JP3288589B2 - Differential GPS receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Positioning System) that performs positioning by receiving radio waves from a plurality of GPS satellites.
More specifically, the present invention relates to an apparatus for realizing a differential GPS that obtains GPS error information from a reference station provided at a known point in advance and performs more accurate positioning.

[0002]

2. Description of the Related Art GPS technology for determining the position of a user by measuring the distance between each satellite and the user by receiving radio waves from a plurality of GPS satellites is not only related to ships but also recently. It has become popular as a core technology for car navigation systems. However, in this GPS positioning, radio wave delay in the troposphere and the ionosphere, SA
(Selective Availability), the positioning accuracy of which is about 100 meters due to the existence of intentional degradation. GPS is used as a car navigation system especially when entering ships and in urban areas. A problem arises when used. To solve this,
An error between the measured distance based on the delay time of the radio wave between the satellite and the reference station by providing a reference station at a known point in advance, and the geometric distance between the two obtained from the satellite orbit information (ephemeris information) and the known reference station position. Differential GPS (hereinafter, referred to as "DGPS") technology has been drawing attention to improve the accuracy of GPS positioning by calculating the GPS position and distributing it to GPS users.

[0003] Error information in this GPS positioning (hereinafter referred to as "error")
The standard of the data format of “DGPS information” is RTCM (Radio Technical Commission for Marit
RT Service SC-104 (R)
TCM RECOMMENDED STANDARDS
FOR DIFFERENTIAL NAVSTAR
GPS SERVICE DEVELOPED BY
RTCM SPECIAL COMMITTEE N
O. 104), and since this standard has become a de facto industry standard, most DGPS receivers conform to this format. Therefore, in order to realize DGPS positioning smoothly, it is necessary to transmit DGPS information in a data format conforming to RTCM SC-104.

Since a reference station for generating DGPS information is provided at a known point in a good radio wave reception environment, almost all of the satellites located above the horizontal plane become visible satellites, and are transmitted from each of the satellites. We can receive electric wave,
An error between the two is calculated from the measured distance from the received radio wave and the geometric distance calculated from the orbit information of the satellite, and is distributed to each DGPS user as DGPS information. Also, the orbit information (ephemeris information) of such a satellite is included in the radio wave received from the satellite and is updated every certain period (hereinafter, referred to as “ephemeris information”).
"Ephemeris Update"),
The geometric position information of the satellite changes, and as a result, the error information before and after updating the ephemeris, that is, the error information corresponding to the old ephemeris differs from the error information corresponding to the new ephemeris. Since the reference station is in a good location for receiving radio waves from satellites, the reference station does not delay acquiring the new ephemeris from the user when the ephemeris is updated. Then, even when the user obtains the new ephemeris later than the reference station, the reference station distributes error information corresponding to each of the new and old ephemeris so that DGPS positioning can be executed without interruption.

In the above-mentioned RTCM SC-104 standard, when updating ephemeris, first, error information corresponding to the new ephemeris, and then difference information between error information corresponding to the new and old ephemeris (hereinafter referred to as “ error difference ”). In this way, D is transmitted regardless of which new or old ephemeris is used.
GPS positioning can be continued. In other words, if the user has already obtained new ephemeris information,
If only the error information corresponding to the new ephemeris is used and the old ephemeris information is still used, the new ephemeris is used.
By using the error information and error difference information corresponding to the male, error information corresponding to the old ephemeris can be obtained, and in either case, DGPS positioning can be executed. After a certain period of time elapses after updating the ephemeris, only error information corresponding to the new ephemeris is distributed.

[0006] On the other hand, in recent years, FM multiplex broadcasting which provides various services by superimposing digital data on the higher frequency side of the audio band of conventional FM broadcasting has been put into practical use in recent years. The data format used for this is a DARC (DAta Radio Channel) format (DAR
C: registered trademark) , but in DGPS, it is considered that DGPS information from a reference station is also distributed to a car that performs car navigation using the FM multiplex broadcasting.
The data format used for distributing the GPS information is based on the broadcasting technology development council standard “BTAR-003 FM multiplex broadcasting DG
PS data format ".

[0007]

As described above, DGPS
DGPS information from base station to user is RTCM SC-
If the data is distributed using the above data format different from the 104 format, a DGPS receiver conforming to the RTCM SC-104 standard naturally needs to convert received data. In other words, the DARC standard
In the case of distributing the S information, the user who receives it needs to convert data from the DARC standard to the RTCM SC-104 standard. However, the following problems occur when the orbit information of the GPS satellite is updated. Will be.

[0008] In the RTCM SC-104 format, the GPS
When the ephemeris of the satellite is switched, the error information corresponding to the new ephemeris and the error difference information corresponding to the difference between the error information corresponding to the old and new ephemeris are converted to DGPS.
It specifies that it is information. On the other hand, when the DGPS information is distributed using the DARC method using FM multiplex broadcasting, in the DARC method, when the ephemeris is switched, the error information corresponding to the new ephemeris and the old ephemeris are added for a certain period of time. Corresponding error information
Information is transmitted alternately, it is not only necessary to hold past information to detect that ephemeris switching has occurred, but also error information corresponding to old and new ephemeris is alternately transmitted. When being broadcast,
If you start the DGPS receiver apparatus, which of the error information corresponding to the two ephemeris it is impossible to know whether the error information corresponding to the new ephemeris, during that period adapted RTCM SC-104 format DGPS information cannot be generated, and DGPS positioning cannot be performed.

[0009] Even when the ephemeris is received before the update of the ephemeris, the end of the period that is alternately transmitted when the ephemeris is updated is such that the error information corresponding to the new ephemeris is continuously transmitted. However, if only error information corresponding to the old ephemeris cannot be received due to a decrease in reception quality, if it is recognized that the period of alternate transmission has ended, However, if the reception quality is improved and the error information corresponding to the new and old ephemeris can be alternately received again, it may be erroneously recognized that a new ephemeris update has occurred. It is necessary to take some measures to prevent this from happening, which is troublesome.

The present invention has been made in view of the above-mentioned problems in the prior art. Therefore, the ephemeris used for positioning at the time of updating the orbital information of the GPS satellite and the ephemeris of the DGPS information from the DGPS base station correspond to each other without error. It is an object of the present invention to provide a DGPS receiver capable of efficiently acquiring data without causing a malfunction.

[0011]

In order to solve the above-mentioned problems, the present invention provides a method of receiving a radio wave from a plurality of GPS satellites and performing positioning by using a reference station provided at a known point in advance. A differential GPS, comprising: a differential GPS receiver that introduces error information to perform more accurate positioning; and an error information receiver that receives the error information from the reference station, and introduces the error information into the differential GPS receiver. In the receiving device,
The out of the by error information receiver introduces satellite identification number and Effects Meri scan information satellites that use the least positioning from the differential GPS receiver, the error information said error information receiver itself has received The present invention is characterized in that information matching the satellite identification number and the ephemeris information is selected and introduced into the differential GPS receiver.

Further, the present invention is usable Selected introduced the error information as the information that matches the satellite identification number and ephemeris information for satellites that are utilized in positioning even without least in the differential GPS receiver data It is characterized by being converted into a format.

Further, according to the present invention, at the time of GPS positioning in which positioning is performed by receiving radio waves from a plurality of GPS satellites, error information previously determined by a reference station provided at a known point in advance or new error information is obtained.
Indicates the difference between the error information corresponding to the old ephemeris
In differential GPS receiver to perform positioning with higher precision by introducing an error differential information is the error information
Or a temporary storage unit for temporarily storing the error difference information , an information reading unit for reading at least a part of the contents of the information stored in the temporary storage unit, and an error information used for positioning calculation. A first information storage unit and a second information storage unit that perform positioning calculation to calculate position information;
Position a calculation unit, said information held in temporary storage unit a first information storage unit, a first switching unit for switching the introduction destination to be introduced into one of the second information storage unit or the positioning calculation unit A second switching unit that switches an introduction source to introduce one of the information held in the first information storage unit and the second information storage unit into the positioning calculation unit; and the first information. and a storage management unit that manages the storage unit and the information content stored in the second information storage unit, the one o'clock
When the information held in the storage unit is the error information
Stores the error information held in the temporary storage
Introduced into the first information storage unit or the second information storage unit,
The information held in the temporary storage unit is the error difference information
In the case of, the error difference stored in the temporary storage unit is
Minute information is introduced into the positioning operation unit, out of the first information storage unit and the error information retained in the second information storage unit, ephemeris of the satellite to which the differential GPS receiver is used for positioning calculations Error fitting information
An information storage unit holding information is selected by the storage management unit , and the positioning calculation unit performs positioning calculation.

According to the present invention , error information reception
The DARC from the reference station , eg, in DARC format
GPS information is received, and from now on, for example, RTCM
The DGPS information of the SC-104 format is generated and introduced into the DGPS receiver. When the information of the RTCM SC-104 format is generated, first, the DGPS receiver has information about satellites acquired by the DGPS receiver. Get ephemeris information. This ephemeris information is included in the radio waves that the DGPS receiver is receiving from GPS satellites. Since the ephemeris information is distinguished by a number called IOD (Issue Of Data), the DGPS receiver obtains the satellite identification number and IOD of each GPS satellite used for positioning calculation, and obtains this information. The error information receiver uses the RTCM only for the information of the received error information whose satellite identification number and IOD match.
It is converted into SC-104 format error information.

Further, in the present invention , the DGPS receiver temporarily stores input error information (for example, in the RTCMSC-104 format) or error difference information in a temporary storage unit, and at least stores the information type of the information. , Ephemeris information, that is, the IOD and the satellite identification number, are read by the information reading unit, and the information is notified to the storage management unit.
Then, the the difference information erroneous information held in the temporary storage unit, the data already in the same IOD information of the satellite identification number overwrites it, if the first or second information storage unit, unless the While holding the second information storage unit, if the data at that time the second information storage unit is held, it performs this operation it from moving to the first information storage unit. The first and second information storage units each have a sufficient number of storage holding areas, that is, the maximum number of GPS satellites, and the IOD of the information held in each of the storage management areas is the storage management unit. Registered in. Meanwhile, the or temporary storage information error differential information in the storage unit, when was the information other than the error information such as the reference station operation information, switches the <br/> first switching unit, direct positioning operation unit Will be introduced. The positioning calculation unit needs the error information every time the positioning calculation is performed. Each time, the positioning calculation unit introduces error information that matches the IOD of the satellite used for the positioning. In other words, that the storage management unit notifies the satellite identification numbers and IOD, the know desired error information is in the first, one of the information storage section of the second, switching the second switching unit Is realized by:

[0016]

FIG. 1 is a block diagram showing an outline of an embodiment of a DGPS receiving apparatus according to the present invention. In FIG. 1, a DGPS receiving apparatus 1 includes an error information receiver 3 that receives DGPS information A in DARC format from a reference station, and an RTCMSC-
The DGPS receiver 2 performs DGPS positioning by introducing DGPS information B in the 104 format. Since the DGPS receiver 2 outputs the positioning calculation result as the position information D, the DGPS receiver 2 operates as a navigation device by superimposing this information on, for example, map information stored in a CD-ROM on a display device (not shown).

In the error information receiver 3, the DARC format DGP
When the RTCM SC-104 format DGPS information B is generated from the S information A, the positioning information C including the satellite identification number and the ephemeris information (IOD) of each satellite used by the DGPS receiver 2 for positioning at the time is described above. By introducing from the DGPS receiver 2, information matching the positioning information C is selected from the DARC-format DGPS information A and R
Generates DGPS information B in TCM SC-104 format.
At that time, ephemeris is updated and DARC format DGP
Even if the S information A transmits the error information corresponding to the new and old ephemeris alternately, the error information receiver 3 uses the two pieces of information to correspond to the error information corresponding to the new ephemeris and the new and old ephemeris. Instead of generating two pieces of error difference information indicating a difference between the pieces of error information, only the error information corresponding to the ephemeris used by the DGPS receiver for positioning at that time is created.

FIG. 2 is a block diagram schematically showing an embodiment of the DGPS receiver according to the present invention. In the embodiment of FIG. 2, the receiver includes a temporary storage unit 20,
A first switching unit 22 for switching which information stored in the temporary storage unit 20 is introduced into the first information storage unit 24, the second information storage unit 25, or the positioning operation unit 27;
A second switching unit 26 that switches which of the information held in the first and second information storage units 24 and 25 is to be introduced into the positioning calculation unit 27; It comprises a satellite identification number of information held in the information storage units 24 and 25, and a storage management unit 23 having an IOD table. Input RTCM SC-104 format DG
The PS information is held in the temporary storage unit 20, and the information reading unit 21 reads the information type of the DGPS information, the satellite identification number and the IOD included in the DGPS information, and notifies the storage management unit 23. Here, the storage management unit 23 is a temporary storage unit.
If erroneous difference information information held in the 20, the information is already first matching notified satellite identification number and IOD, if it is held in the second one of the information storage unit 24, it Is returned to the information reading unit 21, and in response, the information reading unit 21 switches the first switching unit 22 to overwrite the information.

The information corresponding to the notified satellite identification number and IOD is stored in any of the first and second information recording sections 24 and 25.
Even if it is not held, it switches the first switching unit 22 so as to hold the information of the temporary storage unit 20 in the second information storage unit 25. If error information of a different IOD is already stored in the second information storage unit 25, the above operation is performed after moving the error information to the first information storage unit 24.

When the IOD stored in the first and second information storage units 24 and 25 changes, the contents are notified to the storage management unit 23. The temporary storage unit 20
Is not error information, but error difference information.
If was broadcast and other information, the so information reading unit 21 the information is introduced into the positioning operation unit 27 first
The switching unit 22 is switched.

When the positioning calculation unit 27 performs positioning calculation, DGPS information is required. Therefore, the positioning calculation unit 27 stores the satellite identification number and IO of the satellite required for positioning in the storage management unit 23.
Notify D. The storage management unit 23 stores the information in the first,
Information on which of the second information storage units 24 and 25 is stored is returned, and upon receiving the information, the positioning calculation unit 27 returns to the second information storage unit 24 or 25.
Switch unit 26 to obtain desired information.

[0022]

Effect of the present invention : The ephemeris of the error information in the RTCM SC-104 format output from the error information receiver always matches the ephemeris used for positioning by the DGPS receiver. Does not need to generate error difference information that is difference information between error information corresponding to new and old ephemeris even when ephemeris is updated. Further, since it is sufficient generating select information that matches the ephemeris utilizing the positioning of introducing the DGPS receiver, is either if the erroneous difference information that corresponds to the new and old ephemeris in DARC format is transmitted alternately There is no need to recognize which is the old ephemeris in the new ephemeris, and even when the device is started during the transmission being performed alternately or when information cannot be continuously received due to reception quality, the RTCM SC-104 can be surely performed. Format data can be generated. Also, in order to obtain the satellite identification number from the DGPS receiver in order to check the coincidence of the IODs, it is only necessary to generate data for the satellites actually used by the DGPS receiver for positioning, which is efficient.

Further advantage of the present invention : Difference information is not required for error information to be introduced. Therefore, even if ephemeris is updated, even if error information corresponding to two ephemeris is transmitted in the DARC format, the error information is not the error difference information but the RTCM SC-104.
Since the data may be converted into the format, the algorithm for data conversion can be simplified. In this case, the DGPS receiver does not need to perform any communication with the outside. Book D
The GPS receiver uses RTCM SC-
Even if error information at the time of ephemeris update is input in the 104 format, it operates normally, and therefore has high versatility.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of an embodiment of a DGPS receiving apparatus of the present invention.

FIG. 2 is a block diagram schematically illustrating an embodiment of a DGPS receiver according to the present invention.

[Explanation of symbols]

A: DARC format DGPS information, B: RTCM SC-
104 format DGPS information, C positioning information, D positioning result, 1 DGPS receiving device, 2 DGPS receiver, 3
.. Error information receiver, 20 temporary storage unit, 21 information reading unit, 22 first switching unit, 23 storage management unit, 24 first information storage unit, 25 second information storage unit 26 ... second
Switching unit, 27 ... positioning calculation unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-278360 (JP, A) JP-A-6-342054 (JP, A) JP-A-8-292247 (JP, A) JP-A-8-278 327719 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 5/00-5/14 G01C 21/00-21/24 G01C 23/00-25/00 G04G 5/00 -7/02 G08G 1/00-9/02 H04B 7/14-7/195 H04B 7/22 JICST file (JOIS)

Claims (1)

(57) [Claims] At the time of GPS positioning for performing positioning by receiving radio waves from a plurality of GPS satellites, error information determined by a reference station provided at a known point in advance or new and old ephemeris
Differential G for performing positioning with higher accuracy by introducing error difference information indicating a difference between the error information corresponding to
In the PS receiver, the error information or the error difference
A temporary storage unit for temporarily storing minute information , an information reading unit for reading at least a part of the content of the information stored in the temporary storage unit, and a first storage unit for storing error information used for positioning calculation. an information storage unit and the second information storage unit, measuring
A positioning calculation unit for performing position calculation and calculating position information; and storing the information held in the temporary storage unit in the first information storage unit.
A first switching unit for switching the introduction destination to be introduced into one of the second information storage unit or the positioning calculation unit, one held in the first information storage unit and the second information storage unit a second switching unit for switching the introduction source in order to introduce the information to the positioning calculation unit, a memory management unit for managing the first information storage unit and the information content stored in the second information storage unit Which is stored in the temporary storage unit.
If the obtained information is the error information, the temporary storage unit
The error information held in the first information storage unit or
Introduced to the second information storage unit, while stored in the temporary storage unit
If the held information is the error difference information,
The error difference information held in the temporary storage unit is stored in the positioning
Into the first information storage unit and the second information storage unit.
Of the error information stored in the information storage section of the diffusion <br/> Arensharu GPS receiver holds the error information matches the ephemeris information of the satellite is used for positioning calculations
The information storage unit is selected by the storage management unit , and the positioning is performed.
A differential GPS receiver characterized in that a positioning operation is performed by an operation unit .