JPH0668378A - On-vehicle receiver - Google Patents

Abstract

PURPOSE:To prevent a direction from being misdiscriminated and a position from being misdetected by starting reception at the time of an entry to less than a specific distance from a beacon and starting the direction distribution and position detection at a specific point where the influence of a reflected wave is a little. CONSTITUTION:The CPU 23 is equipped with a program which reads the output of a comparator 19, controls the start of reception when there is the output, and adjusts the timing of the direction discrimination and position detection start corresponding to the read vehicle speed of a vehicle speed sensor 22 to starts the direction discrimination and position detection within <=20m from the beacon. Namely, when the comparator 19 generates the output at a point which is 50m away from the beacon, the CPU 23 outputs a reception start signal to a memory control part 20 to reads out the value of the vehicle speed sensor 22. Then the time from the reception start to the direction discrimination and position detection start is adjusted corresponding to the vehicle speed. For example, when the reception is started at a point which is 30m away from the beacon, the direction discrimination and position detection are started at a point which is 20m away from the beacon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road-automobile communication system (Road Automobile Communication).
Hereinafter, this is referred to as RACS. ), Or road traffic communication system, or
The present invention relates to a vehicle-mounted receiver in a communication system nominally called a traffic information communication system. In addition, here
Application to RACS will be described as an example.

[0002]

2. Description of the Related Art In RACS, a modulated signal transmitted from beacons arranged every 2 km on the road is received,
In addition to displaying traffic jam information and road guidance information on the in-vehicle display, car navigation is performed by displaying the current position on the road map displayed on the in-vehicle display. Therefore, the in-vehicle receiver has a function of demodulating data and storing it in the memory, and a function of directly below the beacon (hereinafter referred to as NUL to correct the position).
A position detection function for detecting (referred to as L point) and a direction identification function for determining the traveling direction of the vehicle are required. The modulated signal transmitted from the beacon includes a phase-modulated data and 1 kH _Z AM signal amplitude modulated direction identified. The data starts to be received at a point 50 m from the beacon in order to receive one cycle of data. The distance from the beacon was determined by measuring the received electric field level, and when the received electric field level became equal to or greater than the value corresponding to 50 m from the beacon, reception was started, and with this as an opportunity, direction identification and position detection were started. . Data reception, direction identification, and position detection in the conventional vehicle-mounted receiver will be described below. FIG. 8 shows a beacon 32 in RACS.
FIG. 3 is a diagram showing a state of modulation of a 1 KH _Z AM signal for direction identification transmitted from a device, and as shown in the drawing, a region (AM negative) that is negatively modulated and a region (AM negative) that is positively modulated with the beacon 32 as a boundary. AM positive). Negative modulation is to apply AM modulation to the beginning of the transmission data frame so as to synchronize the falling edge of the direction identifying 1KH _Z AM signal as shown in FIG. 9, and positive modulation is transmission data frame. it is to subject the AM modulation to synchronize the rising direction identification 1 kH _Z AM signal at the beginning of. Immediately below the beacon and in the vicinity thereof, the positive modulation signal and the negative modulation signal interfere with each other, so that the amplitude of the received 1KH _Z AM signal for direction identification is "0". FIG. 7 relates to a conventional vehicle-mounted receiver. In the figure, reference numeral 1 is a reception electric field level and 1K for direction identification upon receiving a modulated signal transmitted from a beacon.
The receiving unit 5 that outputs the H _Z AM signal 2, the clock 3 and the data 4 is the clock 3 and the data 4 reproduced by the receiving unit 1.
Is input to detect the frame synchronization pattern (the 32-bit pattern at the beginning of each frame) and outputs the frame synchronization signal 6, and 7 is the frame synchronization signal 6 output from the frame synchronization pattern detection circuit 5 and the receiving unit 1. in the reproduced divided clock that is synchronized with the frame synchronization signal to input clock 3 (CLK2 8:! 2KH _Z clock, CLK2
9: inverted output of CLK2, CLK1 10: 1 kH _Z clock) frequency divider for outputting a flip-flop for sampling the direction identification 1 kH _Z AM signal 2 receiving unit 1 outputs at CLK2 8 11, 13 flip-flop A shift register for shifting in the sampling signal 12 of the direction identifying 1 KH _Z AM signal 2 sampled at 11, and 14 for CL the 2-bit output of the shift register 13.
A 2-bit pattern holding flip-flop for sampling with K1 10 and a reference numeral 15 for inputting the output of the 2-bit pattern holding flip-flop 14 for detecting a "01" pattern 0
1 pattern detection comparator, 16 is a 10 pattern detection comparator for inputting the output of the 2-bit pattern holding flip-flop 14 and detecting a "10" pattern, 17 is set by a significant signal of the 01 pattern detection comparator 15 01 Pattern detection flip-flop, 18 is a 10-pattern detection flip-flop set by a significant signal of the 10-pattern detection comparator 16, 1
Reference numeral 9 is a comparator for inputting the received electric field level output from the receiving unit 1, 31 is a 01 pattern detection flip-flop 17 and a 10 pattern detection flip-flop 18 by CLK1 10.
And a CPU for reading the output of the comparator 19, 20 is a CPU
A memory control unit 21 which starts input of data 4 by the reception start signal of 31 and outputs the data 4 input in synchronization with the frame synchronization signal 6 and the clock 3, 21 stores the values output by the CPU 31 and the memory control unit 20. It is a memory. Figure 1
0 is a diagram showing the phase relationship of the signals in FIG. 7.

Next, the operation will be described. 7 and 1
At 0, the receiving unit 1 receives the modulated signal transmitted from the beacon and outputs the received electric field level, the direction identifying 1 KH _Z AM signal 2, the clock 3 and the data 4. The frame synchronization pattern detection circuit 5 inputs the reproduced clock 3 and data 4, detects the frame synchronization pattern, and outputs a frame synchronization signal 6. The frequency divider 7 inputs the frame synchronization signal 6 and the clock 3 and outputs a frequency division clock synchronized with the frame synchronization signal 6. The output of the divided clock is C
LK2 8 and (2KH _Z clock)! CLK29 (C
Inverted output) and their phase relationship is a three CLK1 10 (1 kH _Z clock) LK2 is shown in FIG. 10. Here, the frame synchronization signal 6 is synchronized with the direction identification 1KH originally transmitted from the beacon.
Since _Z AM signal 2 are modulated in synchronization with the beginning of the frame, if the sampling direction identification 1 kH _Z AM signal 2 at a clock synchronized with the frame synchronization pattern, just the direction identification 1 kH _Z AM signals bistable This is because the points to be sampled can be sampled. The flip-flop 11 is shown in FIG.
1K for direction identification output from the receiving unit 1 as indicated by 0
The phase is adjusted so that the H _Z AM signal 2 is input and the points exactly shifted by π / 4 and 3π / 4 are sampled. The sampled sampling signal 12 is then input to the shift register 13! It shifts with CLK29. Assuming that the vehicle progresses from the AM negative area to the AM positive area in FIG. 8, the values sampled at this time and input to the shift register 13 are as shown in FIG.
1 "," 0 "," 1 "," 0 "," 1 "," 0 ",
..., "0", "0", ..., "0", "1", "0", "
1 "," 0 "," 1 "," 0 "," 1 "... The 2-bit output of the shift register 13 is set to CLK1 1
When sampling at 0, the 2-bit pattern holding flip-flop 14 has "10" and "1" as shown in FIG.
0 "," 10 "," 10 ", ...," 10 "," 00 ",
..., "01", "01", "01", "01" ... Patterns are held. Reference numeral 15 refers to the output of the 2-bit pattern holding flip-flop 14 and outputs a logic 1 when detecting a "01" pattern, and the 01 pattern detection flip-flop 17
The output is sampled at LK1 10. Similarly, 16 sees the output of the 2-bit pattern holding flip-flop 14 and outputs a logic 1 when detecting a "10" pattern.
10-pattern detection flip-flop 17 has CLK1 10
To sample the output. On the other hand, the comparator 19 is set so that the output becomes significant when the reception electric field level output from the reception unit 1 is input and the distance is within 50 m from the beacon, and the CPU 31 sequentially reads the output of the comparator 19 and When the value becomes significant, reception is started, and with this as an opportunity, direction identification and position detection are started. CPU3
When No. 1 starts reception, it outputs a reception start signal to the memory control unit 20. When the reception start signal is output, the memory control unit 20 starts inputting the data 4. Here, the data 4 is input in synchronization with the clock 3 by using the frame synchronization signal 6 as a trigger. The input data 4 is stored in the sequential memory 21.
Write to. Further, when the CPU 31 starts the direction identification, C
The output of the 01 pattern detection flip-flop 17 is read by using LK1 10 as a trigger and stored in the memory.
Next, the CPU 31 reads out the latest stored 25 bits and adds them. If the addition result is 20 or more, "01"
Pattern detection. Similarly, the "10" pattern is also detected, and both the "01" pattern and the "10" pattern are detected until either the "01" pattern or the "10" pattern satisfies the above judgment. To do. Then, the direction is identified by the one detected first. If the "01" pattern is detected first, the traveling direction is positive and "1" is detected first.
When the 0 ″ pattern is detected, it is determined to be negative. After the direction is identified, only the detection of the pattern opposite to the previously detected pattern is started for position detection. Then, the time when the opposite pattern is detected is NULL. It is a point.

[0004]

As described above, the conventional vehicle-mounted receiver starts reception at a point within 50 m from the beacon in order to receive one cycle of information.
Also, this triggered the start of direction identification and position detection. However, at the point 20 m or more away from the beacon, the data phase-modulated by the reflected wave from a truck or a passenger car is hardly affected, but the amplitude-modulated 1 KH _Z AM signal for direction identification is affected, and the signal is not directly under the beacon. There was a case where it was mistakenly detected as a NULL point, and also the traveling direction was mistaken. If the traveling direction is erroneously detected, for example, when the destination guidance sign is displayed on the in-vehicle display, the guidance sign in the direction completely opposite to the actual traveling direction is displayed, which gives incorrect information to the driver. Therefore, erroneous inspection of the traveling direction is a problem that should be absolutely prevented.

The present invention has been made in order to solve the above-mentioned problems, and in order to prevent erroneous detection of the NULL point and erroneous detection of the traveling direction, the zone is less susceptible to the reflected wave within 20 m from the beacon. It provides a means for position detection and orientation identification.

Furthermore, in order to prevent erroneous detection of the traveling direction, 20 m from the beacon from the time 50 m from the beacon
A means for discriminating the direction is provided by the majority decision of the outputs of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop until the time point within the range.

[0007]

In a vehicle-mounted receiver according to the present invention, a beacon is obtained by inputting a receiving section for receiving a modulated signal transmitted from a beacon on a road and a received electric field level output by the receiving section. A comparator set so that the output becomes significant within 50 m, a vehicle speed sensor that detects the vehicle speed, and the output of the comparator is read to control reception start when the output becomes significant. The CPU is provided with a program for adjusting the timing of the direction identification and the position detection start from the reception start according to the reading vehicle speed and starting the direction identification and the position detection within 20 m from the beacon, and the receiving unit reproduces. The frame synchronization pattern detection circuit that detects the frame synchronization pattern by inputting the input data and clock and the frame output by the frame synchronization pattern detection circuit. A divider synchronization signal receiving unit outputs a divided clock synchronized with the frame synchronization pattern by inputting a clock reproduced is output to 1 kH _Z AM signal direction identification is reproduced by the receiver from the frequency divider A flip-flop that samples with a divided clock, a shift register that shifts the output of this flip-flop with the divided clock, and a sample of the output of the shift register with the divided clock, such as "10" and "01". A pattern holding flip-flop for holding a bit pattern, a comparator for inputting an output of the pattern holding flip-flop to detect a "01" pattern, a 01 pattern detecting flip-flop set by a significant signal of the comparator, A comparator for detecting the "10" pattern by inputting the output of the pattern holding flip-flop, and the comparator 10 pattern detection flip-flops set by an intention signal, a memory for storing the values of the 01 pattern detection flip-flops and the 10 pattern detection flip-flops read by the CPU at the start of the position detection, and the reception start as described above. And a memory control unit for writing the data reproduced by the receiving unit in a memory.

Further, by inputting the received electric field level output from the receiving unit, the output of the comparator set so that the output becomes significant within 50 m from the beacon is read, and if the output becomes significant, reception and direction identification are performed. The position detection is started within 20 m from the beacon by adjusting the timing of the reception and the direction identification start from the vehicle speed sensor according to the vehicle speed and the direction identification from the direction identification start to the position detection start. A CP comprising a program for judging by majority of outputs of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop.
It is equipped with U.

Further, it is set so that the output is significant within 50 m of the beacon by inputting the received electric field level output from the receiving section, and the output is significant within 20 m of the beacon. Read the output of the comparator and the former comparator, and start receiving when the output becomes significant,
CPU having a program for starting direction identification and position detection when the output of the latter comparator becomes significant
It is equipped with.

The comparator is set so that the output is significant within 50 m of the beacon by inputting the received electric field level output from the receiving section, and the comparator is set so that the output is significant within 20 m of the beacon. The output of the other comparator and the former comparator is read, and when the output becomes significant, reception and direction identification are started, and when the output of the latter comparator becomes significant, position detection is started and direction identification is started. The CPU is provided with a program which is determined by the majority decision of the outputs of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop from the time to the start of position detection.

Further, the A / D converter for inputting the received electric field level output from the receiving section and the output of the A / D converter are input, and if the output exceeds a value corresponding to 50 m from the beacon, reception is performed. Further, the CPU is provided with a program which starts the direction identification and the position detection when the output of the A / D converter is equal to or more than the corresponding value within 20 m from the beacon.

Further, the A / D converter for inputting the received electric field level output from the receiving unit and the output of the A / D converter are input, and if the output exceeds a value corresponding to 50 m from the beacon, reception and Direction detection is started, and position detection is started when the output of the A / D converter becomes equal to or greater than a corresponding value within 20 m from the beacon, and direction detection is performed by the 01 pattern from the direction identification start to the position detection start. The CPU is provided with a detection flip-flop and a program for judging by the majority decision of the outputs of the 10-pattern detection flip-flops.

[0013]

In the vehicle-mounted receiver configured as described above, the direction identification is performed by detecting the vehicle speed at the reception start point 50 m before the beacon and adjusting the timing of the direction identification and the position detection start from the reception start. The direction identification and position detection are performed within 20 m from the beacon where the 1 KH _Z AM signal for use is not easily affected by the reflected wave. In this way, by dividing the reception start point and the direction identification and position detection start point, one cycle of data can be received, and there is an effect of preventing erroneous detection of direction identification and erroneous detection of position detection.

Further, even if the on-vehicle receiver erroneously detects the direction identification and the position detection due to a very strong reflected wave immediately after the direction identification and the position detection are started, the direction identification and the position detection are started from the reception start. By making a decision based on the majority of the outputs of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop until the position detection is started, it is possible to prevent the erroneous detection of the direction identification even if the erroneous detection of the position detection cannot be prevented.

Further, there are provided two comparators, a comparator which makes the output significant if it is within 50 m from the beacon and a comparator which makes the output significant if it is within 20 m from the beacon,
The same effect as above can be obtained by separating the reception start and the position detection start by the change of the outputs of the two comparators. Further, in the above method, the vehicle speed at the reception start point is measured to measure the timing of the position detection start. Therefore, if the vehicle speed changes suddenly from the reception start point to the position detection start, at a point 20 m or more away from the beacon. The position detection may be started, or the position detection may be started after the beacon is passed. On the other hand, in this method, the reception start point and the position detection start point are detected by the reception electric field level regardless of the vehicle speed.
Position detection can be started within m and before passing.

Further, by using the A / D converter instead of the comparator to detect the point within 50 m and the point within 20 m from the beacon, the same effect as above can be obtained.

[0017]

【Example】

Example 1. FIG. 1 is a diagram showing an embodiment of a vehicle-mounted receiver according to the present invention. In the figure, 1 to 21 are the same as the conventional device. Reference numeral 22 is a vehicle speed sensor, and 23 is an output of the comparator 19, which controls reception start when the output becomes significant. Further, the vehicle speed sensor 22 is read and the timing of direction identification and position detection start from reception start is adjusted according to the vehicle speed. Then, the CPU is provided with a program for starting the direction identification and the position detection within 20 m from the beacon.

In the vehicle-mounted receiver configured as described above, when the output of the comparator 19 becomes significant at a point 50 m from the beacon, the CPU 23 outputs a reception start signal to the memory control unit 20 to cause the vehicle speed sensor 22 to operate. Read the value. Then, the time from the start of reception to the start of direction identification and position detection is adjusted according to the vehicle speed. For example, if the vehicle speed at the time of starting reception is 120 km / h, the direction identification is started after 0.9 seconds, and if the vehicle speed is 30 km / h, the direction identification is started after 3.6 seconds. In this way, if the reception start is 30 m from the beacon, the direction identification and position detection start is 20 m from the beacon. The subsequent operations for direction identification and position detection are exactly the same as those of the conventional vehicle-mounted receiver.

Example 2. FIG. 2 is a diagram showing another embodiment according to the present invention. In the figure, 1 to 22 are the same as the device of the first embodiment. A beacon 24 reads the output of the comparator 19 and starts reception and direction identification when the output becomes significant, and further reads the vehicle speed sensor 22 and adjusts the timing from the start of reception and direction identification to the position detection start according to the vehicle speed. The position detection is started within 20 m from the start, and the direction identification is 0 from the direction identification start to the position detection start.
The CPU is provided with a program for judging by the majority of the outputs of the 1-pattern detection flip-flop 17 and the 10-pattern detection flip-flop 18.

In the vehicle-mounted receiver configured as described above, when the output of the comparator 19 becomes significant at a point 50 m from the beacon, the CPU 24 outputs a reception start signal to the memory controller 20 to start reception at the same time. Start direction identification. At this time, the value of the vehicle speed sensor 22 is read, the time from the start of reception to the start of position detection is adjusted according to the vehicle speed, and position detection is started at a point within 20 m from the beacon. Here, the direction identification differs from the conventional method in that 01 from the direction identification start to the position detection start.
The majority of the outputs of the pattern detection flip-flop 17 and the 10-pattern detection flip-flop 18 is used for the determination. And
The majority pattern obtained by the majority decision is used as the first pattern detection, and thereafter, the reverse pattern detection is started in the same manner as the conventional method for position detection. The time point when the reverse pattern is detected is set as the NULL point.

Example 3. FIG. 3 is a diagram showing still another embodiment according to the present invention. In the figure, 1 to 21 are the same as the conventional device. Reference numeral 29 is a comparator whose output becomes significant when it is within 20 m of the beacon, and 25 is a comparator 19
When the output of is read and the output becomes significant, reception starts,
It is a CPU provided with a program that starts direction identification and position detection when the output of the comparator 29 becomes significant.

In the vehicle-mounted receiver configured as described above, the output of the comparator 19 becomes significant when the distance from the beacon is within 50 m, and the CPU 25 starts reception when the output of the comparator 19 becomes significant. Further, when it comes within 20 m from the beacon, the output of the comparator 29 becomes significant, and the CPU 25 starts the direction identification and the position detection when the output of the comparator 29 becomes significant. The operations of reception, direction identification and position detection are the same as those in the first embodiment.

Example 4. FIG. 4 is a diagram showing still another embodiment according to the present invention. In the figure, 1 to 21,
29 is the same as that in the third embodiment. Reference numeral 26 reads the output of the comparator 19, starts reception and direction identification when the output becomes significant, starts position detection when the output of the comparator 29 becomes significant, and further performs direction detection from the direction identification start for position identification. 01 pattern detection flip-flops 17 and 10 until the start
The CPU is provided with a program for judging by the majority decision of the output of the pattern detection flip-flop 18.

In the vehicle-mounted receiver configured as described above, the output of the comparator 19 becomes significant when the distance from the beacon is within 50 m, and the CPU 26 starts reception and direction identification when the output of the comparator 19 becomes significant. To do. Furthermore, the output of the comparator 29 becomes significant when entering within 20 m from the beacon,
The CPU 26 starts the position detection when the output of the comparator 29 becomes significant. The operations of reception, direction identification and position detection are the same as those in the second embodiment.

Example 5. FIG. 5 is a diagram showing still another embodiment according to the present invention. In the figure, 1 to 21 are the same as the conventional device. 30 is an A / D converter that inputs the received electric field level output from the receiving unit 1 and converts it to digital, 27 is an input of the output of the A / D converter 30, and the output is a value corresponding to 50 m or more from the beacon If the output of the A / D converter 30 is 20 m or more from the beacon and the output is equal to or more than the corresponding value, the direction identification and the position detection are started.
It is PU.

In the vehicle-mounted receiver configured as described above, the A / D converter 30 inputs the received electric field level output from the receiver 1 and converts it into digital. CPU27 is A
The output of the / D converter 30 is sequentially read, and if the value becomes equal to or greater than the value corresponding to 50 m from the beacon, reception is started,
Further, when the output of the A / D converter 30 becomes equal to or more than a value corresponding to within 20 m from the beacon, direction identification and position detection are started. The operations of reception, direction identification and position detection are the same as those in the first embodiment.

Example 6. FIG. 6 is a diagram showing still another embodiment according to the present invention. In the figure, 1 to 21,
30 is the same as that in the fifth embodiment. 28 receives the output of the A / D converter 30 and starts reception and direction identification when the output exceeds a value corresponding to 50 m from the beacon. Further, the output of the A / D converter 30 is within 20 m from the beacon. The position detection is started when the value becomes equal to or more than the value corresponding to, and the direction identification is provided with a program that judges by majority of the outputs of the 01 pattern detection flip-flop 17 and the 10 pattern detection flip-flop 18 from the direction identification start to the position detection start It is a CPU characterized by that.

In the vehicle-mounted receiver configured as described above, the CPU 28 inputs the output of the A / D converter 30, and when the output exceeds the value corresponding to 50 m from the beacon, reception and direction identification are started. The A / D converter 30
Position detection is started when the output exceeds the value within 20 m from the beacon, and direction identification is performed by the output of the 01 pattern detection flip-flop 17 and the 10 pattern detection flip-flop 18 from the direction identification start to the position detection start. Judge by majority vote. The operations of reception, direction identification and position detection are the same as those in the second embodiment. By the way, the above-mentioned Example 1
In the second embodiment, the vehicle speed sensor may not be provided to adjust the timing from the start of reception to the start of position detection, and control may be performed only by the timer. In addition, the above-mentioned fifth and sixth embodiments
Then, the digital output of the A / D converter was read by the CPU to determine the distance from the beacon, but the output of the A / D converter was compared with a comparator having a set value according to the distance from the beacon, and the You may input a comparison result into CPU and determine the distance from a beacon.

[0029]

Since the present invention is constituted as described above, it has the following effects.

The distance from the beacon at the start of reception and the identification of direction and the start of position detection are separated, and the start of reception is 50 from the beacon.
By starting from a point within 20 m, direction identification and position detection can be received from a beacon within 20 m from a beacon that is not easily affected by reflected waves, and one cycle of data can be received, and direction identification There is an effect of preventing the erroneous detection of and the false detection of the position detection.

The direction identification is determined by the majority of the outputs of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop from the time point within 50 m from the beacon to the time point within 20 m from the beacon. The false positive rate can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a vehicle-mounted receiver according to the present invention.

FIG. 2 is a diagram showing another embodiment of the vehicle-mounted receiver according to the present invention.

FIG. 3 is a diagram showing still another embodiment of the vehicle-mounted receiver according to the present invention.

FIG. 4 is a diagram showing still another embodiment of the vehicle-mounted receiver according to the present invention.

FIG. 5 is a diagram showing still another embodiment of the vehicle-mounted receiver according to the present invention.

FIG. 6 is a diagram showing still another embodiment of the vehicle-mounted receiver according to the present invention.

FIG. 7 is a diagram showing a conventional vehicle-mounted receiver.

FIG. 8 1 KH _Z A for direction identification transmitted from beacon
It is a figure which shows the mode of modulation | alteration of M signal.

FIG. 9 is a diagram showing a definition of modulation of a direction identifying 1KH _Z AM signal.

FIG. 10 is a diagram showing a phase relationship of each signal in a conventional vehicle-mounted receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 receiver 5 frame synchronization pattern detection circuit 7 frequency divider 11 flip-flop 13 shift register 14 2-bit pattern holding flip-flop 15 01 pattern detection comparator 16 10 pattern detection comparator 17 01 pattern detection flip-flop 18 10 pattern detection flip-flop 19 comparator 20 memory control section 21 memory 22 vehicle speed sensor 23 CPU 24 CPU 25 CPU 26 CPU 27 CPU 28 CPU 29 comparator 30 A / D converter

Claims (6)

[Claims] 1. A comparison in which a reception unit that receives a modulated signal transmitted from a beacon on a road and a reception electric field level output by the reception unit are input so that the output becomes significant within 50 m from the beacon. Device, a vehicle speed sensor that detects the vehicle speed, and when the output of the comparator is read, the reception start is controlled if the output becomes significant. Further, the vehicle speed sensor is read and the direction identification and position detection start from the reception start to the position detection start. A frame for detecting the frame synchronization pattern by inputting the data and the clock reproduced by the receiving unit, the CPU including a program for adjusting the timing and starting the direction identification and the position detection within 20 m from the beacon. The synchronization pattern detection circuit, the frame synchronization signal output by the frame synchronization pattern detection circuit, and the clock reproduced by the receiving unit are input to synchronize the frames. Frequency divider that outputs a frequency-divided clock synchronized with the period pattern, and 1K for direction identification reproduced by the receiver
A flip-flop that samples the H _Z AM signal with the divided clock output from the divider, a shift register that shifts the output of this flip-flop with the divided clock, and the output of the shift register with the divided clock The pattern holding flip-flop that holds a 2-bit pattern such as "10" or "01", the comparator that inputs the output of the pattern holding flip-flop to detect the "01" pattern, and the significant signal of the comparator A 01 pattern detection flip-flop to be set, a comparator for inputting the output of the pattern holding flip-flop to detect a "10" pattern, a 10 pattern detection flip-flop set by a significant signal of the comparator, The 01 pattern detection flip-flop read by the CPU when the position detection is started. Memory and in-vehicle receiver, characterized in that a memory controller for writing data to the receiving portion is reproduced by the reception start to the memory for storing the values of the 10 pattern detecting flip-flop with. 2. The reception electric field level output from the receiving unit is input, and the output of the comparator set so that the output becomes significant within 50 m from the beacon is read, and if the output becomes significant, reception and direction identification are performed. Start the vehicle, read the vehicle speed sensor, and adjust the timing from the start of receiving and direction identification according to the vehicle speed to start the position detection within 20 m from the beacon. Further, the direction identification starts from the direction identification start to the position detection start. Of the 01 pattern detection flip-flop and the 10 pattern detection flip-flop
The vehicle-mounted receiver according to claim 1, further comprising U. 3. A comparator which is set so that the output is significant within 50 m from the beacon by inputting the received electric field level output from the receiving unit, and is set so that the output is significant within 20 m from the beacon. And a program that reads the output of the former comparator and starts reception when the output of the former comparator becomes significant, and starts direction identification and position detection when the output of the latter comparator becomes significant. The vehicle-mounted receiver according to claim 1, further comprising a CPU. 4. A comparator which is set so that the output becomes significant within 50 m from the beacon by inputting the received electric field level output from the receiving section, and the comparator is set so that the output becomes significant within 20 m from the beacon. The output of the other comparator and the former comparator is read, and when the output becomes significant, reception and direction identification are started, and when the output of the latter comparator becomes significant, position detection is started and direction identification is started. From the 01 pattern detection flip-flop to the position detection start
2. The vehicle-mounted receiver according to claim 1, further comprising a CPU, which is provided with a program for judging by a majority decision of the output of the 0-pattern detection flip-flop. 5. An A / D converter for inputting a reception electric field level output by a receiving section, and an output of the A / D converter for input, and if the output exceeds a value corresponding to 50 m from a beacon, reception is performed. 2. The CPU according to claim 1, further comprising a program for starting direction detection and position detection when the output of the A / D converter becomes equal to or greater than a value corresponding to within 20 m of the beacon. In-vehicle receiver. 6. An A / D converter for inputting a reception electric field level output from a receiving section, and an output of the A / D converter for inputting and receiving if the output exceeds a value corresponding to 50 m from a beacon. Direction detection is started, and position detection is started when the output of the A / D converter becomes equal to or greater than a corresponding value within 20 m from the beacon, and direction detection is performed by the 01 pattern from the direction identification start to the position detection start. A detection flip-flop and a program for making a decision based on the majority decision of the outputs of the 10-pattern detection flip-flops.
The vehicle-mounted receiver according to claim 1, further comprising a PU.