JPH0362749A - Road-to-vehicle communication device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a road-to-vehicle communication device, and more specifically, to a road-to-vehicle communication device used to calibrate a vehicle position and traveling direction in a navigation system that displays the current position of a vehicle. The present invention relates to an inter-vehicle communication device. <Prior art> Road-vehicle crossing devices are based on roadside beacons, which emit signage radio waves carrying position data of the roadside beacon in a narrow area, thereby detecting vehicles passing through the radiation area of the roadside antenna. It was intended to provide signals for position and heading calibration of navigation systems. However, by providing the following traffic information and progress as an additional service not only to vehicles equipped with a navigation system but also to vehicles without a navigation system, it is possible to alleviate recent road congestion, etc. A road-to-vehicle communication system is being considered. In other words, (1) assist the smooth operation of vehicles by providing additional traffic information to vehicles, such as road congestion, construction, and other road usage conditions around the location where the roadside antenna is installed; (2) Adding detailed map information including residential locations and personal names around the location where the roadside antenna is installed to make it easier to reach the final destination; (3) Roadside antenna By adding and giving road map information covering a fairly wide range, including locations where road maps are installed, to the vehicle, the road map displayed on the display device can be updated, allowing smooth operation to remote areas. It is also possible to perform additional services. By the way, if such additional services are to be provided, it is essential to expand the transmission band using the signals radiated from the roadside antenna and to expand the area covered by the transmitted signals. As described above, when the transmission area and the area covered by the transmitted signal are expanded, the reception area of the in-vehicle device is expanded, and the detection of the directly facing position of the roadside antenna becomes more difficult than it should be. A problem arises in that the vehicle position cannot be calibrated accurately due to the influence of the above-mentioned deviation. Furthermore, since the data necessary for the vehicle is the data on the direction of travel, it is necessary to identify the direction of travel and retrieve the data corresponding to the direction of travel from a large amount of traffic information (7). In the second case, if the vehicle is equipped with a navigation system, it is possible to identify the direction of travel using the direction detection sensor, but if the vehicle is not equipped with a navigation system, it is only possible to identify the direction of travel, so a large amount of traffic information is required. will be taken in regardless of the direction of travel. Therefore, it is necessary to transmit a signal for direction identification from the roadside device. In order to solve the above problem, the inventors of the present invention have already proposed a roadside beacon system in Japanese Patent Application No. 63-45616. The roadside beacon system according to the earlier application consists of a roadside antenna consisting of two antenna elements with different main radiation directions, and PSK, PSK, and PSK with different data corresponding to the road direction.
Divide the third modulated wave signal subjected to FSK or ASK modulation into two, and apply anti-phase amplitude modulation to the divided signal 7.
By generating a second modulated wave signal at −7 and feeding this second modulated wave signal ↓≦ to the first modulation] or f4 in the same phase, the first modulated signal has a wide transmission area. The modulated wave f1; component and the second modulated wave signal component whose electric field strength suddenly drops at the position directly opposite the roadside antenna are made to appear simultaneously.Then, on the vehicle side, the first modulated component At the same time, the amplitude modulation component (second modulation wave signal) is extracted, and the phase of the second modulation wave signal is synchronously detected, and whether this phase is positive phase or negative phase is detected. Based on this, the system determines whether it is in the main radiation area of the roadside antenna and identifies the direction of travel.It also detects a sharp drop point in the amplitude modulation component and captures position data at the detection timing of this drop point. ,
This is the current position. <Problems to be Solved by the Invention> Incidentally, in the above-mentioned prior invention, the vehicle-side receiving device is equipped with a receiver compatible with the modulation method (PSK, FSK, ASK) of the roadside device. However, when PSK or FSK is adopted as a modulation method on the roadside equipment side in order to provide a large amount of information or improve performance, low-cost receivers using the ASK demodulation method cannot perform position detection or navigation. It becomes impossible to distinguish direction. In this case, by providing additional services, the high-cost PSK system or PSK system receiver is forced on the vehicle, making it impossible to reduce the cost of the in-vehicle device. Therefore, there is a problem in that the roadside beacon becomes far removed from its original purpose of providing position data to as many vehicles as possible. The present invention was made in view of the above-mentioned problems.
It is an object of the present invention to provide a road-to-vehicle communication device that allows a vehicle equipped with an ASK receiver to accurately detect the position and identify the direction of travel. <Means for Solving the Problems> The present invention provides a road-to-vehicle communication device that transmits and receives various data between a roadside device installed on the roadside and a vehicle. a roadside antenna consisting of at least two antenna elements; a first data generation means for generating a first transmission data frame consisting of various data; a first modulating means that performs ASK modulation to generate a first modulated wave signal; and an initial data generator that generates initial data consisting of at least direction identification data and position data in synchronization with this ↓ modulated wave (≦). a means for differentially initializing the initial data, and a combination of the differentially encoded initial data and the non-differentially encoded initial data to generate rXJ.
a second data generation means for inverting the second transmission data frame l; and an inversion means for inverting the second transmission data frame l; ASK modulation is performed on the first modulated wave signals -, L, and the data frame to be transmitted, and the ASK modulated wave signals are transmitted to at least one of the first modulated wave signals having different main radiation directions so that the first modulation power is in phase. The receiving device mounted on the vehicle receives the transmission signal from the roadside device and demodulates the ASK modulation component. K demodulation means and differential means for restoring the initial data by subtracting the differentially encoded data of the second transmission (≦data frame 1) frame, etc. a direction determining means for determining whether the data is original data or inverted initial data, and determining which main radiation region of the roadside antenna the roadside antenna is in;
According to the above invention, according to the first aspect of the present invention, The modulation means performs PSK based on the first transmission data frame consisting of various data.
A first modulated wave signal is generated by performing modulation, FSX modulation, or ASK modulation. Then, the initial data generating means generates initial data including at least direction identification data and position data in synchronization with the first modulated wave signal, and the second data generating means converts the initial data and the initial data into differential codes. A second transmission data frame is generated by combining the converted Gita. This second transmitted data frame, and @
An ASK modulated wave signal is generated by zero-amplitude modulating the first- modulated wave signal using a transmission data frame obtained by inverting the second transmission data frame. By feeding these mutually reversed ASK modulated wave signals to the pair of antenna elements of the roadside antenna, the first
The modulated wave signal components are combined to form a wide radiated electric field strength distribution in the transmission region. In addition, at the boundary line of the ASK modulation component main radiation region, they meet each other and the radiation intensity distribution suddenly drops to 0 (0).The receiver mounted on the vehicle uses ASK demodulation means ,
A transmission signal from a roadside antenna is received and an ASK modulated signal, that is, a second transmission data frame is reproduced. Then, the difference means restores the initial data by subtracting the differentially encoded data of this second transmission data frame. The direction determining means synchronously detects data that is not differentially encoded in the second transmission data frame based on the restored initial data, and determines whether the synchronously detected data is the inverted initial data. Then, it is determined whether the main radiation area of the vehicle or the roadside antenna is the one from which the vehicle has entered. Furthermore, when the vehicle moves and reaches the boundary line of the main radiation area, the position detecting means can detect a sudden level drop of the ASK modulation component and detect this level drop point as the position of the roadside antenna. can. Furthermore, if a receiver is equipped with a combination of the conventional PSK or FSK demodulation method and the ASK demodulation method, it is possible to demodulate the transmitted data frame based on the first modulated wave signal as well as to demodulate the transmitted data frame based on the first modulated wave signal. 2 transmission data frames can be demodulated, and all data provided from the roadside device can be captured based on these demodulated signals. <Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a split beam antenna applied to the roadside device of the present invention.
This configuration includes antenna elements 2 and 3 having different radiation directions in the A direction and the B direction. When a signal is fed in phase with this antenna, the radiated signals radiated from each antenna element l-2 and 3 become a composite sum, and when a signal is fed with reverse phase, the boundary line in the main radiation direction In this case, the electric field intensity of the emitted a. FIG. 1A is a configuration block diagram of a roadside device according to an embodiment of the present invention, and FIG. 2 is a diagram schematically showing signals of each part of the roadside device of FIG. 1A. In FIG. 1A, a first data transmitter 1 converts road information, traffic information (in the case of a two-way communication roadside beacon system, includes data such as messages and FAX) into a serial code string, This is a component that outputs. The signal sent from this data transmitter 11 is shown in FIG.
As shown in the "transmission data frame" of 3, it is sent out repeatedly in frame units intermittently, and this frame contains header common data, traffic information in the direction (for example, up), and traffic information in the direction B (for example, 3, down). direction). Here, the header arranged at the beginning of the frame is the synchronization of code elements,
It is a part that has functions necessary for communication such as frame synchronization. Also, the transmission rate of the transmission data frame is
In this example, it is set to 512 kbps. The transmission data frame sent out from the data transmitter 11 is
Data modulator I2 is supplied. The data modulator 12 modulates the carrier wave fc (carrier wave with center frequency fc) provided from the carrier wave generator 14 with a transmission data frame to generate a first modulated wave signal. As a modulation method in the data modulator 12, a PSK modulator, an FSX modulator, or an ASK modulator is used. The first modulated wave signals produced by data modulator 12 are supplied to amplitude modulators 15 and 16, respectively. The modulation signal generator 13 is a component that generates initial data Sl (see FIG. 2C) based on a clock (see FIG. 2C) obtained by dividing the same clock as that of the data transmitter I]. ]4 The differential encoding circuit 17 generates data S2 by 1-bit differential encoding of the initial data S1. for example,
The initial data Sl is “1” as shown in FIG. 2C. 00001
]" is inverted at the next clock for "]" and maintains the original state for "0". The output data S2 of this differential encoding circuit 17 is "11". .11 1
, ] 00" (see the second diagram). This differentially encoded data S2 is supplied to the changeover switch circuit 18. The changeover switch circuit (8 (second data modulation means) After outputting the encoded data S2 from the encoding circuit 17, and then switching to and outputting the initial data S1 from the modulation signal generator 13, the data S2 from the differential encoding circuit 17 is output again.
Outputs 2. Therefore, this changeover switch circuit 18
The transmission data frame S3 output from S2-8l
-52 in order. The first data S2 of this transmission data frame is a synchronization frame, the data SJ is a frame indicating the radiation area in the A force direction, and the next data S of Sl
2 is an information frame (see FIG. 2G). This 5 information frame includes data consisting of several bits (e.g. location data, traffic jam section, etc.), and is similar to the first one described above.
It is also possible to overlap the transmitted data frame. The transmission data frame S3 is supplied to an amplitude modulator 15 and an inverter 19. The inverter 19 inverts the transmission data frame S3. This inverted transmission data frame S4 is sent to the amplitude modulator 1.
6. Here, data S1° (E
) indicates the radiation area in the B direction. Note that the differentially encoded data S2° of the transmission data frame S4 is obtained by shifting the differentially encoded data S2 of the transmission data frame S3 by 1 bit (
(See figure F). The amplitude modulator 15 modulates the amplitude of the first modulated wave signal supplied from the data modulator 12 by 1M using the transmission data frame S3 from the modulated signal generator 13. The signal modulated by the amplitude modulator 15 is supplied to the split beam antenna 1. 6. The amplitude modulator 16 also has the same configuration as the amplitude modulator 15, and amplitude modulates the first modulated wave signal with the transmission data frame S4 from the modulated signal generator 13. As a result of this, the output of the amplitude modulator 16 is the inverse of the output of the amplitude modulator 15. This reverse phase signal is also supplied to the split beam antenna. The radiated electric field intensity distribution of this split beam antenna 1 is as follows. That is, since the first modulated wave signals are in phase, they are combined with each other to form a wide electric field strength distribution in the transmission area, and the ASK modulated component (transmission data frame 1)
-muS3. Since S4) is completely out of phase, the electric field strength distribution becomes such that the level rapidly decreases at the boundary line of the main radiation region. In the roadside device of the above embodiment, the data modulator 12 performs PSK, FSK, or ASK modulation on the traffic information, and generates the first modulated wave signal (2). The signal is modulated by the signal ζ3 generator 13f:, ↓-re, transmission data frame S3. Whether it is an in-vehicle device or a receiving device using ASK demodulation method.

[)J, i′
It is possible to provide mortar identification data 1-l and a position detection signal. Furthermore, conventional receiving devices that combine the PSK demodulation method and AM demodulation method and receiver devices that combine the FSK demodulation method and AM demodulation method (for example, the in-vehicle device shown in the road-to-vehicle communication method of Japanese Patent Application No. 63-45616) are also available. etc.),
In addition to directional identification data and location data, it can provide a large amount of traffic information. FIG. 1B is a block diagram showing an example of an in-vehicle receiver using the ASK demodulation method. In FIG. 18, a signal radiated from a split beam antenna 1 of a roadside device is received by a receiving antenna 21, and this received signal is amplified to a required level by a receiving amplifier 22, subjected to AM detection, and then sent to an ASK demodulator. 23, and a position detector 24. The ASK demodulator 23 is an amplitude modulator of the roadside device] 5.16
The ASK modulated wave component (transmission data frame S3 or S4) is demodulated and supplied to the bit differentiator 25 and the data processing section 26. The 1-bit difference unit 25 corresponds to the differential encoding circuit 817 of the roadside device, and is used to convert transmission data frames S3. Or data S2 in the synchronization frame and information frame of S4. Or S2" is subjected to a bit difference, and the initial data S1 is restored and supplied to the data processing unit 26. Since the data S2° is the data S2 shifted by a bit, the bit difference results in both Initial data St
becomes. The position detector 24 detects the AM detected signal, that is, the drop point of the reception level, and supplies this position detection signal to the data processing section 26. The data processing unit 26 is a component that identifies the direction, captures traffic information in the direction of travel, and detects the current position. More specifically, the data processing section 26 is constituted by a microcomputer or the like, and performs the following processing. That is, based on the initial pig S] restored by the 1-bit differencer 25, the ASK demodulator 2
The data of the direction identification frame supplied from 3 is synchronously detected, and the data of the synchronous frame is either initial data Sl (for example, “1]-000011” in FIG. 3A) or data SL that is an inversion of initial data 9 St. ' (For example, "
00 1, 1, 1. 1, OO”) to determine from which direction the vehicle approached the split beam antenna 1. Also, following the direction identification frame, the information frame sent from the 1-bit difference unit 25 (Initial data Sl), the traffic information in the direction of travel is taken in. Furthermore, position data is taken in at the input timing of the position detection signal from the position detector. The output of the data processing section 26 (traffic information in the direction of travel, ) is displayed on the display unit 27 so that it can be visually recognized by the driver of the vehicle, etc. FIG. 5 is a diagram for explaining the reception operation of the receiving device shown in FIG. 1B when the receiver is running. In (a), A-B corresponds to the direction A-B in FIG. It is radiated with split beam characteristics of the main radiation beam in the direction A and the main radiation beam in the B direction. The signal output from the reception amplifier 22 is supplied to the ASK demodulator 23 and the position detection section.The transmission data frame S3 demodulated by the ASK demodulator 23 is sent to a 1-bit differencer. The synchronization frame data S2 of the transmission data frame S3 is then supplied to the initial data S by the 1-bit difference unit 25.
After being restored to L, it is supplied to the data processing section 26. Next, the data processing unit 26 synchronizes based on the restored initial data S1, and synchronously detects the undifferentiated data sent from the ASK demodulator 23. Since the vehicle is currently in the radiation area of the roadside device in the A direction, the pig in the direction identification frame is the same as the initial data S1, and the data processing unit 26 is connected to the beam antenna 1.
It is determined that the object entered the radiation area from direction A. Furthermore, following the direction identification frame, the data processing unit 26 inputs the initial data SL sent from the bit differentiator 25.
Traffic information in the direction of travel is selected from (restored data S2 of the information frame) and imported, and displayed on the display section 27. Next, when the vehicle continues to drive and reaches a position directly facing the split beam antenna 1, the reception level rapidly drops. The position detector 24 detects this sudden drop in the reception level and supplies it to the data processing section 26. Upon receiving this position signal, the data processing section 26 causes the display section 27 to display the position of the split beam antenna by blinking or the like. Thereby, the driver can accurately recognize the position of the split beam antenna 1, that is, the current position. Furthermore, when the vehicle continues to drive and passes through the position directly facing the split beam antenna 1 and enters the main radiation area in the B direction, the data of the direction identification frame detected by the data processing unit 26 changes to the initial data Si. It becomes a reversed version,
The data processing unit 26 determines that the beam has passed through the split beam antenna 1 and moved to the radiation area in the B direction. However, if the vehicle is traveling towards road B-A,
The operation of the receiving device is opposite to that described above, and the B-direction transmission data frame S4 is first received. <Effects of the Invention> As described above, the present invention configures the roadside antenna with two antenna elements with different main radiation directions, and the PS
K modulated, FSX modulated or ASK modulated signal,
By performing ASK modulation with the second transmission data frame containing at least direction identification data and position data and feeding this to each antenna element, a wide radiated electric field area by the first modulated wave signal and ASK modulation are achieved. Since the radiation electric field region with split beam characteristics caused by wave signals can appear simultaneously, the receiving device on the vehicle side can
Even with the K demodulation method, the second transmission data frame based on ASK modulation provides the effect that at least the traveling direction determination and position detection can be performed reliably in JJE. In addition, conventional 3 high-performance receiving devices (for example, the invention of Japanese Patent Application No. 63-45616, a combination of PSK demodulation method and AM demodulation method, or a combination of FSK demodulation method and AM demodulation method) As before, position detection,
Direction detection and various data can be provided.

[Brief explanation of drawings]

FIG. 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. FIG. 3 is a schematic perspective view showing a configuration example of a split beam antenna included in the roadside device shown in FIG. 1A, and FIG. 4 is a diagram for explaining signals of each part of the roadside device shown in FIG. 1A. FIG. 5 is a diagram for explaining the operation of the receiving device shown in FIG. 1B. ]...Split beam antenna, 4 11...Data transmitter, 12.Data modulator, 13...
Modulation signal generator, 14...Carrier wave generator, 15, 16
... Amplitude modulator, 17. Differential encoding circuit 18. Changeover switch circuit, 19. Inverter, 22.. Reception amplifier, 23. ASK demodulator, 24.. Position detector, 25.
...1-bit differencer, 26...data processing section

Claims (1)

[Claims] 1. A road-to-vehicle communication device configured to transmit and receive various data between a roadside device installed on the roadside and a vehicle, wherein the roadside device has at least two antennas having different main radiation directions. a roadside antenna consisting of an element; a first data generation means for generating a first transmission data frame consisting of various data; a first modulating means for generating a modulated wave signal; and at least direction identification data in synchronization with the first modulated wave signal;
An initial data generating means for generating initial data consisting of position data, a differential encoding means for differentially encoding this initial data, and this differentially encoded initial data and initial data that is not differentially encoded. a second data generation means for combining to generate a second transmission data frame; an inversion means for inverting the second transmission data frame; and a second transmission data frame inverted by the inversion means and a second data frame that is not inverted. ASK modulation is performed on each of the first modulated wave signals using the transmission data frames of ASK modulation means for feeding power to each element, and the receiving device mounted on the vehicle has an ASK demodulation means for receiving a transmission signal from a roadside device and demodulating an ASK modulation component, and a second transmission A difference means for restoring initial data by differentiating the differentially encoded data in the data frame, and whether the non-differentially encoded data in the second data frame is an inversion of the initial data. direction determination means for determining whether the roadside antenna is located in the main radiation region of the roadside antenna; and position detection means for detecting a sudden drop point of the second modulated wave component and determining the drop point as the current position. A road-to-vehicle communication device comprising: