JP4121749B2 - Temperature monitoring system and temperature monitoring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature monitoring system and a temperature monitoring device, and more particularly to a temperature monitoring system and a temperature monitoring device that can accurately measure the temperature of a monitoring target and can reliably transmit the measured temperature signal by radio waves.
[0002]
[Prior art]
Conventionally, in a power distribution section such as a transmission line to which a high voltage is applied, if power is supplied beyond the transmission capacity of the line, there is a risk of serious accidents such as burnout of the line, and the part where the power load increases The temperature is monitored to prevent malfunctions.
[0003]
In performing such monitoring, for example, temperature monitoring is known in which a thermo label that changes color according to temperature is attached to a monitoring target, and monitoring is performed by a worker's visual observation or a monitoring device such as a monitoring camera. The thermolabel changes color when exposed to a predetermined temperature for a certain period of time, thereby indicating that a temperature abnormality has occurred in the monitored object.
[0004]
As another aspect of temperature monitoring, for example, there is a monitoring system disclosed in Japanese Patent Laid-Open No. 10-162280.
[0005]
FIG. 10 shows a schematic configuration of a monitoring system disclosed in Japanese Patent Application Laid-Open No. 10-162280. A tower 40 that supports a power transmission line 41, and a voltage, current, phase, conductor temperature, and outside air temperature that are attached to the power transmission line 41. A wireless sensor 42 that measures and wirelessly transmits information, an optical electric field sensor 43 that receives radio waves transmitted from the wireless sensor 42 and outputs modulated light, and an optical fiber composite ground wire ( (OPGW) 45 and a substation 46 provided with a monitoring device 47 for transmitting the modulated light via OPGW 45.
[0006]
This monitoring system outputs unmodulated transmission light L from the monitoring device 47 to the OPGW 45. The optical electric field sensor 43 outputs the modulated light Lm obtained by modulating the transmission light L to the OPGW 45 based on information according to the state of the power transmission line 41 wirelessly transmitted from the wireless sensor 42. The monitoring device 47 monitors the state of the power transmission line 41 by analyzing the modulated light Lm received via the OPGW 45.
[0007]
[Problems to be solved by the invention]
However, according to the conventional monitoring system, if the antenna structure for transmitting the radio wave from the wireless sensor is insufficient, there is a risk that the radio wave will not be transmitted after being attached to the monitoring target. This is remarkable when grounding cannot be secured. In order to increase the radioactivity of the radio wave, it is conceivable to use an antenna structure having a shape corresponding to the transmission frequency. However, depending on the frequency, there is a problem that the antenna structure increases in size, which in turn increases the size of the device itself.
[0008]
Accordingly, an object of the present invention is to provide a temperature monitoring system and a temperature monitoring device capable of stably transmitting radio waves according to the state of a monitoring target without causing an increase in size of the device.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides a main body case of a temperature monitoring device, a temperature sensor that is provided outside the main body case and generates a temperature signal corresponding to the temperature of the monitoring target, and an inside of the main body case. A wireless transmission unit including an antenna unit that wirelessly transmits a modulated wave generated by encoding the acquired temperature signal, and provided inside the main body case, transmits the modulated wave at a predetermined transmission cycle. A control unit, and a receiving unit that receives the modulated wave wirelessly transmitted from the temperature monitoring device, wherein the antenna unit is provided outside the main body case and an antenna provided inside the main body case It was and a ground line of the temperature sensor, the ground line is connected to a power supply line for supplying power to the amplifier connected to the antenna, the antenna and the ground Radio waves to provide a temperature monitoring system for causing radiated into space by.
[0010]
In order to achieve the above-mentioned object, the present invention provides a main body case of a temperature monitoring device, a temperature sensor provided outside the main body case and generating a temperature signal according to the temperature to be monitored, and the main body case. A wireless transmission unit including an antenna unit that wirelessly transmits a modulated wave that is generated by encoding the acquired temperature signal, and is provided inside the main body case, and the modulated wave is transmitted at a predetermined transmission cycle. A control unit for transmission, and a reception unit for identifying and receiving the wireless transmission unit upon reception of the modulated wave wirelessly transmitted from each of the plurality of wireless transmission units . It has an antenna provided inside and a ground wire of the temperature sensor provided outside the main body case, and the ground wire supplies power to an amplifier connected to the antenna. Is connected to the power supply line, the antenna and the radio wave is radiated into space by the ground line, wherein, at the transmission timing based on the value of the random number generated by the random number generating circuit of the modulated wave to the wireless transmission unit There is provided a temperature monitoring system characterized in that a transmission operation is executed.
[0011]
In order to achieve the above-mentioned object, the present invention provides a main body case of a temperature monitoring device, a temperature sensor provided outside the main body case and generating a temperature signal according to the temperature to be monitored, and the main body case. A wireless transmission unit including an antenna unit that wirelessly transmits a modulated wave that is generated by encoding the acquired temperature signal, and is provided inside the main body case, and the modulated wave is transmitted at a predetermined transmission cycle. A control unit to transmit, the antenna unit includes an antenna provided inside the main body case, and a ground wire of the temperature sensor provided outside the main body case , the ground wire is the antenna is connected to the power supply line for supplying power to the amplifier connected, temperature monitoring instrumentation, characterized in that to emit radio waves in space by the antenna and the ground line To provide.
[0012]
In order to achieve the above-mentioned object, the present invention provides a main body case of a temperature monitoring device, a temperature sensor provided outside the main body case and generating a temperature signal according to the temperature to be monitored, and the main body case. A wireless transmission unit including an antenna unit that wirelessly transmits a modulated wave generated by encoding the acquired temperature signal, and a unique transmission unit provided inside the main body case for identifying the modulated wave A control unit that applies identification information to the modulated wave and transmits the modulated wave at a predetermined transmission period, and the antenna unit is provided inside the main body case and outside the main body case A ground line of the temperature sensor, and the ground line is connected to a power supply line that supplies power to an amplifier connected to the antenna, and is not connected to the antenna and the ground line. To radiate the radio waves in space, the control unit, a temperature monitoring device, characterized in that to execute the transmission operation of the modulated wave to the wireless transmission unit at a transmission timing based on the value of the random number generated by the random number generating circuit provide.
[0013]
According to the temperature monitoring system and the temperature monitoring device described above, the main body (main body case) that accommodates the wireless transmission unit, the control unit, and the like is compact by using a configuration in which a part of the temperature sensor circuit is transmitted as an antenna. And the radioactivity of radio waves can be improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a temperature monitoring system and a temperature monitoring device of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 schematically shows a configuration of a temperature monitoring apparatus according to an embodiment of the present invention. This temperature monitoring device 1 is attached to a monitoring target and outputs temperature signals 10 and 11 according to temperature, signal lines 10A and 11A for transmitting temperature signals from the temperature sensors 10 and 11, and temperature The sensor power supply lines 10B and 11B for supplying power to the sensors 10 and 11, the ground (GND) lines 10C and 11C of the temperature sensors 10 and 11, and the temperature signals of the temperature sensors 10 and 11 are wirelessly transmitted as signal waves. A control unit 12 for performing control, a modulator 14 for generating a modulation wave based on a temperature signal by a predetermined modulation method, and an amplifier 15 for amplifying the modulation wave output from the modulator 14 to a required power, , An antenna 16 that radiates the amplified modulated wave as a radio wave, a data line 17 for transmitting data, a battery 18 provided as a power source, and power for each part Having a power supply line 19 for supplying. Further, the control unit 12 includes an interface unit that can be connected to an external terminal device (for example, a PC device).
[0016]
Each of the temperature sensors 10 and 11 is assigned a unique identification number (sensor ID). In the present embodiment, a known semiconductor temperature sensor that detects the temperature based on the temperature dependence of the voltage applied to the semiconductor is used, and details thereof are omitted.
[0017]
The control unit 12 is activated based on a trigger signal output from a built-in clock circuit, and outputs a temperature signal input from the temperature sensors 10 and 11 to the modulator 14 as a signal wave. When the measured temperatures of the temperature sensors 10 and 11 are different, the average temperature is calculated and output to the modulator 14.
[0018]
The modulator 14 encodes a signal wave input from the control unit 12 via the data line 17 by performing ASK (Amplitude Shift Keying) modulation to generate a modulated wave of 315 MHz band, and outputs this to the amplifier 15.
[0019]
The antenna 16 is formed so that the length from the tip thereof to the amplifier 15 is λ / 4 of the transmission frequency (315 MHz). Similarly, the GND lines 10C and 11C are formed to have a length of λ / 4 of the transmission frequency. The antenna 16 and the GND lines 10C and 11C form an aerial part for transmitting radio waves in cooperation.
[0020]
FIG. 2 shows the overall configuration of the temperature monitoring device 1, in which an antenna 16, an amplifier 15, and a control circuit 20 formed as a substrate-like member are housed in a laminated form inside a main body 2 made of polycarbonate. The antenna 16 has a folded pattern 16A formed of a copper foil on the surface of the substrate-like member. The temperature sensors 10 and 11 are provided separately from the main body 2 and are connected to the control circuit 20 via the sensor lines 10D and 11D in which the signal line, the sensor power supply line, and the GND line are covered with a sheath and integrated. It is connected. The control circuit 20 is equipped with the control unit 12 described above, and houses the battery 18 in the space below it.
[0021]
FIG. 3 shows a state in which the temperature monitoring device 1 is mounted on a power transmission line 24 as a monitoring target. The temperature monitoring device 1 is fixed to a cable clamp 22 with a screw 21, and the cable clamp 22 is made of a copper alloy. And a pair of divided bodies that clamp the power transmission line 24 by tightening the two bolts 23. Further, the temperature sensors 10 and 11 and the sensor wires 10D and 11D exposed from the main body 2 of the temperature monitoring device 1 are fixed to the power transmission line 24 with a tape 25 as a fixing member.
[0022]
FIG. 4 shows a circuit configuration of the control unit 12, a signal input / output circuit 120 for inputting / outputting a temperature signal of the temperature sensors 10 and 11 via the data line 17, data necessary for wireless transmission, The main memory 121 for storing a program such as arithmetic processing, a random number generating circuit 122 for generating a random number used for variable control of wireless transmission timing, and a time counting process by counting a reference clock generated by a built-in reference clock generating circuit. A clock circuit 123 to be performed, a scratch pad memory 124 that is an 8-byte RAM for holding a temperature signal input from the temperature sensors 10 and 11, a high temperature threshold register, a low temperature threshold register for the temperature measured by the temperature sensors 10 and 11, And the register 125 which is an EEPROM including an environment setting register, and a CR for data error check A CRC generation circuit 126 that generates a code and a CPU 127 that controls each unit are connected by an internal bus 128. The CPU 127 is normally in a standby state (SLEEP) and receives a trigger signal input from the clock circuit 123. Based on this, it performs various processes necessary for temperature signal processing and wireless transmission.
[0023]
The random number generation circuit 122 generates a random number based on the trigger signal generated by the clock circuit 123 and outputs the random number to the CPU 127. This random number is randomly generated in the range of 0 to 255 by performing arithmetic processing such as multiplication congruence on the seed value (seed value). In the present embodiment, the sensor ID of the temperature sensor is used as the seed value, and the random number generated thereby varies depending on the value of the sensor ID. The generation cycle is 61124 times to form one cycle.
[0024]
FIG. 5 shows a memory map of the scratch pad memory 124 and the EEPROM 125, and each byte includes lower digit data (0th), upper digit data (first), high temperature threshold (second) of the measured temperature (or average temperature). ), Low temperature threshold value (third), and environment setting (fourth) data are stored. Spare areas are reserved from the fifth to the seventh. As the high temperature threshold value, the low temperature threshold value, and the environment setting data, the data stored in the high temperature threshold value register, the low temperature threshold value register, and the environment setting register stored in advance in the register 125 are input.
[0025]
Further, the high temperature threshold register of the register 125 stores a transmission cycle when a temperature signal is transmitted from the temperature monitoring device.
[0026]
6A shows an antenna structure formed by the antenna 16 and the GND lines 10C and 11C of the temperature sensors 10 and 11, and a circuit in which the GND lines 10C and 11C of the temperature sensors 10 and 11 are provided inside the main body 2. FIG. Is connected to the power supply line 19 to form a common ground, thereby forming a completely balanced two-line dipole antenna 32 connected to the high-frequency power supply 31 with a structure not grounded to the ground 30. In the figure, the λ / 4 side becomes the antenna 16, and the λ / 2 side becomes the GND lines 10C and 11C, and the antenna becomes 3 λ / 4 as a whole. (B) shows a virtual state when the antenna of (a) is oscillated, and maximum amplitude points are formed at two locations A and B as shown in the figure, and radio wave radiation is ensured.
[0027]
In addition, this is not the case when a plurality of temperature monitoring devices are provided close to each other, and transmission power may be consumed by the same antenna of the adjacent temperature monitoring devices. In order to prevent transmission from being disabled due to such absorption of radio waves, it is possible to prevent transmission from being disabled by changing the length of the antenna so that a plurality of maximum amplitude points of the dipole antenna 32 are formed. If close to the temperature monitoring device having antenna total of 3 lambda / 4 as described above providing another temperature monitoring device, for example, lambda / 4, GND line 10C in the length of the aerial antenna 16 side, 11C side in 3 and lambda / 4 of the total 1 [lambda, may be to have the antenna length of more than 3 lambda / 4. Further, a total of 1λ, which is λ / 4 on the GND lines 10C and 11C side and 3 λ / 4 on the antenna 16 side, may be used.
[0028]
Hereinafter, the operation of the temperature monitoring apparatus will be described. In the following description, it is assumed that temperature monitoring is performed with the power transmission line 24 illustrated in FIG. 3 as a monitoring target.
[0029]
(1) Initial setting of temperature monitoring device An initial setting value corresponding to the power transmission line 24 to which the temperature monitoring device is attached is input. The input operation is performed, for example, by the operator writing the high temperature threshold value, the low temperature threshold value, and the environment setting in the register 125 by the PC device connected to the control unit 12 via the interface unit. The modulation wave transmission period is written in the high temperature threshold region. In addition, the temperature signal correction coefficient, the transmission processing procedure according to the remaining battery level, and the temperature signal transmission delay time are written in the environment setting area.
[0030]
(2) Mounting of temperature monitoring device The temperature monitoring device 1 is fixed to the cable clamp 22 with the screw 21, and the cable clamp 22 is mounted to the power transmission line 24. Further, the temperature sensors 10 and 11 and the sensor wires 10D and 11D exposed from the main body 2 of the temperature monitoring device 1 are fixed to the power transmission line 24 with the tape 25. The sensor lines 10D and 11D may be wound around the power transmission line 24 in a spiral shape. The sensors 10 and 11 start temperature measurement after being attached to the power transmission line 24.
[0031]
(3) Temperature measurement and wireless transmission FIG. 7 shows a flowchart of temperature measurement and wireless transmission. When the clock circuit 123 counts the reference clock, the transmission cycle read from the high temperature threshold register of the register 125 is reached. A trigger signal is generated (S1). The CPU 127 is activated based on the generation of the trigger signal (S 2), inputs a temperature signal corresponding to the temperature of the power transmission line 24 from the temperature sensors 10 and 11 via the signal input / output unit 120, and enters the scratch pad memory 124. Store (S3). When the temperature signals input from the temperature sensors 10 and 11 are different, the CPU 127 calculates and stores the average value of the temperature signals. Or you may make it manage by providing sensor ID and measurement time to a different temperature signal, respectively. Further, the random number generation circuit 122 generates a random number R based on the generation of the trigger signal and outputs it to the CPU 127 (S4).
[0032]
When the random number R is larger than 125 (S5), the CPU 127 performs wireless communication based on the temperature signal at 205 msec by adding a delay time (95 msec) to the transmission start timing calculated from the start as shown in FIG. 8A. A radio wave (DATA) transmission operation is executed (S6). When the random number R is smaller than 125, a radio wave transmission operation based on the temperature signal is executed at a normal transmission start timing (110 msec) calculated from the start as shown in FIG. 8B (S7). ). This delay time is set to a time that is at least twice as long as one radio wave transmission time in order to prevent duplication of reception operations at the receiver, particularly when a plurality of temperature monitoring devices are installed and temperature monitoring is performed simultaneously. It is preferable.
[0033]
The CPU 127 outputs the temperature lower digit data and the temperature upper digit data of the temperature signal stored in the scratch pad memory 124 to the modulator 14 via the data line 17 at the transmission timing (S8). The modulator 14 outputs a modulated wave obtained by ASK-modulating the input temperature lower digit data and temperature upper digit data to the amplifier 15 via the data line 17 (S9). The amplifier 15 amplifies the modulated wave to an output necessary for transmission and transmits it from the antenna 16 (S10). The modulated wave wirelessly transmitted from the antenna 16 is received by a receiver (described later).
[0034]
FIG. 9 shows a temperature monitoring device and a radio wave receiver as a temperature monitoring system, and the temperature monitoring devices 1A, 1B, 1C, and 4D mounted on four independent power transmission lines 24A, 24B, 24C, and 24D, respectively. The receiver 34 receives radio waves transmitted from 1D, and the receiver 34 is an antenna for receiving radio waves based on temperature signals transmitted from the temperature monitoring devices 1A, 1B, 1C, and 1D. 34A, a display unit 34B such as a liquid crystal display for displaying the received temperature signal, and an operation switch group 34C for operating the receiver 34. Each of the operation switch groups 34C is a push button switch. The power switch 34D that is formed by turning on the power, the display switch 34E for changing the display mode, and the display reset And a reset switch 34F to.
[0035]
The radio waves transmitted from the temperature monitoring devices 1A, 1B, 1C, and 1D have mismatched transmission timings due to the transmission timing variable control based on the above-described random numbers, so that the receiver 34 can receive them all at once. become.
[0036]
According to the above-described embodiment, the following operations and effects can be achieved. Since the temperature sensors 10 and 11 for measuring the temperature of the monitoring target are separated from the main body 2 of the temperature monitoring device 1 and exposed, the attachment to the monitoring target and the sensor responsiveness to the temperature change of the monitoring target are improved. Can do. Further, since the temperature sensor is not built in the main body 2, it can be easily attached to the monitoring target using an existing device such as a cable clamp. The physical quantity to be monitored is not limited to the above-described temperature, and may be humidity, strain, or deformation quantity, and may measure these plural physical quantities simultaneously.
[0037]
Since the dipole antenna is formed by connecting the GND wires 10C and 11C of the temperature sensors 10 and 11 exposed to the outside of the main body 2 to the power line 19 of the circuit in the main body, it is sufficient even in a situation where grounding to the ground cannot be secured. Radio wave radiation can be secured. It is also possible to change the lengths of the GND lines 10C and 11C according to the monitoring target and the installation environment.
[0038]
Since the circuit is in the SLEEP state except during temperature measurement and wireless transmission, temperature monitoring can be performed over a long period even in a configuration using a battery as a power source. Further, since the modulation wave based on the temperature signal is generated based on the ASK modulation, it is possible to minimize power consumption required for wireless transmission.
[0039]
Since the modulation wave transmission timing is irregularly set using random numbers, for example, even in a situation where a plurality of temperature monitoring devices 1 are arranged close to each other, a reception operation is performed while suppressing a collision of modulation waves with one receiver. And efficient operation at one frequency becomes possible.
[0040]
In the above-described embodiment, the configuration using the antenna 16 built in the main body 2 has been described. However, when there is no restriction in mounting on the monitoring target, the flip type antenna or other structure antenna is used. May be used.
[0041]
Further, the configuration of only the transmitter has been described as the wireless device incorporated in the temperature monitoring device 1, but it may be a receiver / transmitter.
[0042]
【The invention's effect】
As described above, according to the temperature monitoring system and the temperature monitoring device of the present invention, the temperature sensor for measuring the temperature of the monitoring target is provided outside the main body, and the GND wire of the temperature sensor is used as a part of the antenna. Wireless radio waves according to the state of the monitoring target can be stably transmitted without increasing the size of the apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a temperature monitoring device according to an embodiment of the present invention. FIG. 2 is a perspective view showing the entire temperature monitoring device. FIG. 3 is a front view of the temperature monitoring device mounted on a power transmission line. FIG. 5 is an explanatory diagram showing a memory map of a scratch pad memory and an EEPROM. FIG. 6 is a circuit configuration diagram of an antenna formed in the temperature monitoring device. FIG. 8 is a timing chart showing wireless transmission timing. FIG. 9 is a schematic configuration diagram showing an operation mode using a plurality of temperature monitoring devices. FIG. 10 is a schematic configuration showing a conventional monitoring system. Figure [Explanation of symbols]
1, temperature monitoring device 1A, 1B, 1C, temperature monitoring device 2, main body 10D, 11D, sensor line 10B, 11B, sensor power supply line 10A, 11A, signal line 10, 11, temperature sensor 10C, 11C, sensor line 12, Control unit 14, modulator 15, amplifier 16, antenna 16A, antenna pattern 17, data line 18, battery 19, power supply line 20, control circuit 21, screw 22, cable clamp 23, bolt 24, power transmission lines 24A, 24B, 24C , Transmission line 25, tape 30, ground 31, high frequency power supply 32, dipole antenna 34, receiver 34A, antenna 34B, display unit 34C, operation switch group 34D, power switch 34E, display switch 34F, reset switch 40, steel tower 41, Transmission line 42, wireless sensor 43, optical electric field sensor 44, optical fiber 6, the substation 47, the monitoring device 120, the signal output circuit 120, the signal input unit 121, a main memory 122, a random number generation circuit 123, clock circuit 124, the scratch pad memory 125, registers 126, generator 128, an internal bus

Claims (12)

The body case of the temperature monitoring device;
A temperature sensor that is provided outside the main body case and generates a temperature signal corresponding to the temperature of the monitoring target;
A wireless transmission unit including an antenna unit that is provided inside the main body case and wirelessly transmits a modulated wave generated by encoding the acquired temperature signal;
A control unit that is provided inside the main body case and transmits the modulated wave at a predetermined transmission cycle;
A receiving unit that receives the modulated wave wirelessly transmitted from the temperature monitoring device;
The antenna portion includes an antenna provided inside the main body case, and a ground wire of the temperature sensor provided outside the main body case ,
The temperature monitoring system , wherein the ground line is connected to a power supply line that supplies power to an amplifier connected to the antenna, and radio waves are radiated to space by the antenna and the ground line. The body case of the temperature monitoring device;
A temperature sensor that is provided outside the main body case and generates a temperature signal corresponding to the temperature of the monitoring target;
A wireless transmission unit including an antenna unit that is provided inside the main body case and wirelessly transmits a modulated wave generated by encoding the acquired temperature signal;
A control unit that is provided inside the main body case and transmits the modulated wave at a predetermined transmission cycle;
A reception unit that identifies and receives the wireless transmission unit when receiving the modulated wave wirelessly transmitted from each of the plurality of wireless transmission units,
The antenna portion includes an antenna provided inside the main body case, and a ground wire of the temperature sensor provided outside the main body case,
The ground line is connected to a power supply line that supplies power to an amplifier connected to the antenna, and radiates radio waves into space by the antenna and the ground line.
The temperature monitoring system, wherein the control unit causes the wireless transmission unit to perform the transmission operation of the modulated wave at a transmission timing based on a random number value generated by a random number generation circuit. 3. The temperature according to claim 1, wherein the antenna portion is formed to have an antenna length of 3λ / 4 or more with respect to a wavelength of a transmission frequency of the modulated wave. Monitoring system. The antenna according to claim paragraph 1 or claim temperature monitoring system of the second term, wherein it has a lambda / 4 or more in length to the wavelength of the transmission frequency of the modulated wave. 3. The temperature monitoring system according to claim 1, wherein the ground line has a length of λ / 4 or more with respect to a wavelength of a transmission frequency of the modulated wave. 4.   3. The temperature monitoring system according to claim 1, wherein the wireless transmission unit wirelessly transmits the modulated wave encoded by performing ASK (Amplitude Shift Keying) modulation on the temperature signal. 4. . The body case of the temperature monitoring device;
A temperature sensor that is provided outside the main body case and generates a temperature signal corresponding to the temperature of the monitoring target;
A wireless transmission unit including an antenna unit that is provided inside the main body case and wirelessly transmits a modulated wave generated by encoding the acquired temperature signal;
A control unit that is provided inside the main body case and transmits the modulated wave at a predetermined transmission cycle;
The antenna unit includes an antenna provided inside the main body case, and a ground line of the temperature sensor provided outside of the main body case,
The temperature monitoring device , wherein the ground line is connected to a power supply line that supplies power to an amplifier connected to the antenna, and radiates a radio wave to the space by the antenna and the ground line. The body case of the temperature monitoring device;
A temperature sensor that is provided outside the main body case and generates a temperature signal corresponding to the temperature of the monitoring target;
A wireless transmission unit including an antenna unit that is provided inside the main body case and wirelessly transmits a modulated wave generated by encoding the acquired temperature signal;
Provided inside the main body case, and having a control unit that gives unique identification information for identifying the modulated wave to the modulated wave and transmits it in a predetermined transmission cycle,
The antenna portion includes an antenna provided inside the main body case, and a ground wire of the temperature sensor provided outside the main body case,
The ground line is connected to a power supply line that supplies power to an amplifier connected to the antenna, and radiates radio waves into space by the antenna and the ground line.
The temperature monitoring device, wherein the control unit causes the wireless transmission unit to execute the modulated wave transmission operation at a transmission timing based on a random number value generated by a random number generation circuit. The temperature according to claim 7 or 8 , wherein the antenna portion is formed to have an antenna length of 3λ / 4 or more with respect to a wavelength of a transmission frequency of the modulated wave. Monitoring device. The temperature monitoring apparatus according to claim 7 or 8 , wherein the antenna has a length of λ / 4 or more with respect to a wavelength of a transmission frequency of the modulated wave. The temperature monitoring device according to claim 7 or 8 , wherein the ground line has a length of λ / 4 or more with respect to a wavelength of a transmission frequency of the modulated wave. The wireless transmitting unit, the temperature signal ASK (Amplitude Shift Keying) modulation to coded the modulated wave radio transmitting temperature monitoring device according to claim 7 wherein or claim 8 wherein, wherein that the .

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