relative time of this satellite-signal transmission equals to accomplish the difference of time and satellite-signal launch time of bit synchronous, followingly provides concrete embodiment and describes, and repeats no more at this.

In step S104, according to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity.

In step S105, according to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts.

In embodiments of the present invention, the mode of calculating user coordinates according to the pseudorange ρ that calculates can have multiple situation, and following situation with 4 satellites describes;

According to the pseudorange ρ that calculates, the calculating formula of calculating user coordinates is:

$\mathrm{\ρ}1=\sqrt{{(x1-x)}^2+{(y1-y)}^2+{(z1-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}2=\sqrt{{(x2-x)}^2+{(y2-y)}^2+{(z2-z)}^2}+\mathrm{c\Δt}$ ；

$\mathrm{\ρ}3=\sqrt{{(x3-x)}^2+{(y3-y)}^2+{(z3-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}4=\sqrt{{(x4-x)}^2+{(y4-y)}^2+{(z4-z)}^2}+\mathrm{c\Δt}$

Wherein, (xi, yi, zi) expression co-ordinates of satellite, (x, y, z) the indicate user coordinates that calculates, the pseudorange between ρ 1 to ρ 4 expression receiver and the satellite, Δ t representes the clock correction of user clock and gps clock, is unknown quantity.

Wherein, because the almanac data of 4 satellites is known, therefore, in the aforementioned calculation formula; Δ t with (x, y z) are unknown number, other all be known; Therefore can calculate user coordinates, after the calculating of accomplishing user coordinates, promptly accomplish location, accomplish the startup of navigational system customer location.

In embodiments of the present invention, as shown in Figure 2, navigation message is made up of for three layers subframe, word, bit.

For all satellites; As shown in Figure 3; Be identical the launch time of z bit of y word of x subframe (for example the 1st bit among the figure) expression signal; So work as the bit synchronous that T1 just in time accomplishes 4 satellites constantly, just can calculate the relative time T of every satellite-signal transmission, promptly every frame starts the time between the moment to T0.

As one embodiment of the present of invention, every frame starts the computing method of the time between the moment to T0, is not having under the situation of other timing tools, can calculate through sampling number:

$\mathrm{ti}=N\×\frac{1}{F_s};$

Wherein, when representing T0, N is carved into the sampled point quantity of bit starting position, F _sThe expression SF.

As one embodiment of the present of invention; Above-mentioned T1 accomplishes synchronous Bit data constantly and differs and establish a capital the same bit of the same word that is same subframe; Reason is that the signal of different satellites arrives maximum about 20 milliseconds mistimings of time existence on ground; Such as Fig. 4 demonstration, T1 accomplishes in 4 bits of 4 synchronous satellites constantly, have 1 with other 3 be not same bit; If will be certain to make mistakes with this compute pseudo-ranges, therefore need be to the satellite-signal of accomplishing bit synchronous is carried out the word verification operation.Because each word (30 bits) all includes parity check code; Search for the initial bits of each word so can utilize verification; If initial bits has been confirmed; Just can confirm that it is respectively which bit in which word that T1 accomplishes synchronous Bit data constantly,, only need get final product to front or rear position of moving a bit if not same bit.

Fig. 5 shows the structured flowchart of the start-up system of the navigational system that the embodiment of the invention provides; For the ease of explanation; Only provided the part relevant among the figure with the embodiment of the invention; Wherein, the start-up system of this navigational system can be built in software unit, hardware cell or the software and hardware combining unit of receiver.

Transmission signals trapping module 11 systems power on, and the transmission signals of at least 4 satellites is caught in control; Same bits is searched the same bits that acquisition module 12 is searched the transmission signals output of obtaining at least 4 satellites that said transmission signals trapping module captures; 13 pairs of said same bits of relative time computing module are searched the same bits of said at least 4 satellite transmission signal output that acquisition module 12 gets access to and are carried out bit synchronous, calculate the relative time T of satellite-signal transmission; Its computation of pseudoranges module 14 is according to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, and wherein, said pseudorange ρ=T*C, C are the light velocity; Locating module 15 calculates user coordinates according to the pseudorange ρ that calculates, and customer location is positioned, and the control navigational system starts.

Wherein, the relative time T of satellite-signal transmission equals to accomplish the difference of time and satellite-signal launch time of bit synchronous.

In embodiments of the present invention, the pseudorange ρ that said basis calculates, the calculating formula of calculating user coordinates is:

$\mathrm{\ρ}1=\sqrt{{(x1-x)}^2+{(y1-y)}^2+{(z1-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}2=\sqrt{{(x2-x)}^2+{(y2-y)}^2+{(z2-z)}^2}+\mathrm{c\Δt}$ ；

$\mathrm{\ρ}3=\sqrt{{(x3-x)}^2+{(y3-y)}^2+{(z3-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}4=\sqrt{{(x4-x)}^2+{(y4-y)}^2+{(z4-z)}^2}+\mathrm{c\Δt}$

Wherein, (xi, yi, zi) expression co-ordinates of satellite, (x, y, z) the indicate user coordinates that calculates, the pseudorange between ρ 1 to ρ 4 expression receiver and the satellite, Δ t representes the clock correction of user clock and gps clock, is unknown quantity.

Wherein, the satellite-signal that 116 pairs of said bit synchronous modules 13 of word verification module are accomplished bit synchronous is carried out the word verification operation, and its concrete verification realizes that above-mentioned have concrete method embodiment to describe, and repeats no more at this.

Above-mentionedly be merely a system embodiment of the present invention, the function of its each module such as above-mentioned method embodiment are said, repeat no more at this, but not in order to restriction the present invention.

In embodiments of the present invention, the same bits in the transmission signals of the satellite-signal that captures is carried out bit synchronous, calculate the relative time T of satellite-signal transmission; According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity; According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts, and has shortened start-up time, does not also need extra increase hardware cost simultaneously; It is synchronous to utilize parity checking to accomplish word simultaneously, realizes the location more accurately.

The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1. the startup method of a navigational system is characterized in that, said method comprises the steps:

System powers on, and the transmission signals of at least 4 satellites is caught in control;

Search the same bits of the transmission signals output of obtaining said at least 4 satellites;

Same bits to said at least 4 satellite transmission signal that get access to are exported is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

According to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, wherein, said pseudorange ρ=T*C, C are the light velocity;

According to the pseudorange ρ that calculates, calculate user coordinates, customer location is positioned, the control navigational system starts.

2. the method for claim 1; It is characterized in that; Said transmission signals at least 4 satellites capturing is followed the tracks of; The transmission signals of said at least 4 satellites is carried out after the step of bit synchronous, and said when accomplishing bit synchronous, the step of calculating the relative time T of every satellite-signal transmission also comprises the steps: before

Satellite-signal to accomplishing bit synchronous is carried out the word verification operation.

3. the method for claim 1 is characterized in that, the relative time T of said satellite-signal transmission equals to accomplish the difference of time and satellite-signal launch time of bit synchronous.

4. the method for claim 1 is characterized in that, the pseudorange ρ that said basis calculates, and the calculating formula of calculating user coordinates is:

$\mathrm{\ρ}1=\sqrt{{(x1-x)}^2+{(y1-y)}^2+{(z1-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}2=\sqrt{{(x2-x)}^2+{(y2-y)}^2+{(z2-z)}^2}+\mathrm{c\Δt}$ ；

$\mathrm{\ρ}3=\sqrt{{(x3-x)}^2+{(y3-y)}^2+{(z3-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}4=\sqrt{{(x4-x)}^2+{(y4-y)}^2+{(z4-z)}^2}+\mathrm{c\Δt}$

Wherein, (xi, yi, zi) expression co-ordinates of satellite, (x, y, z) the indicate user coordinates that calculates, the pseudorange between ρ 1 to ρ 4 expression receiver and the satellite, Δ t representes the clock correction of user clock and gps clock, is unknown quantity.

5. the start-up system of a navigational system is characterized in that, said system comprises:

The transmission signals trapping module is used for system and powers on, and the transmission signals of at least 4 satellites is caught in control;

Same bits is searched acquisition module, is used to search the same bits of the transmission signals output of obtaining at least 4 satellites that said transmission signals trapping module captures;

The relative time computing module, the same bits that is used for said same bits is searched said at least 4 satellite transmission signal output that acquisition module gets access to is carried out bit synchronous, calculates the relative time T of satellite-signal transmission;

Its computation of pseudoranges module is used for according to every the satellite of relative time T calculating of every the satellite-signal transmission that calculates and the pseudorange ρ of receiver, and wherein, said pseudorange ρ=T*C, C are the light velocity; And

Locating module is used for calculating user coordinates according to the pseudorange ρ that calculates, and customer location is positioned, and the control navigational system starts.

6. system as claimed in claim 5 is characterized in that, said relative time computing module also comprises:

Word verification module is used for the satellite-signal of accomplishing bit synchronous is carried out the word verification operation.

7. system as claimed in claim 5 is characterized in that, the relative time T of said satellite-signal transmission equals to accomplish the difference of time and satellite-signal launch time of bit synchronous.

8. system as claimed in claim 5 is characterized in that, the pseudorange ρ that said basis calculates, and the calculating formula of calculating user coordinates is:

$\mathrm{\ρ}1=\sqrt{{(x1-x)}^2+{(y1-y)}^2+{(z1-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}2=\sqrt{{(x2-x)}^2+{(y2-y)}^2+{(z2-z)}^2}+\mathrm{c\Δt}$ ；

$\mathrm{\ρ}3=\sqrt{{(x3-x)}^2+{(y3-y)}^2+{(z3-z)}^2}+\mathrm{c\Δt}$

$\mathrm{\ρ}4=\sqrt{{(x4-x)}^2+{(y4-y)}^2+{(z4-z)}^2}+\mathrm{c\Δt}$

Wherein, (xi, yi, zi) expression co-ordinates of satellite, (x, y, z) the indicate user coordinates that calculates, the pseudorange between ρ 1 to ρ 4 expression receiver and the satellite, Δ t representes the clock correction of user clock and gps clock, is unknown quantity.

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