JP2003066131A - Navigation system performing dgps navigation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a car navigation system in which DGPS data are received stably and the positioning accuracy can be enhanced continuously. SOLUTION: The car navigation system performing DGPS navigation comprises a digital broadcast receiver and a car navigation unit. The digital broadcast receiver broadcasts video or audio broadcast as main broadcast, receives digital broadcast providing DGPS data including DGPS correction information as data broadcast and delivers DGPS correction data received by a DGPS reference station closest to the current position from the car navigation unit side selectively to the car navigation unit side. The car navigation unit receives the DGPS correction information through a communication interface and enhances the accuracy of positioning operation utilizing the DGPS correction information.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a DGPS (Differ
The present invention relates to a navigation device that uses navigation to improve positioning accuracy.

[0002]

2. Description of the Related Art A GPS receiver receives and tracks a GPS signal, measures the distance between a GPS satellite and the GPS receiver itself (vehicle), and calculates the vehicle position, moving speed, and heading. Perform GPS positioning calculations. GP installed in general car navigation equipment
The GPS signal that can be received by the S receiver is called the C / A code of the L1 frequency (about 1.5 GHz) that is open to the private sector. Here, the GPS signal is converted to GPS
The distance measured by receiving at the receiver is called pseudorange.

It is said that, in GPS positioning using the C / A code, the positioning result can be generally estimated to have an error of about 20 m due to a plurality of error factors.
These error factors include ionospheric delay error, tropospheric delay error,
There are satellite orbit information error, satellite clock error, error due to multipath, error due to thermal noise of GPS receiver, etc. Of these error factors, DGPS removes or reduces pseudorange measurement errors due to ionospheric delay error, troposphere delay error, satellite orbit error, and satellite clock error,
This is a system for improving the positioning accuracy by GPS. As a system for DGPS, for example, DARC
DGPS correction data broadcasting by FM multiplex broadcasting called a (Data Radio Channel) system is known.

FIG. 3 is a diagram showing the concept of DGPS. The reference station 31 is installed at a fixed point whose position is known in detail. Therefore, the reference station 31 includes the reference station 31 and the GPS satellites 3.
It is possible to calculate the distance between the two accurately. The difference between the calculated distance and the pseudo distance measured by receiving the GPS signal at the reference station 31 is an error caused by an error factor to be removed by the DGPS. In the reference station 31, after obtaining this error for a plurality of GPS satellites, D
Converted to a predetermined format as GPS correction data,
It is provided to the user 33 by FM multiplex broadcasting. DG
The effect of using PS depends most on the distance between the reference station and the user, but generally the distance from the reference station is 200
It is estimated to be effective up to about km, and the error in the positioning result after applying DGPS is estimated to be several meters.

FIG. 4 is a block diagram showing the configuration of a car navigation device mounted on the vehicle of the user 33 side (FIG. 3). The car navigation device 20 of FIG.
It is possible to improve the GPS positioning accuracy by providing an RC system FM multiplex DGPS receiver. The operation of the car navigation device 20 will be described with reference to FIG.

The GPS receiver 2 receives and tracks the GPS signal captured by the GPS antenna 5, and GPS positioning for calculating a positioning result including the "position, moving speed, and heading" of itself (own vehicle). The calculation is executed and the calculated positioning result is output as the GPS output message 3. Here, two-dimensional positioning is possible when the number of satellites tracked by the GPS receiver 2 is three, and three-dimensional positioning is possible when the number of satellites is four or more. The data that can be calculated by the two-dimensional positioning is “latitude, longitude”, and the three-dimensional positioning is “latitude, longitude, altitude”. The number of signals (satellite) that can be simultaneously received by the GPS receiver is determined by the number of reception processing units (reception channels) included in the GPS receiver, and a general GPS receiver has 8 to 16 channels.

[0007] The FM multiplex DARC receiver 7 acquires DARC data from multiple channels of FM broadcasting. The DARC data 8 output from the FM multiplex DARC receiver 7 is
NAVI_CPU via I / F (interface) 6
1 is processed and processed into data of only DGPS correction information, and then GPS as one of the GPS input messages 4
It is input to the receiver 2.

The speed pulse 13 is a pulse signal whose frequency changes in proportion to the traveling speed of the automobile. The gyro 12 is a sensor for detecting the angular velocity in the turning direction of the automobile, and outputs a DC voltage according to the angular velocity.
The digital map 11 is a digital map of a map mainly composed of roads, such as a CD-ROM or a DVD-R.
It is recorded in OM.

The NAVI_CPU 1 is a general microcomputer, and has a GPS output message 3, a speed pulse 13, a gyro output 15, and digital map information 1.
Each of the 4 is properly processed to execute software for estimating the current vehicle position, and various processes necessary for car navigation such as calculation of a route from the current position to a destination are performed. GPS receiver 2 is NAV
The positioning accuracy is improved by correcting the measured pseudo distance using the DGPS correction information received from the I_CPU 1. As a result, the accuracy of the vehicle position estimation of the car navigation device as a whole is improved.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
While the car navigation device 20 using DGPS by the system FM multiplexing has an advantage that the positioning accuracy is improved, the FM multiplexing DARC receiver 7 needs to be built in the main body or provided as a separate unit. This is a factor that raises the cost of car navigation systems. In addition, when FM broadcast is received by a mobile body such as an automobile, there is a problem that reception failure easily occurs due to the influence of multipath. In a car navigation device that uses DGPS by the DARC system FM multiplexing, DGPS data may be lost and the accuracy of position estimation may be deteriorated due to the influence of multipath, especially in an urban area.

The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide a car navigation device capable of stably receiving DGPS data and continuously improving positioning accuracy.

[0012]

Therefore, the invention described in claim 1 is a navigation device using GPS as positioning means, which broadcasts video or audio broadcast as main broadcast and DGPS correction as data broadcast. A digital broadcast receiving means for receiving a digital broadcast that provides DGPS data including information is provided. Since this digital broadcast receiving means receives the digital broadcast and acquires the DGPS data, the DGPS data can be stably received as compared with the case where the analog FM broadcast or the like is received.
Further, the navigation device includes a positioning calculation unit that performs GPS positioning calculation using the DGPS correction information acquired by the digital broadcast receiving unit and calculates a positioning result including the current position. Since the DGPS correction information is stably acquired, the positioning calculation means can continuously improve the positioning accuracy.

In this case, the positioning calculation means may perform GPS positioning calculation without using the DGPS correction information when DGPS data is not acquired by the digital broadcast receiving means (claim 2).

The DGPS data provided by the data broadcasting is position data relating to respective positions of a plurality of DGPS reference stations existing in the area where the digital broadcasting service is provided, and each DGPS acquired by the plurality of DGPS reference stations. When including the correction information, the positioning calculation means selects and uses the DGPS correction information regarding the DGPS reference station closest to the current position obtained by the GPS positioning calculation from the DGPS correction information acquired by the digital broadcast receiving means. Is preferred (claim 3). In this case, the DGPS that is closest to the current position and has the highest accuracy
The correction information will be available.

The invention according to claim 4 broadcasts video or audio broadcast as a main broadcast and DGPS as a data broadcast.
A digital broadcast receiver capable of receiving a digital broadcast that provides DGPS data including correction information and outputting the DGPS correction information to the outside, and a car navigation device that performs GPS positioning. The car navigation device side communicates via communication means. It is a system that receives DGPS correction information from a digital broadcast receiver and uses the DGPS correction information to perform GPS positioning calculation to improve positioning accuracy. here,
The digital broadcast receiver is a digital broadcast receiving unit for receiving the digital broadcast, a data processing unit for extracting DGPS data from the received data received by the digital broadcast receiving unit, and an interface for performing data communication with the outside. And a first control means for performing a process of transmitting DGPS correction information of the extracted DGPS data via the interface. Further, the car navigation device receives a GPS signal, executes a GPS positioning calculation and calculates a positioning result including the current position, and a position for estimating the own vehicle position based on at least the positioning result of the GPS positioning means. Communication means for performing data communication between the estimating means and the interface section of the digital broadcast receiver, and DGPS from the digital broadcast receiver via the communication means.
Second positioning means for performing processing for receiving the correction information, and the GPS positioning means receives the DG received by the second controlling means.
GPS positioning calculation is performed using the PS correction information.

[0016] In this case, the DGPS data provided by the data broadcast is the position data relating to the respective positions of the plurality of DGPS reference stations existing in the area where the digital broadcast service is provided, and the plurality of DGPS.
When including the respective DGPS correction information acquired by the reference station, the second control means of the car navigation device further performs a process of sending the current position by the GPS positioning means to the digital broadcast receiver via the communication means. The first control means of the digital broadcast receiver selects, from the DGPS data, DGPS correction information regarding the DGPS reference station closest to the current position based on the current position received from the car navigation device via the interface, and the selection is performed. It is preferable that the DGPS correction information is transmitted via the interface (claim 5). In this case, the GPS positioning means of the car navigation device can use the DGPS correction information that is closest to the current position and has the highest accuracy.

[0017]

1 is a block diagram showing the configuration of a car navigation system 100 as an embodiment of the present invention. Hereinafter, the operation of the car navigation device 100 will be described with reference to FIG.

The GPS receiver 52 mainly down-converts the GPS signal input from the GPS antenna 55 into a digital signal, and uses the down-converted signal to perform correlation processing and PR on the carrier wave.
The NAVI_CP is composed of a reception processing unit that performs a correlation process with respect to an N code (pseudo random code) and a calculation unit that performs a positioning calculation, and the positioning result “own vehicle position, speed, moving direction” as a GPS output message 53.
Send to U51. The NAVI_CPU 51 is a general microcomputer, and the positioning result acquired from the GPS receiver 52, for example, map data from a digital map 61 that is a DVD-ROM, the output of a gyro 62 that is a gyro sensor, and the speed pulse 63 are appropriate. In addition to estimating the current position of the own vehicle, all the processes necessary for the car navigation device such as calculating the route from the current position to the destination are performed.

The digital broadcast receiver 71 is a satellite digital audio broadcast receiver. In satellite digital audio broadcasting,
For example, by using convolutional interleaving and error correction coding, it is considered that a mobile body such as an automobile can stably receive, and compared with the case where the mobile body receives a conventional analog broadcast such as FM system, The reception quality is improved by making it less susceptible to the effects of multipath.

This satellite digital audio broadcasting includes data broadcasting services, and the data broadcasting enables DGPS.
It shall be configured to provide the data. Here, the DGPS data provided by the data broadcast is
It refers to the DGPS data acquired by all the DGPS reference stations in the area where the DGPS broadcasting service is implemented. The DGPS data is a pair of position data (latitude / longitude) of each DGPS reference station and DGPS correction information.

The digital broadcast receiver 71 is constructed so as to be able to obtain DGPS data from a data broadcast that is carried out together with the main broadcast, and is also connected to the NAVI_CPU 51 via an I / F (interface) 56. With the function of data communication. The digital broadcast receiving antenna 72 is an antenna compatible with the above satellite digital audio broadcast.

The NAVI_CPU 51 calculates that it is the car navigation device and the current position (latitude / latitude).
The information about the longitude is put into the control data 24 via the I / F 56 and sent to the digital broadcast receiver 71 by a predetermined communication protocol.

FIG. 2 is a block diagram showing a detailed configuration of the digital broadcast receiver 71. In FIG. 2, the channel selection / demodulation unit 81 performs a process of selecting a signal of a desired channel with respect to a signal from the antenna 72, and, for example, QPS.
Demodulation processing including K demodulation and error correction processing is performed, and the transport stream (TS) limited reception processing unit 82 is performed.
Send to. What is a transport stream?
It is generally used in digital broadcasting, etc.,
The video data, the audio data, and the data for data broadcasting divided into TS packets of a predetermined length are multiplexed.

When the DGPS data service is charged, for example, the conditional access processing unit 83 performs ID confirmation, descrambling, etc. on the received data so that only users who have the right to receive the service can receive the DGPS data. Perform processing. The demultiplexing unit 83 separates the video data and the audio data from the transport stream, and sends them to the video decoder 84 and the audio decoder 85, respectively. The video decoder 84 receives the video data from the demultiplexing unit 83, decodes the video data, and outputs the video signal to the outside. The audio decoder 85 receives the audio data from the demultiplexing unit 83, decodes it, and outputs it as an audio signal to the outside. Also, the demultiplexing unit 83 extracts the TS packet 86 of the data broadcast from the transport stream in which the main broadcast and the data broadcast are multiplexed, and the host processor 8
Send to 7. The host processor 87 is a general CPU.

In the host processor 87, NAVI_C
The DGPS data of the DGPS reference station closest to the current position notified from the PU 51 is selected and output as the data output 73. In this case, the data output 73 is
In addition to DGPS data, V provided as data broadcasting
ICS (Vehicle Information and Communication Syst)
Data broadcasting contents useful for the car navigation device such as em) information and POI (Point Of Interest) information may be included.

The NAVI_CPU 51 transfers the DGPS correction information received from the host processor 87 via the I / F 56, alone or together with other commands, to the GPS receiver 52 as a GPS input message 54 of a predetermined format. The GPS receiver 52 is NA
Using the DGPS correction information received from the VI_CPU 51, the pseudo distance is corrected and the positioning calculation is executed to improve the accuracy of the positioning result. NAVI_CPU51 is GPS
By estimating the own vehicle position using the highly accurate GPS positioning result received from the receiver 51, the accuracy of the final estimation of the own vehicle position is improved.

Here, the process of sending the current position from the NAVI_CPU 51 to the digital broadcasting receiver 71, and the digital broadcasting receiver 72 receiving the DGPS data and NA
The process of selecting and sending the DGPS correction information to the VI_CPU 51 can be performed periodically at predetermined time intervals, for example.

Several variations can be made to the above-described embodiment. For example, the digital broadcast receiver 21
In addition to the satellite digital audio broadcast receiver as shown in the above embodiment, for example, a terrestrial digital audio broadcast receiver, a terrestrial digital television receiver, etc., which are scheduled to start broadcasting sequentially from 2002, It can be replaced with any receiver that adopts a broadcasting system for mobile units and supports digital broadcasting capable of data broadcasting.

[0029]

As described above, the car navigation system according to the present invention can stably obtain DGPS data even while moving, and can continuously improve the GPS positioning accuracy. . Further, in the conventional use of the DARC system FM multiplex DGPS service, the car navigation device needs a dedicated FM multiplex DARC receiver to obtain the DGPS correction information, whereas the present invention functions as a digital broadcast receiver. Since one of the above is used, a dedicated receiver for obtaining DGPS correction information is not required.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a car navigation device that is an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a digital broadcast receiver of the car navigation device of FIG.

FIG. 3 is a diagram for explaining the concept of DGPS.

FIG. 4 is a block diagram showing a configuration of a car navigation device that employs an FM multiplex DARC receiver.

[Explanation of symbols]

51 NAVI_CPU 52 GPS receiver 55 GPS antenna 56 I / F 61 Digital Map 62 Gyro 71 Digital Broadcast Receiver 72 Digital broadcasting receiving antenna

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Claims (5)

[Claims] 1. GPS (Global Positioning System)
A navigation device that uses D as a positioning means, and that broadcasts a video or audio broadcast as a main broadcast and includes DGPS (Differential GPS) correction information as a data broadcast.
A digital broadcast receiving means for receiving a digital broadcast providing GPS data; a positioning operation means for performing a GPS positioning operation using the DGPS correction information acquired by the digital broadcast receiving means to calculate a positioning result including a current position; A navigation device for performing DGPS navigation, comprising: 2. The positioning calculation means performs the GPS positioning calculation without using the DGPS correction information when the DGPS data is not acquired by the digital broadcast receiving means. DG described
Navigation device for PS navigation. 3. The DGPS data provided by the data broadcast includes position data regarding respective positions of a plurality of DGPS reference stations existing in an area where the digital broadcast service is provided, and the plurality of DGPS.
Each of the DGPS correction information acquired by the reference station, the positioning calculation means relates to a DGPS reference station closest to the current position obtained by the GPS positioning calculation among the DGPS correction information acquired by the digital broadcast reception means. The navigation device for DGPS navigation according to claim 2, wherein the DGPS correction information is selected and used. 4. A DGPS that broadcasts a video or audio broadcast as a main broadcast and includes DGPS correction information as a data broadcast.
A digital broadcast receiving unit that receives a digital broadcast that provides data, and a DG based on the received data received by the digital broadcast receiving unit.
A data processing unit for extracting PS data, an interface unit for performing data communication with the outside, and a process for transmitting the DGPS correction information of the extracted DGPS data via the interface. 1 control means, a digital broadcasting receiver including: a GPS positioning means for receiving a GPS signal, executing a GPS positioning calculation, and calculating a positioning result including the current position; and at least based on the positioning result of the GPS positioning means. A position estimating means for estimating the own vehicle position, a communication means for performing data communication between the interface portion of the digital broadcast receiver, and the DGPS correction information from the digital broadcast receiver via the communication means. A car navigation device having a second control means for performing a process of receiving the car navigation device. The GPS positioning means of the device
A car navigation system for performing DGPS navigation, characterized in that the GPS positioning calculation is performed using the DGPS correction information received by the second control means. 5. The DGPS data provided by the data broadcasting includes position data regarding respective positions of a plurality of DGPS reference stations existing in an area where the digital broadcasting service is provided, and the plurality of DGPS.
Processing for transmitting the current position by the GPS positioning means to the digital broadcast receiver via the communication means, the second control means including the respective DGPS correction information acquired by the reference station. The first control means of the digital broadcast receiver, based on the current position received from the car navigation device via the interface, from the DGPS data, the DGPS relating to the DGPS reference station closest to the current position. The car navigation system for performing DGPS navigation according to claim 4, wherein correction information is selected and the selected DGPS correction information is transmitted via the interface.