JPH10142274A - Drawing up device for electric field strength distribution map - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always draw up an accurate electric field strength distribution map even in the case where an error occurs in the result of measurements at the measuring spot of an electric field strength by automatically correcting the above error. SOLUTION: In a device for displaying an electric field strength distribution map on a display device 14 which is drawn up in such a way as a nondirectional antenna 2 and a GPS antenna 6 are loaded on a vehicle, and the electric strength E1 is measured from the received signal of the nondirectional antenna 2 by an electric field strength measuring apparatus 12, and the measuring position of the electric field strength E1 is measured by a GPS receiver 8, and thus the distribution of the electric field strength obtained from a ground station is inscribed on the map, a directional antenna 4 is loaded to also measure an electric field strength E2 from the received signal sent by the antenna 4. A position where the electric field strength E2 becomes an extreme value is detected from the data rows of the measured electric field strength E2, and the error of measured position due to the GPS receiver 8 is obtained from the above detected position and the installation position of the ground station to correct position data for drawing up the electric field strength distribution map. Consequently, the electric field strength distribution map can be exactly drawn up and displayed without the influence of the measuring position error due to the GPS receiver 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric field intensity distribution map creating apparatus for creating an electric field intensity distribution map of a radio wave transmitted from a ground station for mobile communication.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
No. 46, Japanese Patent Publication No. 2518153, etc., the electric field intensity of a radio wave transmitted from a ground station is measured by a measuring device mounted on a vehicle, and a map and an electric field at each measuring point are displayed on a display device. 2. Description of the Related Art There is known an electric field intensity distribution map creating apparatus which displays the intensity.

[0003]

In this type of device, an electric field intensity distribution map can be automatically created simply by measuring the electric field intensity when the vehicle is running and sequentially storing the measurement results. Can be created very easily in, for example, a ground station (so-called cell station) for a personal handyphone system (hereinafter, referred to as PHS) in an urban area or the like. In a communication system in which the ground stations are dispersedly arranged, it can be a very useful device when creating an electric field strength distribution map of the transmission radio wave from each ground station.

[0004] Incidentally, in order to create an electric field intensity distribution map using the above-described apparatus, it is necessary to measure not only the electric field intensity but also the measurement point of the electric field intensity. And as a method of measuring such an electric field intensity measurement point, conventionally, for example,
A so-called self-contained navigation type positioning method that measures the position by integrating the traveling direction of the vehicle obtained by a steering angle sensor or geomagnetic sensor and the traveling speed of the vehicle obtained by a vehicle speed sensor, for GPS (Global Positioning System) To measure position based on transmission data from multiple satellites
S-type positioning method, a method of measuring a more accurate position by interpolating the positions measured by each of these methods, and correcting the measured position to a position on a road by map matching to obtain a more accurate position Various measurement methods are known, such as a method for measuring the temperature.

However, such a conventional measuring method cannot always accurately measure an absolute position, and an error occurs in a measurement result. When the measurement error at the electric field intensity measurement point occurs, the distribution of the electric field intensity shifts on the map due to the measurement error, and a problem arises that an accurate electric field intensity distribution map cannot be obtained.

For example, of the various positioning methods described above, the relative position and the absolute position obtained by the two positioning methods of the self-contained navigation method and the GPS method are interpolated with each other to determine the absolute position of the electric field strength measurement point. According to the method of correcting the absolute position to a position on the road by map matching, the measurement error can be minimized. However, in this positioning method, a GPS-based positioning method for measuring a reference absolute position uses a transmission radio wave from an artificial satellite, so that the measurement result varies depending on the surrounding environment such as a combination of receiving satellites and weather conditions. The measurement result may have an error of about one hundred and several tens m. Therefore, even if the error is absorbed by interpolation and map matching as described above, the measurement error cannot be reduced to zero, and an error of several tens of meters occurs.

[0007] Even if there is such a measurement error,
If the service area of the ground station is, for example, several kilometers to several tens of kilometers in radius
When the service area is as narrow as, for example, a radius of several hundred meters, as in the cell station for PHS described above, the electric field intensity distribution is not a big problem when the area is as wide as m. The position is greatly shifted from the installation position, and it becomes impossible to grasp the service area of the cell station from the created electric field intensity distribution map.

The present invention has been made in view of such a problem, and measures the electric field intensity and the current position of a radio wave transmitted from a ground station using a measuring device mounted on a vehicle. The purpose is to automatically correct even if an error occurs in the measurement result at the field strength measurement point in the device that creates the map, so that an accurate field strength distribution map can always be created. And

[0009]

An electric field intensity distribution map creating apparatus according to claim 1 for achieving the above object is mounted on a vehicle, and a ground station for mobile communication as the vehicle travels. Sequentially measure the electric field strength of the transmitted radio wave from
An electric field intensity distribution map creating apparatus for creating an electric field intensity distribution map from the measurement results, wherein storage means in which map data for creating the electric field intensity distribution map and position data indicating an installation position of the ground station are stored in advance. An omni-directional antenna that receives a transmission radio wave from the ground station, and is capable of receiving a transmission radio wave from the ground station, and is fixed so as to have a directional characteristic perpendicular to the traveling direction of the vehicle, from the ground station. A directional antenna that receives the transmitted radio wave, and an electric field intensity measuring unit that measures the electric field intensity of the transmitted radio wave received by each of the antennas based on signals received from the omnidirectional antenna and the directional antenna, Position measurement means for measuring the reception position of the transmission radio wave that changes with the movement of the vehicle, and at a predetermined cycle corresponding to the movement of the vehicle, a current reception position from the position measurement means. The electric field intensity distribution map is created by reading the electric field intensity of the transmission radio wave currently received by each of the antennas from the electric field intensity measuring means, and sequentially storing the read reception position and each electric field intensity. Data generating means for generating measurement data for use, and a receiving position at which the electric field strength of the transmission radio wave received by the directional antenna becomes an extreme value is detected based on the measurement data generated by the measurement data generating means. Based on the receiving position detected by the receiving position detecting means and the position data of the ground station stored in the storage means, the measurement error of the receiving position by the position measuring means. Calculating means for correcting reception position data in the measurement data created by the measurement data creation means in accordance with the calculation result; and measurement data corrected by the correction means. From the reception position data in the data and the electric field strength data of the transmission radio wave received by the omni-directional antenna, and the map data stored in the storage means, the distribution of the electric field strength centered on the ground station is shown on a map. And an electric field intensity distribution map creating means for creating the electric field intensity distribution map described in (1).

The present invention thus configured (Claim 1)
In the electric field intensity distribution map creating apparatus, the electric field intensity measuring means measures the electric field intensity of the transmission radio wave received by each of the omnidirectional antenna and the directional antenna based on the received signals from these antennas, and performs the position measurement. Means measures a reception position of the transmission radio wave that changes as the vehicle moves.

The measurement data generation means reads the current reception position from the position measurement means at a predetermined period according to the movement of the vehicle, and the omnidirectional antenna and the directional antenna receive the current reception position from the electric field strength measurement means. The electric field strengths of the transmitted radio waves are read, and the read reception positions and the electric field strengths are sequentially stored to generate measurement data for creating an electric field strength distribution map.

[0012] Further, based on the measurement data created by the measurement data generating means, the pole receiving position detecting means sets the electric field strength of the transmission radio wave received by the directional antenna to an extreme value (that is, a local maximum value or a local minimum value). The receiving unit detects the receiving position, and the correcting unit, based on the receiving position detected by the polar receiving position detecting unit and the position data of the ground station stored in the storing unit,
The measurement error of the reception position by the position measurement means is calculated, and the reception position data in the measurement data created by the measurement data creation means is corrected according to the calculation result.

The electric field intensity distribution map creating means stores the reception position data in the measured data corrected by the correcting means, the electric field intensity data of the transmission radio wave received by the omnidirectional antenna, and the storage means. From the map data,
An electric field intensity distribution map is created in which the electric field intensity distribution centered on the ground station is described on a map.

That is, in the present invention, an electric field intensity distribution map is created using electric field intensity measured based on a signal received from an omnidirectional antenna (hereinafter, this electric field intensity is referred to as E1). Further, when creating an electric field intensity distribution map, position data representing a measurement point of the electric field intensity E1 is necessary. Therefore, the reception position is separately measured and used together with the electric field intensity E1 to create an electric field intensity distribution map. Is stored as measurement data. However, an error may occur in the reception position measured by the position measurement means, and if an error occurs in the measurement result of the reception position, an accurate electric field intensity distribution map cannot be created.

Therefore, according to the present invention, a transmission radio wave from a ground station is received by a directional antenna, and the electric field strength (hereinafter, this electric field strength is referred to as E2) is also measured from the received signal.
The measurement results are also sequentially stored as one of the measurement data for creating the electric field intensity distribution map. Since the measured electric field strength E2 is less affected by the reflected wave and accurately corresponds to the reception level of the direct wave from the ground station, the position at which the electric field strength E2 shows an extreme value is determined by the travel of the vehicle. It is the position closest to the ground station on the route. According to the present invention, by searching the data string of the electric field intensity E2 for the electric field intensity having an extreme value from among the measurement data created along with the travel of the vehicle, the ground station on the traveling route of the vehicle is most searched. A near reception position is detected, a measurement error of the reception position is calculated based on this position and the position data of the ground station, and the reception position data in the measurement data is corrected according to the calculation result.

As a result, according to the present invention, even if an error occurs in the measurement result by the position measuring means, the reception position data in the measurement data can be made to correspond to the actual position. By the intensity distribution map creating means, it is possible to always create an accurate electric field intensity distribution map.

As the electric field intensity distribution map creating means, for example, the electric field intensity distribution map created may be simply stored in a predetermined storage medium.
It is preferable that the created electric field intensity distribution map is displayed on the display means as described in (1), since the measurement result can be confirmed on the display screen of the display means simultaneously with the measurement of the electric field intensity.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a block diagram showing the configuration of the entire electric field intensity distribution map creating apparatus of the embodiment. The electric field intensity distribution map creating apparatus of the present embodiment is mounted on an automobile for electric field intensity measurement (hereinafter referred to as a “measurement vehicle”), and several hundred meters to several km in order to secure a service area in an urban area or the like.
Cells, which are ground stations for PHS distributed at intervals of
This is for creating an electric field strength distribution map of a radio wave transmitted from a station (hereinafter, referred to as CS).

As shown in FIG. 1, the electric field intensity distribution map creating apparatus of the present embodiment can receive a transmission radio wave of a predetermined frequency band (for example, 1906.55 ± 11.5 MHz) transmitted from the CS as a vertically polarized wave. And a directional antenna 4 and a GPS antenna 6 for receiving a transmission radio wave from a GPS artificial satellite.

Then, a received signal from the GPS antenna 6 is input to a GPS receiver 8 as position measuring means.
In the GPS receiver 8, the received signal is frequency-converted and demodulated to calculate position data (absolute coordinates of latitude and longitude) representing the current position of the measurement vehicle, speed data representing the moving speed of the measurement vehicle, and the like. Used for In addition, GPS
The antenna 6 and the GPS receiver 8 are used in a navigation device for a vehicle and the like, and are well known in the related art, and therefore, detailed description will be omitted.

The signals received from the omnidirectional antenna 2 and the directional antenna 4 are input to an antenna switch 10, and the antenna switch 10 converts one of the signals received from each of the antennas 2 and 4. Selected. Then, the selected received signal is input to an electric field intensity measuring device 12 as electric field intensity measuring means, and the electric field intensity measuring device 1
2 is used to measure the electric field strength from the signal level of the received signal. Further, the electric field intensity data obtained by the electric field intensity measuring device 12 and the GPS
Position data, speed data, and the like obtained by the receiver 8 are input to a control device 20 for creating an electric field intensity distribution map.

The control device 20 includes a CPU, a ROM, and a RAM.
A known microcomputer (a so-called microcomputer) composed of, for example, is configured to execute predetermined arithmetic processing in accordance with a control program stored in a ROM in advance.
An electric field intensity distribution map is created according to the data.

The control device 20 includes a liquid crystal display (LCD) for displaying an electric field intensity distribution map and the like, a display device 14 comprising display means such as a CRT, map data necessary for creating the electric field intensity distribution map, and the like. CS position data (latitude and latitude) indicating the installation position of CS, which is the center of the electric field strength distribution
A storage medium (corresponding to the storage means of the present invention) 16a composed of a magnetic disk, a magneto-optical disk, an IC card, or the like in which the absolute coordinates of the longitude are stored in advance can be mounted, and map data can be read from the mounted storage medium 16a. 16 comprising a drive device 16 for reading the data of the position and the CS, and for storing the data of the created electric field intensity distribution map, and an operation unit comprising a mouse, a keyboard, and the like for inputting data and various commands to the control device 20. 18, etc. are connected.

Although not shown, the control device 20 includes:
A printer output port for outputting the created electric field intensity distribution map data to the printer and printing the electric field intensity distribution map on paper, and a communication port for transmitting and receiving data to and from other devices are also provided. ing.

Next, in the control device 20, in order to create an electric field strength distribution map of the radio wave transmitted from the CS (display on the display device 14 in this embodiment), the control device 20 executes the control according to a preset control program. The electric field intensity measurement / distribution display processing will be described with reference to the flowcharts shown in FIGS.

This process is started when the user operates the operation unit 18 and inputs a command for measuring the electric field strength. In order to execute this processing, it is necessary to enable the directional antenna 4 to receive a transmission radio wave from the CS whose electric field intensity is to be measured. Is fixed in a direction in which the transmission radio wave from the CS can be received. For example, if the CS is installed on the left side of the road on which the measurement vehicle runs, the direction of the directional antenna 4 is fixed such that the left direction with respect to the traveling direction of the measurement vehicle is the directivity direction.

As shown in FIG. 2, when this process is started, first, in step S110 (S indicates a step), a flag F used in a process to be described later is reset (0) and various parameters are initialized. At the same time, an initial setting process of reading position data (absolute coordinates) from the GPS receiver 8 and displaying a map near the current position on the display device 14 is executed. The map display on the display device 14 includes the storage medium 1
The map data stored in 6a is used.

Next, in step S120, the position data is read from the GPS receiver 8 and stored in the RAM as position data P indicating the reception position where the radio wave transmitted from the CS was received. If the position data read from the GPS receiver 8 is off the road of the map drawn by the map data, the position data is moved to a position on the road by a well-known map matching process. Correct P.

Then, in S130, it is determined from the position data read in S120 whether or not the current position is on a map (hereinafter referred to as a display map) displayed on the display device 14, and the current position is displayed. If not on the map, S14
At 0, after updating the display map so that the current position is located on the display map, the process proceeds to S150. If the current position is on the display map, the process directly proceeds to S150.

In S150, the antenna switching device 10 is switched to the omnidirectional antenna 2 side, and the electric field strength is read from the electric field strength measuring device 12, whereby the omnidirectional antenna 2 is read.
The electric field intensity E1 of the transmission radio wave from the CS received at step S120 is read, and the position data P stored this time at step S120 is stored in the RAM.
Is stored in association with.

In S160, the antenna switch 10
Is switched to the directional antenna 4 side, and the electric field strength measuring device 1
2, the electric field intensity E2 of the transmission radio wave from the CS received by the directional antenna 4 is read, and is stored in the RAM in association with the position data P stored this time in S120.

That is, S120, S150, S16
The process 0 is a process for realizing the measurement data generating means of the present invention. By repeatedly executing this series of processes, as shown in FIG. , Y), position data P-1, P-2,
, And electric field strengths E1-1, E1-2,... Measured at the receiving position by the omnidirectional antenna 2, and electric field strengths E2-1, E measured at the receiving position by the directional antenna 4 as well.
2-2,... Are generated.

Then, in S170, based on the position data P read in S120 and the electric field intensity E1 read in S150, the reception position on the display map is displayed in a color or display pattern corresponding to the electric field intensity E1. Tentatively displays the electric field strength of the transmission radio wave from the.

In this embodiment, as shown in FIG.
The distribution of the electric field strength is
Electric field intensity E1 is at the first level (for example, 20 dBμ / m)
As described above, the low-level area where the electric field intensity E1 is equal to or higher than the second level and the low-level area where the electric field strength E1 is equal to or higher than the second level are displayed in two stages. From the measured electric field strength E1, it is determined whether the current measurement point is a low-level area, a high-level area, or a non-display area that does not belong to any of the low-level area and the high-level area. A color or pattern corresponding to the result of the determination is displayed.

Next, in S180, it is determined whether or not the flag F, which is reset in the initialization processing of S110 and is set in the processing described later, is set (1). If the flag F has not been set, the process proceeds to S190, where the electric field strength E1 read in S150 is set to a predetermined CS vicinity determination level E1max (for example, 50 d
Bμ / m) or more.

If it is determined in S190 that E1 <E1max and the current position is not near CS, the process proceeds directly to S240. Then, in S240, it is determined whether or not the measurement vehicle has traveled a predetermined distance (for example, 10m), so that the measurement vehicle waits for the predetermined distance to travel. When the measurement vehicle has traveled the predetermined distance, the process returns to S120. Then, a series of processing of S120 to S170 is executed.

As a result, a series of processes of S120 to S170 are executed every time the measuring vehicle travels a predetermined distance, and the display map on the display device 14 displays every time the measuring vehicle travels a predetermined distance. A low-level region or a high-level region representing the distribution of the electric field strength is sequentially displayed on the traveling road, and finally, as shown in FIG. 5, the distribution of the electric field strength is displayed on the road on which the measurement vehicle traveled. Will be.

Note that the position data from the GPS receiver 8 is used for measuring the traveling distance. The CS vicinity determination level E1max used in S190 is the electric field strength E1
Is a judgment value for judging that the measurement vehicle has approached the vicinity of the CS based on the reference value. The predetermined value is used as the judgment value. And a value of 20 mW, a plurality of values are set in advance also in the CS vicinity determination level E1max according to the type of CS. In S190, the current electric field intensity is to be measured. The CS vicinity determination level E1max corresponding to the type of CS is used. Such a type of CS is also displayed on the display screen when displaying the distribution of the electric field strength on the display map (see FIG. 5).

Next, in S190, if E1 ≧ E1max and it is determined that the current position is near CS,
The process proceeds to S200, where a peak of the electric field intensity E2 is detected based on the data string of the electric field intensity E2 measured by the directional antenna 4. This peak detection process is a process for detecting a peak (extreme value) of the electric field intensity E2 when the electric field intensity E2 increases and decreases when the measurement vehicle approaches and moves away from the CS, and is sequentially used as measurement data. Stored electric field strength E
This is performed by analyzing a change in the data string of No. 2.
This peak detection processing corresponds to the pole receiving position detecting means of the present invention.

Then, in S210, it is determined whether or not a peak has been detected by this peak detection processing.
If the measurement vehicle is still approaching CS and a peak cannot be detected from the data string of the electric field strength E2, the process directly proceeds to S240, and conversely, if the measurement vehicle has already passed near CS, If the peak has been detected from the data string of the intensity E2, the process proceeds to S220.

In step S220, CS position data (absolute coordinates) indicating the installation position of the CS whose current electric field intensity is to be measured is read from the storage medium 16a, and the CS position data and a peak detected in step S200 are detected. Based on the position data P representing the reception point of the electric field strength E1, the deviation (position error) ΔP of each of the position data P-1, P-2,. Remember in

That is, since the position data obtained by the GPS receiver 8 has an error due to the combination of the receiving satellites at the time of measurement, the surrounding environment, and the like, as shown in FIG. 6, the measured electric field strength (measurement strength) E1 , E2 may deviate from the actual measurement position (actual position) in the measurement data, and only the measurement data obtained by repeatedly executing the above-described processes of S120 to S170 is accurate. It is not possible to create (display) a simple electric field intensity distribution map.

Therefore, in the present embodiment, at S220, the point closest to CS on the road on which the measurement vehicle traveled (X in FIG. 6) is determined from the installation position of CS (CS position data).
The point indicated by the mark) is determined, and this point is used as the actual position to calculate the position error ΔP of the measurement position at which the electric field strength E2 becomes a pole (peak).
Based on P, position data P-1, P-2,.
Is corrected.

In calculating the position error ΔP of the measurement position, the electric field intensity E measured by the omnidirectional antenna 2 is used.
6, the peak of the electric field intensity E2 measured by the directional antenna 4 is not detected. As is apparent from FIG. 6, the electric field intensity E1 obtained by the omnidirectional antenna 2 is equal to CS. In the vicinity, it is held near the extreme value, and since it also receives radio waves reflected by surrounding buildings,
This is because it is difficult to accurately detect the position closest to CS from the electric field strength E1.

That is, in the present embodiment, the data string having the maximum value (peak) at the position closest to CS is generated by measuring the electric field strength E2 of the transmission radio wave from CS using the directional antenna 4. C from the peak position of the data sequence
The position closest to S can be easily and accurately detected.

Further, the position data and the CS position data in the measurement data are absolute coordinates representing the latitude and longitude, and the position of the point closest to CS on the road can be specified by the absolute coordinates of the latitude and longitude. The error △ P is also obtained as the amount of deviation △ X · △ Y on the coordinates of latitude and longitude, and the position data P in the measurement data is calculated based on the position error △ P (△ X · △ Y) in a process described later. When correcting -1, P-2, ...
Each error △ X △ Y is added (or subtracted) to the coordinates (X ・ Y) of the position data P.

As described above, in S220, the position error ΔP
Is obtained and stored in the RAM, the flow shifts to S230, and the flag F is set. Then, after setting the flag F, the process proceeds to the subsequent S240, and the creation of the measurement data by the series of processes of S120 to S170 is continued.

When the flag F is set as described above,
A positive determination is made in S180, and S250 is executed. Then, in S250, it is determined whether or not the electric field strength E1 has fallen below a preset end determination level E1min (for example, 20 dBμ / m).
Proceeding to 240, the creation of measurement data is continued. Conversely, if E1 <E1min, the process proceeds to S260,
The position data in the measurement data created so far is stored in S220
The electric field intensity distribution correction / display processing for correcting the electric field intensity distribution map displayed on the display device 14 by performing correction based on the position error ΔP calculated in the step (1) is executed.

After the execution of S260, S
After moving to 270 and resetting the flag F, S28
At 0, it is determined whether or not a command to end the electric field strength measurement has been input from the user via the operation unit 18, and if the command to end the electric field strength measurement has been input, the process is terminated. If the end command has not been input, the process returns to S120 to restart the series of processes.

The end determination level E1min used in S250 is based on the electric field strength E1, and the measurement vehicle
This is a determination value for determining that it is no longer necessary to measure the electric field strength of the radio wave transmitted from the CS outside of the service area of the CS. Then, the electric field intensity distribution correction / display processing (S260) executed when the electric field intensity E1 falls below the end judgment level E1min and the end judgment is made in S250 is executed as shown in FIG.

That is, in the electric field intensity distribution correction / display processing,
First, in S310, one of the position data P in the measurement data stored in the RAM is read, and in S320, the read position data P is obtained in S220 and corrected based on the position error ΔP stored in the RAM. Then, by storing the corrected position data P in the RAM again, the position data P is corrected. At S330, it is determined whether or not all the position data P in the measurement data have been corrected. If the position data has not been corrected, the procedure moves to S310 again. For example, the position data P in the measurement data is sequentially corrected, for example, in the order of registration. When the correction of all the position data P is completed, in S340, The display of the electric field intensity distribution from the CS is updated using the corrected measurement data.

As a result, the electric field intensity distribution map displayed on the display device 14 becomes a map showing an accurate electric field intensity distribution without being affected by the measurement error of the position by the GPS receiver 8. It becomes possible to know the intensity distribution accurately. Further, if the electric field intensity distribution map is converted into printing data and output from the printer output port to the printer, the electric field intensity distribution map can be printed on desired paper, and the electric field intensity distribution map can be printed. If data (only measurement data may be stored) is stored in the storage medium 16a mounted on the drive device 16, the created electric field intensity distribution map can be used by other devices via the storage medium 16a. Becomes possible.

In this embodiment, the position error ΔP
The processing in S220 executed to calculate the position data P, and the processing in S310 to S330 for correcting all the position data P in the measurement data according to the calculation result correspond to the correction means of the present invention, and the position data P is corrected. S to update the electric field intensity distribution map displayed on the display device 14 according to the measured data thus obtained.
The process at 340 corresponds to the electric field intensity distribution map creating means of the present invention.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
Various embodiments can be adopted. For example, in the above embodiment, the control device 20 has been described as storing the control program for executing the electric field intensity measurement / distribution display processing in advance, but the control device 20 is configured by a general-purpose personal computer. At the same time, a control program for executing the above processing is stored in a storage medium (a magnetic disk, a magneto-optical disk, an IC card, or the like), and when the electric field intensity distribution map is created, the control program stored in the storage medium is personalized. The above-described electric field strength measurement / distribution display processing may be executed by inputting the data to a computer.

Further, in the above embodiment, when the electric field strength measurement / distribution display processing is executed, it is assumed that the direction of the directional antenna 4 is fixed by the user in a direction in which the radio wave transmitted from the CS can be received. However, the user does not always need to perform such antenna direction adjustment,
The directional antenna 4 may simply be fixed so as to have a directional direction in either the left or right direction perpendicular to the traveling direction of the vehicle.

That is, the CS is not arranged on the road, and when the vehicle passes near the CS, the CS is always located in the right or left direction of the vehicle. And when the directional antenna 4 is facing in the opposite direction to CS,
When passing near CS, the peak of the electric field intensity E2 cannot be detected, and the measurement data cannot be corrected.
However, in such a case, make the vehicle U-turn,
If the vehicle travels in the opposite direction, the peak of the electric field intensity E2 can be detected and the measurement data can be corrected. Therefore, it is not always necessary to adjust the direction of the directional antenna 4 in executing the electric field intensity measurement / distribution display processing.
It may be simply fixed so as to have a pointing direction perpendicular to the traveling direction of the vehicle in the right or left direction with respect to the traveling direction of the vehicle.

Further, two directional antennas are fixed to the right and left directions of the vehicle, respectively, and a received signal having a higher received signal level among them is selected, and the electric field intensity E2
Or the directional antenna used for measuring the electric field strength E2 may be selected according to the position of the CS with respect to the road.

On the other hand, as the directional antenna 4 for measuring the position error ΔP, for example, as shown in FIG. 7A, two directional antennas 4a and 4b are arranged at an arbitrary interval in the same direction. A so-called stack antenna may be used. In this case, if the phase of the received signal from one of the directional antennas 4a or 4b is shifted (that is, inverted) by 180 degrees, and each received signal is synthesized by the synthesizer 4c, The resulting electric field strength E2 'is
As shown in FIG. 7B, since the local minimum value is at the position closest to CS, the electric field intensity E2 obtained from each of the directional antennas 4a and 4b is set as a peak position where the electric field intensity measured from the combined signal is used as the peak position. What is necessary is just to detect the null point where E2 'is minimum.

Next, in the above embodiment, when displaying the distribution of the electric field strength on the display map, the measured electric field strength E
1 has been described as being displayed in two stages: a low level region where the first level is equal to or higher than the second level and lower than the second level, and a high level region where the electric field intensity E1 is equal to or higher than the second level.
For example, as shown in FIG. 8, roads on the display map are divided at predetermined distance intervals (for example, 50 m intervals) around CS, and the average value of the electric field intensity E1 measured in each section is numerically calculated for each section. May be displayed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an electric field intensity distribution map creating device according to an embodiment.

FIG. 2 is a flowchart showing an electric field intensity measurement / distribution display process executed to create an electric field intensity distribution map by a control device.

FIG. 3 is a flowchart showing electric field intensity distribution correction / display processing executed in S260 of FIG. 2;

FIG. 4 is an explanatory diagram illustrating measurement data sequentially created as the measurement vehicle travels.

FIG. 5 is an explanatory diagram showing an example of a display map when the distribution of the electric field strength is identified and displayed by colors and display patterns.

FIG. 6 is an explanatory diagram illustrating a change in the electric field strengths E1 and E2 with respect to a change in the reception position due to the travel of the vehicle and a deviation of the measurement strength due to a position measurement error.

FIG. 7 is an explanatory diagram illustrating a configuration when a directional antenna is a stack antenna and its reception characteristics.

FIG. 8 is an explanatory diagram showing an example of a display map when the distribution of the electric field strength is displayed by numerical values.

[Explanation of Signs] 2 ... omnidirectional antenna 4 ... directional antenna 6 ...
GPS antenna 8 ... GPS receiver 10 ... antenna switch 12 ...
Electric field strength measuring device 14 ... Display device 16 ... Drive device 18 ... Operation unit 20 ... Control device

Claims (2)

[Claims] 1. An electric field intensity distribution which is mounted on a vehicle and sequentially measures the electric field intensity of a radio wave transmitted from a ground station for mobile communication as the vehicle travels, and creates an electric field intensity distribution map from the measurement result. A map creating device, comprising: storage means in which map data for creating the electric field intensity distribution map and position data indicating an installation position of the ground station are stored in advance; and an omnidirectional receiving a transmission radio wave from the ground station. An antenna, a directional antenna for receiving a transmission radio wave from the ground station, fixed to have a directivity direction perpendicular to a traveling direction of a vehicle with respect to a transmission radio wave from the ground station, Electric field strength measuring means for measuring electric field strengths of transmission radio waves received by the respective antennas based on a reception signal from a directional antenna; and reception of the transmission radio waves changing with movement of the vehicle. Position measuring means for measuring the position, and at a predetermined cycle according to the movement of the vehicle, while reading the current reception position from the position measuring means, and transmitting radio waves each antenna is currently receiving from the electric field strength measuring means. A measurement data generating means for generating measurement data for creating an electric field intensity distribution map by sequentially storing the read reception positions and the respective electric field intensities, and generating the measurement data by the measurement data generating means. Based on the measured data obtained, a receiving position detecting means for detecting a receiving position at which the electric field intensity of the transmission radio wave received by the directional antenna has an extreme value; a receiving position detected by the receiving position detecting means And calculating the measurement error of the reception position by the position measurement means based on the position data of the ground station stored in the storage means and the measurement data in accordance with the calculation result. Correction means for correcting the reception position data in the measurement data created by the data creation means, reception position data in the measurement data corrected by the correction means, and the electric field of the transmission radio wave received by the omnidirectional antenna. Electric field intensity distribution map creating means for creating an electric field intensity distribution map in which an electric field intensity distribution centered on the ground station is described on a map from intensity data and map data stored in the storage means. An electric field intensity distribution map creating apparatus, characterized in that: 2. The apparatus according to claim 1, further comprising a display unit for displaying an electric field intensity distribution map, wherein the electric field intensity distribution map creating unit displays the created electric field intensity distribution map on the display unit. Electric field intensity distribution map making device.