KR19990015845A - DGPS Implementation Using Multiple Reference Stations - Google Patents

Abstract

The present invention relates to a method for implementing DGPS (Differential Global Positioning System), and to providing a more accurate and stable position measurement by using a plurality of reference stations by using position error correction information generated from multiple reference stations. It is about. The present invention includes a plurality of reference stations that receive a signal from a GPS satellite to produce a position error correction value, and obtains a user's position using the position error correction values generated by the plurality of reference stations. It provides a method for implementing DGPS using stations, which entails improving the accuracy, stability, economics and efficiency of the system compared to a single reference station DGPS system.

Description

DGPS Implementation Using Multiple Reference Stations

The present invention relates to a method for implementing DGPS (Differential Global Positioning System), and to providing a more accurate and stable position measurement by using a plurality of reference stations by using position error correction information generated from multiple reference stations. It is about.

GPS (Global Positioning System) is a new satellite navigation system developed for military use by the US Department of Defense. It uses 24 GPS satellites.Precise Positioning Service (PPS) using P code for military use is 16m. Standard Positioning Service (SPS) using the allowed C / A code has a positioning accuracy of 100 m. However, this degree of accuracy does not meet the positional accuracy required for various applications.

Various methods have been developed to obtain more accurate location information, and DGPS has emerged as the most widely used method. 1 illustrates a typical configuration of a conventional DGPS system. DGPS calculates an error component in pseudorange measurements based on information sent from the current satellite (3) at a reference station (1) whose location is known and informs the surrounding user (5) for improved location. It is a navigation system that enables the decision. The DGPS system compares its own position pre-measured at the reference station (1) with the position calculated by receiving the GPS signal, calculates the position error correction message by the GPS signal at that moment, and transmits the correction information. It is then transmitted to the receiver in the RTCM (Radio Technical Commission for Maritime Services) format to reflect the position calculation to calculate a more accurate user position than otherwise.

This process involves several error factors included in the GPS signal: GPS satellite orbital error, GPS satellite clock error, ionospheric delay error and tropospheric delay error that occur when the GPS signal passes through the ionosphere and troposphere, multipath error, and receiver noise error. The error except the multipath error and receiver noise error is considered as common error between the reference station and the user.

However, if the distance between the DGPS reference station and the user increases (typically 100 km or more), the common properties of the errors that were considered as common errors become less and less, and the DGPS effect is lost. This limiting factor acts as a limiting factor in the area (service area) that a DGPS reference station can cover. When using DGPS consisting of a single reference station, the area is not as large as in Korea, but there is a limit to guaranteeing a certain degree of error in mountainous terrain. In addition, such a single DGPS reference station system has a problem that it is very difficult to overcome when a problem occurs in the reference station upon which the user depends.

An object of the present invention is to provide an optimal DGPS implementation method in consideration of the above-mentioned conventional problems, further expanding the service range while minimizing the positioning error, and considering the specificity of the region and the stability of the communication network.

In order to achieve the above object, the present invention improves accuracy by installing multiple reference stations instead of using a single reference station, thereby increasing accuracy and providing service without interruption even if a problem occurs in one reference station. It provides a DGPS implementation method that can provide a.

1 is a configuration diagram of a conventional DGPS system using a single reference station;

2 is a configuration diagram of an embodiment of a DGPS system using multiple reference stations according to the present invention;

3 is a configuration diagram of another embodiment of a DGPS system using multiple reference stations according to the present invention;

4 is a diagram illustrating an embodiment in which a multi-reference station used in a DGPS system according to the present invention is applied to a Korean terrain.

* Description of the symbols for the main parts of the drawings *

1,2a, 2b, 2c, 4a, 4b, 4c: DGPS reference station

3: GPS satellite 4: Central control station

5: user

The present invention includes a plurality of reference stations that receive a signal from a GPS satellite to produce a position error correction value, and obtains a user's position using the position error correction values generated by the plurality of reference stations. It provides a DGPS implementation method using a station.

When two adjacent GPS receivers receive a signal from the same satellite and calculate their position, each receiver has its own inherent error and common error. It is more accurate to remove the common error and measure the position more precisely. This is the basic concept of DGPS. However, there are some limitations here. First, as the distance of the baseline increases, the assumptions of common error have different values. This is largely due to satellite orbit error, ion-layer delay error, and tropospheric delay error. Therefore, the range in which a single reference station can guarantee an error within a certain degree is limited. Second, there is an error due to propagation delay time that occurs during real-time implementation. The propagation delay time refers to the time it takes for the calibration data generated by the reference station to be used by the user, including software, hardware processing time, transmission time according to the baseline distance, and parity check (check whether the transmitted data is intact). Time followed. In order to solve this problem, a multi-reference station DGPS system capable of receiving correction terms from multiple reference stations is required.

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

The configuration of the present invention is as follows. First, select the location of multiple reference stations and assign unique numbers to the reference stations. Second, analyze the position correction information received from each reference station and select the information of the reference station closest to its own location or It consists of an algorithm to correct the position by multi-processing the information received from the station, synchronization between each reference station, and protocol selection according to the transmission method.

2 shows an embodiment of implementing a DGPS system using the proposed multi-reference station. A plurality of DGPS reference stations (2a, 2b, 2c ...) is a network to transmit the position error correction information calculated at each reference station to the user (5). The method of correcting the position on the user's side (5) is to take the information of the reference station closest to the user from the error correction information received from each reference station (2a, 2b, 2c ...), or to receive the information of all the reference stations. There is a way to correct the position. According to this method, since the position error correction information received from several reference stations is used, it is more accurate than a single reference station DGPS, and unlike a single reference station DGPS, where accuracy decreases when the user is far from the reference station, the multiple reference stations DGPS systems are less affected by this distance.

3 shows another embodiment of a method for implementing DGPS using multiple reference stations according to the present invention. In the DGPS system of FIG. 3, the user does not directly receive position error correction information from several reference stations, but sets one of the multiple reference stations as the central control station 4 so that the reference stations 4a, 4b, 4c, ... The position error correction information from the collections is collected by the central control station 4 and sent back to the user.

There are two methods of transmitting position error correction information collected from various reference stations, which are based on a communication method and a concept of WASS that transmits an error to each user by using a predetermined algorithm. The latter approach can ensure better accuracy.

There may be a variety of communication methods for transmitting the position error correction information of the proposed concept, for example, radio pager, frequency common communication (TRS), wireless data, cellular, personal mobile communication (PCS), multi-purpose low-orbit satellite , Satellite, FM broadcast, VHF and UHF networks.

In areas that are not as large as Korea, but difficult to serve as a single reference station, a multi-reference station DGPS system that considers our regional characteristics is urgently needed to guarantee a certain margin of error throughout the region.

4 shows an embodiment in which the DGPS implementation method using the multi-reference station according to the present invention is applied to Korea. In FIG. 4, five reference stations are selected, but in the future, the addition or reduction of reference stations may be considered for the specificity of the region, the form of the transmission scheme, and the location accuracy. In case of using high-speed pager, each region has a reference station at the wireless pager base station and broadcasts to a pager number unified with a number of the same number through a specific allocated channel, and the user receives it and passes it to the DGPS module to correct the position. can do.

As described in detail above, the DGPS system implementation method using the multi-reference station according to the present invention improves the accuracy, stability, economical efficiency and efficiency of the system compared to a single reference station DGPS system. Therefore, it can be used in a wide range of applications of navigation systems requiring precise accuracy, and the wavelength effect of the industry is great. For example, it has a great business potential as a core technology such as logistics business and Intelligent Transportation System (ITS), which are recently discussed. In addition, a preferred embodiment of the present invention is disclosed for the purpose of illustration, those skilled in the art can be various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications, changes, etc. fall within the scope of the claims Should be seen.

Claims (4)

A plurality of reference stations are provided which receive a signal from a GPS satellite and produce a position error correction value, and obtain a user's position using the position error correction values generated from the plurality of reference stations. How to implement DGPS. The method of claim 1, DGPS using a multi-reference station, characterized in that for transmitting to the user the position error correction information of the reference station that is located closest to the user among the plurality of reference stations. The method of claim 1, Multi-reference, characterized in that any one of the plurality of reference station is set as a central control station to collect the position error correction value generated from the other reference station in the central control station and to transmit the collected correction value to the user DGPS implementation method using station. The method of claim 1, DGPS implementation method using a multi-reference station, characterized in that for transmitting the calculated position error correction value of each of the plurality of reference stations to each user.