JPS613078A - Detector for vehicle existing area - Google Patents

Abstract

PURPOSE:To simply determine the area where a vehicle exists with a simple construction utilizing a broadcasting radio wave, by providing a broadcasting frequency detector section, a memory section and an area discriminating section. CONSTITUTION:A broadcasting frequency detecting section 13 is equipped with a signal detection circuit 15 which provides an output when the reception level of the broadcasting signal received with an antenna 10 exceeds a fixed value, a synthesizer 16 for oscillating a local oscillation signal and a frequency counter 17 for counting the frequency thereof. A control section 14 is provided with an area-wise received frequency memory section 18 where the combination of preset broadcasting frequencies by areas is memorized and an area discrimination processing section 20 which discriminates the area where a vehicle exists by comparing the broadcasting frequency memorized in the memory section 18 to the broadcasting frequency corresponding to the local oscillation frequency obtained by counting with a frequency counter 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle presence area detection device that is capable of detecting the area where a vehicle exists from a combination of broadcast frequencies that can be received by the vehicle.

(Prior Art) Conventionally, as a device for detecting the position of a vehicle using radio waves, there has been known a device shown in FIG. 5 that utilizes Loran C, which is used in hyperbolic navigation systems for ships and aircraft, for example. JP-A No. 58-39968, etc.).

In Fig. 5, 1 is an antenna mounted on the vehicle, 2 is a Loran C receiver, and 3 is a vehicle position calculation circuit.
0 to 110KHz (center frequency 100KHz) Loran radio waves are received by antenna 1, and 3 received by antenna 1.
The relative reception delay time of the station's Loran C signal is measured by the Loran C receiver 1112, and based on the result, the vehicle position calculation circuit 3 calculates the longitude and latitude to detect the vehicle position.

(Problems to be Solved by the Invention) However, in the conventional vehicle presence position detection device using Loran C, since the Loran C receiver is mounted on the vehicle, first the Loran C is used. Because it is necessary to install a whip antenna with a length of 1 meter or more as an antenna to receive radio waves, it is too large to be mounted on a vehicle, and
Since the Loran C receiver itself is intended for precision navigation systems for aircraft and ships, there are problems in that the device is complex and expensive, and furthermore, it is difficult to miniaturize.

(Means for Solving the Problems) In order to solve these conventional problems, the present invention is based on detecting the area where a vehicle is present using broadcast radio waves. A broadcast frequency detection unit that detects broadcast frequencies above a certain reception level by frequency sweep, a storage unit that stores broadcast frequencies for each region, and a comparison between the detection frequency of the broadcast frequency detection unit and the broadcast frequency stored in the storage unit. A vehicle location detection device is configured to include a region determination section that determines the region where the vehicle is present.

(Function) According to the vehicle position detection device of the present invention having such a configuration, since FM and TV (Vl-(F, Ul-IF) broadcast radio waves are used), a conventional vehicle antenna can be used as is. In addition, the broadcast frequency detection section can be implemented using a circuit equivalent to the receiving circuit of a vehicle FM tuner or TV tuner, and the storage section and area determination section can be implemented by program control using a microcomputer. Since the broadcast frequencies that can be received differ from region to region, by knowing the combination of reception frequencies, it is possible to reliably detect the region where the vehicle is present.

(Example) FIG. 1 is a block diagram illustrating the invention in detail.

First, the configuration will be described. Reference numeral 10 denotes an antenna installed in the vehicle, and a conventional pillar antenna or trunk lid antenna can be used as is. ,
Reference numeral 11 denotes an FM-AM receiver that receives and reproduces FM or AM broadcasts received by the antenna 10.

The broadcast frequency detection unit 13 includes a signal detection circuit 15 that outputs an output when the reception level of a broadcast signal (for example, VHF) received by the antenna 10 is above a certain level, and a signal detection circuit 15 that converts the frequency of the received signal into an intermediate frequency signal. a synthesizer 16 that oscillates a local oscillation signal used for
A frequency counter 17 that counts the local oscillation frequency of the synthesizer 16 is provided.

Here, the synthesizer 16 uses a stable crystal oscillator as an oscillation source, and has the function of obtaining a precise variable frequency by synthesizing the oscillation frequencies. Specifically, a PLL etc. is used, and a control signal from an external The local oscillation frequency can be varied by

The control unit 14 also includes a regional reception frequency storage unit 18 that stores predetermined broadcast frequency combinations for each region.
and a region determination processing section that determines the region where the vehicle is present by comparing the broadcast frequency stored in the region-specific reception frequency storage section 18 with the broadcast frequency corresponding to the local oscillation frequency obtained by the count of the frequency counter 17. 20. - FIG. 2 is a circuit block diagram showing a more specific configuration of the vehicle presence area detection device shown in FIG. 1.

In FIG. 2, a signal detection circuit 15 which is offset by the tli transmission frequency detection section 13 includes a frequency amplification circuit 21 for high frequency amplifying the received signal from the antenna 10, and a synthesizer 1.
a mixer 22 that converts the frequency into an intermediate frequency signal by mixing the local oscillation signal from the mixer 22 and the received signal; and an intermediate frequency amplifier circuit that performs DC detection on the amplified intermediate frequency signal from the mixer 22 and outputs a DC voltage. 23 and intermediate frequency amplification circuit 23
The output voltage V ref is determined by the output voltage and the reference voltage 124.
A comparator 25 is provided to compare the . Here, the reference voltage vre of the reference voltage source 24 for the comparator 25
For example, if we take FM broadcast reception as an example,
20dB that can ensure S/N ratio of 30dB or more
A reference voltage Vref is set that provides an intermediate frequency signal level corresponding to an electric field strength of μ/I11 or higher.

Next, the control section 14, which is composed of the regional reception frequency storage section 18 and the regional judgment processing section 2o in FIG.
) 27 and a memory 28 including RAM and ROM under program control of a microcomputer. The ROM of the memory 28 provided in the control section 14 stores combinations of broadcast frequencies predetermined for each region. For example, taking the Yokohama area as an example, the following table-1
F'M Tokyo NHK, FM Tokyo and FM Yokohama NHK shown in
Since it is possible to receive broadcasts from these three stations, a combination of these three broadcast frequencies is stored as frequency information for identifying the Yokohama area.

Table 1 Of course, the locations and broadcasting frequencies of broadcasting stations in other regions nationwide are known in advance, and the regional distribution of electric field strength that provides a certain reception level based on the transmission power of each broadcasting station is also determined. Therefore, combinations of broadcast frequencies that can be received by region, such as by prefecture or by city, are stored in advance.

Furthermore, the actually received broadcast frequencies counted by the frequency counter 17 are sequentially written and stored in the rewritable RAM constituting the memory 28.

Next, as a control process for area determination by the central processing unit 27, first, a frequency sweep signal for sweeping the received frequency in a predetermined frequency band is output to the synthesizer 16 via the input/output interface 26, and this A control program is provided that executes control to write the counted value of the frequency counter 17 in the RAM of the memory 28 when a detection output having a constant reception level is obtained from the signal detection circuit 15 by sweeping the reception frequency. If a broadcast frequency that exceeds a certain reception level is detected in this reception frequency sweep process, a comparison process is performed between the detected broadcast frequency and a frequency stored in advance in the memory 28, and the presence of a vehicle is determined based on the result of this comparison process. The control program includes a control program that executes processing to determine the area where the area is located.

Next, the operation of the embodiment shown in FIG. 2 will be explained with reference to the flowchart shown in FIG. In order to simplify the explanation, let us take as an example the area determination based on the FM broadcast frequency in the Yokohama area shown in Table 1 above.

First, when region discrimination processing is started by operating a switch, etc., the synthesizer 16 is set to F by initial setting.
A local oscillation frequency f of 65.3 MHz that provides an intermediate frequency of 10.7 MHz at 76 MHz, which is the lower limit broadcast frequency of M broadcasting. 11. The oscillation state of o is set, and the mixer 20
is output to. Next, the determination block 30 determines whether or not there is a received signal that exceeds the threshold determined by the reference voltage ref of the signal detection circuit 15. If reception is not performed, the process proceeds to determination block 34 without performing the processing in blocks 31, 32, and 33, and determines whether the upper limit frequency fmax at which the frequency sweep ends, for example, fmax-240 MHz, has been reached, and is now below fmax. Therefore, in block 35, a constant step frequency Δr, for example Δf=100KH2, is added to the current reception frequency fn, and the process moves to the next reception process.

Through the processing of the determination blocks 30, 34 and 35, the receiving frequency is repeatedly swept, and for example, the receiving frequency is 80.0 MHz (local oscillation frequency = 69.3 MHz).
), as is clear from Table 1 above, the signal detection circuit 15 receives the broadcast of FM Tokyo, and
The output voltage of the intermediate frequency amplification circuit 23 is the reference voltage V ref
As a result of the above, the comparator 25 generates an H level output. By reading the H level output of the comparator 25 into the central processing unit 27 via the input interface 26, it is determined that there is a received signal exceeding the threshold, and the process proceeds to the next block 31. FM in block 31
Since the local oscillation frequency 69.3 MH2 for receiving the Tokyo 80.0 MHz broadcast is counted by the frequency counter 17, it is read into the central processing unit 27 via the input/output interface 26, and the next block 32 calculates the local oscillation frequency f. Intermediate frequency fq = Lo = 69.3MHz
Adding 10.7MHz, receiving frequency fn -80,
Calculate 0M HZ, rn = 80 with blow 33. OM
Put f-1z into memory 28.

Hereinafter, each time a broadcast of FM Yokohama NHK with a broadcast frequency of 81.9 MH7 and FM Tokyo NHK with a broadcast frequency of 82.5 MHz is received, the broadcast frequency that has been neutralized in block 32 is stored in memory based on the detection output of the signal detection circuit 15. 28.

In this way, the sweep of the received frequency is the upper limit f of the sweep frequency.
When the maximum value is reached, the process proceeds to block 36, in which a memory map previously stored in the memory 28 is searched for broadcast stations corresponding to the reception frequencies f1 to fn stored in the memory 28iC by frequency sweep.

In this case, FM Tokyo NHK shown in Table 1 above.

Since the broadcast reception of three broadcast stations, FM Tokyo and FM Yokohama MNHK, is determined, next in block 37 the memory 2
8, it is determined that it is in the Yokohama area, and the determination result is output and displayed.

It should be noted that although the above description of the operation took FM broadcast reception processing as an example, region determination based on VHF television broadcast reception processing can be performed in exactly the same manner simultaneously with FMtli transmission.

Next, the heavy vehicle position detection device according to the present invention can be used to confirm the area where a vehicle is present by detecting the broadcast frequency. It can be used for devices, traffic guidance devices, etc.

In addition, the reason why VHF band broadcast waves are used in the above embodiment is that VHF radio waves are less affected by the ionosphere, whereas AM broadcast waves have a lot of sensitivity differences and interference between day and night, and are stable. Since it is difficult to determine the reception of broadcast frequencies in the VHF radio band, it is desirable to use broadcast reception in the VHF radio wave band.

Furthermore, in the above embodiment, the broadcast frequency detection unit 13 was provided separately from the FM receiver, but the FM receiver with a synthesizer function
By sharing the circuit elements of the receiver and the broadcast frequency detection section 13, the device configuration can be further simplified.

FIG. 4 is a block diagram showing another embodiment of the present invention, and this embodiment is capable of detecting broadcast frequencies in the VHF band.
It is characterized by detecting the HF television frequency.

That is, the VHFHF simultaneous transmission frequency detection unit 13, the region-specific reception frequency storage unit 18, and the area determination processing unit 2o have the same basic configuration as in FIG. In addition to providing U)-
A UHF broadcast frequency detection unit 4 detects that the broadcast reception signal from the IF antenna 38 exceeds a certain reception level.
0 is newly set. With the newly provided UHF broadcast frequency detection section 40, the regional reception frequency storage section 18 stores in advance the UHF broadcast frequency for each region in addition to the VHF broadcast frequency for each region. .

For example, if we take the Yokohama area as an example, the Ul-
(F broadcasting frequency is fixed.

Table 2 UHF Satellite Stations As is clear from Table 2, the output of the UHF satellite stations is small, ranging from 500,111W to 10W, and the reception area is limited. You can learn more about the area where it exists.

(Effects of the Invention) As described above, according to the present invention, in a vehicle position detection device that uses broadcast radio waves to detect the area where the own vehicle is present, the reception level exceeds a certain level due to a frequency difference in a predetermined frequency band. The broadcast frequency is detected by the broadcast frequency detection section, and on the other hand, the broadcast reception frequency for each region is stored in advance in the storage section, and the broadcast frequency detected by the broadcast frequency detection section is compared with the broadcast reception frequency stored in the storage section. 7. The location of the own vehicle is determined by the area determination means. - Therefore, the receiving antenna that is conventionally installed in the vehicle can be used as is, and the broadcast frequency detection section has the same circuit configuration as the receiving circuit of a vehicle FM tuner or TV tuner. In addition, the storage unit and area determination unit can be put into practical use under program control using a microcomputer, which simplifies the device configuration, reduces costs, and reduces size and weight. You can easily know by using it.

Furthermore, the reception of broadcasting frequencies used for regional determination is
By expanding the range, the area where the vehicle is present can be detected in more detail by taking advantage of the narrow reception area of the UHF satellite station.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a block diagram showing a specific embodiment of the invention, and FIG. 3 is a flowchart showing the operation of the embodiment of FIG. Fourth
The figure is a block diagram showing another embodiment of the present invention, and FIG. 5 is an explanatory diagram of a conventional example. 10: Antenna 11: FM-AM receiver 12: Antenna coupler 13: tIi transmission frequency detection section: Control section 15: Signal detection circuit 16 Synthesizer 17: Frequency counter 18: Regional reception frequency storage section 20: Region determination processing Section 21: High frequency amplification circuit 22: Mixer 23: Intermediate frequency amplifier 24: Reference voltage source 25: Comparator 26: Input/output interface 27: Central processing unit (CPLI) 28: Memory 38: UI-IF antenna 40: IJI-IF Broadcast frequency detection section patent applicant
Nissan Motor Co., Ltd. Figure 1

Claims (1)

[Scope of Claims] A broadcasting frequency detection unit that detects broadcasting frequencies above a certain reception level by frequency sweeping of a predetermined frequency band; a storage unit that stores broadcasting reception frequencies for each discrimination area; 1. A vehicle presence area detection device comprising: area determination means for comparing the broadcast frequency and the broadcast reception frequency stored in the storage unit to determine the location of the own vehicle.