KR100311055B1 - System for determining the location of mobile objects - Google Patents

Abstract

In order to reduce the transmission capacity requirements for the correction data in the differential GPS system, the continuous error reading 7, while improving in particular the interpretation of any correction data suffered from transmission interference and ensuring the quickest possible correction, From the fixed position of the GPS signal (12, 22, 32, 42) and known position coordinates (6) In accordance with the present invention, an evaluation system 60 is provided to recalculate the revision readings that finish at the last full time at a particular time point. The modified reading 8 calculated by the evaluation system is transmitted by the at least one radio transmitter 80 in the radio data signal RDS included in the program signal. Attached to the moving object 5, whose position coordinates are determined by the mobile GPS receiver 120, is to connect the RDS decoder 100 to receive and decode the received RDS signal incorporating the processed correction readings 8 Radio receiver 90 and a computer 110 that extracts the modified reading 7 from the decoded RDS and updates it to the current time. The computer reconstructs a standard correction signal (7) consistent with the RTCM standard. The reconstructed standard correction data is finally supplied to a GPS receiver that corrects the reading in accordance with the received reconstruction correction reading (7).

Description

[0001] SYSTEM FOR DETERMINING THE LOCATION OF MOBILE OBJECTS [0002]

A method based on a satellite derived from a Global Positioning System (GPS system) is disclosed, wherein a so-called GPS satellite is used to track and track a moving object, for example on a 1.575 GHz frequency, The GPS receiver extends the GPS satellite's orbit to continuously vary its position relative to a fixed position on the earth. The GPS receiver measures the time it takes for the signal to travel from the satellite to the receiver, Since the GPS satellite position is known, the spatial coordinates of the Earth's receiver position and the internal clock error of the GPS receiver are calculated by four GPS satellites, but this is only +/- 100 meters of precision. Since this precision is not suitable for many applications, It is known to determine an error value from the PS receiver and transmit the error value in the form of modified data (US Docket No. 20005 Shoot 300, published by Radio Technical Commission, Fomaler Time Service, January 3, 1994 Version 2.1 Chapter 4 RTCM Opening Standard for Differential GPS Services) GPS measurement data determined by a mobile GPS receiver is modified with the help of received correction data The data format of the correction data formed by the RTCM standard Lt; RTI ID = 0.0 > 4-3 < / RTI >

For each individual GPS satellite, an indication taking into account the scale factor, the error range (UDRE = user differential range error), the associated satellite identification table (satellite ID), the so called pseudo range correction value (PRC = There is each " message " consisting of an inspection signal (ferritet), an expected ratio value of the PRC data change (PRC = ratio range modification), and an indication that the correction value is associated (data result) orbit data. Each " message " is directly combined with each other to form a string, and the string is split into a series of words of 30 bits in length despite the limit of each " message ". Each " message " string is preceded by a header consisting of two words of 30 bits in length to indicate the beginning of each string. The first 30-bit word of the header consists of a sequence (special) followed by an identification (message type) of the next message type, an identification (station ID) of the transmitting station and a check word (parity). The second 30-bit word of the header includes an indication (frame length) taking into consideration the time information (modified z count), a sequence number, a total length of a later " message " And a check word (ferritic).

For the real-time transmission of correction data, DE 41 36 136 C1 discloses the use of the station's current transmitter network, the correction data is inserted into the 37-bit free group of each periodic transmission radio data (RDS) signal, The group is transmitted inaudible in the radio program signal. Since the data format of the radio data system does not match the data format of the GPS correction data, the header of each string and the next " message " are segmented into portions of 37 bits each allocated to the free RDS group in consecutive RDS signal cycles do. The partial contents of the RDS group are completely arbitrary and can not be identified as above. The data format of the GPS correction data can be reconstructed from this part and can be evaluated if all the RDS groups to which the headers of each string and the consecutive " messages " are assigned are received consecutively without confusion. For example, in the case of VHF reception confusion, a combination of only a single RDS group causes a loss of full string information, which means that the correction value of all "messages" associated with the string is lost for all relevant GPS satellites. In addition, the modification "message" for all GPS satellites, ie the transmission duration of the string, takes several seconds because of the limited capacity of the RDS system, even though each RDS cycle (cycle period 1 second) is consumed by three RDS groups; This causes the simultaneously calculated correction values for all GPS satellites to gradually decrease until the string progress transmission. This aging problem is more noticeable when smaller free capacity is used in the RDS system for transmission of correction values, since other services require RDS system capacity, if necessary.

The invention relates to a system according to the preamble of claim 1 and to a receiver according to the preamble of claim 6. Systems and receiving devices of this type are described in DE 41 36 136 C1.

1 is a schematic diagram of a known positioning system according to the so-called " differential GPS ".

Figure 2 is a block diagram of a transmission configuration component of a system according to the present invention;

3 is a block diagram of a receiver end component of a system according to the present invention;

4 is a schematic diagram of a data format of a consecutively transmitted RDS signal cycle with complete correction data for a GPS satellite;

5 is a schematic diagram of a data format of an occasionally transmitted RDS signal cycle having time information (modified Z count) derived from a received GPS signal;

6 is a schematic diagram of a data format of an RDS signal cycle having data identification information (IOD) derived from a received GPS signal;

In comparison, it is an object of the present invention to provide a system of the first-mentioned type in which the requirement for transmission capacity is reduced and the ability to interpret the correction data is significantly improved in the case of transmission confusion and the flow of the transmitted correction data is improved To improve. In addition, a receiving device is formed to perform these purposes on the receiver end.

This object is achieved according to the features of claims 1 and 6 of the present invention.

Preferred embodiments and modifications of the system according to the present invention and the receiving apparatus according to the present invention are respectively shown in the dependent claims 2 to 5 and 7 and 8, respectively.

The invention is described by way of example with reference to the drawings.

As shown in Fig. 1, the illustrated positioning system is based on so-called GPS satellites 1 to 4 which revolve around the earth in such a manner that the position changes continuously with respect to the earth's anchorage point. Only four GPS satellites shown represent a minimum number; In practice, there are a greater number of GPS's orbiting around the earth in a precision mesh net.

The GPS receiver 120 (FIG. 3) installed on the moving object 5 on the earth surface 8 can determine the spatial coordinates based on the received GPS signals 11, 21, 31 and 41, It is approximately ± 100 meters in accuracy due to the error factors caused in part by environmental disruption. In order to improve the measurement accuracy, a so-called " differential GPS " is provided at a fixedly installed reference GPS receiving and processing unit 50 location 6 with precise location coordinates. From the GPS signals 12, 22, 32 and 42 received by the unit and the known position coordinates, the reference GPS reception and processing unit 50 determines whether the correction data 7 is continuously updated by the error value formed in the standardized data format And the correction data is transmitted to the GPS receiver 120 on the moving object 5 in real time. The unit 50 includes, for example, a downstream computer as well as one or more GPS receivers. In such a computer, the reference station software can supply especially the correction data 7. Optionally, the unit 50 may consist of one GPS receiver, where the generation of the correction data 7 occurs through an integral component. Based on the correction data 7 received by the mobile GPS receiver 120, the measured instantaneous position coordinates can be modified to an accuracy of up to +/- 1 meter. These values are only effective within some perimeter around the reference GPS receiving and processing unit 50.

In order to ensure wide area transmission of the correction data 7, the system according to the invention provides that the correction data 7 is transmitted in the radio program signal. For this purpose, the coordinates are determined (measured) from the GPS signals 12 to 42 received by the reference GPS receiving and processing unit 50 via the satellite receive antenna 51 as shown in FIG. 2; However, these coordinates are distorted due to various influences. By comparing with the positional coordinates of the known known receive antenna 51, the reference GPS receiving and processing unit 50 generates the standardized correction data 7. These correction data 7 are processed by the downstream computer 60 and supplied to the RDS coder 70 of the radio station 80 (FM or AM station). The RDS coder 70 inserts the processed correction data 8 into the RDS data stream that conforms to the format in the manner described in detail below. The radio station 80 sends out the RDS signal 9 added to the wide area in the radio program signal through the transmitter's mast 81 (mast) of the station.

3) tuned to the carrier frequency of the radio station 80 and processed with the radio program signal of the radio station 80 via the receiver's receive antenna 91 And receives the RDS signal 9 added by the correction data 8. In the downstream (RDS) decoder 100, the RDS signal 9 is separated and decoded from the radio program signal and supplied to the computer 110 which separates the processed correction data 8 from the RDS signal, And reconstructs the correction data (7). From the computer 110, the reconstructed and standardized correction data 7 is supplied to the GPS receiver 120 of the moving object 5 that receives the GPS signals 11 to 41 via the satellite receive antenna 119, Derive coordinate values. The derived measurement coordinate values are modified in the GPS receiver 120 with the aid of the reconstructed coordinate modification data 7. The GPS receiver 120 supplies the corrected coordinate value 121 to the output device 130. [

According to the earlier cited standard, the correction data 7 (for GPS satellites 1, 2, 3, and 4, respectively) generated in the reference GPS receiving and processing unit 50 are useful pseudo range correction values As identified below as PRC data). In addition, the correction data formed in the reference GPS receiving and processing unit includes a value for the rate of change of the PRC data. In the following context, these change rate values are identified as PRC data. From the PRC data and the RRC data, the actual PRC value is deduced from the actual moment that comes later than the calculation moment of the PRC data, and the precision of the estimated actual PRC value is determined from the precision range in which the first change rate picked up as PRC data matches the actual change rate Function.

For transmission of the correction data 7, the present invention provides that a Radio Data System (RDS) for FM or AM radio is used, wherein the RDS data stream is modulated, for example with a 57 kHz auxiliary carrier, This is inserted in the program signal baseband of the FM or AM radio station to prevent it from listening. The data format of the RDS data stream is composed of periodically transmitted data block sequences having RDS cycles as shown in Fig. 4, and the longer data separated by the shorter check words 10a, 20a, 30a and 40a Blocks 10, 20, 30 and 40. [ In each case, four data blocks 10.20, 30, and 40 form an RDS group with a 37-bit free data capacity. In the example shown in FIG. 4, the longer data blocks 10 and 20 include a program identification code (PI) and a program type code (PTY) according to the European RDS standard (CENELEC) EN 50067. The free data capacity of the RDS group is used to integrate the correction data for the GPS satellites and the PRC data is used to identify each GPS satellite's identification ("satellite number"), time flag ("time switch"), &Quot; IOD switch ").

In order to reduce the data capacity of the RDS signal cycle group, that is, the amount of data for each satellite PRC data and RRC data for 37 bits, the standardized data format of the GPS correction values (the standard for the differential GPS service initially discussed) And check words (ferries). The check words (ferrites) of the RTCM standard are easily omitted because the RDS data format already includes format property check words in data blocks shorter than two long data blocks each. However, the omission of the header includes a consecutive transfer disclaimer of information (modified Z count) that takes into account the calculated moments of correction for all GPS satellites. In order to assign a correction value in terms of time in spite of such abandonment, the present invention provides that the PRC data is recalculated in the computer 60 (Fig. 2) at the last minute with the aid of the RRC data. This is illustrated by the following example:

At the moment 12:01:11, the Z count has a value 71 (60 seconds plus 11 seconds after the moment 12:00:00), the PRC value is estimated at +10.32 m, the RRC value is +0.98 m / s Respectively.

In the change ratio (RRC value) of +0.98 m / s, the inverse calculation (Z count with value 60) for the moment 12:01:00 is obtained by multiplying the PRC value of -0.46 m (+10.32 m minus 0.98 m / sx 11s) ≪ / RTI >

The recalculated PRC data is transmitted along with the RRC as the processed correction data 8. The receiver end computer 110 extrapolates the PRC data recalculated with the help of the computer internal Z counter for the associated RRC data and instantaneous actual values. This is illustrated by the following examples.

The extrapolation method for the moment 12:01:12 (Z count with value 72) at + 0.980 m / s change ratio (RRC value) is +11.30 m (-0.46 m plus 0.98 m / sx 12 s) PRC < / RTI > value).

The time flags (0 = excellent minutes; 1 = the radix) described above are applied to block 40 (< RTI ID = 0.0 > . In addition, the computer internal Z count is synchronized by occasional, for example, 1 to 2 times per minute (modified Z count), and the time information is synchronized with blocks 30 and 40 (Station ID) at a time. In addition, the identification (IOD) (data identification) allows the computer 110 to transfer all of the data and identification to another frequency, which is needed to reconfigure the standardized RTCM modification signal from the partial information arriving at the RDS data stream Blocks 30 and 40 from time to time. The computer 110 easily derives the parity check word of the RTCM modification signal that conforms to the standard and conforms to the standard from the received partial information in accordance with the parity rule relating to the standard and inserting the signal.

By reducing the per-cell modification data to 37 bits, it is possible to transmit all of the satellite's modified data in a single RDS group (37-bit capacity) that reduces from 680 bits to 333 bits (9x37) for 9 satellites, Clear reproducible allocation is achieved with the RTCM data format. Therefore, in the case of transmission disruption, the loss of the RDS group does not mean that all of the nine satellite corrected data are lost as in the above description, but that the correction data for one satellite associated with the disrupted RDS group is lost do.

In this way, the system according to the present invention can achieve significantly improved benefits against transmission confusion.

In order to improve the flow of the transmitted correction data, the PRC and RRC data associated with the remaining satellites are updated in the computer 110 after inserting all PRC and RRC data into the RDS group. In this way, the mean age of the correction data is reduced by at least 遜 compared to the state of the art, wherein the correction data has to be calculated for all satellites with a common moment, and without renewability due to partial insertion into the RDS data stream Should be transmitted.

An additional option for improving the flow of data is to insert PRC data, and the rate of change (RRC) of the data is the same as the RDS data stream having a lower priority than the PRC data where the rate of change (RRC) They remain almost the same. The faster regeneration of the RRC value, which is poorly predicted by the more updated RRC value, further increases the position correction accuracy. To perform the priority control for satellite selection, at least two predictions are calculated for each satellite for a time period of, for example, 20 seconds. One prediction is based on the actual PRC and RRC values, and the other prediction is based on the PRC and RRC values already sent. Some prediction deviations represent errors that may be of a different magnitude for each satellite such that this error magnitude is used as a reference for decisions taking priority.

Claims (8)

(11, 21, 31, 41) for continuously changing the position with respect to the fixed position on the earth and allowing the GPS receiver 120 installed on the moving object 5 to determine its instantaneous position coordinates, (GPS satellites 1, 2, 3, 4) , the system comprises means for determining the position of the moving object (5) Precise position coordinates are operating as a known reference section, determining a continuous error values from the known position coordinates of continuously received GPS signals (12, 22, 32, 42) and the place (6) and fix from the error value data And at least one GPS receiving and processing unit (50) for generating a correction data (7), said correction data (7) A pseudo range correction value (PRC data) valid for the calculation moment, and A value (RRC data) for the instantaneous rate of change of RRC data; At least one radio station (80) having an RDS coder (70) for transmitting the generated correction data (7) as data of a radio data system signal (RDS signal) embedded in a program signal; A radio receiver (90) having an RDS decoder (100) for receiving and decoding an RDS signal provided in moving object (5) and provided with correction data (7); And (7) to a GPS receiver (120) that separates the correction data (7) from the decoded RDS signal and corrects the measurement result according to the correction value (7) installed in the moving object (5) A computer-readable medium having computer- a) the GPS receiver and processing unit 50 is followed by an evaluation device 60, The PRC data calculated at a particular moment is recalculated with the help of the associated change value ratio (RRC data) to the moment of the last total time, For each GPS satellite, discard the header provided in the standard format for the GPS correction signal, insert the recalculated PRC data along with the associated RRC data and the identification of the associated satellite into a single RDS group of RDS signal cycles, b) In the computer 110 arranged after the RDS decoder 100 of the radio receiver 90, the re-computed PRC data is stored in the memory of the RDS decoder 100 with the help of the associated change ratio ratio (RRC data) and computer internal generation time information Extrapolated in real time for each GPS satellite, c) The non-transmitted header is reconstructed from the computer 110 into a check word and successive time information and forms a standardized format of correction data 7 with extrapolated PRC data for each GPS satellite and associated RRC data The system comprising: 6. The system of claim 1, wherein after inserting all processed modified data (8) for the GPS satellite in the RDS signal cycle, the PRC data and the RRC data are updated for all satellites. The system of claim 1 or 2, wherein the evaluating device (60) is adapted to calculate a received GPS signal used by the computer (110) to synchronize the time information (internal Z count) Lt; RTI ID = 0.0 > RDS < / RTI > signal cycle. The system of claim 1 or 2 , wherein the evaluating device (60) is adapted to determine whether the data identification information is derived from a received GPS signal used by the computer (110) to reconstruct the normalized corrected data (7) And inserts data identification information (IOD) into the group of RDS signal cycles from time to time. (Correction) The apparatus of claim 1 or 2 , wherein the evaluation device ( 60 ) continuously determines, for each GPS satellite, the precise range in which the last rate of change transmitted as RRC data matches the actual rate of change value And inserts correction data for the satellite that sub-matches the actual data change on the priority reference compared to the correction data for the satellite that top-matches the rate of change to the RDS signal cycle for priority control. (Correction) position search and navigation satellite (GPS) which continuously changes the position in relation to the fixed point on the earth and sends out a GPS signal which causes the GPS receiver 120 installed on the moving object 5 to determine the instantaneous position and the altitude coordinate In the receiving apparatus for determining the position of the moving object 5 with the aid of the GPS satellite, the receiving apparatus not only has a value (RRC data) for the rate of change of the PRC data, but also a pseudo range correction value PRC Data), and the correction data is transmitted as data of a radio data system signal (RDS signal) embedded in a radio program signal, An apparatus (90, 100) for continuously receiving and decoding an RDS signal provided with correction data, and And a computer for separating correction data from the decoded RDS signal and supplying correction data to a GPS receiver (120) installed on the moving object (5), the GPS receiver corrects the measurement result according to the separated correction data A receiving apparatus for positioning a movable object, comprising: For the evaluation of the processed correction data 8, the PRC data calculated at a particular moment is again calculated with the help of the relevant ratio of the change value (RRC data) to the final total time moment, a) the re-computed PRC data is extrapolated in real time for each GPS satellite with the help of the associated change value ratio (RRC data) and computer internal generation time information (internal Z count) b) a non-transmission header provided in a standardized format for the correction data is reconstructed into a check word and successive time information and forms a standardized format of correction data together with extrapolated PRC data and associated RRC data for each GPS satellite And wherein the receiving device is designed to be configured to transmit the received signal. 7. The method of claim 6 wherein the time information derived from the GPS signal, sometimes inserted and received in the group of RDS signal cycles, is used by the computer (110) to synchronize internal generation time information / RTI > (Correction) of claim 6 or claim 7, wherein in order to reconfigure the associated data (7) from time to time into the group of the RDS signal cycle and identified data derived from the received GPS signal information (IOD) is consistent with the standard Is used by the computer (110).

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