JPH11101638A - Slope collapse detecting method, collapse detecting sensor used for this method, alarm receiving device, and slope collapse detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make contractible a high-reliability slop collapse monitoring system by providing a collapse detecting sensor detecting the change of attitude of a case from a vertical attitude to an inclined attitude and transmitting radio waves. SOLUTION: The collapse detecting sensor 200 detecting the change of the case attitude from a vertical attitude to an inclined attitude is supported in the vertical attitude by a support 300 in the state before a collapse. When a slope 100 is collapsed and changed into a slope 102, the sensor 200 is inclined or overturned, then the sensor 200 transmits radio waves DN, and the radio waves DN are received by an alarm receiving device 400. A signal is transmitted to an observation station 504 through a cable 406 from the cable connection port 402 of the alarm receiving device 400, e.g. through a railway telephone network 502, and an alarm unit is operated to report the occurrence of a collapse. A luminous display unit 602 is lighted via a cable 408 from a cable connection port 404 to report a danger to the driver of a train.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a landslide on a road or a railway line, which is capable of detecting and confirming a landslide caused by embankments or cuts formed during construction work or a natural landslide at a remote place. The present invention relates to an apparatus using the slope failure detection method.

[0002]

2. Description of the Related Art On roads or railroad tracks, slopes formed by embankments or cuts or natural slopes created during construction work may cause slope collapse due to loosening of ground due to heavy rain. If the crew of a car or train does not foresee this situation, they will know this only after reaching the slope collapse site, and will encounter a very dangerous situation (major accident) in which the car or train itself falls or rolls over. It can be a thing.

Conventionally, to detect such an accident, a method has been adopted in which an observer patrols periodically during a security period to artificially detect the accident. Also, various countermeasures have been conventionally proposed and implemented as a detecting device. Among them, there is Japanese Patent Application No. 3-264225 “Slope collapse detecting device”. This detector is provided with a detection shelf on the slope, and this detection shelf is supported by a load detector in a position almost perpendicular to the slope.When the slope collapses and the earth and sand rises on the detection shelf, the load detector detects the load. It employs a method of detecting an increase and notifying the occurrence of collapse.

[0004]

However, the conventional method for detecting a slope failure that is artificially found requires a large amount of human power by periodically patroling a dangerous section. In addition, there are drawbacks such as that the observer always involves danger and it takes time to confirm safety. Also, Japanese Patent Application No. Hei 3-26422
The method of No. 5 and all other methods are disadvantageous in that the structure is complicated, the construction is difficult due to the wired system, and the facility cost is high.

[0005] For these reasons, there has been a demand for an inexpensive detection method and apparatus which are easy to handle, easy to install, and inexpensive. The present invention has been made in view of the above circumstances, and provides a slope failure detection method and apparatus capable of detecting a slope failure using a small and easily installed collapse detection sensor and wirelessly notifying a remote location. It is intended to be.

[0006]

According to a first aspect of the present invention, a collapse detection sensor for detecting that a case has changed from a vertical posture to an inclined posture and transmitting a radio wave having a predetermined frequency, and the collapse detection sensor. A receiver for receiving radio waves transmitted by the receiver and a display for displaying that the receiver has received the radio waves, the collapse detection sensor is installed in a vertical position at the monitored location, and the receiver has a predetermined frequency. The present invention proposes a slope failure detection method in which it is determined that an installation location of a collapse detection sensor has collapsed by displaying the reception of a radio wave on a display.

[0007] According to the slope failure detection method of the present invention, the collapse detection sensor may be installed in the position to be monitored in a vertical posture, and there is no need to provide wiring such as a cable. Therefore, an advantage that the installation can be easily performed is obtained. Claim 2 of the present invention proposes a configuration of a collapse detection sensor installed at a monitored location. A collapse detection sensor according to the present invention includes a tilt detector that outputs a contact signal according to the tilt of a case, a radio transmitter that transmits a radio wave of a predetermined frequency by the contact signal output by the tilt detector, and a radio transmitter. And a transmitting antenna for emitting radio waves emitted by the antenna into the air.

According to the collapse detection sensor proposed in claim 2, the structure can be made simple and inexpensive. Therefore, even if the collapse detection sensor is damaged in the event of a collapse disaster, there is no great burden on the economy. Claims 3 and 4 of the present invention propose a configuration of an alarm receiving device. The alarm receiving device proposed in the present invention is a receiver that receives a radio wave transmitted by a collapse detection sensor, a display that detects and displays that the receiver has received a radio wave transmitted by the collapse detection sensor, and a receiver that includes: It is characterized by having a cable connection port or a wireless transmission means for notifying another place that the radio wave has been received.

According to the alarm receiving apparatus of the present invention, when the collapse detection sensor changes from the vertical posture to the inclined posture, and the collapse detection sensor emits a radio wave, the radio wave is received and the indicator attached to the self is activated. , Indicating that a radio wave has been transmitted. Therefore, even if the alarm receiving device is installed at a distance (about 500 meters) of radio waves from the collapse detection sensor, occurrence of collapse can be known.

Further, in the present invention, since a cable connection port or a relay device using radio waves is provided, the occurrence of a collapse disaster can be notified outside the range of the radio wave reach of the collapse detection sensor. Therefore, there is an advantage that the train can be stopped in advance by notifying the management office or the station of the occurrence of the collapse. Further, claim 5 of the present invention
The present invention proposes a collapse detection sensor having a configuration in which a code storage is provided in the collapse detection sensor and the code storage modulates a radio wave transmitted by each collapse detection sensor by a code and transmits the modulated radio wave.

According to the collapse detection sensor proposed in claim 5, a plurality of collapse detection sensors can be grouped, and radio waves modulated by different codes can be transmitted from each collapse detection sensor in the group. According to claim 6, the code is read from the radio wave transmitted from the collapse detection sensor proposed in claim 5, collated with the code table stored therein, and the radio wave is received only when the code matches. An alarm receiving device configured to make a determination is proposed.

Therefore, by combining the collapse detection sensor and the alarm receiving device proposed in claims 5 and 6,
Even if a radio wave of the same frequency is simply transmitted from another, unless the radio wave is modulated by a specific code, the alarm receiving device does not malfunction and a highly reliable slope failure detection device can be configured. According to the collapse detection sensor according to the seventh aspect, when the slope is collapsed, the light-emitting indicator installed along the road or the railroad is turned on immediately to notify the driver of danger, so that the train or the like must be stopped before the collapse site. be able to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for detecting a slope failure according to the present invention will be described with reference to FIG. In the figure, reference numeral 100 denotes a slope whose collapse is to be monitored, and reference numeral 102 denotes a slope after the collapse. In the present invention, the collapse detection sensor 2 is used for the slope 100 before collapse.
00 is set. The collapse detection sensor 200 includes a support 300
Thus, in a state before collapse, it is supported in a vertical posture as shown by a dotted line in FIG.

The slope 100 collapses and the slope 102 shown by a solid line.
, The collapse detection sensor 200 is inclined or falls as shown by the solid line in FIG. When the collapse detection sensor 200 is tilted from the vertical posture or falls down, the collapse detection sensor 200 transmits a radio wave DN from the antenna 202. This radio wave is set to a predetermined frequency, and the radio wave receiving device 400 receives the radio wave DN of this frequency.

Alarm receiving device 400 and collapse detection sensor 20
The distance from the installation location 0 is, for example, about 500 meters, and the alarm receiving device 400 is installed in a safe place within this distance. The alarm receiver 400 is provided with a display indicating that the radio wave DN has been received, or an alarm such as a buzzer, as described later, so that if a monitor is nearby, the occurrence of collapse can be known. Have been.
According to the present invention, cable connection ports 402 and 404 for notifying another place 500 that the radio wave has been received by the alarm receiving apparatus 400 are further provided.

The cable connection port 402 is connected to, for example, a railway telephone network 502 through a cable 406 in this example.
The nearest station or monitoring station 50 through the railway telephone network 502
A signal indicating that the radio wave has been received is transmitted to an alarm device 5.
06, etc., to signal the occurrence of collapse. 1 shows an example in which the light emitting display 602 is connected to the cable connection port 404 via the cable 408. The light-emitting indicator 602 is installed along the railroad track 600 and is turned on under a dangerous situation such as a collapse of a slope, and is provided to inform a driver of a train of a danger and stop the train before entering a danger zone. . Therefore, by controlling lighting of the light-emitting indicator 602 based on the detection signal of the alarm receiving device 400, the train can be reliably stopped just before the collapse site when the slope collapses.

From the above, the outline of the slope failure detection method according to the present invention will be understood. Hereinafter, the configuration of the collapse detection sensor 200 and the configuration of the alarm receiving device 400 according to the present invention will be described in detail. FIG. 2 shows an example of a specific structure of the collapse detection sensor 200. In this embodiment, case 2
01 shows a case where a metal cylindrical tube is used. A screw cover 203 is screwed into the lower end of the case 201, and the battery 204 is stored in the screw cover 203. Case 20
In 1, a radio wave transmitter 205 and an inclination detector 206 are stored in addition to the battery 204.

As shown in FIG. 3A, the tilt detector 206
The electrode 206B is placed in the conductive cup 206A with the insulating lid 2
A mercury bulb 206D is placed between the electrode 206B and the bottom surface of the conductive cup 206A while being insulated and supported by 06C. That is, the concave portion 206 is provided at the center of the bottom surface of the conductive cup 206A.
E is formed, and the mercury bulb 206D is engaged with the concave portion 206E. By keeping the conductive cup 206A in a vertical position, the mercury sphere 206D maintains the state of being engaged with the concave portion 206E. The electrode 206 </ b> B has a dish shape in which a central portion is concave downward. Therefore, the mercury sphere 206D is
In the state of being engaged with 06E, the mercury sphere 206D is maintained in a non-contact state with the electrode 206B.

On the other hand, when the conductive cup 206A takes an inclined posture as shown in FIG.
6E, and is discharged to the periphery of the conductive cup 206A. In this state, the mercury bulb 206D is
B, and the terminal 206F is electrically connected between the conductive cup 206A and outputs a contact signal. By making the planar shape of the dish-shaped electrode 206B circular, a contact signal can be always output even if the conductive cup 206A is inclined in any direction of 360 °.

The tilt detector 206 having such a structure is mounted inside the case 201 in a vertical posture. Reference numeral 207 denotes a printed circuit board 207 that supports the tilt detector 206 and the radio wave transmitter. When the inclination detector 206 outputs a contact signal, the radio wave transmitter 205 is activated (power is turned on).
To transmit a radio wave DN of a predetermined frequency. Radio transmitter 20
Reference numeral 5 denotes a transmission controller 205A and a transmitter 20 as shown in FIG.
5B.

Each collapse detection sensor 200 is assigned a calling code for specifying the alarm receiver called by itself.
In other words, if the alarm receiving device 400 is configured to respond only to the reception of a radio wave (carrier), there is a disadvantage that the alarm receiving device 400 responds due to noise or the like transmitted from another device. Alarm receiving device 4
00 is provided with a code collator, and operates so as to detect the collapse only when the code transmitted from the collapse detection sensor 200 matches the code stored in the alarm receiving device 400.

For this purpose, a code storage 205C is added to the transmission controller 205A. The code storage unit 205C can be constituted by a read-only memory called a ROM or the like, for example. The digital code assigned to each collapse detection sensor 200 is stored in the code storage 205C.
This digital code can have a bit length of, for example, about 64 bits. This digital code is read out from the code storage unit 205C as a serial signal, and a carrier wave is modulated by a code of “1” and “0” and transmitted. The collapse detection sensor is configured to be identified.

The alarm receiving device 400 is constituted by combining, for example, about 16 collapse detection sensors 200 into one set, and different digital codes are all assigned to each set of the collapse detection sensors. By adopting a bit length of 64 bits, the number of combinations becomes enormous, so that the same digital code is not assigned to any of the sets of collapse detection sensors 200. Therefore, even if a plurality of sets of collapse detection systems are operated in close proximity to each other, different sets of alarm receiving devices 40 may be used.
It is possible to avoid a malfunction in which 0 incorrectly identifies signals from different sets of collapse detection sensors.

The radio wave transmitted by the radio wave transmitter 205 is supplied to an antenna 202 attached to the upper end of the case 201 and emitted from the antenna 202 into the air. Here, each collapse detection sensor 200 intermittently transmits a radio wave modulated by each digital code. That is, a plurality of collapse detection sensors 2
When 00 transmits radio waves at one time, the alarm receiver 400 cannot identify the digital code assigned to each collapse detection sensor 200. Therefore, each collapse detection sensor 200 intermittently transmits a radio wave modulated by the digital code, thereby causing interference. To reduce the rate of At the same time, by making all the pause times different for each collapse detection sensor 200, the interference rate is further reduced. As the transmission time and pause time of the radio wave, for example, about 0.2 seconds are allocated to transmission, and 2 to 3 seconds are allocated to the pause time.

As shown in FIG. 4, the alarm receiving device 400 includes a receiving antenna 401, a receiver 403, and a reception controller 40.
5, an alarm 407, and a display 409. The receiver 403 receives a radio wave transmitted by the collapse detection sensor 200. The reception controller 405 demodulates the digital code carried on the radio wave received by the receiver 403, and checks the digital code against the digital code stored therein. As a result of the comparison, when a match is detected, an alarm 407 constituted by a sounding device such as an electronic buzzer is activated by the match detection signal to notify the collapse of the slope. At the same time, which of the collapse detection sensors 2
The display 409 displays whether the radio wave is from 00.

That is, the reception controller 405 is provided with a code storage 405A and a collator 405B. Code storage 40
5A stores all digital codes of the collapse detection sensor 200 managed by the alarm receiving apparatus 400, and compares the demodulated digital codes with the code storage 405A by the collator 405B.
Is compared with the code stored in the memory, and the presence or absence of a matching digital code is determined. When a coincident digital code is detected, the alarm 407 is activated. For example, the display 409 assigns a number to the collapse detection sensor 200 managed by itself, and displays the number to indicate which collapse detection sensor 200 is inclined. There is only one display 409, and displays the number of the collapse detection sensor 200 received last.

At the same time, the reception controller 405 activates the output circuit 411, and the output circuit 411 that outputs contact signals to both the cable connection ports 402 and 404 can be constituted by, for example, a relay. By temporarily energizing the relay and controlling the contact to, for example, an on state, the relay is self-held, and the contact signal is continuously output even if the radio wave from the collapse detection sensor 200 is temporarily stopped.

FIGS. 5 and 6 show the structure of a support 300 for supporting the collapse detection sensor 200. FIG. The support 300 includes a pile 301 made of, for example, a metal tube, a first cylindrical body 302 engaged with the peripheral surface of the pile 301, and a first cylindrical body 302.
The first cylindrical body 30 is screw-coupled to the first cylindrical body 30 by a screw feed operation.
By moving in the direction of the axis 2, a tightening ring (not shown but the same as 308 described later) is tightened to tighten the pile 301, and the first clamp supporting the first cylindrical body 302 at an arbitrary position of the pile 301. Screw 303 and the first
A first protruding piece 304 that protrudes radially from the peripheral surface of the cylindrical body 302 and has a hole at the tip, and is tightened and supported by a screw 305 that penetrates a hole formed at the tip of the first protruding piece 304. The second protrusion 306 and the second protrusion 30
6, a second cylindrical body 307 attached to the other end of the second cylindrical body 307, and a male screw formed on the peripheral surface of the second cylindrical body 307. A second clamp screw 309 for tightening and fixing the peripheral surface of the collapse detection sensor 200 inserted into the hollow portion of the body 307.

According to the structure of the support 300, the pile 30
Since the end having the tapered shape of No. 1 is inserted into the ground, the pile 301 is implanted into the monitored inclined surface 100 in a substantially vertical posture by driving. After planting the pile 301, the first cylindrical body 3
The first cylinder 302 may be fixed to the pile 301 by inserting the pile 301 into the hollow hole 02 and rotating the first clamp screw 303. Alternatively, the pile 301 may be inserted into the ground in a state where the pile 301 has been penetrated through the first cylindrical body 302 in advance.

In any case, if the pile 301 is implanted in a vertical posture, the collapse detection sensor 200 supported by the pile 301 can be installed in a vertical posture. A screw 305 for fastening the first projection 304 and the second projection 306 is used.
Indicates a case where the lever 311 is formed integrally, and the screw 305 is manually rotated by the lever 311 to perform an operation of tightening the first protrusion 304 and the second protrusion 306.

In the embodiment shown in FIG. 1, when the alarm receiver 400 receives a radio wave transmitted by the collapse detection sensor 200, the alarm receiver 400 connects the cable connection ports 402 and 40.
4 shows a configuration in which a contact signal is directly output to the cables 406 and 408 connected to the first alarm receiver 400A and the second alarm receiver 40A, as shown in FIG.
0B, and a relay 70 is provided to the first alarm receiving device 400A.
0 when the first alarm receiving device 400A receives the radio wave transmitted by the collapse detection sensor 200,
0 is activated, and a radio wave is transmitted from the repeater 700.
It can be configured to relay radio waves to the alarm receiving device 400B.

The relay 700 is, for example, an alarm receiver 400
An output circuit 4 attached to one of the cable connection ports 402 and 404 provided in the alarm receiving device 400.
11 (see FIG. 4), the power of the repeater 700 is turned on by the contact signal output from the output circuit 411, and the repeater 700 is started. Repeater 700 transmits a radio wave having the same frequency as that of collapse detection sensor 200, and relays this radio wave to second alarm receiving device 400B. The repeater 700 is also provided with a code storage similar to the collapse detection sensor 200, reads a code from this code storage, modulates a radio wave, and transmits the code together with the radio wave to the second alarm receiving device 400B.

The second alarm receiving device 400B has a repeater 70
A code memory and a collator for collating the codes sent from 0 and detecting a match are provided. That is, the second alarm receiving device 400B can use a receiver having the same configuration as the first alarm receiving device 400A except for the code stored in the code storage device. By storing a plurality of codes in the code storage provided in the second alarm receiving device 400B, the second alarm receiving device 400B can receive radio waves transmitted by the plurality of repeaters 700. That is, radio waves transmitted from a plurality of grouped collapse detection sensors or radio waves from the repeater 700 and the plurality of collapse detection sensors 200 can be received in a mixed state.

By connecting, for example, cables 406 and 408 to the cable connection ports 402 and 404 of the second alarm receiving device 400B, it is possible to notify another place 500 or the light emitting display 602 of the collapse of the slope. FIG. 8 shows an example of the external structure of the alarm receiving device 400. 412 indicates a case body. A lid 414 is placed on the upper surface of the case body 412. The lid 414 is detachably attached to the case main body 412 by a stopper 416 and a hinge (not shown). When the cover 414 is covered, the upper surface of the case main body 412 is sealed so that rainwater or the like does not enter the case main body 412 even if it is exposed to wind and rain.

In the example shown in FIG.
Shows a case in which the repeater 700 is mounted on the device. By attaching the repeater 700 to the cable connection port 402, the repeater 70
0 is the output circuit 411 of the alarm receiver 400 (see FIG. 4)
The relay 700 is activated by the contact signal of the output circuit 411. FIG. 9 shows an upper surface portion of the case body 412 with the lid 414 removed. Case body 4
A display 409 is arranged at the center of the upper surface of the display 12. The collapse detection sensor 200 that last transmitted radio waves to the display 409
Number is displayed. 418 is a power switch, 420A
420D is a setting switch, 407 is an alarm, 422 is an alarm lamp, and 423 is a charging connector.

[0036]

As described above, according to the present invention, the collapse detection sensor 200 can be implanted in a vertical posture on the slope to be monitored by the support 300, and no wiring work is required. Installation can be performed easily. Further, since the collapse detection sensor 200 has a simple structure and can be manufactured at low cost, even if it is broken or lost due to the collapse of the slope, no large loss is caused. Further, since the alarm receiving device 400 responds only to the radio wave from the collapse detection sensor 200 having the code assigned to itself, it does not erroneously respond to another radio wave. Therefore, occurrence of false alarm can be reduced, and a highly reliable slope failure monitoring system can be operated.

When the alarm receiver 400 identifies and receives radio waves from the collapse detection sensor 200, the
Since the configuration is such that the contact signal of No. 11 is held and the contact signal is continuously output, an alarm can be continuously output even if the collapse detection sensor 200 is buried in the earth and sand and transmission of radio waves is stopped. Therefore, the advantage that a reliable slope failure monitoring system can be constructed also from this point is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a slope failure detection method according to the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a structure of a collapse detection sensor used in the slope failure detection method of the present invention.

FIG. 3 is a cross-sectional view illustrating an example of an inclination detector used in the collapse detection sensor shown in FIG.

FIG. 4 is a block diagram for explaining an electrical configuration of a collapse detection sensor and an alarm receiving device used in the slope failure detection method shown in FIG. 1;

FIG. 5 is a side view for explaining a support of the collapse detection sensor used in the slope failure detection method shown in FIG. 1;

FIG. 6 is a plan view of FIG. 5;

FIG. 7 is a view for explaining a modified example of FIG. 1;

FIG. 8 is a side view for explaining an example of the external structure of the alarm receiver used in the present invention.

FIG. 9 is a plan view for explaining an example of the structure of the upper surface portion of the alarm receiver used in the present invention.

[Explanation of symbols]

 100 Slope before collapse 102 Slope after collapse 200 Collapse detection sensor 201 Case 202 Antenna 204 Battery 205 Radio wave transmitter 205A Transmission controller 205B Transmitter 205C Code storage 206 Tilt detector 207 Printed circuit board 300 Support 400 Alarm receiving device 401 Receiving antenna 403 Receiver 402,404 Cable connection port 405 Reception controller 405A Code memory 405B Collator 407 Alarm 409 Indicator 411 Output circuit 500 Other places 502 Railway telephone network 504 Monitoring station 506 Indicator, alarm 600 Line 602 light emitting display 700 repeater

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Nobuyuki Aikawa 2-2-2 Yoyogi, Shibuya-ku, Tokyo East Japan Railway Company (72) Inventor Akihiro Yoshida 2-2-2 Yoyogi, Shibuya-ku, Tokyo No. Tohnichi Passenger Railway Co., Ltd. (72) Inventor Yuji Omagari 2-2-2 Yoyogi, Shibuya-ku, Tokyo Tohnichi Passenger Railway Co., Ltd. (72) Inventor Masato Koizumi 2-chome, Yoyogi, Shibuya-ku, Tokyo No. 2 East Japan Railway Company (72) Inventor Yoshihisa Kaneko 1-2-2, Zenpukuji, Suginami-ku, Tokyo

Claims (7)

[Claims] 1. A collapse detection sensor that detects that a case has changed from a vertical posture to an inclined posture and transmits a radio wave having a predetermined frequency, a receiver that receives a radio wave transmitted by the collapse detection sensor, and a receiver that receives the radio wave. A warning device comprising a display for displaying that the device has received a radio wave, and the collapse detection sensor is installed in a monitored position in a vertical position, and the warning receiving device emits a radio wave of a predetermined frequency. A slope failure detection method for determining that the installation location of the collapse detection sensor has collapsed by displaying the reception on the display. 2. A. B. an inclination detector that outputs a contact signal according to the inclination of the case; B. a radio wave transmitter stored in the case and transmitting a radio wave of a predetermined frequency by a contact signal output by the tilt detector; A collapse detection sensor comprising a transmission antenna for emitting radio waves emitted by the radio wave transmitter into the air. 3. A. A receiver for receiving a radio wave transmitted by the collapse detection sensor according to claim 2; B. an indicator for indicating that the receiver has received radio waves; An alarm receiving device comprising: a cable connection port that outputs a contact signal for notifying another place that the receiver has received a radio wave. 4. A. A receiver for receiving a radio wave transmitted by the collapse detection sensor according to claim 2; B. an indicator for indicating that the receiver has received radio waves; And a wireless repeater for notifying another place that the receiver has received the radio wave. 5. A collapse detection sensor according to claim 2, further comprising a code storage unit, reading a code stored in the code storage unit as a serial signal, and modulating a radio wave with the read code. 6. The alarm receiving device according to claim 3, wherein
Providing a code table and matching means, demodulates the code from the radio wave sent from the collapse detection sensor, checks the demodulated code against the code table, and contacts the cable connection port only when the code matches the code in the code table. An alarm receiving device configured to output a signal. 7. A. A receiver for receiving a radio wave transmitted by the collapse detection sensor according to claim 2; B. an alarm receiver that outputs a signal indicating that the receiver has received radio waves; A light-emitting indicator controlled to emit light by a signal output from the alarm receiver.