KR100570710B1 - High Precision Position Correction Information Transmission Method, Transmission System and Receiver using FM Broadcasting - Google Patents

Abstract

In order to improve the technical quality compared to other commercial wireless networks such as wireless data and to use DGPS services at low cost, the RTCM SC-104 code, which is the correction information for DGPS, is formatted to be suitable for the FM DARC scheme. In order to transmit the DGPS correction information by a transmission method that converts the FM DARC receiver into an RTCM SC-104 compatible code, only a facility for adding data to the FM broadcast covering the whole country is added. There is no enormous cost to construct a separate nationwide wireless network, and it does not take network construction time that usually takes more than a few years, and broadcasts with high quality VHF, optimal transmission station location, and powerful output. Receive rate can be maintained, especially 24 hours broadcast DGPS day without any additional transmission request Not only is it possible to receive, but all receivers can receive the same data at the same time without limiting the number of receivers, and it adds data to the existing FM broadcast signal, so there is no extra transmission cost, so there is no burden of service fee. The receiver also adds a decoder part for data reception to an easy-to-use FM receiver, thereby enabling a low-cost receiver.

Description

High Precision Position Correction Information Transmission Method and Transmission System Using FM Broadcasting, Receiver

The present invention provides a DGPS (differential GPS) code, which is a high-precision position correction information for correcting position information errors due to various sources of error, such as a selectable availability (SA) error of a global positioning system (GPS), which is a positioning system using a satellite. The present invention relates to a transmission system, and more particularly, to a method of transmitting a DGPS code using FM broadcasting, a transmission system, and a receiver for transmitting and receiving the same.

It was a long dream for passengers to know where they are currently driving on a mobile chain car. The navigation system was developed in the early 80's for this purpose, and the navigation system loads the map data on the screen, and measures the driving direction with the gyro sensor and the driving distance with the wheel sensor. It was a way of marking with a bright point.

In addition, with the development of satellite communication technology, GPS has been developed to measure the arrival time of radio waves emitted from satellites and to calculate the position of the vehicle by calculating the distance from the satellite. One is done by the principle of triangulation.

However, the position coordinate acquired by the GPS receiver has an error of up to 100 meters due to various sources of error such as SA. In order to overcome this error, various correction methods (DGPS; differential GPS) are used. That is, the DGPS receiver receives the DGPS information through the downlink from the DGPS reference station by performing an uplink requesting the DGPS data to the DGPS reference station through a commercial wireless communication network, and then transmitting the DGPS information to the GPS receiver. Is authorized. Then, the GPS receiver corrects an error of up to 100 meters existing due to various sources of error such as SA to about 1 meter to 10 meters according to the DGPS information to indicate the exact position of the moving object.

However, such a correction scheme usually requires an uplink that requires data in a commercial wireless communication network, and thus receives the requested data through the downlink, resulting in a time delay and a burden of transmission charges. The number of receivers that can be limited is limited.

In addition, in the case of a commercial wireless communication network used for such a correction method, a large number of relay base stations are required to cover a large area with a small cell radius. Since the frequency band is high from several hundred KHz to several GHz, propagation characteristics such as diffraction are high. Not only is it vulnerable, but it is also necessary to transmit data one-on-one or broadcast using short message service (SMS), but in this case, the amount of data that can be transmitted is limited and the cost of the call channel is increased. Done.

The present invention has been made to solve the above problems, the object of which is to improve the technical quality compared to using other commercial wireless communication network, such as wireless data, and to transmit and receive a transmission scheme that can use the DGPS service at a low cost To provide a transmission system and a receiver for.

In order to achieve the above object, the present invention is to format the RTCM SC-104 code, which is the correction information for DGPS to suit the FM DARC scheme, and converts it into a RTCM SC-104 compatible code in the FM DARC receiver By the DGPS correction information.

In the above, the DGPS correction information is inserted into the first two packets of the DARC frame having the 16-bit prefix and the 160-bit data block, respectively. The content of the DGPS correction information data includes a data head having 24 bits of the first data block. 16 bits of CRC end code at the end of the second block, and 280 bits of data code for transmitting 35 bits of information per satellite, and the data head includes all messages defined in the RTCM SC-104. Of the two word information appearing in the first part of the format, it consists of a 6-bit message type code, a 13-bit message information reference time code, and a 5-bit frame size code to indicate the contents of 1 and 2 of the RTCM message. The 35-bit data code for each satellite is the error correction information which is the core among the 40-bit DGPS information for each satellite provided by the RTCM SC-104. 1 and 2 messages are abbreviated, and the precision is set to be 0.08 meters in PRC and 0.004 meters in RRC, and the encoding is performed. The information of the RTCM SC-104 omitted from the data head is zero. Where the first 8-bit preamble is replaced with a value of 0x66 defined in RTCM SC-104, and the information for each satellite provided by RTCM SC-104 omitted in the data code is replaced by 0. It is characterized by encoding and decoding by a Hamming code defined in GPS-200.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

First, a high-precision location information transmission method using FM broadcasting according to the present invention will be described with reference to FIGS. 1 to 7.

In the present invention, the DARC method is adopted among the FM additional broadcasting, and another FM additional broadcasting method may include a RDS (radio data system). Both methods transmit digital data to existing FM broadcasts, but the transmission rate is 1187.5 bps for RDS, but DARC is more than 12 times higher at 16 kbps. In particular, in the DARC method, data levels are linked (LMSK; level controlled MSK) according to the level of the audio (L-R), which is an effective method for reducing audio quality and data error rate by minimizing interference between audio and data. In addition, the error correction method is an efficient method for recovering an error that may occur when a mobile signal is received or when a received signal is weak by using the "(272, 190) product code method".

The data transmitted by the FM information broadcasting system is sub-modulated at a data rate of 16 kbps by using a minimum minimum shift keying (LMSK) modulation method as shown in FIG. 1 with 76 KHz as the center frequency.

Particularly, in the present invention, the RTCM SC-104 code or ASCII (ASCII) type information, which is the position correction information for DGPS, is formatted to be suitable for the FM DARC scheme, and is converted to the RTCM SC-104 compatible code by the FM DARC receiver receiving the same. It is possible to correct the GPS error of up to 100 meters to 1 to 10 meters class, this format is defined as DARC / KDGPS (korea DGPS) format.

DARC / KDGPS complies with the ITU-R 807 system specification, which is the international recommendation of DARC. In addition, as shown in FIG. 2, only two packets of packets which are basic units in OSI layer 2 (DARC frame), which is the "(207, 190) red code method" defined in the ITU-R 807 system standard, are used. It is inserted into the first 2 packets of the frame and is defined as a KDGPS packet.

The DARC / KDGPS packet for applying the DGPS position correction information to the FM DARC scheme recommended in ITU-R 807 is configured as shown in FIG. 3 (OSI layer 3). This is a 176-bit information part except for the 16-bit cyclic redundancy check (CRC) code, which checks whether the 82-bit row parity code and the data group have been correctly received after error correction decoding by short-set set cyclic code. It consists of a prefix and a 160-bit data block. At this time, the data packet of the KDGPS information in the DARC frame is separated by the service identification code in the prefix configured as shown in FIG.

Data group for KDGPS (OSI layer 4) is composed of two data blocks (KDGPS packet 1, KDGPS packet 2), as shown in Figure 4, the data block of the KDGPS format is defined to have 160 bits, so a total of 320 bits of data Has At this time, the contents of the data are the data head occupying 24 bits of the first data block (KDGPS packet 1), the 16-bit CRC end code and the two data blocks (KDGPS packet) coming from the end of the second data block (KDGPS packet 2). It consists of 280-bit KDGPS data codes occupying 1, 2).

The data head appears at the head of the first data block (KDGPS packet 1) in the KDGPS format data packet and occupies 24 bits. And, as shown in Fig. 5, the data head is a 6-bit message type required for the KDGPS format among two word (60 bits total; 30 bits / word) information appearing at the beginning of all message formats defined in the RTCM SC-104, 13 bits of modified Z-count and 5 bits of Length of frame can be encoded in total of 24 bits. That is, among the types and sizes of information indicated by the two words corresponding to the header of the RTCM SC-104, as shown in Table 1 below, only information necessary for restoring the RTCM SC-104 code by the FM DARC receiver is selected. To the header of the DGPS packet.

[Table 1] Header information (unit; bit) of RTCM SC-104 and DARC / KDGPS

RTCM SC-104 DARC / KDGPS Preamble 8 x Message type 6 6 Station ID 10 x Modified Z-count 13 13 Sequence No. 3 x Length of frame 5 5 Station health 3 x Parity 12 x sum 60 24

At this time, as shown in Table 1, the header information of DARC / KDGPS includes 8-bit preamble and 10-bit Station ID, 3-bit Sequence No., 3-bit Station Health, and 12 in the header information of the 60-bit RTCM SC-104. The parity of the bits is omitted to be 24 bits.

[Table 2] RTCM message types and contents

Message type number condition Contents One Fixed differential GPS corrections 2 Fixed delta differential GPS corrections 3 Fixed reference station parameters 4 Retired surveying 5 Fixed constellation health 6 Fixed null frame 7 Fixed beacon almanac 8 Tentative pseudolite almanac 9 Fixed partial satellite set differential corrections 10 Reserved P-code differential corrections (all) 11 Reserved C / A-code L1, L2 delta corrections 12 Reserved pseudolite station parameters 13 Tentative ground transmitter parameters 14 Reserved surveying auxiliary message 15 Reserved ionosphere (troposphere) message 16 Fixed special message 17 Tentative ephemeris almanac 18 Tentative uncorrected carrier phase measurements 19 Tentative uncorrected pseudorange measurements 20 Tentative RTK carrier phase corrections 21 Tentative RTK pseudorange corrections 22-58 - undefined 59 Tentative propriety message 60-63 Reserved multipurpose usage

The Message type is the DGPS message type, and the format is defined in RTCM SC-104. Type numbers are defined from 1 to 63, and each message has a status of fixed, tentative, reserved, undefined, and retired. Table 2 shows the types and contents of RTCM messages, and DARC / KDGPS transmits message information 1 and 2 of them.

The modified Z-count indicates a reference time of the message information, and means a start time of the next message when transmitted from a pseudo signal generator. This information differs in the Z-count and scale of the GPS signal (RTCM; 0.6 seconds, GPS; 6 seconds) because it takes into account the variable length of RTCM information. In addition, the length of frame represents the frame size of the RTCM message, the unit is a word (30 bits) used in the GPS signal system.

The KDGPS data code, which occupies 280 bits of the data block of the DARC / KDGPS packet, abbreviates and transmits messages 1 and 2, which are key error correction information (Table 2), among the DGPS information provided by the RTCM SC-104. It is set to. RTCM SC-104 transmits 40 bits of information per satellite, but DARC / KDGPS sets 35 bits per satellite as shown in FIG. 6 to provide 280 bits of information of up to 8 satellites. At this time, data is loaded by the number of satellites provided with error correction information, and other data is replaced with a FILL code filled with bits of 1 and 0 repeated, and each 35-bit data code is configured as shown in FIG. 7. In addition, the types and bit sizes of the DGPS information provided in messages 1 and 2 of the RTCM SC-104 and the information and the number of bits used in the DARC / KDGPS format are shown in Table 3 below. In this case, KDGPS omits two bits of user differential range error (UDRE) from 40-bit RTCM SC-104, two bits from pseudorange corrections (PRC), and one bit from rangerate corrections (RRC) to 35 bits. do. The precision is set to 0.08 meters for PRC and 0.004 meters per unit time (sec).

RTCM SC-104 Precision KDGPS Precision Scale factor One One UDRE 2 x Satellite ID 5 5 PRC 16 0.02m 14 0.08m RRC 8 0.002 m / s 7 0.004 m / s IOD 8 8 sum 40 35

When the DARC / KDGPS format is converted from the FM DARC receiver to the RTCM SC-104 compatible code, the following format is used.

Station ID, Sequence No., and Station Health, which are omitted in the two headers (60 bits) appearing as headers in all messages of RTCM SC-104, are replaced with 0, and the first 8 bits, Preamble, are defined in RTCM SC-104. To a value of 0x66 (Table 1).

In addition, of the total 40 bits of information about each satellite transmitted in message 1 and 2, the omitted information UDRE (2 bits) is replaced with 0, and 2 bits and 1 bit respectively omitted in PRC and RRC are also replaced. Replace with 0 (Table 3).

In addition, the DGPS information type received at the FM DARC receiver and added with the omitted information is encoded by the "hamming code" defined in ICD-GPS-200 and reduced to the information of the original RTCM SC-104 format. .

8 and 9 illustrate a transmission system and a receiver for transmitting and receiving high-precision location information using FM broadcasting in this manner.

First, in order to transmit the DGPS correction information, as shown in FIG. 8, the DGPS reference station 1 transmits the RTCM SC-104 code, which is the DGPS correction information for correcting the position error of the GPS, and transmits the FM DARC server ( 2) receive it in real time. Then, the FM DARC encoder 3 encodes the DGPS correction information of the RTCM SC-104 code received in real time to the FM DARC server 2 in accordance with the above-described scheme and formats the DARC / KDGPS data to be suitable for the FM DARC scheme. Make up. Subsequently, the stereo generator 4 performs DARC / KDGPS coded by the FM DARC encoder 3 by LMSK modulation using a center frequency of 76 KHz within the FM baseband of the audio signal simultaneously with the modulation of the audio signals L and R. Is sub-modulated at a data rate of 16 Kbps to generate a stereo signal, and the microwave transmission encoder 5 encodes the stereo signal and transmits it to each transmission station in the country as microwave (M / W). Then, the microwave reception decoder 6 of each transmitting station decodes the stereo signal from the received microwave (M / W) signal, modulates the stereo signal in the FM generator 7 to generate an FM broadcast signal, and then R / F. The amplifier 8 amplifies the signal and transmits the FM broadcast of airwaves.

In this state in which DGPS correction information is transmitted through the FM broadcast, DARC / KDGPS transmitted through the FM additional broadcast in the FM tuner 11 receiving the FM broadcast as shown in FIG. Upon receiving the signal, the FM DARC decoder 12 decodes the DARC / KDGPS signal received through the FM tuner 11 and converts it into a DGPS correction information signal of RTCM SC-104 compatible code. Then, the DGPS module 13 corrects the GPS position information of the maximum 100-meter error received through the GPS receiving module 14 of the moving object by the DGPS correction information signal received from the FM DARC decoder 12, so that the user is presently present. The position of the moving body can be confirmed within an error range of 1 meter to 10 meters.

As such, the present invention uses the existing FM broadcasting covering the whole country, and since only a facility for adding data to it is added, the enormous cost for establishing a separate nationwide wireless network and a network construction period that usually takes several years or more Because it broadcasts with high quality VHF (88-108MHz), optimal transmitting station location, and powerful output, it has good radio wave characteristics, so it can maintain excellent data reception rate on the move. Not only is it possible to receive DGPS data at any time, but all receivers can simultaneously receive the same data without limiting the number of receivers, and it adds data to the existing FM broadcast signal. The receiver also has a decoder section for receiving data in an easy-to-use FM receiver. In addition, low cost receivers can be implemented.

1 illustrates baseband frequency spectrum and DARC data of an FM broadcast;

2 illustrates an insertion position of a KDGPS packet according to a frame configuration of ITU R-807 according to the present invention;

3 illustrates a prefix configuration of a DARC / KDGPS packet according to the present invention,

4 illustrates a data block of a KDGPS packet according to the present invention;

5 illustrates a configuration of a KDGPS data head according to the present invention.

6 illustrates a DARC / KDGPS data code according to the present invention,

7 shows a configuration of a KDGPS data code according to the present invention,

8 is a block diagram showing a high-precision location information transmission system using FM broadcasting according to the present invention,

9 is a block diagram illustrating a high-precision location information receiver using FM broadcasting according to the present invention.

Claims (3)

In the high-precision location information transmission method using the FM broadcasting to format the RTCM SC-104 code, which is the correction information for DGPS, to conform to the FM DARC method, and converts it into an RTCM SC-104 compatible code in the FM DARC receiver. The DGPS correction information is inserted into the first two packets of a DARC frame having a 16-bit prefix and a 160-bit data block, respectively. The contents of the DGPS correction information data include a data head having 24 bits of the first data block, 16-bit CRC end code at the end of the first block, 280-bit data code for transmitting 35 bits of information per satellite, and the data head is composed of all message formats defined in RTCM SC-104. Of the two word information appearing at the beginning, 6-bit message type code, 13-bit message information reference time code, and 5-bit frame size code for indicating the contents of 1 and 2 of the RTCM message are composed. The 35-bit data codes for satellites are the error correction information 1 and 2, which are the core of the 40-bit DGPS information for each satellite provided by RTCM SC-104. And to transmit a message digest, accuracy and PRC is encoded set to be 0.08 meters, per unit time, RRC is 0.004 meters, In the encoding, the information of the RTCM SC-104 omitted from the data head is replaced with 0, and the first 8-bit preamble is replaced with a value of 0x66 defined in the RTCM SC-104, and the RTCM SC- omitted from the data code. The high-precision location information transmission method using FM broadcasting, which replaces the information about each satellite provided by 104 with 0 and encodes and decodes by a Hamming code defined in ICD-GPS-200. In the FM DARC transmission system in which the base frequency is 76KHz in the FM baseband by sub-modulation at 16Kbps data rate by the LMSK modulation method, It includes an FM DARC encoder for formatting the RTCM SC-104 code, which is the correction information for DGPS of the DGPS reference station received through the FM DARC server, to be suitable for the FM DARC method. The FM DARC encoder inserts correction information for DGPS into the first two packets of a DARC frame having a 16-bit prefix and a data block of 160 bits, respectively, and the contents of the correction information data for DGPS have 24 bits among the first data blocks. A data head, a 16-bit CRC end code at the end of the second block, and a 280-bit data code for transmitting 35 bits of information per satellite, and the data head is defined in RTCM SC-104. 6-bit message type code, 13-bit message information reference time code, and 5-bit frame size code to indicate the contents of 1 and 2 of the RTCM message among the two word information appearing at the beginning of every message format. The 35-bit data code for each satellite is the core of the 40-bit DGPS information for each satellite provided by the RTCM SC-104. And to transmit the correction information of the short messages 1 and 2, the accuracy is PRC is 0.08 m, RRC is a high-precision position information transmission system using the FM broadcast, characterized in that for encoding the set so that per unit time is 0.004 meters. In the DGPS module for correcting the position error of the GPS received by the GPS receiving module according to the received DGPS correction information, Includes an FM DARC decoder for converting the DARC method DGPS correction information of the FM additional broadcasting received through the FM tuner to RTCM SC-104 compatible code and transmits it to the DGPS module, The FM DARC decoder replaces the information of the RTCM SC-104 omitted from the data head of the DARC type DGPS correction information data with 0, and replaces the first 8-bit preamble with a value of 0x66 defined in the RTCM SC-104. High-precision positional information using FM broadcasting, characterized in that the information about each satellite provided by the RTCM SC-104 omitted from the data code is replaced with 0 and encoded and decoded by the Hamming code defined in the ICD-GPS-200. receiving set.