JP2736724B2 - Underwater long-term observation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater long-term observation system comprising an underwater station installed underwater or on the seabed, and a data transmission buoy detachably mounted on the underwater station. About.

[0002]

2. Description of the Related Art As a long-term observation system of the seafloor for observing crustal deformation on the seafloor, conventionally, a seismometer, an anemometer, a water thermometer,
By installing a seafloor station equipped with a sensor such as a depth gauge on the seafloor in the target sea area, and connecting a processing device installed on the ground and a processing unit that performs data processing to the seafloor station with a cable, the data observed by the seafloor station A system has been proposed which can process in real time.

However, in this system, the cost increases in proportion to the length of the cable. In addition, since maintenance and inspection of the equipment after installation becomes difficult, a system that eliminates this problem has been proposed. In this system, the storage capacity of data at the seafloor station can be stored for a long time such as one year. With the available storage capacity, submarine stations can be installed on the sea floor for as long as one year,
Collect observation data. When the observation data is taken into the processing device, the seafloor station is pulled up from the seafloor.

However, when this system is used, observation data can only be processed at long-term intervals, such as one year, and real-time data processing cannot be performed. A data transmission buoy is provided, and the data transmission buoy is provided with a transmission device for transmitting data to a communication satellite, and is collected by the submarine station through each of the data transmission buoy, the communication satellite, and the ground station. A configuration for guiding data to a processing device has also been proposed, and one of the above three types of systems is to be used depending on the installation situation.

[0005]

However, when the above system is used for observing the crustal deformation of the trench where the oceanic plate sinks, the location of the seafloor station is far from the coast and the water depth is several thousand meters. A system that connects the submarine station and the processing unit on the ground with a cable,
Alternatively, the use of a system for connecting a submarine station and a data transmission buoy with a cable has been difficult to adopt due to experience limitations. Therefore, the configuration of the submarine station must be such that data is stored in it for a long period of time, and a system for collecting the stored data on the ground side every year must be adopted. In the worst case, after the crustal deformation occurred, the data had to wait for one year before being obtained on the ground.

The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to obtain observation data on the ground with a short time delay even when an underwater station is installed on the deep sea floor. It is to provide a long-term underwater observation system.

[0007]

In order to solve the above-mentioned problems, an underwater long-term observation system according to the present invention comprises an underwater station installed on the sea or under the sea, and a plurality of data transmission buoys detachably attached to the underwater station. The underwater station consists of an observation device compatible with seafloor observation, a storage device for storing data from this observation device, and a storage device for the attached data transmission buoy. A data transmission unit for transmitting data transmitted from the submarine station. The data transmission buoy has a data storage unit for storing data transmitted from the data transmission unit when the submarine station is attached to the submarine station. When he emerged,
A data transmission unit for transmitting the data stored in the data storage unit to the communication satellite, wherein at least one data transmission buoy is transmitted from the underwater station every predetermined period or when special data is observed by the observation device. Use a separating configuration. In addition, the undersea station includes a disconnection confirmation unit that sends a disconnection signal indicating disconnection of the data transmission buoy when the disconnection of the data transmission buoy is detected. Is not transmitted, one of the other data transmission buoys which are attached without being separated is used in place of the other data transmission buoy. The data transmission buoy has a signal path for transmitting a non-disconnection signal to the data transmission unit, and the disconnection confirmation unit performs detection of the non-disconnection signal guided through the signal path. When the non-disconnection signal is no longer detected, a disconnection signal is transmitted. In addition, underwater station,
A sensor for detecting the outer wall of the data transmission buoy attached to a predetermined position or the object provided on the outer wall is provided.The disconnection confirmation unit stops the sensor from detecting the outer wall or the object to be detected. And a disconnection signal is transmitted when the connection is made. The data transmission buoy includes a conductive portion provided on an outer wall portion, and the undersea station includes a pair of detectors that come into contact with the conductive portion when the data transmission buoy is mounted at a predetermined position. The unit is configured to transmit a disconnection signal when the resistance between the pair of detectors exceeds a preset value.

[0008]

The data transmission buoy which is attached to the underwater station is supplied with data from the storage device via the data transmission unit, so that the data transmission buoy stores the supplied data in the data storage unit. When the data transmission buoy is separated from the underwater station and rises to the sea surface, the data transmission buoy transmits the data stored in the data storage unit to the communication satellite by using the data transmission unit.
Further, data transmission to the communication satellite after the data transmission buoy ascends to the sea surface is performed in accordance with conditions (wave detection, detection of GPS and communication satellite signals, etc.) for each of a predetermined series of data amounts. The process is repeated until all data stored in the storage unit is transmitted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the long-term underwater observation system according to the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.

In the figure, the trench where the ocean plate sinks
An underwater station installed at each point (such as a crack in the seabed) as required for observation on the deep sea floor along 17
11 has a structure in which a frame 111 formed in a substantially quadrangular pyramid shape is a structural member, and each lower end of the frame 111 also serves as a detachment ballast in order to stably install the frame 111 on the deep sea floor 16. Leg 112 is provided.

In the space surrounded by the frame 111, an observation device corresponding to the seafloor observation such as crustal deformation on the deep sea floor and a device 114 such as a power supply are mounted. Each is provided with a buoy fixing part 113 to which four data transmission buoys 12 are detachably attached (the number of the data transmission buoys 12 is set to one year, and the number of data transmission buoys 12 is set to one year. Since they are separated at monthly intervals, the number of spares is 16 including spares.)

[0012] Data transmission buoy 12
12a) is a substantially spherical hermetic glass container having an outer shell 25 formed with a connection 26 at the lower end.
(Or metal container) and a hard hat covering the outside
(Or protective cover).

Inside the outer shell 25, a space is provided above the sea surface 18 when it floats, and is provided with a reflector 212 and a helical part 211, and a communication satellite (Inmarsat-C is planned). 13) A helical antenna for satellite communication (hereinafter referred to as a helical antenna) 21 for transmitting radio waves to 13 and a GP incorporated in a reflector 212
An S antenna 23 is provided.

Below the helical antenna 21,
A communication device 24 having a data transmitting unit for transmitting a signal to the helical antenna 21 and a GPS receiving unit and the like is provided.

On the other hand, by receiving the radio wave of the data transmission buoy 12 provided on the ground side and relayed by the communication satellite 13, the output of the ground station 14 for receiving the observation data is transmitted via a data line such as a telephone line. In this way, it is guided to the ground station 15 configured as a main part with an arithmetic unit for processing observation data.

FIG. 2 is a block diagram showing an electrical configuration of an embodiment of the present invention.

Observation device installed in underwater station 11
31 is a seismometer 311, which detects vibrations below the sea floor, a hydrophone 312, which detects sounds emitted from below the sea floor, an inclinometer 313, which detects changes in the inclination of the installation position, and a current velocimeter 314, which detects bottom laminar flow. , Salinity meter 315 to detect salinity, thermometer 316 to detect water temperature, depth gauge 317 to detect water depth,
It consists of a heat flow meter 318 that detects the heat flow and temperature gradient of the earth's crust on the seabed.The outputs 319 of these detectors 311 to 318 are sent to a station control unit 33 that controls the main functions of the underwater station 11. ing.

An output 321 of the transponder 32 for notifying the position of the underwater station 11 on the seabed is guided to the station control unit 33, and a large-capacity rewritable storage device (optical disk is used). 34 is bidirectionally connected (shown as 341)
. The data transmission buoy 12 attached to the underwater station 11 is bidirectionally connected to the station control unit 33 by a signal line 331.

FIG. 3 is a block diagram showing details of the electrical configuration of the station control unit 33 and the data transmission buoy 12.

First, the connection of each block will be described. The output of the main control unit 36 is sent to the data transmission unit 37, and the disconnection signal 381 sent from the disconnection confirmation unit 38 is sent to the main control unit 36. Has been introduced. The data transmission unit 37 and the disconnection confirmation unit 38 are both connected to a signal line via a waterproof connector 51.
331 are bidirectionally connected to the transmission control unit 42.

The output of the transmission control unit 42 is stored in a data storage unit 44.
The output of the data storage unit 44 is provided to the data transmission unit 43, and the output of the GPS reception unit 41 is output to the data transmission unit 43.
Has been sent to. The GPS receiving unit 41 is connected to the GPS antenna 23, and the data transmitting unit 43 is connected to the helical antenna 21.

The station control unit 33 includes a main control unit.
36, a data transmission unit 37, and a disconnection confirmation unit 38. The three blocks are a GPS antenna 23, a helical antenna 21, a GPS reception unit 41, a data transmission unit 43, a transmission control unit 42, and a data storage unit. 44 is a data transmission buoy
It is a block provided inside 12.

A signal line 421, which is a signal line constituting the signal line 331 and guides a signal from the transmission control unit 42 to the data transmission unit 37 and the disconnection confirmation unit 38, constitutes a signal path according to claim 3. Signal line. Although a power supply unit for supplying power to each block is provided, illustration of this power supply unit is omitted.

The details of the configuration of each block will be described below.

The data transmission unit 37 is a block for sending data from the observation device 31 guided through the main control unit 36 to the transmission control unit 42. The transmission control unit 42 The supplied data is stored in the data storage unit 44, and a digital signal indicating that the data transmission buoy 12 is in the mounted state is used as a non-disconnection signal as a disconnection confirmation unit.
It is a block to send to 38.

The GPS receiver 41 is connected to the data transmission buoy 12
Is a block for receiving a GPS signal to provide a signal indicating an accurate time (also a signal indicating confirmation of rising to the sea surface) to the data transmission unit 43 when the data ascends to the sea surface 18. The unit 43 is a block that transmits the data stored in the data storage unit 44 to the communication satellite 13 together with data indicating the exact time at the time of transmission.

Further, the disconnection confirmation unit 38 connects the data transmission buoy 12 to the buoy fixing unit 11 in order to float the data transmission buoy 12 on the sea surface.
3 to detect a non-disconnection signal guided through the signal path 421, and when this signal is no longer detected, the data transmission buoy 12 is disconnected and a disconnection signal 381 is transmitted to the main control unit 36. It is a block to send.

The operation of one embodiment of the present invention having the above configuration will be described below. At the underwater station 11 installed on the deep sea floor 16, data is collected by the observation device 31 every moment or at a constant time interval. These data are led to the storage device 34 via the main control unit 36,
It is memorized. When the operations of data collection and data storage are performed for a certain period of time, for example, over a month, an operation for transmitting these data is started.

Of the 16 data transmission buoys 12, the storage device 34 is transmitted to the transmission control unit 42 of the data transmission buoy 12 designated as the first buoy via the main control unit 36 and the data transmission unit 37. Is given a predetermined amount of data among the data for one month stored in. Therefore, the transmission control unit 42
Are sequentially sent to and stored in the data storage unit 44.

When the above operation is completed, the main control unit 36
An instruction to start transmission of the non-separation signal is given to the transmission control unit 42 via the data transmission unit 37. In addition, the main control unit 36 operates a disconnecting device (not shown) provided in the buoy fixing unit 113 to disconnect the data transmission buoy 12.

Until the data transmission buoy 12 is separated from the buoy fixing unit 113, the transmission control unit 42 is connected via the signal path 421.
Is supplied to the disconnection confirmation unit 38, the disconnection confirmation unit 38 maintains a state in which the disconnection signal 381 is not transmitted.

When the connector 51 is disconnected due to the disconnection of the data transmission buoy 12, the disconnection confirmation unit 38 does not detect a non-disconnection signal. A disconnection signal 381 indicating disconnection is transmitted to the main control unit 36.

For this reason, the main control unit 36 controls the data transmission buoy 12
Is disconnected, it is determined that the operation in the underwater station 11 for data transmission has been completed (the operation of storing the data collected by the observation device 31 in the storage device 34 is performed in parallel with the operation related to the disconnection). Has been done).

On the other hand, the data transmission buoy 12 separated from the underwater station 11 flies toward the sea surface by buoyancy. Then, when ascending to the sea surface, the operation of the GPS receiving unit 41 and the data transmitting unit 43 is started, and the data transmitting unit 43 stores in the data storage unit 44 together with data indicating the time given from the GPS receiving unit 41. The transmitted data is transmitted to the communication satellite 13.

Since the observation data transmitted to the communication satellite 13 is received by the ground station 14 using the communication satellite 13 as a relay station, the received data is guided to the ground station 15 via a line and processed. You.

When, for example, one month has elapsed since the data transmission buoy 12 was disconnected, the storage device 34 stores observation data for two months.

In this state, the main control unit 36 stores a predetermined amount of data of the month data stored in the storage device 34 most recently in the data transmission buoy 12 set as the next floating schedule. The control to store the data in the unit 44 is performed, and the same operation as described above is repeated to disconnect the data transmission buoy 12.

Therefore, the separated data transmission buoy 12 floats toward the sea surface, and when it floats, performs an operation of transmitting the data stored in the data storage unit 44 to the communication satellite 13. Therefore, the observation data is
And the ground station 15 through the
It is led to.

Hereinafter, the same operation is repeated, and each time one month elapses, the next data transmission buoy 12 to be levitated is disconnected from the underwater station 11 and a predetermined amount of the latest January observation data is obtained. Is transmitted to the communication satellite 13.

A trouble occurs when the data transmission buoy 12 is disconnected, and the data transmission buoy 12 is
When a situation occurs in which the disconnection is not separated from 3, the disconnection confirmation unit 38 continues to detect the non-disconnection signal, so that the disconnection confirmation unit 38 does not transmit the disconnection signal 381.

Therefore, the main control unit 36 controls the data transmission buoy 12
After the disconnection control is performed, the disconnection signal
If 381 is not guided, it is determined that there is a problem in disconnecting the data transmission buoy 12 and the data transmission buoy 12 to be disconnected next (for clarity of explanation, this data transmission buoy 12 is Control for storing observation data.

When the operation of storing data in the buoy 12b is completed, control for disconnecting the buoy 12b is performed.
Wait for the disconnection signal 381 to be sent from the disconnection confirmation unit 38.
Then, when the disconnection signal 381 is transmitted, it is determined that the buoy 12b has been safely disconnected (the operation of storing observation data in the storage device 34 is performed in parallel with the series of operations).

That is, every time the data transmission buoy 12 is disconnected, the main control unit 36 determines whether or not the disconnection signal 381 is transmitted from the disconnection confirmation unit 38. The operation for confirming whether or not the disconnection has occurred, and when a failure occurs in the disconnection, the operation for storing the data again and the disconnection are performed using the data transmission buoy 12 to be disconnected next.

FIG. 4 is a block diagram showing an electrical configuration of a second embodiment of the means for detecting disconnection of the data transmission buoy 12.

In this embodiment, the non-disconnection signal is generated by the disconnection confirmation unit 38a, and the non-disconnection signal generated by the disconnection confirmation unit 38 is transmitted to the connector 51.
Guided to data transmission buoy 12 by signal line 422 via a. The signal line 422 is connected to the signal path 421a on the data transmission buoy 12 side. Therefore, the non-disconnection signal is guided to the disconnection confirmation unit 38 via the signal path 421a.

As the non-disconnection signal in this embodiment, in order to simplify the configuration of the disconnection confirmation unit 38a for detecting the non-disconnection signal, a digital signal in which a pulse appears every predetermined period or its voltage is constant. Is used.

With the above configuration, when the data transmission buoy 12 is in the state of being attached to the buoy fixing unit 113, a non-disconnection signal is guided to the disconnection confirmation unit 38, and the data transmission buoy 12 is connected to the buoy. When detached from the fixed part 113,
The connector 51a is disconnected and the non-disconnect signal is
Will not be led to.

When the non-disconnection signal is no longer guided, the disconnection confirmation unit 38 determines that the data transmission buoy 12 has been disconnected, and outputs a disconnection signal 381 indicating disconnection to the main control unit 36.
To send to.

FIG. 5 shows a third embodiment of the means for detecting the disconnection of the data transmission buoy 12, and the electric configuration of the embodiment in which a block for generating a non-disconnection signal is provided on the data transmission buoy 12 side. FIG.

In this embodiment, a signal generation unit 45 for generating a non-disconnection signal (a signal in which a pulse appears every predetermined period or a DC signal whose voltage is constant) is provided on the data transmission buoy 12 side. The disconnection signal is transmitted to the disconnection confirmation unit 38b by the signal path 421b via the connector 51b.
It is a structure led to.

When the data transmission buoy 12 is disconnected, the disconnection confirmation unit 38b sends the disconnection signal 381 to the main control unit 36 because the connector 51b is disconnected and the non-disconnection signal is not guided. .

FIG. 6 is an embodiment corresponding to the fourth aspect of the present invention, and is a cross-sectional view schematically showing fourth to sixth embodiments of the means for detecting disconnection of the data transmission buoy 12.

In the fourth embodiment, the fixing hole 11 formed in the buoy fixing portion 113 and into which the connecting portion 26 of the data transmission buoy 12 is inserted.
The light-emitting unit 611 and the light-receiving unit 612 as sensors for detecting the outer wall of the data
And the light emitting unit 611 and the light receiving unit 612 are both connected to the disconnection confirmation unit 38.

When the light from the light emitting unit 611 is received by the light receiving unit 612, the disconnection confirmation unit 38 determines that the data transmission buoy 12 has been disconnected and performs an operation of transmitting a disconnection signal 381.

Further, in the fifth embodiment, the bottom 11 of the fixing hole 116 is formed.
7 has a connection 26 which is a part of the outer wall of the data transmission buoy 12.
Limit switch 62 which is a sensor for detecting the bottom 261 of the
And the output of the limit switch 62 is guided to the disconnection confirmation unit 38.

Therefore, the data transmission buoy 12 is disconnected,
When the detector 621 of the limit switch 62 no longer detects the bottom portion 261, the connection of the limit switch 62 is switched.Therefore, when the connection is switched, the disconnection confirmation unit 38 determines that the data transmission buoy 12 has been disconnected. ,
An operation for transmitting the disconnection signal 381 is performed.

In the sixth embodiment, the bottom 11 of the fixing hole 116 is
7, a magnetic proximity switch 63 is provided as a sensor, and the output of the proximity switch 63 is connected to the disconnection confirmation unit 38. A ferromagnetic metal plate 64 is provided at the bottom of the connection portion 26 at a position corresponding to the detection surface of the proximity switch 63 as a detection target.

With the above arrangement, when the data transmission buoy 12 is disconnected, the proximity switch 63 does not detect the detection target 64. 381 to the main controller 36.

FIG. 7 is a sectional view schematically showing an embodiment corresponding to the fifth aspect of the present invention.

In this embodiment, a substantially U-shaped conductive portion 71 made of a corrosion-resistant metal plate is provided on the bottom portion 261 of the connection portion 26, and a corrosion-resistant metal plate is provided on the bottom portion 117 of the fixing hole 116. It has a configuration provided with a pair of detectors 72 that are in contact with the conductive portion 71, and the detectors 72 are electrically connected to the disconnection confirmation portion 38.

With the above configuration, when the data transmission buoy 12 is not disconnected, the resistance value between the detectors 72 is close to 0. When the data transmission buoy 12 is disconnected, the resistance between the detectors 72 is reduced. The resistance value is an electric resistance value of seawater, and the value is a sufficiently large resistance value.

Therefore, when the resistance value between the detectors 72 becomes larger than a preset value, the disconnection confirmation unit 38 determines that the data transmission buoy 12 has been disconnected and sends a disconnection signal 381 to the main control unit 36. Perform sending operation.

The present invention is not limited to the above embodiment, and the proximity switch according to the embodiment of the fourth aspect of the present invention has been described with reference to the case where the proximity switch 63 is magnetic. A configuration using a proximity switch using ultrasonic waves, a proximity switch using capacitance, or the like can be used.

The number of data transmission buoys 12 is 16
In the above description, the separation interval was set to one month. However, the separation interval can be set to any other period. The number of data transmission buoys 12 is determined by the separation interval and the duration of observation. The other arbitrary number corresponding to the above can be, for example, 20 or the like.

The helical antenna 21 and the GPS antenna
Although the description has been given of the case where the antennas 23 and 23 are provided separately, a configuration in which these antennas 21 and 23 are shared by one antenna is possible.

The storage device 34 has been described as having a configuration using an optical disk. However, another rewritable storage device, for example, a storage device using an IC board or the like can be used.

The underwater station has been described as being installed on the deep sea floor. However, the underwater station can be installed under the deep sea or the like.

[0068]

The undersea long-term observation system according to the present invention comprises:
A data transmission buoy is provided at the underwater station so as to be detachable, and an observation device corresponding to seafloor observation and a data transmission unit for transmitting data from the observation device to the data transmission buoy are provided at the underwater station, and transmitted from the data transmission unit. A data transmission unit for storing data stored in the data transmission buoy, and a data transmission unit for transmitting data stored in the data storage unit to a communication satellite when ascending to the sea surface,
Since at least one data transmission buoy is separated from the underwater station at predetermined intervals, a submarine cable for data transmission is not required, and observation data is obtained on the ground at predetermined intervals. Therefore, even if the underwater station is installed on the deep sea floor, it is possible to obtain observation data on the ground with a short delay.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of one embodiment of the present invention.

FIG. 3 is a block diagram showing details of an electrical configuration of a station control unit and a data transmission buoy.

FIG. 4 is a block diagram showing an electrical configuration of a second embodiment of a means for detecting disconnection of a data transmission buoy.

FIG. 5 is a block diagram showing an electrical configuration of a third embodiment of the means for detecting disconnection of the data transmission buoy, in which a block for generating a non-disconnection signal is provided on the data transmission buoy side; It is.

FIG. 6 is an embodiment corresponding to the invention described in claim 4,
Fourth to sixth means for detecting disconnection of data transmission buoy
It is sectional drawing which shows the outline of Example of 1st.

FIG. 7 is a sectional view schematically showing an embodiment corresponding to the invention described in claim 5;

[Explanation of symbols]

 11 Underwater station 12 Data transmission buoy 13 Communication satellite 34 Storage device 37 Data transmission unit 38 Disconnection confirmation unit 43 Data transmission unit 44 Data storage unit 64 Detected object 71 Conductive unit 72 Detector 381 Disconnection signal 421 Signal path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirokazu Iwasaki 9-52, Ashihara-cho, Nishinomiya-shi, Hyogo Furuno Electric Co., Ltd. (72) Inventor Hiroshi Hotta 2-2-1 Natsushima-cho, Yokosuka-shi, Kanagawa Marine Science and Technology Center (56) References JP-A-6-118172 (JP, A) JP-A-61-195488 (JP, U)

Claims (5)

(57) [Claims] An undersea long-term observation system comprising: an undersea station installed in the sea or on the sea floor; and a plurality of data transmission buoys detachably attached to the undersea station. And a storage device for storing data from the observation device; and a data transmission unit for transmitting data from the storage device to the attached data transmission buoy. The buoy has a data storage unit that stores data transmitted from the data transmission unit when attached to the undersea station, and stores in the data storage unit when the buoy is separated from the undersea station and rises to the sea surface. And a data transmission unit for transmitting the data to the communication satellite. (B) disconnecting at least one of the data transmission buoys from the undersea station when special data is observed by the observation device. 2. The undersea station further includes a disconnection confirmation unit that transmits a disconnection signal indicating disconnection of the data transmission buoy when the disconnection of the data transmission buoy is detected. 2. The data transmission buoy, which is one of the other data transmission buoys attached without being separated, when the disconnection signal is not transmitted from the disconnection confirmation unit, is used. Underwater long-term observation system. 3. The data transmission buoy includes a signal path for transmitting a non-disconnection signal to the data transmission section, and the disconnection confirmation section includes a signal path guided through the signal path. The undersea long-term observation system according to claim 2, wherein the non-disconnection signal is detected, and the disconnection signal is transmitted when the non-disconnection signal is no longer detected. 4. The undersea station includes an outer wall of the data transmission buoy attached at a predetermined position or a sensor provided on the outer wall for detecting an object to be detected. The undersea long-term observation system according to claim 2, wherein the disconnection signal is transmitted when the sensor stops detecting the outer wall portion or the object to be detected. 5. The data transmission buoy includes a conductive portion provided on an outer wall portion, and the undersea station includes a pair of contact portions that contact the conductive portion when the data transmission buoy is mounted at a predetermined position. The undersea detector according to claim 2, further comprising: a detector, wherein the disconnection confirmation unit transmits the disconnection signal when a resistance between the pair of detectors exceeds a preset value. Long-term observation system.