JP2000111643A - Reception sensitivity adjustment circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the position detecting accuracy of a running vehicle by selecting an optimum digital enveloping extracted signal of a maximum level not causing an overflow among a plurality of digital enveloping extracted signals, and calculating the distance between antennas based on the extracted signal. SOLUTION: In a detection part 30, electromotive force (voltages V1, V2) of a detection antenna 31 is detected 32, and an LPF 33 extracts a direct-current signal component, detects an enveloping signal, converts 34 it into a digital signal, and send it out to a position detecting part 60. In a detection part 40, a received signal of the antenna 31 is amplified by an amplifier 41 to a level not causing an underflow and outputted. In a detection part 50, the received signal of the antenna 31 is attenuated by an attenuator 51 to a level not causing an overflow and outputted. Output (voltages V1, V2) of the detection parts 30, 40, 50 is memorized 61. A controller 63 calculates the difference between the voltage V1, V2, and the value of distance between a lane marker 1 and an on-vehicle questioner 2 is calculated by using dada of a detection part of a maximum level not causing an overflow selected from among the detection parts 30, 40, 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reception sensitivity adjustment circuit applied to a lane marker system for automatically determining the position of a vehicle traveling on a road.

[0002]

2. Description of the Related Art Hitherto, as one of the traveling vehicle support systems, a lane marker system which determines a position of a traveling vehicle, issues a warning when the vehicle departs from a lane, alerts the driver, and enables automatic driving control. As a known lane marker system, a system using magnetism or radio waves is well known. FIG. 5 shows a configuration diagram of a conventional lane marker system using a radio wave method. As shown in FIG. 5, in this lane marker system, a plurality of lane markers 1 are arranged at regular intervals in the center of the lane of the road, and an in-vehicle interrogator 2 is provided at a predetermined position of the vehicle 3 (below the license plate). . The in-vehicle interrogator 2 detects the position of the lane marker 1 and controls the traveling position of the traveling vehicle (lane holding).

FIG. 6 is a block diagram showing a detailed configuration of the in-vehicle interrogator 2, and FIG. 7 is a block diagram showing a detailed configuration of the lane marker 1. 6 and 7, the in-vehicle interrogator 2 includes a detection antenna 31 (second antenna) for transmitting a reception signal to a marker antenna 90 (first antenna) on the lane marker 1 side, and a reception signal ( Detecting unit 30 for detecting voltages V1 and V2 corresponding to logical values 1 and 0 of the marker information signal by turning on and off SW1, which will be described later.
And a position calculation unit 60. The detection antenna 31 is configured by a coil element and attached near the bumper of the vehicle 3.

As shown in FIG. 6, a detector 30 includes a detector 32 for detecting a signal received from a detection antenna 31 and a detector 32 for detecting the signal.
Extract the DC signal component in the detection output signal from 32,
And a low-pass filter (LP) for removing high-frequency signal components
F) 33, and an A / D converter 34 for converting the detection signal from the LPF 33 into a digital signal and outputting the digital signal. As described later, the voltage between terminals (both ends) of the detection antenna 31 is detected by the detector 32.

[0005] The position calculator 60 is composed of a memory or the like.
It has a storage area 61 for storing (storing) a digital signal (data) from the A / D converter 34, a controller 63 having a determining function, and a table 62. In this table 62, the relative relationship between the voltage change and the distance (data for calculating the distance value) is stored in advance. The position calculator 60 analyzes the measurement data indicating the positional relationship between the lane marker 1 and the vehicle 3 based on the detection data from the detector 30.

On the other hand, as shown in FIG.
Is a marker antenna 90, a capacitor 92 (C2) for parallel resonance connected to the marker antenna 90, and a switching element (for example, F
A switch 91 (SW1) using an ET transistor).
And a control circuit 93 for transmitting a marker information signal for turning on / off the switch 91. The marker antenna 90 is also formed of a coil element similarly to the detection antenna 31, and is magnetically coupled by electromagnetic induction (electromagnetic coupling) when a current flows through each coil.

This electromagnetic coupling will be described with reference to an equivalent circuit diagram of the lane marker 1 and the in-vehicle interrogator 2 shown in FIG. Here, R1 and R2 are distributed resistors, and C1 and C2 are matching capacitors for determining the resonance frequency. L1 is the self-inductance of the detection antenna 31, L2
Is the self-inductance of the marker antenna 90, and M is the mutual inductance between the detection antenna 31 and the marker antenna 90. Mutual inductance M increases as the distance between detection antenna 31 and marker antenna 90 decreases.

FIG. 9 is a simplified version of FIG.
Will be described with reference to the equivalent circuit diagram of FIG. FIG. 9 shows the lane marker on the right side of the broken line in FIG. As shown in FIG.
When the switch 91 on the side is turned on / off by the marker information signal (logical value 1, 0), the specific impedance Z changes to Z1, Z2 due to the mutual induction action. In response to the changes in the specific impedances Z1 and Z2, the voltage (electromotive force) generated at both ends of the detection antenna 31 changes to V1 or V2.

[0009] Here, as shown in FIG.
When the distance between the lane marker 1 and the in-vehicle interrogator 2 is long, the received signal (electromotive force, voltage V1, V2) from 31
As shown in FIG. 10A, the logical values 1, 0 of the marker information signal
In the case where the difference (V2−V1) between the voltages V1 and V2 corresponding to the above is small, and when the distance is short, the difference between the voltages V1 and V2 increases as shown in FIG. Here, as described above, the voltage difference between the voltages V1 and V2 is
Since it depends on the electromagnetic coupling state of the marker antenna 90, that is, the mutual inductance M, the detection antenna
The positional relationship between the lane marker 1 and the vehicle (vehicle interrogator 2) can be detected based on the voltage difference (V2-V1) between the voltages V1 and V2 generated at 31.

More specifically, the electromotive force (voltages V1 and V2) at both ends of the detection antenna 31 is detected by the detection unit 30 (FIG. 6).
Is detected by the detector 32 of And then LP
The DC signal component is extracted by F33, and after removing the high-frequency signal component, the envelope signal of the DC component (broken line in FIG. 10) is detected. The envelope signals (voltages V1 and V2) are converted into digital signals by the A / D converter 34, and the digital signals are temporarily stored in the storage area 61. Next, these digital signals (FIGS. 10A and 10B) are fetched by the controller 63, and the difference between the voltages V1 and V2 (V2-V1) is calculated by the controller 63, and finally stored in the table 62. Lane marker 1 and in-vehicle interrogator 2 based on the distance data
An appropriate distance value between is calculated.

[0011]

By the way, in the case where the position is calculated by the voltage change (voltage difference: V2-V1) in the detection unit 30 as described above, the accuracy of the reception level is particularly important. , Detector 32, LPF 33 and A / D converter
34 has a voltage operation range (dynamic range). For example, when the reception level is a level value (overflow) exceeding the input allowable voltage of the A / D converter 34, the output digital signal is the maximum value. Will be fixed to. Therefore, the linearity is not maintained between the input as the analog signal and the output as the digital signal, and an accurate voltage value of the voltage level difference (V2-V1) corresponding to the received signal cannot be obtained.

In order to prevent such an overflow, it is conceivable to provide an automatic gain control (AGC) circuit. However, since the AGC circuit detects overflow and adjusts the gain thereafter, Not applicable to lane marker systems. That is, even if the gain control is executed after the overflow in the automatic gain control has occurred, the data cannot be restored at the time of the distorted overflow, so that a problem occurs that the gain is changed variously on the way.

When the signal level is very small, even if the voltage changes below the resolution of the A / D converter, the change cannot be detected.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, to prevent the occurrence of overflow and underflow which adversely affect the position detection signal, and to improve the position detection accuracy of the traveling vehicle. It is an object of the present invention to provide a reception sensitivity adjustment circuit that can be achieved.

[0015]

In order to achieve the above object, the invention according to claim 1 is directed to a second antenna, which is generated in response to a change in a switch connected to a coiled first antenna. An attenuating means for amplifying or attenuating the antenna voltage and outputting an amplified attenuated signal in a lane marker system for calculating a distance between the first antenna and the second antenna from a variation ratio of the antenna voltage at both ends; Envelope extraction means for extracting an envelope signal from the amplified attenuation signal, A / D conversion means for digitizing the envelope extraction signal output from the envelope extraction means to generate a digital envelope extraction signal, the amplification attenuation means, and envelope extraction means , A plurality of A / D converters with different amplification factors or attenuation factors, and a storage device for storing a digital envelope extraction signal; Selecting means for selecting an optimal digital envelope extraction signal of a maximum level that is not low, and calculating a distance between the first antenna and the second antenna based on the selected digital envelope extraction signal. It is a feature.

According to a second aspect of the present invention, in the first aspect of the present invention, the envelope extracting means performs full-wave or half-wave rectification of the amplified and attenuated signal and passes the signal through a low-pass filter. It is.

According to a third aspect of the present invention, there is provided the coil-shaped first
In a lane marker system for calculating the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna generated according to the change of the switch connected to the antenna, Attenuating means for amplifying or attenuating the signal, and outputting an amplified attenuated signal; A / D converting means for digitizing the amplified attenuated signal to generate a digital amplified attenuated signal; Storage means for storing a plurality of digitally amplified and attenuated signals, and a plurality of digitally attenuated extraction signals for generating a plurality of digitally enveloped extracted signals from the plurality of digitally amplified and attenuated signals. Selecting means for selecting an optimal digital envelope extraction signal having a maximum level which does not overflow among a plurality of digital envelope extraction signals, It is characterized in calculating the distance between the first antenna and the second antenna based on the digital envelope extracting signal.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the digital envelope extracting means squares the digital amplified and attenuated signal by digital processing or leaves the positive value as it is, It is a means for converting to 0 or an absolute value and performing a digital low-pass filtering operation.

According to a fifth aspect of the present invention, there is provided a coil-shaped first device.
A lane marker system that calculates the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna that occurs in response to a change in the switch connected to the antenna, Measuring means for measuring the distance from the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; and adjusting the gain of the antenna voltage according to the ratio. Gain adjusting means, an envelope extracting means for extracting an envelope signal from an output of the gain adjusting means, an A / D converting means for digitizing the envelope extracted signal output from the envelope extracting means to generate a digital envelope extracted signal, Storage means for storing a digital envelope extraction signal, wherein a distance between the first antenna and the second antenna is calculated based on the digital envelope extraction signal. It is an.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the envelope extracting means performs full-wave or half-wave rectification on the output of the adjusting means, and passes the output through a low-pass filter. It is assumed that.

According to a seventh aspect of the present invention, there is provided the coil-shaped first
A lane marker system that calculates the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna that occurs in response to a change in the switch connected to the antenna, Measuring means for measuring the distance from the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; and adjusting the gain of the antenna voltage according to the ratio. Gain adjusting means, A / D converting means for digitizing the output of the gain adjusting means, storing means for storing the output of the A / D converting means, and generating a digital envelope extraction signal from the stored signal. Digital envelope extraction means for calculating a distance between the first antenna and the second antenna based on the digital envelope extraction signal.

According to an eighth aspect of the present invention, the digital envelope extracting means squares the digital amplified attenuated signal by digital processing or converts the negative value to zero or an absolute value by digital processing, It is a means for performing a digital low-pass filtering filter operation.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, in each embodiment of the present invention shown in the drawings, the same parts as those of the prior art will be denoted by the same reference numerals, and description thereof will be omitted, and mainly different parts will be described. FIG. 1 is a block diagram showing a first embodiment of the present invention. The reception sensitivity adjustment circuit of the present invention utilizes a change in mutual inductance as in the related art, and has the same lane marker 1 and in-vehicle interrogator 2 as in the conventional configuration (FIG. 5). A plurality of circuits (detection units) for detecting a signal from the antenna 31 are provided,
The point is that the input signal is amplified and attenuated by each detection unit.

That is, as shown in FIG. 1, the in-vehicle interrogator 2 includes, in addition to the detection unit 30, a detection unit 40 that amplifies a reception signal of the detection antenna 31 to detect an envelope signal and a reception signal of the detection antenna 31. A detection unit 50 that attenuates and detects an envelope signal. The detection units 40 and 50 have a function of extracting an envelope component from the amplified or attenuated signal and converting the envelope component into a digital signal in the same manner as the detection unit 30. 41, which amplifies the signal to a normal level at which no underflow occurs and outputs the amplified signal, a detector 42 that operates in the same manner as the detector 30, an LPF 43, and an A / D converter 44.

The detecting section 50 has an attenuator 51 for attenuating and outputting a received signal from the detecting antenna 31 to a normal level at which overflow does not occur, a detector 52, an LPF 53 and an A / D converter 54. I have. Further, it has a position calculation unit 60 that sends out measurement data for analyzing the positional relationship between the lane marker 1 and the detection antenna 31 based on the detection by the detection units 30, 40, and 50. The lane marker 1 has a marker antenna 90, a capacitor 92 (C2), a switch 91, and a control circuit 93, which are the same as the conventional configuration shown in FIG.

Next, the operation of the first embodiment will be described. The operation principle here is almost the same as the case of the equivalent circuit diagram of the lane marker 1 and the in-vehicle interrogator 2 described with reference to FIGS. Also, the detection status of the marker information signal is
This is the same as the description given with reference to FIG. Note that these operating principles are the same in the second to fourth embodiments described below. That is, in the detection unit 30, the electromotive force (voltages V1 and V2) of the detection antenna 31 is detected by the detector 32, and thereafter, the LPF 33 extracts a DC signal component, removes a high-frequency signal component, and detects an envelope signal. I do. The envelope signal is converted into a digital signal by the A / D converter 34 and transmitted to the position calculating section 60. Then, in the added detection unit 40, the amplifier 41
As a result, the signal received from the detection antenna 31 is amplified (for example, by a factor of 10) and output to a level at which a normal linear operation that does not cause an underflow that cannot be processed unnecessarily occurs. Here, this amplification factor is set to a factor that secures a resolution that was insufficient when amplification was not performed. If necessary, for example, even if the system having an amplification factor of 100 times is increased by another stage, good.

In the detecting section 50, the received signal from the detecting antenna 31 is attenuated by the attenuator 51 to a level at which a normal linear operation without overflow can be obtained (1/1).
0) and output. Here, the attenuation rate is set to an attenuation rate capable of effectively avoiding overflow. For example, a system having an attenuation rate of 1/100 times may be increased by another stage.

Next, the outputs (voltages V1 and V2) from the detection units 30, 40 and 50 are stored in the storage area 61 of the position calculation unit 60. The controller 63 calculates the difference (V2−V1) between the output voltages V1 and V2, and
The data (marker information signal) of the detection unit at the maximum level where no overflow has occurred at 30, 40, and 50 is selected, and the data between the lane marker 1 and the in-vehicle interrogator 2 is selected based on the data stored in the table 62. Calculate the distance value. However, the table 62 in this case is prepared for each detection unit to be used, that is, for each amplification factor and attenuation factor.

As described above, according to the first embodiment, the detection outputs of the plurality of detectors 30, 40, and 50 can be obtained as normal values that do not cause overflow or underflow. Accurate detection can be performed, and the traveling position of the vehicle on the road can be accurately determined. Further, since the influence of the position detection error is eliminated, the method of the conventional lane marker system can be used as it is.

FIG. 2 is a block diagram showing the configuration of the second embodiment of the present invention. In the second embodiment, a detector and an LPF
The configuration is different from that of the first embodiment in that a (low-pass filter) is not provided, and there is no difference in other configurations. The processing function (judgment function) between the detector and the LPF is performed by the signal processor 64 for high-speed processing. That is, as shown in FIG. 2, the position calculation unit 60A
Output signals (voltages V1, V
2) a storage area 61a for storing A / D converters 34a,
It has a signal processor 64 for high-speed processing of digital signals (marker information signals) from 44a and 54a as described below.

Next, the operation principle of the second embodiment will be described. In the detection unit 30A, the signal received from the detection antenna 31 is converted into a digital signal by the A / D converter 34a and transmitted to the position calculation unit 60A. The detection unit 40A uses an amplifier.
41 amplifies and outputs the received signal from the detection antenna 31 in the same manner as described above, converts the received signal into a digital signal by the A / D converter 44a, and sends it to the position calculating unit 60A. Also, the detection unit
At 50A, the attenuator 51 attenuates the received signal from the detection antenna 31 and outputs it. Similarly, the A / D converter 54a converts the received signal into a digital signal and sends it to the position calculator 60A. Then, in the position calculating section 60A, the signal processing processor 64 applies the same detection processing as that of the first embodiment to the digital reception signals transmitted from the detecting sections 30A, 40A, 50A, and the same absolute value conversion and positive conversion. The extraction of only the value or the square processing is performed. That is, the output values from the respective detection units 30A, 40A, and 50A are digitally detected, low-pass filtered, and the results are stored in the storage area unit 61a.

The difference between the voltages V1 and V2 (V2-V
1), a received signal (marker information signal) having a difference between the voltages V1 and V2 by normal linear operation in which no overflow has occurred is selected, and the lane marker 1 and the in-vehicle question are selected from the data stored in the table 62a. The distance value with the container 2 is calculated. As described above, in the second embodiment, the same processing as in the first embodiment is performed by the signal processor 64. By adopting and sharing such a signal processor 64 for high-speed processing, the circuit configuration as a lane marker system can be simplified, and the position detection can be performed without error by this one signal processor 64. It can be realized accurately.

FIG. 3 is a block diagram showing a third embodiment of the present invention. The third embodiment differs from the first embodiment in that a gain adjuster 36 and a distance sensor 70 are added to the conventional configuration as shown in FIG. That is, as shown in FIG. 3, the in-vehicle interrogator 2B has a distance sensor 70 that measures the distance between the road surface on which the lane marker 1 is arranged and the detection antenna 31 in the in-vehicle interrogator 2B using infrared rays or the like.
And a detection unit 30B that detects a reception signal of the detection antenna 31. The distance sensor 70 is installed at the lower part of the vehicle,
The distance to the road surface is measured by the distance sensor 70.
In the table 71, gain information corresponding to the distance information from the distance sensor 70 is stored in advance. In creating the table 71, first, a lane marker is set immediately below the detection antenna 31, and the distance between the detection antenna 31 and the lane marker 1 is measured. Next, the gain adjuster 36 is set to receive the maximum voltage.
Is adjusted and stored in the table 71. The same operation is performed by changing the distance between the detection antenna 31 and the lane marker 1, and the table 71 is created. Further, a position calculating unit 60B for transmitting measurement data indicating the positional relationship between the lane marker 1 and the vehicle based on the detection by the detecting unit 30B is provided.
The detecting unit 30B amplifies or attenuates the received signal from the detecting antenna 31 with the gain control signal from the position calculating unit 60B as it is, and a detector that functions similarly to the first embodiment. 32, an LPF 33 and an A / D converter 34. The position calculation unit 60B also includes a storage area unit 61b, a controller 63b, and a table that function in the same manner as in the first embodiment.
62.

Next, the operation principle of the third embodiment will be described. The distance sensor 70 measures the distance between the road surface on which the lane marker 1 is arranged and the in-vehicle interrogator 2B using infrared rays. The controller 63b sends the gain information to the gain adjuster 36 by referring to the table 71 based on the distance information from the distance sensor 70. Thereby, the detection antenna 31
Is amplified or attenuated by the gain adjuster 36,
The signal can be obtained as a signal without saturation, and its envelope component is extracted by the detector 32 and converted into a digital signal by the LPF 33 and the A / D converter 34.

The position calculating section 60B stores the envelope signals (voltages V1 and V2) from the detecting section 30B in the storage area section 61b, and selects a reception signal (marker information signal) having a difference from the voltages V1 and V2. , The distance value between the lane marker 1 and the in-vehicle interrogator 2B is calculated from the data stored in the table 62. As a result, in the present embodiment, the gain can be determined based on the information obtained from the distance sensor 70, so that a signal without overflow and underflow can be obtained with a simple circuit configuration, and as a result, an accurate signal can be obtained. Distance calculation (calculation) can be performed.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In the fourth embodiment, the in-vehicle interrogator 2
C includes a detection unit 30C that amplifies or attenuates the received signal from the distance sensor 70 and the detection antenna 31 as it is, converts the signal into a digital signal, and outputs the digital signal, and a position calculation unit 60C. The detection unit 30C includes a gain adjuster 36c that amplifies or attenuates the received signal from the detection antenna 31 with the gain control signal from the position calculator 60C and outputs the signal as it is, and converts the received signal from the gain adjuster 36c into a digital signal. An A / D converter 34c for converting the signal into a signal and sending it to the position calculating unit 60C. The position calculation unit 60C includes a storage area unit 61c and a signal processor that operate basically in the same manner as in the second embodiment (FIG. 2).
64 and a table 62c.

Next, the operation of the fourth embodiment will be described. As in the third embodiment, the distance sensor 70 sends distance information directly below the road between the road where the lane marker 1 is arranged and the detection antenna 31 to the signal processor 64. The signal processor 64 refers to the table 71 prepared in advance based on the distance information, and converts the gain control signal into the gain adjuster 36c.
To send to. The detection unit 30C directly converts the attenuated or amplified reception signal from the gain controller 36c into an A / D converter 34C.
The signal is converted into a digital signal by c and sent to the signal processor 64c in the position calculator 60C. Signal processor 64
c is the first signal with respect to the digital reception signal from the detection unit 30C.
Detection processing, absolute value conversion, extraction or squaring processing of only positive values, digital filter processing, and the like are performed as in the embodiment.
The envelope signals (voltages V1 and V2), which are digital reception signals from the detection unit 30C that have been subjected to the detection processing and the digital low-pass filter processing, are stored in the storage area unit 61c. Thereafter, the distance between the lane marker 1 and the in-vehicle interrogator 2 is calculated by the signal processor 64 based on the digitized envelope signal.

As described above, in the fourth embodiment, the distance sensor
The gain is determined based on the distance data obtained from 70, and the subsequent processing is performed by the signal processor 64 for high-speed processing.
Simple circuit configuration (small circuit)
Thus, a signal free from overflow and underflow can be obtained, and as a result, accurate distance calculation (calculation) can be performed.

[0039]

The present invention is as described above. In order to achieve the above object, according to the first aspect of the present invention, according to a change in a switch connected to a coiled first antenna. In a lane marker system that calculates the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna, the antenna voltage is amplified or attenuated, and an amplified attenuation signal is output. Amplifying and attenuating means, an envelope extracting means for extracting an envelope signal from the amplified attenuated signal, an A / D converting means for digitizing an envelope extracting signal output from the envelope extracting means to generate a digital envelope extracting signal, A plurality of attenuating means, envelope extracting means, and A / D converting means having different amplification rates or attenuation rates; a storing means for storing a digital envelope extracting signal; and a plurality of said digital envelope extracting signals. And selecting means for selecting an optimal digital envelope extraction signal having the maximum level without overflow, and calculating a distance between the first antenna and the second antenna based on the selected digital envelope extraction signal. Since the detection output can be obtained as a normal value that does not cause overflow or underflow, the influence of the position detection error is eliminated, the detection can be accurately performed by the lane marker, and the traveling position of the vehicle on the road can be accurately determined. The effect is that it becomes possible. Further, since the influence of the position detection error is eliminated, the method of the conventional lane marker system can be used as it is.

According to a third aspect of the present invention, there is provided the coil-shaped first
In a lane marker system for calculating the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna generated according to the change of the switch connected to the antenna, Attenuating means for amplifying or attenuating the signal, and outputting an amplified attenuated signal; A / D converting means for digitizing the amplified attenuated signal to generate a digital amplified attenuated signal; Storage means for storing a plurality of digitally amplified and attenuated signals, and a plurality of digitally attenuated extraction signals for generating a plurality of digitally enveloped extracted signals from the plurality of digitally amplified and attenuated signals. Selecting means for selecting an optimal digital envelope extraction signal having a maximum level which does not overflow among a plurality of digital envelope extraction signals, Since the distance between the first antenna and the second antenna is calculated based on the digital envelope extraction signal, the circuit configuration as a lane marker system is simplified by adopting and sharing the signal processor 64 for high-speed processing. This signal processor can be
64 has the effect that position detection can be realized accurately and without errors.

According to a fifth aspect of the present invention, there is provided the first coil-shaped device.
A lane marker system that calculates the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna that occurs in response to a change in the switch connected to the antenna, Measuring means for measuring the distance from the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; and adjusting the gain of the antenna voltage according to the ratio. Gain adjusting means, an envelope extracting means for extracting an envelope signal from an output of the gain adjusting means, an A / D converting means for digitizing the envelope extracted signal output from the envelope extracting means to generate a digital envelope extracted signal, Storing means for storing the digital envelope extraction signal, and calculating the distance between the first antenna and the second antenna based on the digital envelope extraction signal; Since the gain is determined based on the distance data obtained from the sensor 70 and the subsequent processing can be performed by the signal processor 64 for high-speed processing, overflow and underflow occur with a simple circuit configuration. Signal without any
There is an effect that accurate distance calculation (calculation) can be performed.

According to a seventh aspect of the present invention, there is provided the coil-shaped first
In a lane marker system for calculating the distance between the first antenna and the second antenna from the variation ratio of the antenna voltage at both ends of the second antenna generated according to the change of the switch connected to the antenna, Measuring means for measuring the distance from the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; and adjusting the gain of the antenna voltage according to the ratio. Gain adjusting means, A / D converting means for digitizing the output of the gain adjusting means, storing means for storing the output of the A / D converting means, and generating a digital envelope extraction signal from the stored signal. A digital envelope extracting unit for calculating a distance between the first antenna and the second antenna based on the digital envelope extraction signal. Data subjected gain based is determined, the signal processor for subsequent processing for high-speed processing
64, it is possible to obtain a signal without overflow and underflow with a simple circuit configuration, and as a result, accurate distance calculation (calculation)
Can be executed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the second embodiment.

FIG. 3 is a block diagram showing a configuration of the third embodiment.

FIG. 4 is a block diagram showing a configuration of the fourth embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional lane marker system.

FIG. 6 is a block diagram showing a configuration of the conventional in-vehicle interrogator.

FIG. 7 is a block diagram showing a configuration of the conventional lane marker.

FIG. 8 is an equivalent circuit diagram of a lane marker and a vehicle-mounted interrogator.

FIG. 9 is another equivalent circuit diagram of the in-vehicle interrogator.

10A is a waveform diagram illustrating a detection state of a marker information signal when the distance is long, and FIG. 10B is a waveform diagram illustrating a detection state of the marker information signal when the distance is short.

[Explanation of symbols]

 1 lane marker 2, 2A to 2C on-vehicle interrogator 31 detecting antenna 30, 30A to 30C, 40, 40A, 50, 50A detecting unit 32, 42, 52 detector 33, 43, 53 LPF 34, 34a, 34c, 44, 44a , 54, 54a A / D converters 36, 36c Gain adjusters 41 Amplifiers 51 Attenuators 60, 60A to 60C Position calculators 61, 61a to 61c Storage areas 62, 62a, 62c, 71 Tables 63, 63b Controller 64 signals Processor 70 Distance sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01S 13/78 G01S 13/78 // G05D 1/02 G05D 1/02 J G08G 1/09 G08G 1/09 V (72) Inventor Maki Hayashi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Makoto Morito 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry F Terms (reference) 2F029 AA02 AB05 AB13 AC01 AC09 2F063 AA02 AA22 BA11 GA01 LA05 LA06 LA09 LA19 5H180 AA01 CC12 FF13 FF27 5H301 AA03 BB20 FF01 GG07 5J070 AA13 AB01 AC01 AC02 AD01 AE01 AF03 AH40 AH33 AH33

Claims (8)

[Claims] The distance between a first antenna and a second antenna is determined based on a change ratio of an antenna voltage at both ends of the second antenna which is generated in accordance with a change in a switch connected to the first antenna having a coil shape. Amplifying or attenuating the antenna voltage to output an amplified attenuated signal, an envelope extracting means for extracting an envelope signal from the amplified attenuated signal, and an output from the envelope extracting means. A / D conversion means for digitizing the envelope extraction signal to generate a digital envelope extraction signal, and a plurality of the amplification / attenuation means, the envelope extraction means, and the A / D conversion means having different amplification rates or attenuation rates, and Storing means for storing a digital envelope extraction signal, and selecting to select an optimal digital envelope extraction signal of a maximum level which does not overflow among a plurality of the digital envelope extraction signals. Means for calculating a distance between a first antenna and a second antenna based on the selected digital envelope extraction signal. 2. The reception sensitivity adjusting circuit according to claim 1, wherein said envelope extracting means rectifies the amplified and attenuated signal by full-wave or half-wave and passes through a low-pass filter. 3. A distance between the first antenna and the second antenna based on a change ratio of an antenna voltage at both ends of the second antenna caused by a change of a switch connected to the coiled first antenna. Amplifying and attenuating the antenna voltage to output an amplified and attenuated signal; an A / D converting means for digitizing the amplified and attenuated signal to generate a digital amplified and attenuated signal; A plurality of digital amplification / attenuation means, a plurality of digital amplification / attenuation signals, and a plurality of digital envelopes; Digital envelope extracting means for generating an extracted signal, and selecting to select an optimal digital envelope extracted signal of a maximum level which does not overflow among a plurality of digital envelope extracted signals Means for calculating a distance between a first antenna and a second antenna based on the selected digital envelope extraction signal. 4. The digital envelope extraction means squares the digital amplified attenuation signal by digital processing or converts a negative value to 0 or an absolute value by digital processing, and converts a negative value to 0 or an absolute value. The receiving sensitivity adjusting circuit according to claim 3, wherein the receiving sensitivity adjusting circuit is a means for performing the setting. 5. A distance between the first antenna and the second antenna based on a change ratio of an antenna voltage at both ends of the second antenna generated according to a change in a switch connected to the coiled first antenna. Measuring means for measuring the distance between the road surface and the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; A gain adjusting means for adjusting the gain of the antenna voltage, an envelope extracting means for extracting an envelope signal from an output of the gain adjusting means, and a digital envelope extracting signal obtained by digitizing the envelope extracting signal output from the envelope extracting means. A / D that generates
A reception sensitivity adjustment circuit, comprising: a conversion unit; and a storage unit that stores a digital envelope extraction signal, and calculates a distance between the first antenna and the second antenna based on the digital envelope extraction signal. 6. The reception sensitivity adjusting circuit according to claim 5, wherein the envelope extracting means rectifies the output of the adjusting means in full-wave or half-wave and passes the output through a low-pass filter. 7. A distance between the first antenna and the second antenna based on a change ratio of an antenna voltage at both ends of the second antenna caused by a change in a switch connected to the first antenna having a coil shape. Measuring means for measuring the distance between the road surface and the vehicle body; calculating means for calculating a ratio for amplifying or attenuating the antenna voltage at both ends of the second antenna based on the distance; Gain adjustment means for adjusting the gain of the antenna voltage, A / D conversion means for digitizing the output of the gain adjustment means, storage means for storing the output of the A / D conversion means, Digital envelope extraction means for generating a digital envelope extraction signal from the signal, and calculating a distance between the first antenna and the second antenna based on the digital envelope extraction signal. Characteristic reception sensitivity adjustment circuit. 8. The digital envelope extracting means squares the digital amplified attenuated signal by digital processing or converts a negative value to 0 or an absolute value by digital processing, and converts a negative value to 0 or an absolute value to perform digital low-pass filtering operation. 8. The receiving sensitivity adjusting circuit according to claim 7, wherein the receiving sensitivity adjusting circuit is a means for performing the setting.