CN102183772A - Method and device for demodulating GPS navigation message data under weak signals - Google Patents
Method and device for demodulating GPS navigation message data under weak signals Download PDFInfo
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- CN102183772A CN102183772A CN2010102067898A CN201010206789A CN102183772A CN 102183772 A CN102183772 A CN 102183772A CN 2010102067898 A CN2010102067898 A CN 2010102067898A CN 201010206789 A CN201010206789 A CN 201010206789A CN 102183772 A CN102183772 A CN 102183772A
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Abstract
The invention discloses a method and device for demodulating GPS navigation message data by using a GPS signal receiver under weak signals. The method is applied to the GPS signal receiver and is characterized in that before the GPS signal receiver performs positioning, the navigation message data of a GPS satellite needs to be demodulated for position calculation, and under the situation that GPS satellite signals are weak, the error rate of the navigation message data demodulation is higher, so that calculation errors of the position are caused. According to the method disclosed by the invention, repeated subframes are adopted for analysis and forecast according to navigation message repetition characteristics of GPS satellite signals, so that the error rate of the GPS satellite navigation message demodulation is enhanced under the condition that the GPS satellite signals are weakest, and thus the positioning accuracy of a GPS receiver is further enhanced.
Description
Technical field:
The present invention relates to a kind of GPS (GPS) positioning and navigation field, more particularly, relate to a kind of gps satellite positioning and navigation receiver realizes the gps navigation message data demodulates under the faint situation of gps satellite signal method and device that be used for.
Background technology:
Gps system, full name are GPS (Global Position System).The aerial gps satellite of this system's ether is the radio-navigation systems on basis, have real-time, round-the-clock, multi-functional, multiple functions such as high-precision location, time service, navigation can provide accurate real-time three-dimensional volume coordinate, velocity, accurately multi-function service such as time service for all kinds of ground receiver users.Nowadays, the GPS technology has been widely used in as a plurality of scientific domains such as geodetic surveying, engineering survey, resource exploration, geodynamicss, simultaneously, multiple civil navigation such as Ge Ren handheld navigation instrument, automatic navigator, mobile phone navigation Service is used also abundant day by day.
The signal system of GPS is based on the mode of the CDMA of spread spectrum.Its basic data source is that a frequency is that 50Hz navigation message data-signal constitutes, from the space transmission, the satellite-signal of gps satellite emission is the signal after numeric data code (navigation message of GPS) is modulated through two-stage through (L1 or L2) after spreading code (C/A sign indicating number or P sign indicating number) spread spectrum and the carrier modulation.First order modulation is C/A sign indicating number and the P sign indicating number that the navigation message data-signal sign indicating number of low frequency is modulated to high frequency respectively, realizes the pseudo-random code spread spectrum to data-signal.Second level modulation is the combinational code that the first order is modulated to be distributed be modulated on two carrier frequencies (L1 and L2), and this two kinds of modulated waves take place last gps satellite earthward.Wherein the L1 carrier frequency is 1575.42MHz, wavelength 19.03cm, and the frequency of L2 carrier wave is 1227.6MHz, wavelength 24.42cm.
Be positioned at the Base-Band Processing of the GPS receiver user on ground by receiver, receive the also satellite-signal of demodulation GPS, after having peeled off the carrier wave and spread-spectrum code signals that is modulated on the gps satellite signal by processing, can obtain to be modulated at the navigation message data on the gps satellite signal, by the navigation message data that obtain, through calculating, can obtain the accurate positional information at receiver user place.Therefore obtain the final goal that correct navigation message data can be described as the GPS receiver, have only correctly final accounts customer location of correct acquisition navigation message data, and the mistake that wrong navigation message data will directly cause customer location to calculate.
Traditional GPS receiver, all comparatively simple usually for the demodulation process of telegraph text data, generally all be by after the Base-Band Processing, will peel off demodulation result behind gps satellite carrier signal and the pseudo-random code signal directly in order to judge the data polarity of navigation message.Method although it is so is simply effective, but under the comparatively faint situation of gps satellite signal, when noise is big after the signal demodulation, causes customer location to calculate makeing mistakes thereby tend to separate the navigation message data that make mistake.
Summary of the invention:
The object of the present invention is to provide a kind of method that is used for GPS receiver realization navigation message data demodulates under the feeble signal situation.This method is said so more specifically at the GPS receiver when carrying out gps satellite navigation message data demodulates, the mode that adopts the circulation subframe to detect, under the faint situation of gps satellite signal, obtain the navigation message data of gps satellite signal more accurately, thereby can calculate the position of receiver user accurately.
Introduce concrete technical scheme of the present invention below in detail:
A kind of under the situation of feeble signal, the method for realization gps signal navigation message data demodulates, this method comprises:
First step, the GPS receiver system is in the state of gps satellite signal navigation message data demodulates, promptly the GPS receiver system tenacious tracking at least one gps satellite signal;
Second step, GPS receiver system do not demodulate the navigation message data of gps satellite signal;
Third step, the demodulation of GPS receiver system receives the navigation message data of gps satellite signal for the first time;
The 4th step, GPS receiver system use the data of the repeatedly symbolism of the gps satellite signal of storage to add up demodulation navigation message data;
The 5th step, the GPS receiver system is by repeatedly calculating the sub-frame data of reusable gps satellite signal, the navigation message data that demodulation is correct.
The device of gps navigation message data demodulates under a kind of weak signal is to be made of the module that places the GPS receiver, it is characterized in that comprising:
The gps signal data acquisition module is in order to gather gps satellite signal data pending and that calculate;
The gps signal trapping module is in order to catch gps satellite signal from described gps signal data acquisition module;
The gps signal tracking module is in order to follow the tracks of the gps satellite signal that described gps signal trapping module has captured;
Gps signal navigation message demodulation module, the gps satellite signal that arrives in order to demodulation gps signal tracking module tenacious tracking, thus realize follow-up receiver location positioning function.
Beneficial effect of the present invention:
The method of the invention is can carry out at the state that the GPS receiver is under the tracing mode, and the GPS receiver system need not to obtain in advance demodulating data, also need not to obtain in advance positional information.
The method of the invention is to carry out algorithm computation under gps navigation message data condition of unknown, and under the situation of weak output signal, when obtaining the navigation message data of other satellite-signals, the navigation message data demodulates of the satellite that calculates will be more accurate.
The method of the invention is to obtain better gps satellite signal signal to noise ratio (S/N ratio) by gps satellite signal sub-frame data cycle calculations, therefore can calculate the carrier-to-noise ratio information of gps satellite signal more accurately, with the tracking operation of assistant GPS satellite-signal.
The method of the invention is when realizing, very little to GPS receiver system demand, the convenient realization, can under the situation of not adding any hardware resource, realize, cyclicity according to the subframe of gps satellite navigation message data, can greatly improve the accuracy of navigation message data demodulates, even under the extremely faint situation of gps satellite signal, also can obtain navigation message information accurately, to be used for the position of correct calculation receiver user.
For further specifying above-mentioned purpose of the present invention, design feature and effect, the present invention is described in detail below with reference to accompanying drawing.
Description of drawings:
Further specify the present invention below in conjunction with the drawings and specific embodiments.
Fig. 1 is the structured flowchart of a typical GPS receiver system.
Fig. 2 is a typical GPS receiver system gps signal flow chart of data processing figure.
Fig. 3 is the navigation message data structure diagram of gps satellite signal modulation.
Fig. 4 is the process flow diagram of navigation message data demodulation method of the present invention.
Embodiment:
Further set forth the present invention below in conjunction with accompanying drawing.Be illustrated in figure 1 as the block diagram of a typical GPS receiver system, common whole receiver system comprises three major parts, the one, in order to receive and to handle the radio-frequency front-end part of gps satellite signal, the 2nd, in order to handling GPS baseband signal and the final baseband processor of calculating receiver location information, the 3rd, in order to receiving position information and carry out the system host of upper application software.
Capture engine 11, tracking passage 12 text demodulation modules 14, processor 13 and some peripheral hardwares 15 and external interface unit 16 have mainly been comprised in GPS baseband processor inside.The function that capture engine 11 is realized mainly is to catch gps satellite signal.Following the tracks of passage 12 is responsible for gps satellite signal is followed the tracks of.14 of text demodulation modules carry out the navigation message data demodulates of gps satellite signal.The function of processor 13 is the position calculation of carrying out receiver according to the navigation message telegraph text data, after calculating the accurate position of receiver, delivers to outside system host 18 to use by Peripheral Interface 16.
Be illustrated in figure 2 as gps signal flow chart of data processing figure in the typical GPS receiver system, according to GPS baseband processor inner structure shown in Figure 1, the gps signal data processing of standard comprises five main flow processs:
S21, the gps satellite signal trapping module is caught carrier wave and the C/A sign indicating number information that operation obtains satellite to satellite-signal in the sky,
S22 after gps satellite signal is hunted down, just enters tracking mode, and the information that the tracking module utilization is caught is followed the tracks of operation to satellite-signal in the sky, keeps the effective demodulation to satellite-signal.
S23, the text demodulation module carries out the text demodulation to the gps satellite that enters tracking mode, and the textual information that obtains satellite is to obtain the temporal information of almanac data and satellite.
S24, the processor utilization obtains the ephemeris of satellite and the position calculation that time information is carried out receiver.
S25 after the correct positional information that calculates, outputs to the outside with positional information and obtains supplementary from the outside.
Be illustrated in figure 3 as gps satellite signal navigation message data structure diagram, the least unit of the navigation message data of gps satellite is position (bit), and its length is 20 milliseconds, takies 20 C/A chips altogether.
It is one of 1 millisecond of expression of per 20 standards.Navigation message, just be meant the numeric data code that comprises navigation information, navigation information refers to: satellite ephemeris, satellite health, the satellite almanac, data system star clock is revised parameter, orbit perturbation corrects parameter, atmospheric refraction corrects parameter, and telemetry code and C/A determine the permutation code of P sign indicating number etc., is that the user carries out the basis that navigator fix calculates.
Navigation message is the binary coding file, and form is in accordance with regulations formed Frame, sends out to unofficial biography frame by frame, and every frame text contains 1500, and broadcasting speed is 50Hz, and the delivery time of a whole frame is 30 seconds.Each subframe comprises 10 words, and each word has comprised 30 positions.
The broadcast ephemeris and the satellite corrected parameter that contain this satellite in the 1st, 2,3 frames per hour upgrade once.
The 4th, 5 frames are deposited the almanac (ephemeris of 24 satellites) of all aerial gps satellites, and quantity of information is huger, so subframe 4, so 5 respectively contain 25 pages. subframe 1, each page or leaf of 2,3 and 4,5, all hook becomes a prime frame. and in fact complete navigation message is 25 frames altogether, totally 37500, all transmission needed finish in 12.5 minutes. and the content of subframe 4,5 then is just to upgrade after injecting new navigation data by the ground injection plant.
From the rule of gps satellite navigation message data as can be seen, the 3rd word to the 10 words (61 to 300bit) of subframe 1, subframe 2, subframe 3 can repeat once in per 30 seconds, and subframe 4 and subframe 5 did not have to repeat once in 12.5 minutes.
When the method for the invention is to carry out gps satellite navigation message data demodulates under faint gps satellite signal situation, use correctly demodulated data of traditional navigation message data demodulation method for those, according to the repeatability of the sub-frame data of navigation message, the data of the symbolism of these repetitions are added up demodulation navigation message data more accurately.Because adding up of the navigation message data of these extra symbolism can improve the signal to noise ratio (S/N ratio) of gps satellite signal.Will further be reduced under the situation of equal carrier-to-noise ratio the bit error rate of navigation message data demodulates after the signal to noise ratio (S/N ratio) of raising satellite-signal.
Be illustrated in figure 4 as the process flow diagram of navigation message data demodulation method of the present invention.
S1, flow process is initially the GPS receiver system and enters the gps satellite tracking mode, beginning demodulation navigation message data.
S2, the symbolism that storage is at first earlier obtained by the tracking module of GPS receiver the navigation message data bit.
S3 after the navigation message data that receive a word (30bit), attempts with traditional method demodulation navigation message data.Judge whether can be correct demodulate the navigation message data.
S44, if can be correct demodulate the navigation message data, then flow process jumps to S49, with correct navigation message data storage in order to follow-up use.
If can not be correct demodulate the navigation message data, then flow process jumps to S45, judges whether it is the telegraph text data of demodulation for the first time.
S45, if the telegraph text data of demodulation for the first time, then flow process jumps to S42, directly returns the navigation message data that continue to receive and store the symbolism of back.
If not demodulation first time telegraph text data, then flow process jumps to S46, adds up with the data of this position of storage before.
S46 attempts carrying out the demodulation of navigation message data to the result who adds up.
S47, if can be correct demodulate the navigation message data, then flow process jumps to S49, with correct navigation message data storage in order to follow-up use.
If can not be correct demodulate the navigation message data, then flow process jumps to S48, the result who adds up is specifically stored in addition in order to the back continue to use.
S48, after event memory was finished, flow process was back to S42, began to continue to receive and store the navigation message data of the symbolism of back.
S49, S410, can correctly separate at every turn mix up the navigation message data after, need to judge whole navigation message data whether all demodulation finish.When whole navigation message after all demodulation is finished, can withdraw from the flow process S411 of navigation message data demodulates, systemic-function such as the navigation message data of institute's demodulation can be used to carry out the GPS receiver location and calculate, and following function is auxiliary.
Aforementioned calculation and operating process are a kind of typical embodiment of the method for the invention, for one of ordinary skill in the art, can do multiple variation on the basis of the foregoing description, can realize purpose of the present invention equally.But this variation obviously should be in the protection domain of claims of the present invention.
Claims (5)
- One kind under the situation of feeble signal, realize the method for gps signal navigation message data demodulates, it is characterized in that may further comprise the steps:First step, the GPS receiver system is in the state of gps satellite signal navigation message data demodulates, promptly the GPS receiver system tenacious tracking at least one gps satellite signal;Second step, GPS receiver system do not demodulate the navigation message data of gps satellite signal;Third step, the demodulation of GPS receiver system receives the navigation message data of gps satellite signal for the first time;The 4th step, GPS receiver system use the data of the repeatedly symbolism of the gps satellite signal of storage to add up demodulation navigation message data;The 5th step, the GPS receiver system is by repeatedly calculating the sub-frame data of reusable gps satellite signal, the navigation message data that demodulation is correct.
- 2. as claimed in claim 1 a kind of under the situation of feeble signal, the method for realization gps signal navigation message data demodulates is characterized in that:In described the 4th step, repeatedly the data of the gps satellite signal symbolism of Chu Cuning are meant the data bit of a standard navigation text, are that the GPS receiver is being followed the tracks of the data message that obtains behind the gps satellite.
- 3. as claimed in claim 1 a kind of under the situation of feeble signal, the method for realization gps signal navigation message data demodulates is characterized in that:In described the 5th step, repeatedly calculate the gps satellite signal sub-frame data and be repeatability,, come the gps satellite navigation message data under the demodulation weak signal by the judgment mode that adds up according to subframe in the gps satellite navigation message data.
- 4. as claimed in claim 3 a kind of under the situation of feeble signal, the method for realization gps signal navigation message data demodulates is characterized in that:Carry out text in use subframe repeatability and separate timing, can use conventional text demodulation method, and not specific to certain fixing demodulation method.
- 5. the device of gps navigation message data demodulates under the weak signal is to be made of the module that places the GPS receiver, it is characterized in that comprising:The gps signal data acquisition module is in order to gather gps satellite signal data pending and that calculate;The gps signal trapping module is in order to catch gps satellite signal from described gps signal data acquisition module;The gps signal tracking module is in order to follow the tracks of the gps satellite signal that described gps signal trapping module has captured;Gps signal navigation message demodulation module, the gps satellite signal that arrives in order to demodulation gps signal tracking module tenacious tracking, thus realize follow-up receiver location positioning function.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103592661A (en) * | 2013-11-26 | 2014-02-19 | 中国科学院嘉兴微电子与***工程中心 | Dipper ephemeris collecting method |
| CN104502927A (en) * | 2014-12-19 | 2015-04-08 | 泰斗微电子科技有限公司 | Satellite navigation message demodulation method and corresponding chip and terminal |
| CN115586975A (en) * | 2022-12-13 | 2023-01-10 | 成都奇芯微电子有限公司 | Dynamic management method for embedded end GNSS memory |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007278756A (en) * | 2006-04-04 | 2007-10-25 | Gnss Technologies Inc | Position information providing system and apparatus, and indoor transmitter |
| CN101493512A (en) * | 2008-01-23 | 2009-07-29 | 中国科学院微电子研究所 | Management method for navigation messages of global positioning system receiver |
| CN101614804A (en) * | 2008-06-27 | 2009-12-30 | 上海盈方微电子有限公司 | Bit synchronous method of gps navigation message data and device under the weak signal |
| CN101614805A (en) * | 2008-06-27 | 2009-12-30 | 上海盈方微电子有限公司 | Gps satellite signal catching method and device |
-
2010
- 2010-06-22 CN CN2010102067898A patent/CN102183772A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007278756A (en) * | 2006-04-04 | 2007-10-25 | Gnss Technologies Inc | Position information providing system and apparatus, and indoor transmitter |
| CN101493512A (en) * | 2008-01-23 | 2009-07-29 | 中国科学院微电子研究所 | Management method for navigation messages of global positioning system receiver |
| CN101614804A (en) * | 2008-06-27 | 2009-12-30 | 上海盈方微电子有限公司 | Bit synchronous method of gps navigation message data and device under the weak signal |
| CN101614805A (en) * | 2008-06-27 | 2009-12-30 | 上海盈方微电子有限公司 | Gps satellite signal catching method and device |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103592661A (en) * | 2013-11-26 | 2014-02-19 | 中国科学院嘉兴微电子与***工程中心 | Dipper ephemeris collecting method |
| CN103592661B (en) * | 2013-11-26 | 2016-03-30 | 中国科学院嘉兴微电子与***工程中心 | A kind of method that Big Dipper ephemeris is collected |
| CN104502927A (en) * | 2014-12-19 | 2015-04-08 | 泰斗微电子科技有限公司 | Satellite navigation message demodulation method and corresponding chip and terminal |
| CN115586975A (en) * | 2022-12-13 | 2023-01-10 | 成都奇芯微电子有限公司 | Dynamic management method for embedded end GNSS memory |
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Application publication date: 20110914 |