JPS63100582A - Road side beacon system - Google Patents

Abstract

PURPOSE:To more exactly decide a position by bringing a signal received by a positioning antenna to an amplitude modulation in a mobile device side, synthesizing it with a receiving signal by a data use antenna and amplifying it, dividing it into two and deciding a position, based on one of them. CONSTITUTION:An antenna 2f radiates a radio wave A by an electric field intensity exceeding a prescribed level extending over a wide range, and an antenna 2g radiates a radio wave B by an electric field intensity exceeding a prescribed level only within a narrow range. A receiving signal from an antenna 41 of a mobile device is supplied to an amplitude modulating circuit 43, brought to an amplitude modulation by a frequency fn, supplied to a receiver in a state that it is synthesized with a receiving signal from a data use antenna 42, and an output signal from the receiver 44 is divided into two, and by supplying one of them to an amplitude detector 45, and also, allowing it to pass through a band pass filter 46, a component of a frequency of the modulation product is obtained. Accordingly, a receiving level distribution of a radio wave going along a road by the positioning antenna 41 is concentrated in the extreme vicinity of a rod side antenna.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a roadside beacon method, and more specifically, after inputting starting point information, at least vehicle speed data and direction data are inputted. This invention relates to a novel roadside beacon method used to calibrate vehicle position in navigation systems designed to display current position.

<Prior art> Conventionally, vehicles are equipped with a small computer and a display device, and road map data stored in a storage device such as a compact disk is read out and displayed on the display device, and the data is also read out from a vehicle speed sensor. Using the vehicle speed data and direction data from the direction sensor, the vehicle's position at each point in time is calculated and the direction of travel is determined.Based on these calculation results and judgment results, the vehicle is displayed on the display device. 2. Description of the Related Art So-called navigation systems have come to be provided in which a display indicating a vehicle is added to a corresponding portion of a road map.

If such a navigation system is used, the current location and traveling direction of the vehicle can be easily identified visually, and the vehicle can be reliably reached the destination without getting lost.

However, in the navigation system with the above configuration, errors that the vehicle speed sensor and direction sensor inevitably have accumulate as the traveling distance increases, and when the traveling distance exceeds a predetermined distance (however, this predetermined distance (It is determined by the degree of error in the vehicle speed sensor and direction sensor in each vehicle, and fluctuations in the atmospheric conditions at the location of each sensor, and is not necessarily a fixed distance.) The vehicle display position on the display device may differ from the actual vehicle position. This results in a situation in which the device deviates significantly from its normal state, becomes unable to perform its original function, and becomes lost.

In order to solve such problems, roadside antennas are installed in the road transportation network at predetermined distances shorter than the distance at which the cumulative error exceeds a predetermined value, and the roadside antennas transmit position data and road direction. A signal containing data is radiated only in a relatively narrow range, and the signal is received by an antenna installed on the vehicle and input into a computer, which calibrates the vehicle's position and driving direction to the correct data based on the received signal. It has been proposed to adopt a so-called roadside beacon method.

If such a roadside beacon method is adopted, it is possible to display information based on accurate position data and direction data while the accumulated error is always below a predetermined value, thereby demonstrating the original performance of the navigation system. In particular, by installing roadside antennas in locations where large errors are likely to occur in the direction sensor, such as near railroad tracks or at railroad crossings, errors caused by external factors can be effectively eliminated. It has the advantage that it can be calibrated.

<Problems to be Solved by the Invention> In the roadside beacon system with the above configuration, a signal containing position data and road direction data is constantly radiated by a roadside antenna with fairly high directionality, and the vehicle Since the signal is received only when passing through the area covered by the radiated signal, and the necessary calibration can be performed based on the received signal, the area covered by the transmitted signal can be widened. In this case, there is a problem that the deviation of the signal reception position with respect to the roadside antenna becomes large, and a sufficient calibration effect cannot be achieved.

To explain in more detail, the basic function of the roadside beacon method is to provide signals containing position data and road direction data to vehicles equipped with a navigation system, but the following functions can also be added to the roadside beacon system. This is required for effective use of the beacon method. In other words, ■ Assist the smooth operation of vehicles by providing the navigation system with additional traffic information such as road congestion, construction, and other road usage conditions around the location where the roadside antenna is installed. , ■ Add detailed map information, including residential locations and personal names, around the locations where roadside antennas are installed.
To make it easier to reach the final destination, ■ To improve the road map displayed by a display device by adding road map information covering a fairly wide range, including the locations where roadside antennas are installed, and providing it to the navigation system. It is being considered that the system will be updated to provide additional services such as smooth operation to remote areas, and if such additional services are to be provided,
It is essential to expand the transmission band of signals radiated from roadside antennas and to expand the area covered by transmitted signals.

When the transmission area and the area covered by the transmitted signal are expanded as described above,
This results in a problem in that the deviation of the signal reception position from the installation position of the roadside antenna becomes large, and the calibration of the vehicle position, which is the original purpose, cannot be performed accurately due to the influence of the deviation.

Additionally, the arrangement of buildings near the location where the roadside antenna is installed and the driving conditions of other vehicles change significantly over time or depending on the installation location of the roadside antenna, causing radiation from the roadside antenna. As shown in FIG. 13, in addition to being directly received by the on-vehicle antenna, the signal is also received by the on-vehicle antenna after being reflected by buildings, road surfaces, other vehicles, etc. Since the signals received through the roadside antenna have different amplitudes and phases, they are summarily or differentially superimposed, and as shown in Figure 10, the intensity distribution of the transmitted signal from the roadside antenna is Since the signals have significantly different intensity distributions (fading phenomenon occurs due to multipath), unexpected errors may occur when calibrating the vehicle position based on the received signals. , there will be a portion where the level is high at a location significantly away from the roadside antenna, and a problem will occur in that the vehicle position and traveling direction will have to be calibrated at the time this portion is detected.

In order to solve this problem, it is conceivable to install a low-pass filter to eliminate the influence of the intensity distribution of the received signal caused by the fading phenomenon.

However, since the intensity fluctuation period caused by the fading phenomenon is usually in the range of several tens of Hz to about 100 Hz,
The low-pass filter needs to have a cutoff frequency of about several Hz. If a low-pass filter with a low cutoff frequency as described above is constructed using a passive circuit, large inductance and capacitance will be required, making it extremely difficult to miniaturize the filter as an on-vehicle device. Further, if the device is configured with an active filter, it is possible to downsize the device, but there are problems in that the number of parts increases, the circuit configuration becomes complicated, and the in-vehicle device becomes expensive as a whole.

In order to solve these problems, the inventor of the present invention
Coverage is provided for data transmission by emitting a modulated wave signal modulated based on the transmitted data as a split beam (the electric field strength is above a predetermined level).
While expanding the area, the electric field strength is suddenly reduced in front of the roadside antenna, allowing necessary data to be transmitted in areas where the electric field strength is above a predetermined level, and detecting a state in which the electric field strength has suddenly decreased. Invented a roadside beacon system that allows position determination to be performed by

However, although this roadside beacon method can expand the area covered for data transmission, the electric field strength drops rapidly in front of the roadside antenna, making it difficult to determine position. A problem arises in that data cannot be transmitted at all.

<Object of the invention> This invention was made in view of the above problems,
To provide a roadside beacon method that can easily cope with the expansion of various functions in the roadside beacon method without interrupting data transmission, and can calibrate the original vehicle position with high accuracy. It is an object.

Means for Solving the Problem> In order to achieve the above object, the roadside beacon system of the present invention has a roadside antenna consisting of a plurality of antennas arranged horizontally, and has a constant amplitude based on transmitted data. A first modulated wave signal that has been modulated is fed to each antenna such that the directivity of the roadside antenna as a whole has an electric field strength of a predetermined value or more over a predetermined range, and the first modulated wave signal is amplitude modulated at a predetermined frequency. The second modulated wave signal is supplied to each antenna so that the directivity of the roadside antenna as a whole becomes sharp.The second modulated wave signal is then mounted on a vehicle, receives the transmission signal from the roadside antenna, and determines the vehicle position. A navigator device that calibrates and displays data has a main radiation direction in the upper direction and a positioning antenna with low sensitivity in near-horizontal directions, and a directional data antenna with a main sensitivity direction in the horizontal direction. an on-vehicle antenna consisting of an antenna, a modulation means for amplitude modulating a second modulated wave received by the positioning antenna, a signal subjected to amplitude modulation by the modulation means, and the data antenna. a receiver that manually receives the received first modulated wave signal; a position determining means that divides the signal output from the receiver into two and performs amplitude detection on one side to determine the position; It is provided with a determination signal and a calibration means for calibrating at least the position data based on the other signal.

However, the carrier signal of a predetermined frequency is divided into two, one is modulated with a constant amplitude based on the transmission data and radiated from the roadside antenna, and the other is modulated with a predetermined frequency and radiated from the roadside antenna. It may be something that radiates,
Alternatively, a carrier wave signal of a predetermined frequency is modulated with a constant amplitude based on transmission data, and this modulated wave signal is divided into two,
One may be radiated as is, and the other may be amplitude modulated at a predetermined frequency before being radiated. Even in the case of the above direction, both harmonic signals are radiated from separate antennas. It may be a thing, or
It may also be radiated from a common antenna. In these cases, the amplitude-modulated modulated wave signal may be radiated from the roadside antenna with sharp directivity, or may be radiated from the roadside antenna in the form of a split beam. It may be something.

Further, it is preferable that the modulated wave signal subjected to amplitude modulation is radiated from the roadside antenna in a state having a weaker electric field strength than the modulated wave signal subjected to constant amplitude modulation.

Further, the first modulated wave signal is obtained by applying phase shift keying, and the second modulated wave signal has an amplitude at a frequency sufficiently higher than the amplitude fluctuation frequency due to fading. Preferably, it is obtained by applying modulation.

Furthermore, the above-mentioned roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second The modulated wave signal may be fed to the two central antennas in substantially opposite phases, or the first modulated wave signal may be fed to all the antennas with predetermined amplitudes. In addition, the second modulated wave signal may be fed to the central two antennas in substantially the same phase. In the above case, the roadside antenna is composed of two antennas that are substantially parallel to the road, and two antennas that are placed at a distance from the road with the two antennas sandwiched between them. In this case, it is preferable that only the feeding level of the first modulated wave signal to the central two antennas is set lower than the feeding level to the other antennas.

Furthermore, the roadside antenna is composed of two antennas, and the first modulated wave signal is fed to both antennas in substantially the same phase, and the second modulated wave signal is fed to both antennas in substantially the same phase. The two antennas may be fed with substantially opposite phases to each other.

Furthermore, it is preferable that the transmission path for the captured data has a transmitter means for removing amplitude fluctuation components.

In the roadside beacon method described above, a modulated wave signal that has been modulated with a constant amplitude based on transmitted data is transmitted to each modulated wave signal so that the directivity of the entire roadside antenna has an electric field strength of a predetermined value or more over a predetermined range. In addition to feeding power to the antenna, a second modulated wave signal that has been amplitude-modulated at a predetermined frequency is fed to each antenna so that the directivity of the roadside antenna as a whole becomes sharp. from the roadside antenna installed at a predetermined location.
radiate different types of modulated wave signals to the vehicle.

In a navigator device mounted on a vehicle, which receives required data from a transmission signal from a roadside antenna as calibration data, calibrates and displays vehicle position data, the main radiation direction is in the upper direction, and , the radio waves based on the second modulated wave signal are received by a positioning antenna with low sensitivity in a direction close to the horizontal direction, and the radio waves are received by a directional data antenna having a main sensitivity direction in the horizontal direction. Receive. Next, the signal received by the positioning antenna is subjected to amplitude modulation by the modulation means, and the signal received by the data antenna is combined and supplied to the receiver to perform amplification, etc. The signal from the receiver is divided into two, and one signal is supplied to the position determining means to perform amplitude detection and determine the position. Further, by supplying the other signal and the position determination signal from the position determination means to the configuration means, at least the position data can be calibrated. In other words, the reception characteristics of the above-mentioned positioning antenna correspond to the product of the directivity of the positioning antenna and the directivity of the roadside antenna corresponding to the second modulated wave signal. The reception level distribution along the roadside antenna exhibits characteristics that are more concentrated near the location of the roadside antenna, which not only makes it possible to further improve the position detection accuracy but also further improves the stability against multipath fading. .

In addition, the carrier wave signal of a predetermined frequency is divided into two, one is modulated with a constant amplitude based on the transmission data and radiated from the roadside antenna, and the other is amplitude modulated with a predetermined frequency and then radiated from the roadside antenna. Even if it radiates,
Alternatively, a carrier wave signal of a predetermined frequency is modulated with a constant amplitude based on transmission data, and this modulated wave signal is divided into two,
Even in the case where one side is radiated as is and the other side is amplitude-modulated at a predetermined frequency and then radiated, data transmission can be performed based on a modulated wave signal that is not amplitude-modulated. Position determination can be performed based on a modulated wave signal subjected to amplitude modulation.

In the case where both harmonic signals are radiated from separate antennas, or when they are radiated from a common antenna, data transmission,
and position determination.

In addition, if the amplitude modulated modulated wave signal is radiated from a roadside antenna with sharp directivity, the amplitude modulated modulated wave signal is demodulated to detect a state exceeding a predetermined level. By detecting the position, the position can be determined with high accuracy.

Furthermore, if the amplitude-modulated modulated wave signal is radiated from the roadside antenna in the form of a split beam, the amplitude-modulated modulated wave signal is demodulated and a state where the level has suddenly decreased is detected. By doing so, position determination can be performed with high accuracy.

Furthermore, if the modulated wave signal subjected to amplitude modulation is radiated from the roadside antenna with a weaker electric field strength than the modulated wave signal subjected to constant amplitude modulation,
The rate at which a modulated wave signal subjected to amplitude modulation is influenced by the modulated wave signal can be reduced, and data transmission can be performed accurately.

Further, the first modulated wave signal is obtained by applying phase shift keying, and the second modulated wave signal is amplitude modulated at a frequency sufficiently higher than the amplitude fluctuation frequency due to fading. In this case, the modulated wave signal can be radiated to the navigation device without being affected by multipath fading or the like.

The roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second modulated wave signal is fed to all the antennas at a predetermined phase. If the signals are fed to the two central antennas in substantially opposite phases, the first modulated wave signal is radiated over a wide range with an electric field strength of a predetermined value or higher. In addition, the second modulated wave signal can be radiated in two directions with sharp directivity, and a portion where the electric field strength of the second modulated wave signal sharply decreases can be generated in the center.

Conversely, the first modulated wave signal is fed to all the antennas at predetermined amplitudes and phases, and the second modulated wave signal is fed to the two central antennas in substantially the same phase. In this case, the first modulated wave signal can be emitted over a wide range with an electric field strength of a predetermined value or more, and the second modulated wave signal can be emitted with sharp directivity in one direction. can be radiated with.

If the roadside antenna is composed of two antennas that are approximately parallel to the road and two antennas that are placed at a distance from the road with the two antennas sandwiched between them, , the above directivity can be easily achieved, especially when only the feeding level of the first modulated wave signal to the central two antennas is set lower than the feeding level to the other antennas. The above directivity can be easily achieved by reducing the number of types of power supply levels.

Furthermore, the roadside antenna is composed of two antennas, and the first modulated wave signal is fed to both antennas in substantially the same phase, and the second modulated wave signal is fed to both antennas in substantially the same phase. If both antennas are fed with power in substantially opposite phases, the first modulated wave signal can be radiated over a wide range with an electric field strength of a predetermined value or higher, and the first 2 modulated wave signals 2
radiates with sharp directivity in the direction, and emits a second beam in the center.
It is possible to generate a portion where the electric field strength of the modulated wave signal suddenly decreases.

Furthermore, if the transmission path for the above-mentioned captured data has a transmitter means for removing amplitude fluctuation components, the amplitude fluctuation components, including those caused by fading phenomena, can be removed and the amplitude fluctuation components can be kept constant. It is possible to reproduce a modulated wave with an amplitude of , and then perform accurate demodulation.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 14 is a diagram schematically showing an example of a road map displayed on a display device, in which arrow A indicates the current position of the vehicle and the direction of travel. Then, the roadside antennas PISP2, ...Pn are displayed corresponding to the actual installation positions (however, this roadside antenna PISP2,...Pn
There is no particular inconvenience even if F3,...Pn are not displayed). Although not shown in the diagram, buildings and the like that serve as landmarks are displayed.

FIG. 12 and FIG. 13 are schematic diagrams explaining the roadside beacon system, in which a road (
A roadside antenna (2) is placed close to the roadside antenna (2) that emits a signal including position data, road direction data, etc., and the signal is placed at a predetermined position of the vehicle (3) traveling on the road (1). In-vehicle antenna (4
) is installed, and the received signal is used to supply power to a navigation device (not shown).

Therefore, the signal radiated from the roadside antenna (concave) is
In addition to being directly received by the vehicle antenna (4), it is also received by the building (1).
'), reflected one or more times by the road surface, other vehicles (3), etc., and received by the in-vehicle antenna (4), and when the received signals are combined, they are summarily and differentially superimposed and sent to the roadside antenna. (This results in an intensity distribution that deviates significantly from the intensity distribution of the transmitted signal from the source (see Fig. 10).

1 and 2 are block diagrams showing an embodiment of the roadside beacon system of the present invention. FIG. 1 shows the transmitting side, that is, the roadside device, and FIG. 2 shows the receiving side, that is, the vehicle-mounted device. are shown respectively.

The roadside device has a first modulation circuit (22) that divides the oscillation signal (frequency f 2 ) output from the carrier oscillator (21) into two and modulates one side with a constant amplitude (PSK modulation, FSK modulation, etc.). and the other to a second modulation circuit (23) that performs amplitude modulation. The data signal to be transmitted is supplied as a modulation signal to the first modulation circuit (22), and the second modulation circuit (23)
is an oscillation signal (frequency f
) is supplied as a modulation signal. Furthermore, the modulated wave signals output from each of the modulation circuits are supplied to a data antenna (2f) and a body identification antenna (2g), respectively. The antenna (2r) has a directivity that can emit radio waves with an electric field strength of a predetermined level or higher over a fairly wide range, and the antenna (2g) has a directivity that can emit radio waves with an electric field strength of a predetermined level or higher only in a very narrow range. It has directivity that allows it to emit radio waves with an electric field strength of .

Therefore, from the antenna (2f), A
As shown in Figure 3, radio waves with strong electric field strength are emitted over a fairly wide range, and from the above antenna (2g), radio waves with strong electric field strength are emitted only in a very narrow range, as shown in B in Figure 3. be able to. That is, it is possible to reliably prevent instantaneous data interruption immediately in front of the roadside antenna, and it is also possible to radiate radio waves for highly accurate position determination. In addition, the above antenna (2f)
Since the radio waves radiated from the antenna (2g) are modulated with a constant amplitude, by making the level of the radio waves radiated from the antenna (2g) not too high (for example, 1g).
By lowering the level by about 5 dB), it is possible to prevent errors from occurring in the transmitted data. Also,
Since the radio waves for position determination are localized only in front of the roadside antenna, it is possible to reliably prevent the influence of fading caused by multipath.

As shown in FIG. 2, the vehicle-mounted device has a positioning antenna (41) that has directivity in the upper direction and has almost no sensitivity in a near-horizontal direction.
, and a data antenna (42) having a main sensitivity direction in a nearly horizontal direction.
have. Then, by supplying the received signal from the positioning antenna (41) to the amplitude modulation circuit (43), amplitude modulation is performed at the frequency fn, and the signal is combined with the received signal from the data antenna (42). It is supplied to the receiver (44) in the same state. Furthermore, the output signal from the receiver (44) is divided into two, one is supplied to the amplitude detector (45), and the center frequency a xf
+b Xf m (however, a and b are any integers other than 0)
By passing the signal through a bandpass filter (46), a component of the frequency aXf +bXf of the modulation product can be obtained. Therefore, by extracting one component of these modulation products, an output proportional to the radio waves radiated from the positioning antenna (2g) received by the positioning antenna (41) can be obtained, and both positioning The characteristics due to the synergistic effect of the antenna (2g) (41) can be obtained. That is, the antenna for positioning (41
), the reception level distribution of radio waves along the road is concentrated in the vicinity of the roadside antenna, which increases the accuracy of position detection and makes it possible to perform stable position determination with almost no influence of multipath fading. can. Specifically, the above one component is extracted and the position determination circuit (47)
By supplying the signal to the signal, the signal is compared with, for example, a predetermined reference level, and a position determination signal is output. In addition, the above receiver (4
The other output signal from 4) is sent directly to the data transmission system (4).
8) (consisting of a data calibration circuit, a processing circuit that processes data other than calibration data, etc.). The data transmission to the calibration circuit is controlled based on the position determination signal, and the data transmission to the calibration circuit is performed when the vehicle is directly facing the roadside antenna (4). .

FIG. 4 is a diagram showing changes in the reception level by the vehicle-mounted antenna (4), and corresponds to a state in which the vehicle (3) passes in front of the roadside antenna (4).

As is clear from the curve A in Figure 4, the reception level by the data antenna (42) is
A predetermined reference level Ll at a position considerably distant from J
, it is possible to secure a wide data transmission area. Furthermore, as is clear from the curve B in Figure 4, the reception level by the positioning antenna (41) exceeds the predetermined reference level L2 only at the position almost directly opposite the roadside antenna (a), so the position determination accuracy is In other words, since the reception level by the positioning antenna (41) exhibits a sharp mountain-shaped characteristic, sufficient position determination accuracy can be ensured without setting the reference level too high. can.

FIG. 5 is a diagram showing changes in the reception level by both antennas (41) and (42) when a split beam antenna is used as the roadside antenna (2).
The reception level by both antennas (41) and (42) decreases rapidly at the position directly facing the roadside antenna]2). Therefore, the antenna for positioning (
By detecting a sudden drop in the reception level due to 41), stable and accurate position determination can be performed.

Even in the case of the above direction, both antennas (41
) (42) are not supplied to each receiver, but the re-received signals are combined and supplied to one receiver (44), making the in-vehicle device as a whole smaller. Not only can this be achieved, but also a significant cost reduction can be achieved by halving the number of expensive receivers compared to the low frequency circuit section.

FIG. 6 is a block diagram of a roadside device showing another embodiment, in which the oscillation signal outputted from the carrier oscillator (21) is supplied to the first modulation circuit (22) to generate data based on the data to be transmitted. Amplitude modulation is achieved by obtaining an output signal that has been modulated with a constant amplitude, dividing this signal into two parts, supplying one part as it is to the antenna (2r), and the other part to the second modulation circuit (23). The antenna (2
g).

Therefore, in the case of this embodiment as well, it is possible to emit radio waves with the field strength shown in FIG. 3, and the on-vehicle device that receives these radio waves can perform the same calibration operation as in the above embodiment.

FIG. 7 is a diagram showing the electric field strength distribution of another embodiment, and the only difference from the embodiment of FIG. 3 is that amplitude-modulated radio waves are emitted as split beams.

Therefore, in the case of this embodiment, highly accurate position determination can be performed based on the rapid decrease in the electric field strength of the amplitude-modulated radio waves.

FIG. 8 is a block diagram more specific to the embodiment shown in FIG. The data signal to be transmitted is supplied as a modulation signal to the phase shift modulation circuit (22) to obtain a modulation output signal having a constant amplitude, which is demultiplexed by the demultiplexer (25) and sent to the roadside antenna (2). Each antenna (2a) (2b)
power is supplied to each of them at a predetermined phase. In addition, part of the output signal from the phase shift modulation circuit (22) is transferred to the amplitude modulation circuit (22).
23), and an oscillation signal (frequency is f.

, and the frequency is sufficiently higher than the frequency f of the amplitude fluctuation caused by the fading phenomenon, for example, the vehicle (3
) with a maximum speed of 200 km/h and a beacon wave carrier frequency f. When is set to 1.5 GHz, that is, the wavelength λo = 200 mm, fF-278 Hz, and the maximum frequency of amplitude fluctuation due to the fading phenomenon is several tens of GHz.
Since it can be regarded as 0Hz, the above frequency f
(preferably set in the range of several kHz to several 100 kHz) as a modulation signal to the amplitude modulation circuit (2).
3) to obtain a modulated output signal subjected to amplitude modulation,
This modulated output signal is divided into two by a splitter (26), and a multiplexer (
27), it is superimposed on the signal that has undergone only phase shift keying, and is fed only to the two central antennas (2b) of the roadside antenna (2). Note that the amplitude-modulated signals are fed to the two antennas (2b) so that they are in opposite phases to each other. To explain this point in more detail, let λ be the wavelength of the carrier wave modulated by the transmitted data. Then, the electric field distribution along the road is λ in the worst case due to the fading phenomenon. There is a possibility that it fluctuates at a cycle of /2.

Therefore, if the speed of the vehicle is ■, the received wave by the on-vehicle antenna is T-λ. /2 V, in this case fF-1/T-2V/λ.

may undergo amplitude modulation at the frequency of Therefore, the frequency at which amplitude modulation is applied may be set to a frequency that is sufficiently higher than the frequency fp.

Then, in a state where such conditions are set, the signal received by the on-vehicle antenna is V-A tx
(t)) 11+M(x)cos(2yr f t)
+ m cos (2πf Ft )IX co
s (2πfot+θ5(t)) (where, X is the distance along the road, A (x) is a function proportional to the electric field distribution along the road, m (x) is the frequency f
mp is the amplitude modulation index due to the fading phenomenon, θ5(t) is the phase function representing the transmitted signal, and f is the frequency of the carrier wave). Therefore, amplitude detection is performed to detect only the amplitude component. If we extract V=Afx(t))(1+M(x)cos(2πf
t)+m cos(2πfFtel, which still contains a component due to the fading phenomenon. However, this amplitude detection signal is
If the frequency f component is extracted through the bandpass filter of A tX(t)l,m (
Since the temporal change of x(t)1■ is slow, V −mi
x(t))Alx(t))cos(2πf t)II

A signal called III is extracted. Therefore, by further amplitude detecting this signal, a signal of V = mfx(t)lAtx(t)1, that is, a signal proportional to the electric field distribution of the amplitude-modulated component at frequency f can be obtained. It becomes.

In addition, if the ratio a of the electric field strength of the signal subjected to amplitude modulation to the electric field strength of the signal not subjected to amplitude modulation satisfies all/(1+m) (where m is the modulation index by the second modulation means), data is acquired. Accurate demodulation becomes possible.

Note that it is also possible to use a frequency shift modulation circuit in place of the phase shift modulation circuit (22), as long as it can provide a modulated output signal with a constant amplitude.

The operation of the roadside beacon system having the above configuration is as follows.

The signal radiated from the roadside antenna (a) consists of a signal obtained by performing phase shift keying or frequency shift keying on a carrier wave of frequency fo based on the transmitted data, and an amplitude resulting from the multipath fading phenomenon. This is a superimposed signal of signals obtained by performing amplitude modulation at a frequency sufficiently higher than the fluctuation frequency (see FIG. 9).

Therefore, the signal received by the on-vehicle antenna (4) (see Figure 10) is equivalent to the transmitted signal subjected to relatively low frequency amplitude modulation due to the fading phenomenon. .

Among the received signals, the signal received by the positioning antenna (41) is transmitted to the amplitude modulation circuit (41).
3), and then combined with a signal received by the data antenna (42) and supplied to one receiver (44). The signal amplified by this receiver (44), that is, the signal on which fading has not been removed, is divided into two parts, one of which is detected by the amplitude detector (45).
), and the state (
(see FIG. 11) and is supplied to the position determination circuit (47). The other one is supplied as is to the data transmission system (48).

A vehicle (3) is traveling on a road (1) and is connected to a roadside antenna (21).
When the vehicle approaches and then moves away from the vehicle, the signal reception level at the on-vehicle antenna (4) is initially approximately zero level. The signal level gradually increases as it approaches the roadside antenna (2), and when the data transmission system (48) can read the data, the transmitted data is stored in the memory (not shown). No data is transmitted to the navigator (not shown) through the vehicle, and the navigator calculates the current position and driving direction based on the vehicle speed data and driving direction data from the vehicle speed sensor and direction sensor (not shown). , determine,
A display device (not shown) can display the current location and driving direction of the vehicle along with the road map.

When the vehicle (3) travels further and reaches a position almost directly facing the roadside antenna (a), if a split beam is being emitted for positioning, the level of the amplitude modulated wave signal is proportional to the electric field distribution function. further increases and the level of the signal supplied to the position determination circuit (47) exceeds the reference level L, so the device determination signal constituted by the position determination circuit (47) is supplied to the navigator and stored in the memory. Preparations are made to transfer the position data.When the vehicle (3) travels further and reaches a position directly facing the roadside antenna (2), the signal level proportional to the amplitude modulated wave signal electric field distribution function suddenly drops to zero. , it immediately returns to the previous level.At that moment, the position data stored in the memory is taken into the navigator, and the current position within the device body is calibrated.

This allows position data, travel direction data, etc. to be calibrated, and accurate current position and travel direction to be displayed on the display device.

On the other hand, if it is simply radiated with high directivity for positioning, the level of the signal proportional to the amplitude modulated signal electric field distribution function will further increase, Since the level of the signal supplied to the position determination circuit (47) exceeds the reference level L, the position data stored in the memory is taken into the navigator at this moment, and the current position within the device body is calibrated. .

This allows position data, travel direction data, etc. to be calibrated, and accurate current position and travel direction to be displayed on the display device.

After that, the vehicle speed data from the vehicle speed sensor and the direction sensor are calculated based on the calibrated position and driving direction.
Based on the traveling direction data, the position of the vehicle (3) at each point in time and the traveling direction can be displayed as arrow A on the display device together with the road map.

Note that FIGS. 9 to 11 show changes in the received signal level when the vehicle (3) is running at a constant speed, but when the speed of the vehicle [3] changes, There is no particular inconvenience, as the above-mentioned position data transfer preparation period varies widely.

<Effects of the Invention> As described above, the present invention makes the signal transmitted from the roadside antenna a superimposed signal of a modulated signal having a constant amplitude and a signal amplitude modulated at a predetermined frequency.
Moreover, the modulated wave signal with a constant amplitude is radiated to reach a certain distance from the roadside antenna, the amplitude modulated wave signal is radiated only in the vicinity of the roadside antenna, and the in-vehicle device side is radiated upward. The signal received by the positioning antenna, which has a main radiation direction and has low sensitivity in directions near the horizontal direction, is amplitude-modulated and combined with the signal received by the data antenna, which is then amplified by a single receiver. , and perform position determination based on one, and data transmission based on the other, so that the effects of multipath fading can be further suppressed and more accurate position determination can be performed. It has the unique effect of increasing the amount of transmitted data, and by supplying signals received by both antennas to a single receiver, it is possible to reduce the size and cost of the entire in-vehicle device. play.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the roadside device used in the roadside beacon method of the present invention, and FIG. 2 is a block diagram showing an embodiment of the book cutting device used in the roadside beacon method of the present invention. , Fig. 3 is a diagram showing the electric field strength of the signal at a position along the road, Fig. 4 is a diagram showing the change in reception level by the vehicle-mounted antenna I), and Fig. 5 is a diagram showing the change in reception level by the roadside antenna (split beam antenna 6 is a block diagram of a roadside device showing another embodiment, FIG. 7 is a diagram showing electric field strength distribution of another embodiment, and FIG. 8 is a diagram showing the above-mentioned FIG. 9 is a diagram showing the electric field strength of the signal at a position along the road; FIG. 10 is a diagram showing changes in the signal reception level by the on-vehicle antenna; The figure shows the relationship between the amplitude modulated wave signal level subjected to fading removal processing and the threshold level. Figure 12 is a perspective view schematically showing the roadside beacon method. Figure 13 is the fading phenomenon caused by multipath. 14 is a diagram schematically showing an example of a road map displayed on a display device. (1) Road, (2) Roadside antenna, (2f
)... Antenna for data, (2g)... Antenna for positioning, (3).
...Vehicle, (4)...Vehicle antenna, (22)...
Phase shift modulation circuit, (23)...amplitude modulation circuit, (41)...positioning antenna, (42)
...Antenna for data, (43)...Amplitude modulation circuit, (44)...Receiver Fig. 4 Fig. 5 Roadside antenna stop @Kan straight e3 side antenna position Fig. 1O Fig. 11 Fig. 2 12 Figure 1, Display of the case, Patent Application No. 246734 filed in 1986, 2, Name of the invention: Roadside beacon system 3, Person making the amendment 6, Scope of claims in the specification to be amended. 7. Contents of amendment (1) The statement in the scope of claims column of the specification is corrected as shown in the attached sheet. 2. Claim 16 Various types of roadside antennas are selected from roadside antennas installed at predetermined positions on the road transportation network, and the roadside antenna is composed of a plurality of antennas arranged in a horizontal direction, and transmits data based on transmitted data. A first modulated wave signal modulated with a constant amplitude is fed to each antenna so that the directivity of the roadside antenna as a whole has an electric field strength of a predetermined value or more over a predetermined range, and the first modulated wave signal is modulated with a predetermined frequency. A second modulated wave signal subjected to amplitude modulation is supplied to each antenna so that the directivity of the entire roadside antenna is sharp,
A navigator device mounted on a vehicle that receives transmission signals from the roadside antenna, calibrates and displays vehicle position data, has a main radiation direction in the upper direction, and has low sensitivity in near-horizontal directions. an in-vehicle antenna comprising a positioning antenna and a directional data antenna having a main sensitivity direction in the horizontal direction; a modulation means for amplitude modulating a second modulated wave received by the positioning antenna; A receiver inputs the signal amplitude-modulated by the modulation means and the first modulated wave signal received by the data antenna, and the signal output from the receiver is divided into two, and one of the signals is divided into two. a position determination means for performing position determination by performing amplitude detection and extracting a modulation product component of amplitude modulation by the roadside antenna and amplitude modulation of a received signal by the vehicle-mounted positioning antenna; a position determination signal from the position determination means; and a position determination means based on the other signal. A roadside beacon system comprising at least a calibration means for calibrating position data. 2. Divide the carrier wave signal of a predetermined frequency into two, modulate one with a constant amplitude based on the transmitted data and radiate it from the roadside antenna, and apply amplitude modulation to the other with a predetermined frequency and radiate it from the roadside antenna. The roadside beacon system according to claim 1, which emits radiation. 3. Apply constant amplitude modulation to the carrier wave signal of a predetermined frequency based on the transmission data, divide this modulated wave signal into two,
The roadside beacon system according to claim 1, wherein one side is radiated as is, and the other is subjected to amplitude modulation at a predetermined frequency before being radiated. 4. The roadside beacon system according to any one of claims 1 to 3, in which both modulated wave signals are radiated from separate antennas. 5. The roadside beacon system according to any one of claims ¥S1 to 3 above, in which both modulated wave signals are radiated from a common antenna. 6. The roadside beacon system according to any one of claims 1 to 5, wherein a modulated wave signal subjected to amplitude modulation is radiated from a roadside antenna with sharp directivity. 7. The roadside beacon system according to any one of claims 1 to 5, wherein a modulated wave signal subjected to amplitude modulation is radiated from a roadside antenna in the form of a split beam. 8. The modulated wave signal subjected to amplitude modulation is radiated from the roadside antenna in a state where the electric field strength is weaker than the modulated wave signal subjected to constant amplitude modulation. Roadside beacon method described in any of the above. 9. The first modulated wave signal is obtained by applying phase shift keying, and the second modulated wave signal is obtained by applying amplitude modulation at a frequency sufficiently higher than the amplitude fluctuation frequency due to fading. A roadside beacon system according to claim 1. 10. The roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second modulated wave signal is fed to the central two antennas. The roadside beacon system according to claim 1, wherein power is supplied to the antennas in substantially opposite phases to each other. 11. The roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second modulated wave signal is fed to the central two antennas. Claim 1 or 9 above, wherein power is fed to the antennas in substantially the same phase.
The roadside beacon method described in any of the paragraphs. 12. Claim No. 1, wherein the roadside antenna is composed of two antennas that are substantially parallel to the road, and two antennas that are placed at a distance from the road with the two antennas sandwiched between them. 10. The roadside beacon system according to any one of Items 10 and 11. 13. Claim 1 above, wherein only the feeding level of the first modulated wave signal to the two center antennas is set lower than the feeding level to the other antennas.
The roadside beacon method according to any one of items 0 to 12. 14. The roadside antenna is composed of two antennas, and the first modulated wave signal is fed to both antennas in substantially the same phase, and the second modulated wave signal is fed to both antennas reciprocally. The roadside beacon system according to any one of claims 1 and 9, wherein power is supplied in substantially reverse phase to the roadside beacon system. 15゜ Claim 1 above, wherein the transmission path of the acquired data has a transmitter means for removing amplitude fluctuation components.
Roadside beacon method described in section.

Claims (1)

[Scope of Claims] 1. In a roadside beacon system in which various data including at least position data is transmitted to vehicles from roadside antennas installed at predetermined positions on a road transportation network, there are a plurality of roadside antennas. The first modulated wave signal is modulated with a constant amplitude based on the transmitted data, and the field strength is such that the directivity of the roadside antenna as a whole exceeds a predetermined value over a predetermined range. Power is fed to each antenna so that , a navigator device mounted on a vehicle that receives transmission signals from the roadside antenna, calibrates and displays vehicle position data, has a main radiation direction in the upper direction, and has low sensitivity in near-horizontal directions. an in-vehicle antenna comprising a positioning antenna and a directional data antenna having a main sensitivity direction in the horizontal direction; and a modulation means for amplitude modulating a second modulated wave received by the positioning antenna. , a receiver inputting the signal subjected to amplitude modulation by the modulation means and the first modulated wave signal received by the data antenna, and a signal output from the receiver divided into two, one a position determination means for performing position determination by amplitude-detecting the amplitude modulation of the signal by the roadside antenna and amplitude modulation of the received signal by the vehicle-mounted positioning antenna; A roadside beacon system, characterized in that the roadside beacon system comprises at least a calibration means for calibrating position data. 2. Divide the carrier signal of a predetermined frequency into two, modulate one with a constant amplitude based on the transmitted data and radiate it from the roadside antenna, and perform amplitude modulation on the other with a predetermined frequency and radiate it from the roadside antenna. The first claim radiating above
Roadside beacon method described in section. 3. Apply constant amplitude modulation to a carrier wave signal of a predetermined frequency based on the transmission data, divide this modulated wave signal into two, radiate one as is, and apply amplitude modulation to the other at a predetermined frequency. A roadside beacon system according to claim 1, which emits a signal. 4. The roadside beacon system according to any one of claims 1 to 3, in which both modulated wave signals are radiated from separate antennas. 5. The roadside beacon system according to any one of claims 1 to 3, in which both modulated wave signals are radiated from a common antenna. 6. The roadside beacon system according to any one of claims 1 to 5, wherein a modulated wave signal subjected to amplitude modulation is radiated from a roadside antenna with sharp directivity. 7. The roadside beacon system according to any one of claims 1 to 5, wherein a modulated wave signal subjected to amplitude modulation is radiated from a roadside antenna in the form of a split beam. 8. The modulated wave signal subjected to amplitude modulation is radiated from the roadside antenna in a state where the electric field strength is weaker than the modulated wave signal subjected to constant amplitude modulation. Roadside beacon method described in any of the above. 9. The first modulated wave signal is obtained by applying phase shift keying, and the second modulated wave signal is obtained by applying amplitude modulation at a frequency sufficiently higher than the amplitude fluctuation frequency due to fading. A roadside beacon system according to claim 1. 10. The roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second modulated wave signal is fed to the central two antennas. Claim 1 or 9 above, wherein power is supplied to the antennas in substantially opposite phases to each other.
The roadside beacon method described in any of the paragraphs. 11. The roadside antenna is composed of four antennas, and the first modulated wave signal is fed to all the antennas at a predetermined phase, and the second modulated wave signal is fed to the central two antennas. The roadside beacon system according to claim 1 or 9, wherein power is fed to the antennas in substantially the same phase. 12. The above-mentioned claim No. 1, wherein the roadside antenna is composed of two antennas that are substantially parallel to the road, and two antennas that are placed at a distance from the road with the two antennas sandwiched between them. The roadside beacon system according to any one of Items 10 and 11. 13. According to any one of claims 10 to 12 above, wherein only the feeding level of the first modulated wave signal to the two center antennas is set lower than the feeding level to the other antennas. Roadside beacon method described. 14. The roadside antenna is composed of two antennas, and the first modulated wave signal is fed to both antennas in almost the same phase, and the second modulated wave signal is fed to both antennas reciprocally. The roadside beacon system according to any one of claims 1 and 9, wherein power is supplied in substantially reverse phase to the roadside beacon system. 15. The roadside beacon system according to claim 1, wherein the transmission path for the captured data has a transmitter means for removing amplitude fluctuation components.