JPH0621793B2 - Roadside beacon method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roadside beacon system, and more specifically, it is used for calibrating a vehicle position in a navigation system that displays the current position of the vehicle. New roadside beacon system.

<Prior Art> Conventionally, as shown in FIG. 6, the road map data stored in a storage device such as a compact disk in which a small computer and a display device (51) are mounted in a vehicle is used. While reading out and displaying it on the display device (51), using the vehicle speed data from the vehicle speed sensor and the direction data from the direction sensor as input, the position of the vehicle at each time point is calculated and the running direction is determined. Based on the determination result, a so-called navigation system has been provided in which a display (52) showing a vehicle is added to a relevant portion of a road map displayed on a display device (51). There is.

By using such a navigation system, the current position of the vehicle and the traveling direction can be easily visually identified, and the destination can be reliably reached without getting lost.

However, in the navigation system configured as described above, the errors that the vehicle speed sensor and the direction sensor inevitably have are accumulated as the traveling distance increases, and when the traveling distance becomes a predetermined distance or more (however, the predetermined distance is It is determined by the degree of error of the vehicle speed sensor and direction sensor in each vehicle, the variation of the atmospheric conditions at the position where each sensor is installed, etc., and not necessarily a fixed distance), the vehicle display position (52) on the display device (51). ) Will deviate significantly from the actual vehicle position, and it will not be able to exert its original function, resulting in a situation where you get lost.

In order to solve such a problem, the road traffic network, a roadside antenna (53) is installed for each predetermined distance shorter than the distance at which the cumulative error is a predetermined value or more, the roadside antenna (53)
Signal including position data and road direction data from
A so-called roadside beacon system that radiates only in a relatively narrow range, receives the above signal with an antenna mounted on the vehicle, captures it into a computer, and calibrates the vehicle position and traveling direction to correct data based on the received signal. The adoption of is proposed.

If such a roadside beacon system is adopted, it is possible to perform display based on accurate position data and azimuth data in a state where the accumulated error is always less than a predetermined value, so that the original performance of the navigation system is demonstrated. In particular, by installing the roadside antenna (53) near a railroad track or at a location such as a railroad crossing where a large error is likely to occur in the direction sensor, the error caused by external factors can be prevented. It has the advantage that it can be effectively calibrated.

In the roadside beacon system with the above configuration, the roadside antenna with a fairly high directivity always emits a signal including position data and road direction data, and the vehicle passes through the area covered by the radiation signal. The signal is received only when the signal is received, and the necessary calibration can be performed based on the received signal.Therefore, if the area covered by the transmitted signal is widened, the signal reception position of the roadside antenna The gap becomes large,
There is a problem that a sufficient calibration effect cannot be achieved.

More specifically, the basic function of the roadside beacon system is to give a signal including position data and road direction data to a vehicle equipped with a navigation system. However, adding the following functions to the roadside Required for effective use of beacon system. That is, assisting the smooth operation of the vehicle by adding traffic information such as road congestion situation, construction, and other road usage conditions around the location where the roadside antenna is installed to the navigation system, Add detailed map information including house placement and personal name around the place where the roadside antenna is installed,
The road map displayed by the display device can be displayed by facilitating the arrival at the final destination and adding road map information over a relatively wide range including the location of the roadside antenna to the navigation system. It has been considered that the service will be updated and additional services such as smooth operation to remote areas will be provided.
If such additional services are to be provided, it is essential to expand the transmission band by the signal radiated from the roadside antenna and the area covered by the transmission signal.

When the transmission area is expanded and the area covered by the transmission signal is expanded as described above, the deviation of the signal reception position with respect to the installation position of the roadside antenna becomes large, which is the original purpose of the vehicle. The problem arises that the position calibration cannot be performed accurately due to the influence of the above deviation.

In order to solve such a problem, the applicant of the present application has already proposed a roadside beacon system in Japanese Patent Application Nos. 62-154922 and 62-255569.

In the roadside beacon system according to the prior application, the roadside antenna is composed of two antenna elements having different main radiation directions, and various data components other than position data are in the first modulation system such as PSK, FSK or ASK modulation. 2 on board the signal
Position data is applied by applying amplitude modulation (second modulation method) of opposite phases to the divided signals, and the signals are fed to each antenna element so that the first modulation components are in phase. On the side, the amplitude modulation component is extracted to detect the position, and the first modulation component is extracted to restore various data.

By the way, in these prior inventions, data is provided from the roadside antenna regardless of the traveling direction, and the provided data is sorted or analyzed on the vehicle side. More specifically, the roadside antenna gives various data (for example, the position of the point, the direction of the road, the information about the next intersection, and other surrounding road guidance), and the various data given are transmitted to the vehicle side. Then, the information is compared with the traveling direction of the automobile, and only the information on the traveling direction side of both automatic vehicles is selected.

Therefore, the vehicle must be equipped with a direction sensor such as a geomagnetic sensor.

On the other hand, theoretically, it is possible to provide various data from the roadside antenna for each traveling direction. That is, a roadside antenna is provided for each traveling lane of the road or for up / down,
All that is required is to emit various information.

<Problems to be Solved by the Invention> However, in the former case, that is, in the case of a system in which an azimuth sensor is installed in a vehicle, an azimuth sensor such as a geomagnetic sensor is expensive, and in the case of a geomagnetic sensor, the vehicle body generates a strong external magnetic field. There is a problem that it malfunctions when received.

Further, in the latter case, not only the number of ground facilities, that is, the number of roadside antennas to be installed, etc., but also the radiated signal leaks to the opposite lane side, and it is possible to separate the radio waves according to the traveling lane or the up / down direction. It has the drawback of being difficult.

Therefore, the present invention has been made in view of the above-mentioned problems, and provides a roadside beacon system capable of detecting both directions without mounting an azimuth sensor on a vehicle, which is complicated. An object of the present invention is to provide a roadside beacon system that can realize a simple and inexpensive vehicle-mounted guide device without requiring a vehicle-mounted device.

<Means for Solving the Problems> The present invention relates to a roadside beacon system in which various data are transmitted and received between a roadside device installed on a roadside and a vehicle, and roadside antennas of the roadside device are different from each other in main radiation. A pair of at least one antenna element having a direction, which divides a first modulated wave signal which is modulated based on a transmission data frame into two parts, which are synchronized with the transmission data frame and are opposite to each other. A second modulated wave signal obtained by performing amplitude modulation with a modulated signal set to a phase is fed to the pair of antenna elements so that the first modulated wave signal has the same phase, The installed receiver receives the transmission signal from the roadside antenna, extracts the amplitude modulation component, demodulates the first modulated wave signal, and transmits the transmission data signal. The main beam direction of the roadside antenna by the vehicle by restoring the boom and reproducing the modulation signal synchronized with the transmission data frame from the restored transmission data frame and comparing the phase of the modulation signal with the amplitude modulation component. It is a roadside beacon method characterized by detecting whether it is in the area.

Further, the present invention is a roadside beacon system in which the receiving device detects a traveling direction of a vehicle based on a change in the phase comparison result.

Furthermore, the present invention is the roadside beacon system in which the receiving device detects the traveling direction of the vehicle based on the result of the phase comparison immediately before the detection of the sudden drop of the amplitude modulation component.

The present invention is a roadside beacon system in which the transmission data includes a plurality of types of data for each traveling direction, and the receiving device takes in the corresponding traveling data based on the detected traveling direction.

<Operation> According to the present invention, the main radiation radiated from the antennas having different main radiation directions by synchronizing the transmission data frame to be subjected to the first modulation and the amplitude modulation signal to be subjected to the second modulation. The receiving device can determine which of the main radiation directions the beam is based on the received signal. Therefore, when the receiving device receives the signal of the roadside device while traveling on the road, it is possible to determine which direction the vehicle is traveling, that is, which direction the vehicle is traveling.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a configuration block diagram of a roadside apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram schematically showing signals in FIG. 1A.

In FIG. 1A, the data transmitter (11) includes position, direction (road direction), road information, traffic information (in the case of a two-way communication roadside beacon system, includes data such as messages and FAX). Is a component that outputs as a serial code string.

The signal transmitted from the data transmitter (11) is intermittently repeatedly transmitted in frame units as shown in "A: Transmission data frame" in FIG. It includes normal phase correspondence data and reverse phase correspondence data. Here, the header arranged at the head of the frame is a portion provided with functions necessary for communication such as code element synchronization and frame synchronization. Further, in the case of this embodiment, the transmission rate of the transmission data frame is
It is set to 512kbps.

The transmission data frame sent from the data transmitter (11) is given to the data modulator (12).

The data modulator (12) modulates the carrier wave fc (carrier wave whose center frequency is fc) given from the carrier wave generator (14) with a transmission data frame to produce a first modulated wave signal. The modulation method in the data modulator (12) is amplitude modulation,
Any modulation method may be used regardless of frequency modulation, phase modulation, or the like.

In the case of this embodiment, a PSK (phase shift keying) modulator or an ASK (amplitude shift keying) modulator is used. In terms of performance, the data modulator (12) is PS
A K modulator is preferable, but an ASK modulator may be used for cost reduction.

The first modulated wave signal generated by the data modulator (12) is divided into two and supplied to the amplitude modulators (15) and (16), respectively.

The modulation signal generator (13) generates an amplitude modulation signal fm (a signal whose center frequency is fm).
Amplitude modulation signal f
m is synchronized with the transmitted data frame.
Specifically, in the case of this embodiment, the same clock signal used in the data transmitter (11) is counted down, and the operation is started in accordance with the synchronization signal from the data transmitter (11). Has been

As the frequency fm of the amplitude modulation signal, a frequency sufficiently lower than the above-mentioned carrier wave fc and data transmission rate is selected. Specifically, in the case of this embodiment, a frequency of about 1 kHz is adopted. The amplitude modulation signal fm synchronized with the transmission data frame output from the modulation signal generator (13) is
It is given to the amplitude modulator (15) as it is, and inverted to the opposite phase by the 180 ° phase shifter (17) and given to the amplitude modulator (16).

The amplitude modulator (15) amplitude-modulates the first modulated wave signal given from the data modulator (12) with the amplitude modulation signal fm output from the modulation signal generator (13). The modulation rate of is selected to be 0.5 or less so that the first modulated wave signal does not become too small. The signal modulated by the amplitude modulator (15) becomes a signal represented by "B: second modulated wave signal (positive phase)" in FIG. 2 and given to the split beam antenna (18).

The amplitude modulator (16) also has the same structure as the amplitude modulator (15), and the second modulated wave signal provided from the data modulator (12) is inverted in phase by the 180 ° phase shifter (17). Amplitude modulation signal f
Amplitude modulation with m. As a result, the output of the amplitude modulator (16) becomes a signal indicated by "C: second modulated wave signal (negative phase)" in FIG. This second modulated wave signal (anti-phase) is also given to the split beam antenna (18).

The split beam antenna (18) has a configuration including antenna elements (19) and (20) having different main radiation directions, as an example is shown in FIG. When the signals are fed in phase, the antenna (18) produces a combined sum of the radiated signals radiated from the antenna elements (19) and (20), and exhibits a radiated electric field strength as shown in FIG. 4A. Further, when signals are supplied in anti-phase, as shown in FIG. 4B, the radiated electric field strength at the boundary line between different main radiation directions sharply decreases, and the split beam directivity is exhibited.

The signal radiated from the split beam antenna (18) of the roadside device is received by the receiving device mounted on the vehicle having the configuration shown in FIG. 1B.

In FIG. 1B, the signal received by the signal antenna (21) is. It is amplified to a required level by the reception amplifier (22) and given to the data demodulator (23) and the modulated signal demodulator (24).
The data demodulator (23) is a data modulator of the roadside device (first A
(See the figure), and is for obtaining a received data frame by demodulating the first modulated wave signal. The received data frame demodulated by the data demodulator (23) is given to the synchronization detector (25).

The synchronization detector (25) detects element synchronization and frame synchronization from the received data frame, and functions to restore the received data and reproduce the modulated signal. The received data restored by the sync detector (25) is given to the data processing unit (26), and the output of the sync detector (25) is given to the modulation signal regenerator (27).

The modulation signal regenerator (27) is the modulation signal generator (13) of the roadside device.
It has the same function as in FIG. 1A, and reproduces the modulated signal fm 'by the frame synchronization signal based on the received data frame and the received data clock. The reproduced modulation signal fm 'is applied to one input terminal of the phase comparator (28).

The modulation signal demodulator (24) described above is an amplitude modulator of a roadside device.
It corresponds to (15) and (16) (see FIG. 1A) and functions to demodulate the second modulated wave signal and extract it with the amplitude modulation signal fm. Modulation signal fm demodulated by the modulation signal demodulator (24)
Is applied to the other input terminal of the phase comparator (28).

The phase comparator (28) compares the phase of the modulated signal fm 'reproduced by the modulated signal regenerator (27) with the modulated signal fm demodulated by the modulated signal demodulator (24), and its output is , Signal f
Depending on whether m'and the signal fm are in phase, it becomes either a positive signal or a binary signal of a reverse signal, which is given to the data processing unit (26).

The modulated signal fm demodulated by the modulated signal demodulator (24) is also given to the level determiner (29). Level judge (29)
Is for detecting a sudden drop in level (see FIG. 4B) that occurs at the boundary line of the split beam antenna (18) in the main radiation direction.
Given to (26).

The data processing unit (26) restores the received data given from the synchronization detector (25), and based on the forward / backward signal given from the phase comparator (28) and the position pulse from the level determiner (29). Is a component that performs various data processing and determination processing. The data processing section (26) is specifically configured by a microcomputer or the like. Then, the output of the data processing unit (26) is given to the display unit (30) and is displayed so that it can be visually recognized by the driver of the vehicle.

FIG. 5 is a diagram for explaining a receiving operation of the receiving device shown in FIG. 1B during traveling.

Next, the operation of the receiving apparatus shown in FIG. 1B will be described with reference to FIG.

In FIG. 5 (a), AB indicates the direction of the road, and the split beam antenna (18) of the roadside device for this road causes the second modulated wave signal It is radiated by the split beam characteristic of the main radiation beam of the opposite phase.

If the vehicle is traveling on the road from A to B,
The receiving device mounted on the vehicle first enters the positive-phase beam emission region and receives the emission signal. Received at this time,
The signal (second modulated wave signal (positive phase)) output from the reception amplifier (22) is a signal having an electric field intensity distribution as shown in FIG. 5 (b). This signal is, as described above, a data demodulator (23), a sync detector (25) and a modulated signal regenerator (2).
In step 7), the modulated signal fm 'is reproduced and the modulated signal demodulator (24) demodulates the modulated signal fm. As shown in FIG. 5 (c), the output of the modulated signal demodulator (24) has an electric field distribution that causes a sharp level drop at the main radiation direction boundary line of the split beam antenna (18). Then, the reproduced modulation signal fm 'and the demodulated modulation signal fm are compared by the phase comparator (28), and if the received signal is the positive phase second modulated wave signal, the data processing unit It is determined in (26).

Next, when the vehicle continues to run, the level determiner (29) detects the position where the level suddenly drops as shown in FIG. 5 (c) and outputs the position pulse shown in FIG. 5 (d). .

In the data processing unit (26), when the position pulse (FIG. 5 (d)) from the level determiner (29) is given, it is the phase of the received signal immediately before the position pulse is given, that is, the positive phase. It is determined that the vehicle has entered the road from the normal phase main radiation beam side, that is, the A side (see FIG. 5 (e)).

Then, the data processing unit (26) selects and acquires the normal phase correspondence data (see “A: Transmission data frame” in FIG. 2) from the reception data given from the synchronization detector (25) ( In FIG. 5 (f), the intersection information, the traffic information in the front, and other data required when traveling on the road in the A → B direction are selected and displayed on the display unit (30).

In the above case, the phase pulse (positive phase) of the received signal immediately before that is taken in with reference to the position pulse (FIG. 5 (d)) output from the level determiner (29), and the positive phase side That is, instead of confirming that the vehicle has entered from the A side of the road, the traveling direction of the vehicle on the road, that is, A →
It may be determined that the vehicle is traveling to B.

When the vehicle travels from B to A on the road, the receiving device and the operation are opposite to those described above, and first, the opposite phase second modulated wave signal is received.

<Effects of the Invention> As described above, according to the present invention, by synchronizing the transmission data frame to be subjected to the first modulation and the amplitude modulation signal to be subjected to the second modulation, an antenna having different main radiation directions can be obtained. The receiving device can determine in which main radiation direction the main radiation beam to be emitted is based on the received signal. Therefore, when the receiving device receives the signal of the roadside device while traveling on the road, it is possible to determine which direction the vehicle is traveling, that is, which direction the vehicle is traveling.

As a result, even if the vehicle does not have a direction sensor such as a geomagnetic sensor, it is possible to select the reception data corresponding to the traveling direction from various reception data.

If the received data corresponding to the traveling direction includes the azimuth data indicating the direction of the road at the point, the vehicle traveling in each direction can know the absolute azimuth of the point corresponding to each direction.

By including the intersection information and traffic information of the area in front of the point in the received data corresponding to the traveling direction, the vehicle traveling in each direction can know the information of the corresponding area in the front. .

When the roadside beacon system is provided with a two-way communication function, it is possible to call the vehicle by designating the traveling direction of the vehicle.

As described above, according to this method, the traveling direction of the vehicle can be recognized in the vehicle even if the vehicle does not include the direction sensor. Therefore, when used in the system proposed by PWRI and the like described above, the system can be designed with a simpler configuration.

Further, the present invention is based on the prior invention (Japanese Patent Application No. 62-154922 and / or Japanese Patent Application No. 62-255569) previously proposed by the present inventor.
(Japanese Patent Laid-Open No. 64-92611), a roadside antenna is composed of two antenna elements having different main radiation directions, and various data components other than position data are PSK,
Position data is added by halving a signal put by the first modulation method such as FSK or ASK modulation, and by applying amplitude modulation (second modulation method) of opposite phases to the halved signal, Power is supplied to the element so that the first modulation component has the same phase, and on the vehicle side, the amplitude modulation component is extracted to perform position detection, and the first modulation component is extracted to restore various data. Since this is done, it is possible to provide a roadside beacon system capable of accurate position detection and various data transmission / reception services.

[Brief description of drawings]

1A is a configuration block diagram of a roadside device according to an embodiment of the present invention, FIG. 1B is a configuration block diagram of a receiving device mounted on a vehicle according to an embodiment of the present invention, and FIG. The figure for demonstrating the signal of each part of the roadside apparatus shown by FIG. 1A, FIG. 3 is the schematic perspective view which shows the structural example of the split beam antenna contained in the roadside apparatus of FIG. 1A, FIG. 4A, and FIG. FIG. 4B is a diagram showing electric field intensity distribution of radiated radio waves in the split beam antenna, FIG. 5 is a diagram for explaining the operation of the receiving device shown in FIG. 1B, and FIG. 6 is an explanatory diagram of the navigation system. Is. (11) …… Data transmitter, (12) …… Data modulator, (13) …… Modulation signal generator, (14) …… Carrier generator, (15), (16) …… Amplitude modulator, (17) …… 180 ° phase shifter, (18) …… split beam antenna, (22) …… reception amplifier, (23) …… data demodulator, (24) …… modulated signal demodulator, (25) …… Synchronous detector, (26) …… Data processing unit, (27) …… Modulation signal regenerator, (28) …… Phase comparator, (29) …… Level judge

Claims (4)

[Claims] 1. In a roadside beacon system in which various data are transmitted and received between a roadside device installed on a roadside and a vehicle, a roadside antenna of the roadside device has at least one antenna element having mutually different main radiation directions. A first modulated wave signal that has been modulated based on a transmission data frame, is divided into two, and the first modulation wave signal is synchronized with the transmission data frame and is set to the opposite phase with respect to each other. A second modulated wave signal obtained by performing amplitude modulation is fed to the pair of antenna elements so that the first modulated wave signal has the same phase, and the receiving device mounted on the vehicle is The transmission signal from the roadside antenna is received, the amplitude modulation component is extracted, the first modulated wave signal is demodulated to restore the transmission data frame, and It is possible to detect which main radiation direction region of the roadside antenna the vehicle is in by reproducing a modulation signal synchronized with the transmission data frame from the transmitted transmission data frame and comparing the phase of the modulation signal with the amplitude modulation component. Roadside beacon system characterized by 2. The roadside beacon system according to claim 1, wherein the receiving device detects a traveling direction of the vehicle based on a change in the phase comparison result. 3. The receiving device according to claim 1, wherein the receiving device detects the traveling direction of the vehicle based on the phase comparison result immediately before the detection of the sudden drop of the amplitude modulation component. Roadside beacon system. 4. The transmission data includes a plurality of types of data for each traveling direction, and the receiving device takes in the corresponding traveling data based on the detected traveling direction. The roadside beacon system according to claim 2 or 3 above.