JPH081459B2 - Security method using emergency signal by radio wave - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a security method utilizing an emergency signal by a radio wave for detecting an emergency signal transmitted from a victim in an emergency and detecting the transmission position.

[0002]

2. Description of the Related Art An alarm device such as an emergency alarm buzzer has been conventionally provided in preparation for a danger of threatening human life or body. This is to surprise the assailant by always carrying it and operating it in an emergency to generate an alarm sound. This warning sound can also inform the neighborhood of the occurrence of an emergency and trigger the police to call for help or rescue.However, the purpose cannot always be achieved in places where the houses are not dense and traffic and traffic are small. There are cases. It is also undeniable that the perpetrator who hears the alarm sounds may have the adverse effect of excitement and further violence. The frequent occurrence of kidnappings has become a major social problem in recent years, but in the normal case, the perpetrator's case is not known until the perpetrator makes a threatening request to the victim's house by telephone or the like. The police learned of the incident by reporting from the victim's family, etc., and started investigating by installing a reverse detector on the telephone, but as a result of the victim's family thinking first of all to save the victim's life, the police Because there are many cases where a report is not made or is delayed, it is difficult to expect a quick search and rescue. In order to solve such a problem, the applicant of the present invention transmits an emergency signal from a portable transmitter in an emergency, as described in Japanese Patent Laid-Open No. 64-66581, so that A plurality of omnidirectional antennas are installed to receive the emergency signals from all positions to receive the emergency signals, thereby determining a general range of the transmission position of the emergency signals, and then two or more. The direction of the maximum electric field strength is detected by rotating the directional antenna of, and this is analyzed by a computer and the principle of triangulation is applied to specify the transmission position of the emergency signal. I proposed a security method to use through reception.

[0003]

However, in the security method performed by transmitting and receiving the emergency signal described in the above publication, when there are a plurality of security target persons, each security target person simultaneously presses the transmission switch of the transmitter. , Since there are transmission positions at a plurality of locations, there is a problem that the transmission position of the transmitter may not be specified in the detection method that applies the principle of the triangulation method from the maximum reception sensitivity direction by the rotating antenna. there were. The present invention has been made in view of such circumstances, and even if there are many persons who have a signal transmitter that is a transmitter that transmits radio waves of the same frequency, the emergency signal of a specific person is selectively emitted. Therefore, it is an object of the present invention to provide a security method using an emergency signal by a radio wave that prevents interference.

[0004]

A method according to the above-mentioned object.
The security method using the emergency signal by the radio wave described is a portable signal transmitter that transmits the emergency signal by the radio wave of a specific frequency including an individual identification code in an emergency, and at least the direction of the emergency signal from the signal transmitter. A plurality of receiving stations having a directional antenna for detecting, and a base station for exchanging signals with each of the receiving stations, and an emergency signal from the signal transmitter is transmitted by the directional antenna of each receiving station. Received,
From the position and the measured angle, the transmission position of the signal transmitter is searched by using the principle of triangulation method, and the transmission position is displayed on the display provided in the base station together with the map information in the vicinity thereof. In the security method utilizing, the signal transmitter includes a receiving unit that receives an emergency signal from another signal transmitter that emits an emergency signal of the same frequency, and the receiving unit is an emergency signal from the other signal transmitter. When a signal is being received, the emergency signal transmission disabled state with the same frequency of the signal transmitter is maintained to prevent simultaneous transmission of the same frequency from different signal transmitters. In addition,
The above invention includes the case where one of the receiving stations is the base station. The present invention is also applicable to the case where two unidirectional antennas arranged in the same direction are used as the directional antenna.

[0005]

According to another aspect of the present invention, there is provided a security method using an emergency signal by radio waves, wherein the signal transmitter includes a receiving section for receiving an emergency signal from another signal transmitter which emits an emergency signal having the same frequency. When an emergency signal from a transmitter is received, the transmission of the emergency signal with the same frequency of the signal transmitter is disabled, so that radio waves are simultaneously emitted from a plurality of signal transmitters within the same reception range. And therefore no interference. Further, when the direction of radio wave transmission is specified by triangulation using a plurality of receiving stations, if two or more signal transmitters emit radio waves of the same frequency, it becomes extremely difficult to specify the transmission position of the radio wave. However, when one signal transmitter transmits, if the other signal transmitters are stopped, there is only one radio wave of the signal transmitter with the same frequency, so it is easy to identify. Become.

[0006]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is a schematic configuration diagram of a security system to which a security method using an electric wave emergency signal according to an embodiment of the present invention is applied, FIG. 2 is a schematic configuration diagram of a signal transmitter, and FIG. 3 is the same signal transmission. Fig. 4 is a schematic diagram of each receiving station,
5 is a graph showing the receiving sensitivity in each direction of the antenna, FIG. 6 is a schematic block diagram showing a signal input method of the antenna according to another embodiment, and FIG. 7 is a waveform diagram of a signal transmitted from a signal transmitter. 8 is a schematic configuration diagram of the base station, FIGS.
1 is a flow chart.

As shown in FIG. 1, a security method using an emergency signal by radio waves according to an embodiment of the present invention is applied.
The security system includes a predetermined number of signal transmitters 10 and four unidirectional antennas 11 to 14 (fixed antennas) (see FIG. 1).
(Only a part of the reference numeral is shown) and a Yagi antenna 15 which is an example of a rotating unidirectional antenna, and a receiving station 16 for receiving an emergency signal from the signal transmitter 10, and a receiving station 16 and a signal It has a base station (center station) 17 for transmitting and receiving.

As shown in FIG. 2, the signal transmitter 10 comprises a transmitter 18 for emitting an emergency signal of an FM wave of one frequency in the 100 to 1000 MHz band and a receiver for receiving an FM wave of the same frequency. A receiving unit 19, a central processing unit (CPU) 20 for controlling them, an identification code generating unit 21 connected to the central processing unit 20,
An omnidirectional antenna 23 connected to the transmission unit 18 and the reception unit 19 via a changeover switch 22 and a power supply unit 24 using a battery as a power supply are configured. The transmitter 1
Reference numeral 8 is an ordinary FM signal transmitter, and as shown in FIG. 7, a digitally encoded individual identification code (ID signal) generated by the identification code generator 21 is sound-modulated and repeated (5 to 20). About 13 times in the embodiment
It can be sent once. In this embodiment, the individual identification code is transmitted only for the first 3 seconds,
After that, there is no modulation wave, but it is also possible to send the individual identification code throughout the entire period.

The receiving section 19 is composed of an ordinary super-heterodyne FM receiver and is capable of receiving an FM radio wave having the same transmission frequency as the receiving section 1.
When the radio wave 9 has a predetermined frequency, the operation of the transmitter 18 can be stopped. A ROM (not shown) is attached to the central processing unit 20, and a program for controlling the entire process of the signal transmitter 10 is written therein. The flow of the signal transmitter 10 having the above configuration will be described with reference to FIG. 3. First, when the power is turned on (step 1a) and the transmission switch (PTTSW) 25 is pressed, the transmission switch is 0.5 seconds or more. Judging whether or not the button is pressed continuously (Step 1
b) If it is pressed, the receiving unit 19 is activated (step 1c). Then, after confirming that the electric field strength of the radio wave received through the antenna 23 is smaller than the threshold value (step 1d), the dead state is provided for 1 second, and then the transmitting unit 18 is operated and the receiving unit 19 is stopped. . At this time, the changeover switch 22, which is normally on the receiving side, is simultaneously operated to connect the antenna 23 to the transmitting unit 18 (step 1f).

Next, the individual identification code (ID code) peculiar to the signal transmitter 10 is read from the identification code generator 21 (step 1g) and converted into a sound signal at a predetermined interval (120).
0 bps) and MSK modulation method using subcarrier (mark frequency 1200 Hz, space frequency 1800H
The radio wave modulated by z) is transmitted from the transmitting unit 18, and the individual identification code signal is repeatedly transmitted for three papers when the radio wave is started to be emitted (step 1h). Then, the individual identification code signal is transmitted three times (in some cases, 4 to
After confirming that it has repeatedly fired (13 times) (step 1i), transmission of the individual identification code signal is stopped (step 1).
j), and after confirming that the transmission radio wave (carrier) has been transmitted for 180 seconds (other predetermined time may be sufficient), the transmission is ended (step 1k), and the above steps are repeated to transmit the emergency radio wave. .

In this embodiment, the transmission unit 18
When the reception unit 19 receives the radio wave of the same frequency and the reception sensitivity is higher than a certain level, the transmission unit 18 is stopped. However, the identification code common to each signal transmitter and the individual identification are used. It is also possible to provide a code, and the transmitter transmits the common identification code at regular time intervals, and the transmitter is stopped by receiving the common identification code transmitted from another signal transmitter. As a result, it is possible to reduce the influence from jamming radio waves. It is also possible to attach a built-in microphone to the signal transmitter so that external sound can be transmitted (sub-modulated if necessary) by using this microphone, and the situation at the site can be grasped by sound. You can also Furthermore, it is possible to provide the receiving unit with a circuit that activates the transmitting unit when the identification code signal peculiar to the signal transmitter is received. The machine can also be operated and the position of the signal transmitter can be confirmed from the outside. In addition, two transmission frequencies are prepared, both of them are received by the reception unit, and when one side is used, the other transmission frequency is selectively used to operate the signal transmitter. It is also possible to extend the range of use of the signal transmitter.

When the receiving unit 19 receives another emergency signal and locks the transmitting unit 18, the transmission switch 25 is further pressed to transmit the emergency signal through the above steps. In some cases, the transmission switch 25 cannot be pressed again depending on the situation. Therefore, if the transmission unit 18 cannot be operated even if the transmission switch 25 is pressed once, a timer (not shown) is provided, for example, 20 to 18
It is preferable to automatically activate the transmission switch 25 every 0 seconds so that the emergency signal can be always issued.
In FIG. 2, reference numeral 26 is an operation indicator lamp and 27 is a speaker for notifying the operation by a sound signal, but both or either one can be omitted.

On the other hand, the outline of the receiving stations 16 is shown in FIGS. 1 and 4. As shown in the figures, each receiving station 16 has unidirectional antennas 11 to 11 oriented in a direction in which the entire circumference of 360 degrees is divided into four. 14
A rotating Yagi antenna 15, antenna switching devices 28 to 32, a main receiver measuring receiver 33,
And a computer 34 for controlling them. In this embodiment, the unidirectional antennas 11 to 14 are 3-element Yagi antennas.
Further, in the rotating Yagi antenna 15, a right antenna 42 and a left antenna 43, which have 10 to 20 elements (12 elements in the embodiment) having a strong directivity, are separated from each other by a certain distance, and their maximum receiving sensitivity directions are the same direction. The ones are arranged at the same height and parallel to each other. As a matter of course, the right antenna 42 and the left antenna 43 have the same structure. The outputs of the antennas 42 and 43 are independently output to the antenna switching device 32, and the sum signal or the difference signal thereof can be obtained. The antenna switching devices 28 to 31 connected to the unidirectional antennas 11 to 14 each are a two-pole switch having a relay structure including an exciting coil, and are turned on and off by transistors 35 to 38 controlled by a computer 34, respectively. It has become so.

On the other hand, the antenna switching device 32 connected to the rotary Yagi antenna 15 has a proper number of relay-structured switching switches inside, and the left and right antennas 4 are connected to each other.
When the output of 2, 43 is turned off (off position),
The computer 3 outputs the sum signal of the left and right antennas 42 and 43 (sum position) and outputs the difference signal of the left and right antennas 42 and 43 (difference position).
It is designed to be switched by the instruction from 4.
A rotator 39 is provided below the rotary Yagi antenna 15, a motor for driving the Yagi antenna 15 and a rotary encoder for detecting the rotation angle of the Yagi antenna are provided, and a drive signal is given by the computer 34. The rotation is controlled by the rotator controller 40, and the rotation angle of the Yagi antenna 15 is detected and transmitted to the computer 34. In addition, as a rotation drive source of the Yagi antenna 15,
It is also possible to omit the rotary encoder by using a pulse motor.

The computer 34 comprises an ordinary personal computer, and cooperates with the host computer 41 of the base station 17 through a dedicated line, and the electric field strength for each antenna of the unidirectional antennas 11 to 14 of each receiving station 16 (that is, The reception strength), the identification code of the antenna, and the individual identification code of the received radio wave are transmitted, and the necessary rotation search is performed using the Yagi antenna 15 according to an instruction from the host computer 41. 42a in FIG.
Indicates a modem. The main receiver 33 is composed of an ordinary FM receiver, and sequentially receives specific frequency radio waves of an emergency signal received by the unidirectional antennas 11 to 14 and the rotating Yagi antenna 15, and determines its reception level. AD
The data is converted and sequentially transmitted to the computer 34, and the individual identification code transmitted by a radio wave signal is decoded and transmitted to the computer 34.

The above steps will be described in more detail. In each receiving station 16, the four unidirectional antennas 11 to 14 are sequentially scanned by the antenna switching devices 28 to 31 in accordance with an instruction from the computer 34, The signal level received by each antenna is measured by the main receiver 33, the signal is converted into a digital signal and taken into the computer 34, and at the same time, the individual identification included in the radio wave transmitted from the unidirectional antennas 11-14. The code is received and entered into the computer 34.
The computer 34 communicates the obtained information to the host computer 41 through the modem 42a and the telephone line, and since each receiving station 16 performs these operations, the base station 17 determines the unidirectional antenna 11 of each receiving station 16. The information of the antenna identification code of 14 to 14, the strength of the signal received by each of the antennas 11 to 14, and the individual identification code of the transmitted signal transmitter 10 are obtained. Here, the host computer 41 of the base station 17 uses the antenna identification code of each of the unidirectional antennas 11 to 14 of each receiving station 16, the strength of the received signal, and the received individual identification code as information. , The approximate position of the signal transmitter 10 that has issued the emergency communication is selected, two or more receiving stations 16 are selected, and the computer 34 of the corresponding receiving station 16 is configured to perform the rotation search by the Yagi antenna 15. Instruct through the line. As a result, the predetermined receiving station 1
6 performs a rotation search using the Yagi antenna 15.

As another method, the unidirectional antennas 11 to 14 of the receiving station 16 are scanned, and the maximum received signal among the signals received by each antenna 11 to 14 is identified as the receiving station 16. Along with the code, the host computer 41 is contacted, and the host computer 41 designates the top two or three or more receiving stations 16 that have received a strong signal,
It is also possible to make a rotational search. In this case, in place of the unidirectional antennas 11 to 14, it is also possible to use an ordinary omnidirectional antenna having a high gain factor (for example, a GP having two or more stages, a multistage collinear antenna, etc.). , In this case, the output value of the antenna and the identification code of the antenna (that is, the receiving station identification code)
And the host computer 41.

Next, the receiving station 16 which has received a strong signal according to an instruction from the host computer 41 performs a rotation search. This situation will be described with reference to FIGS. 4 and 5, and a rotation search by the Yagi antenna 15 will be described. First, the antenna switching device 28-
With the switch 31 off, the antenna switching device 32 is first connected to the position at which the left and right antennas 42 and 43 generate a sum signal (that is, the sum position), and then the rotator controller 40 is controlled to detect the angle. While making one rotation gradually, the main receiver 33 receives this sum signal and AD
It is converted and input to the computer 34 together with the rotation angle of the Yagi antenna 15. The output by this is p of the pie chart
Is shown in. However, since radio waves generally include noise, when the sum signal of the antenna outputs is taken, the noise causes an error. Therefore, in this embodiment, after the sum signal is detected, the antenna switching device 32 is switched to a difference signal according to an instruction from the computer 34, and the rotator controller 40 is controlled to rotate in the reverse direction so that two antennas are arranged in parallel. The main receiver 33 receives the difference signal between the left and right antennas 42 and 43, and outputs the output from the main receiver 33 to the computer 34 together with the rotation angle of the Yagi antenna 15. The output state of this difference signal is shown in FIG.
Of q. Since noise is also canceled out in this difference signal, it indicates a relatively accurate angle. However, since there are various local minimum values of the difference signal, ± () is centered on the angle (θ ₁ degree) of the maximum sum signal. The angle of the minimum difference signal within 5 degrees (θ
₂ times).

In the above method, the Yagi antenna 15
It is necessary to rotate the motor in the normal direction and then to rotate the motor in the reverse direction again or further in the normal direction, which takes time. Therefore, at the time of one rotation, first, the above-mentioned θ ₁ degree is detected, and it is immediately reversed (θ ₁ +5
Position is quickly reversed to a degree), carried to the position of the measurement of the allowed by the difference signal operation of normal after the (theta ₁ -5 degrees), it is also possible to further returned to the position of the stand-by rapidly reversed. In addition, as shown in FIG. 6, receivers 44 and 45 are independently connected to the right antenna 42 and the left antenna 43 that form the Yagi antenna 15 of the stack, and their output values are AD-converted, and addition and subtraction are performed. An adder output (that is, a sum signal) and a subtraction output (that is, a difference signal) are obtained by the device 46, and this is given to the computer 34, and the rotation angle of the Yagi antenna 15 (that is, the output of the rotary encoder) is obtained as an antenna angle detector. It is also possible to input together with the output value detected by 47, store it in memory, and simultaneously obtain the sum signal and the difference signal, so that all measurements can be performed in one rotation.

The configuration of the base station 17 is shown in FIG. 8. As shown in the figure, the host computer 41 is provided with a computer 34 of a predetermined number of receiving stations 16 (1 to n) via a modem 48.
Further, a display 49, a keyboard 50, a printer 51, an auxiliary storage device 52, and a CD / ROM 53 in which map information is written are connected to the host computer 41. Then, the R of the host computer 41
The program of the system is stored in the OM.

9 to 11 show the host computer 4
1 shows the flow of the program written in the ROM, and FIG. 9 (A) shows the flow of data reception from each receiving station 16. When the signal transmitter 10 transmits an emergency signal, the emergency signal is transmitted to the unidirectional antennas 11 to 1.
4 receives and processes this signal by the computer 34, and then is transmitted to the host computer 41 by using a line. However, after the information is temporarily stored in the buffer memory, it is input to the host computer 41. The host computer 41 confirms that the input has been made (step 2
a) First, the identification code of the input antenna is confirmed (step 2b), then the individual identification code included in the emergency signal is confirmed (step 2c), and then the electric field strength of the antenna that has transmitted is read (step 2b). Step 2d). And
These are stored in an intermediate file which is a memory (step 2e). The above process is repeated to read the received data and the like from each receiving station 16, and if there is no data, the data receiving work is ended (step 2f).

Next, the electric field strength for each antenna is compared by the flow shown in FIG. 9 (B). That is, the intermediate file in which the information is described is called (step 3a), the data for each antenna is set (step 3b), the presence or absence of file data is confirmed (step 3c), and then sorting is performed to sort the signals. Arrange in descending order (Step 3
d). Next, since the receiving antennas of the same receiving station are duplicated, only the receiving antenna having the largest received signal in the same receiving station is selected (step 3e) and the upper nth (specifically, the second or The third antenna is selected (step 3f), and the receiving station 16 is instructed to perform rotational search by the rotating Yagi antenna 15 (step 3f).
g). On the other hand, the receiving station 16 which is lower than the upper nth is instructed not to perform the rotation search (step 3).
h). By the above-mentioned operation, the specific receiving station 16 performs the rotational search by the Yagi antenna 15 which rotates as described above, detects the angle of radio wave transmission, and transmits this to the host computer 41 via the computer 34.
As shown in FIG. 10, if these inputs are made (step 4a), the host computer 41 confirms the input Yagi antenna 15 (step 4b), and after confirming the individual identification code included in the emergency radio wave. (Step 4c),
Read the reception strength (electric field strength) of the antenna (step 4
d), the measurement data such as the receiving azimuth angle is read (step 4e) and stored in an intermediate file (step 4).
f). The above process is repeated to read the data input from each receiving station 16, and when there is no data, the process ends (step 4g). In the above process, steps 4c and 4d can be omitted.

Thereafter, as shown in FIG. 11, first, the intermediate file in which the first antenna data is recorded is called (step 5a), and the installation position (latitude, longitude) of the Yagi antenna 15 and the azimuth angle of the transmission signal are called. (Step 5b), then the intermediate file in which the second antenna data is recorded is called (step 5c), and the installation position (latitude, longitude) of the second antenna and the azimuth angle of the transmission signal are read. (Step 5d). Then, the position of the signal transmitter 10 is searched by applying the principle of the triangulation method. For this equation, take the position of the first receiving station at the origin (0,0),
The position of the second receiving station is (b, 0), and the desired point (x,
As y), if the interior angles (α, β) with the apex angles of the first and second receiving stations are obtained from the azimuths obtained by drawing a triangle and by the rotation search, the following expressions are obtained. x = btanβ / (tanα + tanβ) (1) y = (btanα · tanβ) / (tanα + tanβ) (2) Therefore, the position (referred to as point C) of the signal transmitter 10 is determined by calculating the above conditions and expressions. Can be done (step 5e). Regarding these calculations, Japanese Patent Application Laid-Open No. Sho 64-6, filed by the applicant of the present invention and published earlier.
Since it is described in detail in Japanese Patent No. 6581, its detailed description is omitted.

The coordinates (longitude and latitude) of point C calculated above are recorded in the work file (step 5f). In addition, when the receiving station that further performs the rotation search is selected, the processing is performed again, and the calculation position (C ₁ , C ₂ , ...)
To the work file, confirm that all the data have been processed (step 5g), and calculate the average value (Ca point) of the recorded data (C ₁ , C ₂ , ...). (Step 5h).

Since the position of the signal transmitter 10 from which the emergency signal is transmitted is obtained in the above steps, the map file is called from the CD / ROM (step 5i), registered in the user layer (step 5j), and the log file is written. (Step 5k). Then, the zone having the coordinates of the point Ca is designated (step 5l), and the screen is displayed together with the map information (step 5m). When this screen is displayed, the name of the registered caller, from the signal received by any of the unidirectional antennas 11 to 14 in advance,
Address, contact information, phone number, age, gender, blood type, personal data of chronic diseases are called and displayed at the same time. If the emergency signal is received, the individual identification code can be received immediately, but it takes time to identify the position and issue the map information.During that time, the personal information of the person who sent the message is displayed on the screen (display). 49), and when the map information is displayed, it is preferable to provide a small frame and also display the personal information.

As another embodiment method, the antenna identification codes of the unidirectional antennas 11 to 14 of the receiving stations 16 and the receiving sensitivities are transmitted to the host computer, and the host computer roughly determines the position of the emergency signal. After estimating, the specific receiving station is designated, the rotating Yagi antenna is rotated at a high speed to a specific direction, and then the outgoing direction is detected by a normal speed and method (that is, including reverse rotation), and the base station 17 It is also possible to inform the host computer.
As a result, it is possible to swiftly perform rotational surveys using the Yagi antenna.

[0027]

As is apparent from the above description, the security method using the emergency signal by the radio wave according to claim 1 is as follows.
Since the signal transmitter is provided with a receiving unit that prevents a plurality of signal transmitters from transmitting at the same time, and the plurality of signal transmitters do not simultaneously emit radio waves, interference does not occur. Therefore, even if there are many signal transmitters, the transmitting position can be detected with certainty.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a security system to which a security method using an emergency signal by radio waves according to an embodiment of the present invention is applied.

FIG. 2 is a schematic configuration diagram of a signal transmitter.

FIG. 3 is a flowchart of the signal transmitter.

FIG. 4 is a schematic configuration diagram of each receiving station.

FIG. 5 is a graph showing the receiving sensitivity in each direction of the antenna.

FIG. 6 is a schematic block diagram showing a signal input method of an antenna according to another embodiment.

FIG. 7 is a waveform diagram of a signal transmitted from a signal transmitter.

FIG. 8 is a schematic configuration diagram of a base station.

FIG. 9 is a flowchart of a program stored in a host computer.

FIG. 10 is a flowchart of a program stored in a host computer.

FIG. 11 is a flowchart of a program stored in a host computer.

[Explanation of symbols]

 10 signal transmitter 11 unidirectional antenna 12 unidirectional antenna 13 unidirectional antenna 14 unidirectional antenna 15 Yagi antenna 16 receiving station 17 base station 18 transmitting unit 19 receiving unit 20 central processing unit 21 identification Code generation unit 22 Changeover switch 23 Omnidirectional antenna 24 Power supply unit 25 Transmission switch 26 Operation indicator light 27 Speaker 28 Antenna switching device 29 Antenna switching device 30 Antenna switching device 31 Antenna switching device 32 Antenna switching device 33 Main receiver 34 Computer 35 Transistor 36 Transistor 37 Transistor 38 Transistor 39 Rotator 40 Rotator controller 41 Host computer 42 Right antenna 42a Modem 43 Left antenna 44 Receiver 45 Receiver 6 subtractor 47 antenna angle detector 48 modem 49 Deisupurei 50 keyboard 51 printer 52 auxiliary memory device 53 CD · ROM

Claims (1)

[Claims] 1. A portable signal transmitter for transmitting an emergency signal by a radio wave of a specific frequency including an individual identification code in an emergency, and a directional antenna for detecting at least the direction of the emergency signal from the signal transmitter. A plurality of receiving stations, and a base station for transmitting and receiving signals to and from the respective receiving stations,
The emergency signal from the signal transmitter is received by the directional antenna of each receiving station, the transmission position of the signal transmitter is searched from the position and the measured angle using the principle of triangulation, and the transmission is performed. In a security method using an emergency signal by radio waves that displays the position together with map information in the vicinity on a display equipped with a base station, in the signal transmitter, an emergency signal from another signal transmitter that issues an emergency signal of the same frequency A receiver for receiving
When the receiving unit is receiving an emergency signal from the other signal transmitter, the signal transmitter maintains an untransmittable state of the emergency signal at the same frequency, and the signal of the same frequency from different signal transmitters is held. A security method using an emergency signal by radio waves, which is characterized by preventing simultaneous transmission.