Water vapor observation equipment

Abstract

To provide a water vapor content observation device capable of easily observing water vapor content at one observation point.SOLUTION: In an observation device 20, a received signal of a direct wave and a reflected wave input from an input terminal IN is input to a receiving unit 54a, and a complex delay profile of the received signal is generated. Data on the complex delay profile output from the receiving unit is input to a communication unit 55, peaks are searched for, phase information on peaks of the direct wave and the reflected wave is calculated, and phase difference data between the phase information on the direct wave and the reflected wave is generated. Based on the phase difference data, data on water vapor content in the atmosphere within a space between the observation device 20 and a reflector is obtained. The data on water vapor content is uploaded from a communication antenna 91 to a cloud 90.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a water vapor amount observation device that can easily observe the amount of water vapor. [Background technology]

[0002] In recent years, frequent heavy rain disasters caused by localized heavy rainfall (so-called "guerilla downpours"), linear rain bands brought by organized cumulonimbus clouds, rainy season fronts, and typhoons have become a social problem. Detailed rainfall observations are conducted nationwide by weather radars deployed by the Japan Meteorological Agency and the Ministry of Land, Infrastructure, Transport and Tourism. However, these radars monitor the current situation by utilizing radio wave reflections from liquid and solid "water" such as raindrops, snowflakes, and ice crystals. Therefore, weather radar observations cannot predict rainfall, and for this purpose, observation of atmospheric water vapor is crucial. Water vapor, one of the components that make up the atmosphere, undergoes phase changes from gas to liquid to solid. It falls from the sky to the ground as rain or snow, or rises from the ground to the sky due to evaporation on the water surface. This makes it difficult to observe due to its dramatic spatial and temporal changes. One currently used method for observing the distribution of water vapor over a wide area is to calculate the vertically accumulated water vapor (precipitable water) amount from the tropospheric delay of radio waves from GNSS (Global Navigation Satellite System) satellites, such as GPS. This method uses water vapor information obtained from observation data at the Geospatial Information Authority of Japan's nationwide network of approximately 1,300 reference stations (GEONET) to generate initial values ​​for the Japan Meteorological Agency's Mesoscale Numerical Weather Forecast Model (MSM), improving the accuracy of precipitation forecasts. Based on the same principle, research is being conducted on a method for accurately measuring the delay during radio wave propagation of terrestrial digital broadcasting waves and observing the accumulated amount of water vapor along the propagation path, particularly near the ground. Incidentally, it is known that the propagation speed of radio waves changes depending on the amount of water vapor present in the space through which they propagate, and conventional water vapor measurement devices that calculate the amount of water vapor by measuring the propagation time of radio waves received at an observation point are described in Patent Documents 1 and 2. In addition, Non-Patent Documents 1 and 2 describe water vapor observation using terrestrial digital broadcasting waves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-212750 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-10460 [Non-patent literature]

[0004] [Non-Patent Document 1] "Successful development of a water vapor estimation method using terrestrial digital broadcasting waves ~ Measuring radio wave propagation delay with picosecond accuracy, improving the accuracy of forecasting sudden heavy rain ~," March 9, 2017 [online], National Institute of Information and Communications Technology, [Retrieved June 16, 2021], Internet <URL: https: / / www.nict.go.jp / press / 2017 / 03 / 09-1.html> [Non-patent document 2] S. KAWAMURA et al., "Water vapor estimation using digital terrestrial broadcasting waves," [online], National Institute of Information and Communications Technology, [Retrieved June 16, 2021], Internet〈URL: https: / / agupubs.onlinelibrary.wiley.com / doi / full / 10.1002 / 2016RS006191〉 Summary of the Invention [Problem to be solved by the invention]

[0005] A conventional method for water vapor observation using terrestrial digital broadcasting waves, described in Non-Patent Document 2, will be described with reference to Figures 21 to 23. Figure 21 is a diagram for explaining a conventional synchronization method for water vapor observation using terrestrial digital broadcasting waves, Figure 22 is a diagram for explaining a conventional reflection method for water vapor observation using terrestrial digital broadcasting waves, and Figure 23 is a diagram showing an example of a complex delay profile in the reflection method shown in Figure 22. The conventional synchronization method for water vapor observation using terrestrial digital broadcasting waves, as shown in Figure 21, includes measurement point A, which receives terrestrial digital broadcasting waves emitted from broadcasting station 500, and measurement point B, located between measurement point A and broadcasting station 500, and observes the amount of water vapor in the atmosphere between measurement point A and measurement point B. Here, an increase in the amount of water vapor in the atmosphere slightly delays the propagation time of radio waves. For example, under conditions of a 5 km propagation path, ground pressure, and temperature of 20°C, a 1% increase in humidity results in a delay of approximately 17 picoseconds in propagation time. In other words, the propagation delay time is 17 picoseconds. Taking advantage of this, the conventional synchronization method can obtain information on the amount of water vapor by measuring the propagation delay time with high precision using terrestrial digital broadcasting waves. The propagation time of terrestrial digital broadcasting waves can also be expressed as phase information, which is the phase rotation (angle) of the terrestrial digital broadcasting waves.

[0006] A receiving unit capable of receiving terrestrial digital broadcast waves is provided at each of measurement points A and B. Here, phase information corresponding to the propagation time from the broadcast station 500 until the terrestrial digital broadcast wave reaches measurement point A is denoted as τA, and phase information corresponding to the propagation time from the broadcast station 500 until the terrestrial digital broadcast wave reaches measurement point B is denoted as τB. The phase noise of the transmitting unit in the broadcast station 500 is denoted as φ. T , the phase noise of the receiver at measurement point A is φ A , the phase noise of the receiver at measurement point B is φ B Then, the phase information MA corresponding to the propagation time of the terrestrial digital broadcasting wave measured at measurement point A is MA=τA+φ T +φ A (1) The phase information MB corresponding to the propagation time of the terrestrial digital broadcasting wave measured at measurement point B is MB=τB+φ T +φ B (2) The phase information corresponding to the propagation time for the terrestrial digital broadcasting wave to reach measurement point A from measurement point B can be calculated using (MA-MB). (MA-MB)=(τA-τB)+(φ A -φ B ) (3) (φ A -φ B Since the phase noise term in (φ A -φ B ) = 0. If measurement point A and measurement point B are synchronized, then φ A =φ B That is, in the synchronization method, by synchronizing measurement point A and measurement point B, (φ A -φ B ) = 0 to prevent measurement errors as shown in the following equation (4). (MA-MB)=(τA-τB) (4) The phase information (τA - τB) corresponding to the propagation time shown in equation (4) and the speed of radio waves in a vacuum (2.99792458×10 8 The amount of water vapor in the atmosphere between measurement points A and B can be observed based on the propagation delay time, which is the difference between the propagation time it takes for a terrestrial digital broadcasting wave to travel from measurement point B to measurement point A, calculated based on the propagation time (m / s).

[0007] Next, the conventional reflection method for observing water vapor using terrestrial digital broadcasting waves, shown in Figure 22, is equipped with a reflector R that reflects terrestrial digital broadcasting waves emitted from broadcasting station 500 and measurement point C between reflector R and broadcasting station 500, and observes the amount of water vapor in the atmosphere between reflector R and measurement point C. The reflection method also takes advantage of the fact that an increase in the amount of water vapor in the atmosphere causes a slight delay in the propagation time of radio waves. For example, under conditions of a 5 km propagation path, ground pressure, and a temperature of 20°C, a 1% increase in humidity will result in a delay of approximately 17 picoseconds in propagation time, i.e., a propagation delay time of 17 picoseconds. The reflection method obtains information on the amount of water vapor by measuring the propagation delay time with high precision using terrestrial digital broadcasting waves.

[0008] A receiving unit capable of receiving terrestrial digital broadcast waves is provided at measurement point C. Here, phase information corresponding to the propagation time of the terrestrial digital broadcast waves radiated from broadcast station 500 until they are reflected by reflector R and reach measurement point C is denoted as τR, phase information corresponding to the propagation time of the terrestrial digital broadcast waves radiated from broadcast station 500 until they reach measurement point C is denoted as τC, and the phase noise of the transmitting unit in broadcast station 500 is denoted as φ T , the phase noise of the receiver at measurement point C is φ C Then, the phase information MC1 corresponding to the propagation time of the direct wave from the broadcasting station 500 measured at the measurement point C is MC1=τC+φ T +φ C (5) The phase information MC2 corresponding to the propagation time of the wave reflected by the reflector R measured at the measurement point C is MC2=τR+φ T +φ C (6) This becomes:

[0009] The complex delay profile observed at measurement point C is shown in Figure 23. The complex delay profile has a horizontal axis representing time and a vertical axis representing amplitude, with the horizontal axis representing propagation time. In the complex delay profile shown in Figure 23, a convex peak appears at time t1, and another convex peak appears at time t2. The peak at time t1 is a direct wave from broadcast station 500 received at measurement point C, and phase information MC1 is obtained from the peak position at time t1. The peak at time t2 is a reflected wave reflected by reflector R received at measurement point C, and phase information MC2 is obtained from the peak position at time t2. If phase information MC1 corresponds to the propagation time from measurement point C, where it is measured, to reflector R, and then τM is taken as the phase information, then the phase information corresponding to the propagation time for the reflected wave from reflector R to reach measurement point C is also τM. Then, phase information corresponding to the propagation time from when the terrestrial digital broadcasting wave reaches the reflector R from the measurement point C until the reflected wave reflected by the reflector R returns to the measurement point C is calculated by (MC2-MC1). That is, (MC2-MC1)=(τR-τC) (7) As is clear from FIG. 23, (MC2-MC1) shown in equation (7) is phase information corresponding to the round-trip propagation time between reflector R and measurement point C, so (MC2-MC1) is equal to 2τM, τM=(MC2-MC1) / 2=(τR-τC) / 2 (8) As shown in equation (8), the reflection method can cancel out the phase noise between the broadcasting station 500 and the measurement point C without requiring a synchronization means. In the reflection method, phase information τM, which corresponds to the propagation time between the reflector R and the measurement point C, and the speed of radio waves in a vacuum (2.99792458×10 8 The amount of water vapor in the atmosphere between reflector R and measurement point C can be observed based on the propagation delay time, which is the difference between the propagation time of the terrestrial digital broadcasting wave, calculated based on the propagation time (m / s), and the propagation time from reflector R to measurement point C.

[0010] The synchronization method described above has the problem that it requires two measurement points with the location where water vapor volume is to be observed between them, and also requires a synchronization means to synchronize between the two measurement points. Furthermore, since water vapor volume observation utilizes a slight propagation delay time on the order of picoseconds, a highly accurate synchronization means is required, which results in the problem of the synchronization means being expensive. Furthermore, with the reflection method described above, the amount of water vapor can be easily observed at one measurement point as long as there is a reflector, so there is no need for a synchronization means to synchronize between two measurement points. Therefore, an object of the present invention is to provide a water vapor amount observation device that can easily observe the water vapor amount at one observation point. In addition, since it may be difficult to obtain a usable reflector in some cases, another object of the present invention is to provide a water vapor observation device that can easily observe water vapor at a single observation point without using a reflector. [Means for solving the problem]

[0011] The water vapor amount observation device of the present invention, which can achieve the above-mentioned object of the present invention, includes a plurality of receiving units that receive received signals from a plurality of input terminals, generate complex delay profiles of the received signals, and output data of the complex delay profiles, and searches for peaks from the complex delay profile data output from the receiving units, generates phase difference data between phase information of a first peak at the earliest time among the searched peaks and phase information of the other peaks excluding the first peak, and calculates and transmits data on the water vapor amount based on the phase difference data. The most important feature of this system is that it is installed at an observation point between a broadcasting station and a reflector, and when received signals of a direct wave of a terrestrial digital broadcasting wave from the broadcasting station and a wave reflected from the terrestrial digital broadcasting wave by the reflector are input to the input terminal, the communication unit searches for the peak of the direct wave as a first peak and also searches for the peak of the reflected wave, and obtains data on the amount of water vapor in the atmosphere in the space between the observation point and the reflector based on phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the reflected wave.

[0012] Another water vapor amount observation device of the present invention, which can achieve another object of the present invention, includes a plurality of receiving units that receive received signals input from a plurality of input terminals, generate complex delay profiles of the received signals, and output data of the complex delay profiles, and a communication unit that searches for peaks from the complex delay profile data output from the receiving units, generates phase difference data between phase information of a first peak at the earliest time among the searched peaks and phase information of the other peaks excluding the first peak, and calculates and transmits data on the amount of water vapor based on the phase difference data, and includes a gap filler receiving station and a gap filler transmitting station as viewed from a broadcasting station. The most important feature of this communication unit is that it is installed at an observation point beyond a gap filler system that can be used to transmit terrestrial digital broadcast waves, and when received signals of a direct wave of a terrestrial digital broadcast wave from the broadcast station and a retransmitted wave of the terrestrial digital broadcast wave received by the gap filler receiving station and transmitted over a transmission line and then retransmitted from the gap filler transmitting station are input to the input terminal, the communication unit searches for the peak of the direct wave as a first peak and also searches for the peak of the retransmitted wave, and obtains data on the amount of water vapor in the atmosphere in the space between the gap filler receiving station and the gap filler transmitting station based on phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the retransmitted wave.

[0013] Another water vapor observation device of the present invention, which can achieve another object of the present invention, comprises a plurality of receiving units that receive received signals input from a plurality of input terminals, generate complex delay profiles of the received signals, and output data of the complex delay profiles, respectively; a communication unit that searches for peaks from the complex delay profile data output from the receiving units, generates phase difference data between phase information of a first peak at the earliest time among the found peaks and phase information of the other peaks excluding the first peak, and calculates and transmits data of the water vapor amount based on the phase difference data; and the water vapor observation device is installed at an observation point in the same position as a gap filler receiving station in a gap filler system that includes a gap filler receiving station and a gap filler transmitting station, and receives direct waves of terrestrial digital broadcast waves from a broadcast station at the input terminals. When a received signal of a retransmission wave obtained by retransmitting from the gap filler transmitting station the terrestrial digital broadcast wave received by the gap filler receiving station and transmitted over a first transmission line, and a terrestrial digital broadcast signal obtained by retransmitting from the gap filler transmitting station over a second transmission line, is input, the communication unit searches for the peak of the direct wave as a first peak, and searches for the peak of the retransmission wave and the peak of the terrestrial digital broadcast signal, and obtains data on the amount of water vapor in the atmosphere in the space between the observation point and the gap filler transmitting station based on first phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the retransmission wave, and second phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the terrestrial digital broadcast signal.

[0014] In the water vapor amount observation device of the present invention, the communication unit uploads the calculated water vapor amount data to a cloud on the Internet. Furthermore, in the water vapor observation device of the present invention, meteorological data is input to the communication unit from an externally installed ground meteorological instrument, and the communication unit uploads the calculated water vapor data and the meteorological data to a cloud on the Internet. Furthermore, in the water vapor observation device of the present invention, the multiple receiving units, the communication unit, and a power supply unit capable of supplying power to the multiple receiving units and the communication unit are housed in a housing, and the housing is installed at the observation point. [Effects of the Invention]

[0015] When the water vapor amount observation device of the present invention is installed at an observation point between a broadcast station and a reflector, the observation point receives terrestrial digital broadcast waves arriving directly from the broadcast station and waves reflected by the reflector. This allows the water vapor amount observation device of the present invention to easily observe the amount of water vapor in the atmosphere between the observation point and the reflector at a single observation point. Furthermore, when the water vapor observation device of the present invention is installed at an observation point located beyond the gap filler receiving station and gap filler transmitting station as viewed from the broadcast station, the observation point receives terrestrial digital broadcast waves arriving directly from the broadcast station and terrestrial digital broadcast waves received by the gap filler receiving station, transmitted over a transmission line to the gap filler transmitting station, and retransmitted from the gap filler transmitting station. This allows the water vapor observation device of the present invention to easily observe the amount of water vapor in the atmosphere between the gap filler receiving station and the gap filler transmitting station at a single observation point without using a reflector. Furthermore, when the water vapor observation device of the present invention is installed at an observation point in the same location as the gap filler receiving station, the observation point receives terrestrial digital broadcast waves arriving directly from the broadcast station, terrestrial digital broadcast waves received by the gap filler receiving station, transmitted to the gap filler transmitting station via the first transmission line, and retransmitted by the gap filler transmitting station, and terrestrial digital broadcast signals received by the gap filler receiving station, transmitted to the gap filler transmitting station via the first transmission line, and transmitted from the gap filler transmitting station via the second transmission line. This makes it possible to observe the amount of water vapor in the atmosphere between the observation point and the gap filler transmitting station. As a result, the water vapor observation device of the present invention can easily observe the amount of water vapor in the atmosphere between the observation point and the gap filler transmitting station at a single observation point without using a reflector. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a functional block diagram showing the configuration of an observation device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a functional block diagram showing a detailed configuration of an observation device according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a functional block diagram showing the configuration of a receiving unit of the observation device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a functional block diagram showing another configuration of the receiving unit of the observation device according to the first embodiment of the present invention. [Figure 5] FIG. 2 is a functional block diagram showing the configuration of a communication unit of the observation device according to the first embodiment of the present invention. [Figure 6] 2 is a functional block diagram showing the configuration of a signal distribution unit and a power supply superposition unit of the observation device according to the first embodiment of the present invention. FIG. [Figure 7] FIG. 2 is a functional block diagram showing the configuration of a power supply unit of the observation device according to the first embodiment of the present invention. [Figure 8] FIG. 1 is a perspective view showing a connection mode of an observation device according to a first embodiment of the present invention. [Figure 9] FIG. 2 is another perspective view showing the connection mode of the observation device according to the first embodiment of the present invention. [Figure 10] 4 is a flowchart of a water vapor amount calculation process of the observation device according to the first embodiment of the present invention. [Figure 11] 4 is a flowchart of data processing of an external meteorological instrument executed by a communication unit of the observation device according to the first embodiment of the present invention. [Figure 12] 10 is a flowchart of external meteorological instrument time synchronization processing executed by the communication unit of the observation device according to the first embodiment of the present invention. [Figure 13] 4 is a flowchart of communication processing executed by a communication unit of the observation device according to the first embodiment of the present invention. [Figure 14] 1 is a block diagram showing the configuration of a water vapor observation system to which an observation device according to a first embodiment of the present invention is applied, and a schematic configuration of a cloud. [Figure 15] FIG. 1 is a block diagram showing a configuration of a gap filler system. [Figure 16] FIG. 2 is a block diagram showing the configuration of another water vapor observation system to which the observation device according to the first embodiment of the present invention is applied. [Figure 17] FIG. 17 is a diagram showing an example of an actual complex delay profile at the observation point of the water vapor observation system shown in FIG. [Figure 18] FIG. 10 is a functional block diagram showing the configuration of an observation device according to a second embodiment of the present invention. [Figure 19] FIG. 10 is a block diagram showing the configuration of a water vapor observation system to which an observation device according to a second embodiment of the present invention is applied. [Figure 20] FIG. 20 is a diagram showing an example of an actual complex delay profile at the observation point of the water vapor observation system shown in FIG. 19. [Figure 21] FIG. 1 is a block diagram showing the configuration of a conventional synchronization method for observing water vapor using terrestrial digital broadcasting waves. [Figure 22] FIG. 1 is a block diagram showing the configuration of a conventional reflection method for observing water vapor using terrestrial digital broadcasting waves. [Figure 23] FIG. 1 is a diagram showing an example of a complex delay profile in a conventional reflection method for observing water vapor using terrestrial digital broadcasting waves. DETAILED DESCRIPTION OF THE INVENTION

[0017] <First embodiment of the present invention> Fig. 1 shows a functional block diagram illustrating the configuration of an observation device 20 for observing the amount of water vapor according to a first embodiment of the present invention, and Fig. 2 shows a functional block diagram illustrating the detailed configuration of the observation device 20 according to the first embodiment of the present invention. The observation device 20 according to the present invention shown in these figures observes the amount of water vapor by applying the reflection method shown in Fig. 22. Furthermore, the observation device 20 according to the first embodiment of the present invention can be applied to a gap filler system, which will be described later, to observe the amount of water vapor. 1 and 2, the observation device 20 has a housing 40, which houses a lightning protection circuit section 51, a power supply superimposition section 52, a signal distribution section 53, a receiving unit 54 consisting of a desired number of receiving units 54a, 54b, 54c, etc., a communication unit 55, a relay board 56, and a power supply unit 57, and the unitized receiving unit 54, communication unit 55, and power supply unit 57 are housed detachably in the housing 40. The housing 40 is made of metal, but can also be made of synthetic resin.

[0018] An input terminal IN is provided in the housing 40, and this input terminal IN has a plurality of input terminals, one of which receives the received signal of the first antenna 21 and the received signal of the second antenna 22 mixed in a mixer (MIX) 41. The first antenna 21 is capable of receiving terrestrial digital broadcast waves that arrive directly from a broadcast station (hereinafter referred to as "direct waves"), and the second antenna 22 is capable of receiving terrestrial digital broadcast waves that have been reflected by a reflector (hereinafter referred to as "reflected waves"). The lightning protection circuit section 51 is configured by connecting lightning protection elements such as varistors and arresters between each line from the multiple input terminals IN, and suppresses induced lightning surges and other severe transient phenomena applied to each of the input terminals IN, thereby protecting each part of the observation device 20. The power supply superimposing unit 52 superimposes the driving power from the power supply unit 57 onto each line connected to the input terminal IN and outputs it from each of the input terminals IN. In the illustrated example, the driving power output from the input terminal IN is supplied to the preamplifier 42 as operating power. As a result, the preamplifier 42 amplifies the terrestrial digital broadcast signal of the direct wave received by the first antenna 21 and the terrestrial digital broadcast signal of the reflected wave received by the second antenna 22 to a predetermined level.

[0019] Here, the configuration of the input terminal IN, power supply superposition unit 52, and signal distribution unit 53 of the observation device 20 of the present invention is shown in the functional block diagram of Figure 6, and the input unit of the observation device 20 will be described with reference to Figure 6. Note that the lightning protection circuit unit 51 provided between the input terminal IN and the power supply superposition unit 52 is omitted from Figure 6. In the following description, the term "received signal" is synonymous with the term "received terrestrial digital broadcast signal." As shown in Fig. 6, the input terminal IN has n input terminals INa, INb, INc, INd, ..., INn, where INa to IN(n-1) are input terminals for type 1 input and INn is an input terminal for type 2 input. The type 1 input is input to each of the receiving units 54a, 54b, 54c, 54d, ..., 54(n-1), while the type 2 input is divided by a divider (DIV) 170 of the signal dividing unit 53 and input to multiple receiving units 54a to 54(n-1). Note that the type 1 input and type 2 input input terminals receive received signals of direct waves and reflected waves, but the type 1 input INa to IN(n-1) receive received signals of direct waves and reflected waves received by different antennas, and the type 2 input INn receives received signals of direct waves and reflected waves received by one antenna and is divided by the DIV 170.

[0020] In the power supply superimposing unit 52, a capacitor Ca that passes only high-frequency signals is connected in series to the line connected to INa, and one end of a choke coil La that blocks high-frequency signals is connected to the line. The other end of the choke coil La is supplied with driving power from the power supply unit 57 via SW171. SW171 is composed of multiple change-over switches, the number of which is the same as the number of input terminals IN. Each change-over switch is connected to a line from the corresponding INa to INn, and each change-over switch can be switched independently. When the movable contact e1 of the change-over switch for INa is switched to the fixed contact d1 side, driving power from the power supply unit 57 is output from INa to the outside, but is not supplied to the inside due to the action of capacitor Ca. The power output from INa is supplied as operating power to, for example, the preamplifier 42. A similar operation occurs when the change-over switches for INb to INn are operated.

[0021] In the power supply superposition unit 52, a capacitor Cn that passes only high-frequency signals is connected in series to the line connected to INn, and one end of a choke coil Ln that blocks high-frequency signals is connected to the line, with the other end of the choke coil Ln being supplied with driving power from the power supply unit 57 via SW171. When the movable contact en of the changeover switch for INn is switched to the fixed contact dn side, driving power from the power supply unit 57 is output from INn to the outside. The power output from INn is supplied as operating power to a preamplifier or the like connected to INn, but is not supplied internally due to the action of capacitor Cn.

[0022] In the signal distribution unit 53, a line from INa via a capacitor Ca is connected to SW172. SW172 is composed of a plurality of change-over switches, the number of which is the same as the number of type 1 input terminals INa to IN(n-1). The input side of each change-over switch is connected to a line from the corresponding INa to IN(n-1), and the output side is connected to a receiving unit 54a to 54(n-1), respectively. Each change-over switch can be independently switched. Each change-over switch receives a received signal distributed by DIV170. When the movable contact c1 of the change-over switch corresponding to INa is switched to the fixed contact a1 side, the received signal of type 1 input input to INa is output from the movable contact c1 and input to receiving unit 54a of receiving unit 54. When the movable contact c1 of the change-over switch corresponding to INa is switched to the fixed contact b1 side, the received signal of type 2 input distributed by DIV170 is output from the movable contact c1 and input to receiving unit 54a of receiving unit 54. When the changeover switches corresponding to INa to IN(n-1) are operated, the same changeover operation is performed.

[0023] In the signal distribution unit 53, a line from the type 2 input INn via the capacitor Cn is connected to the distributor 170, and the received signal input to the type 2 input input terminal INn is distributed (n-1) by the distributor 170. Each of the distributed received signals is input to the input side of the (n-1) changeover switches of the SW172. As a result, as described above, when the movable contact c1 of the changeover switch for INa is switched to the fixed contact b1 side, the type 2 input received signal input to INn and distributed is output from the movable contact c1 and input to the receiving unit 54a of the receiving unit 54. A similar switching operation is performed when the changeover switches for INa to IN(n-1) are operated.

[0024] In addition, in INb to IN(n-1), capacitor Ca is replaced by capacitors Cb to C(n-1), and in SW171, movable contact e1 is replaced by movable contacts e2 to e(n-1) and fixed contact d1 is replaced by fixed contacts d2 to d(n-1), and in SW172, movable contact c1 is replaced by movable contacts c2 to c(n-1), fixed contact a1 is replaced by fixed contacts a2 to a(n-1), and fixed contact b1 is replaced by fixed contacts b2 to b(n-1). As a result, when the movable contacts c1 to c(n-1) in SW172 are switched to the fixed contacts a1 to a(n-1), the receiving units 54a to 54(n-1) corresponding to the switched changeover switch receive the type 1 input receiving signal input to INa to IN(n-1), and when the movable contacts c1 to c(n-1) are switched to the fixed contacts b1 to b(n-1), the receiving units 54a to 54(n-1) corresponding to the switched changeover switch receive the type 2 input receiving signal input to INn distributed by the distributor 170.

[0025] The receiving unit 54 is made up of (n-1) receiving units 54a to 54(n-1), each of which receives a received signal from the signal distribution unit 53. The receiving units 54a to 54(n-1) have the same configuration, and a functional block diagram showing the configuration of the receiving unit 54-1 of the first embodiment is shown in Figure 3. The receiving unit 54-1 of the first embodiment shown in FIG. 3 is composed of a tuner unit 101 to which a received signal from the signal distribution unit 53 is input, and a complex delay profile generation unit 102 to which a received signal of a channel selected by the tuner unit 101 is input, and data of a complex delay profile generated by the complex delay profile generation unit 102 is output to the communication unit 55. The tuner unit 101 can select and receive any channel from the input received signals. The received signal received by the tuner unit 101 is demodulated into a baseband received signal by the complex delay profile generation unit 102, and complex delay profile data is generated and output from the receiving unit 54-1. When representing a complex delay profile, the horizontal axis is the time axis and the vertical axis is the amplitude axis, and the horizontal axis indicates the propagation time of the received signal. That is, in the complex delay profile, the time of the peak of the direct wave indicates the propagation time of the direct wave, and the time of the peak of the reflected wave indicates the propagation time of the reflected wave. In addition, when the type 2 input distributed in DIV170 is input to multiple receiving units 54a to 54(n-1) in the embodiment of receiving unit 54-1, it is preferable that each receiving unit 54a to 54(n-1) selects a different channel using the tuner unit 101, generates complex delay profile data for each different channel using the complex delay profile generation unit 102, and outputs the data from receiving unit 54-1.

[0026] 4 is a functional block diagram showing the configuration of a receiving unit 54-2 according to a second embodiment of the receiving unit 54. The receiving unit 54-2 according to the second embodiment is capable of multi-channel processing. 4 is composed of a distributor 103 that distributes a received signal from the signal distributor 53, a plurality of tuner units 101a, 101b, ..., 101m to which the received signals distributed by the distributor 103 are respectively input, and a complex delay profile generator 102-2 to which received signals of m channels selected by the plurality of tuner units 101a to 101m are input, and data of the complex delay profiles of m channels generated by the complex delay profile generator 102-2 is output to the communication unit 55. In the tuner units 101a to 101m, the received signal input to the receiving unit 54-2 is distributed by the distributor 103 and input to each of the tuner units 101a to 101m, and any channel of the input received signals can be selected and received. The m-channel reception signals received by the tuner units 101a to 101m are demodulated into m-channel baseband reception signals by the complex delay profile generation unit 102-2, and data of a plurality of complex delay profiles for the m channels is generated. The data of the plurality of complex delay profiles is averaged, and data of one complex delay profile is output from the receiving unit 54-2. It is preferable that the tuner units 101a to 101m select different channels, and the complex delay profile data for the different channels is generated by the complex delay profile generating unit 102-2 and averaged.

[0027] Next, the complex delay profile data output from the receiving units 54a to 54(n-1) is output onto a bus 56a. The receiving units 54a to 54(n-1) and a communication unit 55 are connected to the bus 56a, and the communication unit 55 can receive the complex delay profile data from the receiving units 54a to 54(n-1) via the bus 56a. The bus 56a is, for example, an I2C (Inter-Integrated Circuit) serial bus. The bus 56a is built on a relay board 56, which is also provided with a power line. Driving power is supplied to this power line from a power supply unit 57, and the driving power is supplied to the receiving units 54a to 54(n-1) and the communication unit 55 via the relay board 56 as operating power.

[0028] Next, the communication unit 55 calculates phase difference data from the complex delay profile data from the receiving units 54a to 54(n-1), and obtains the amount of water vapor based on the phase difference data. A functional block diagram showing the configuration of the communication unit 55 is shown in FIG. The communication unit 55 shown in FIG. 5 includes a microcomputer processing unit 150 having a phase difference data calculation unit 151 that calculates phase difference data and a various calculation unit (water vapor amount) 152 that performs water vapor amount and other calculations based on the phase difference data obtained therein, and a wireless communication unit 160 that can communicate with the cloud 90 on the Internet. The communication unit 55 also includes a coaxial terminal (RFOUT) that outputs high-frequency communication signals from the wireless communication unit 160, a serial or RS232C interface (I / F) port 161 that can exchange various data and signals, and a LAN port 162 that can perform various settings and status monitoring of the observation device 20 via a LAN (Local Area Network). The microcomputer processing unit 150 includes a central processing unit (CPU), a memory unit (RAM and ROM), an input / output circuit (I / O), a timer circuit, and the like, and has the basic functions of a computer. The phase difference data calculation unit 151 and the various calculation units 152 are realized by the microcomputer processing unit 150 executing predetermined software. The phase difference data calculation unit 151 calculates the peak positions of the direct wave and the reflected wave from the input complex delay profile data, and calculates the phase information corresponding to the peak positions. In this case, if there is multiple phase information obtained from the same source, the average of the phase information is calculated. This results in first phase information of the direct wave of the terrestrial digital broadcasting received at the observation point where the observation device 20 is installed, and second phase information of the reflected wave of the terrestrial digital broadcasting reflected by, for example, a reflector and received by the observation device 20. Then, the phase difference data between the first phase information and the second phase information is calculated to obtain phase difference data, and the average and standard deviation of the obtained phase difference data are calculated. Next, based on the phase difference data obtained by the phase difference data calculation unit 151, various calculation units (water vapor amount) 152 obtain water vapor amount data, and send this water vapor amount data to the wireless communication unit 160. The phase information corresponds to the propagation time required for a direct wave (reflected wave) of a terrestrial digital broadcast wave to reach the observation device 20, and the phase information can be expressed as a phase rotation (angle) of the terrestrial digital broadcast wave. Furthermore, when type 2 input reception signals are input to multiple receiving units 54a to 54(n-1), the peak positions of the direct wave and reflected wave and the phase information corresponding to the peak positions are calculated for each piece of complex delay profile data received from the multiple receiving units 54a to 54(n-1). In this case, since there is multiple pieces of phase information with the same source, the average of the multiple pieces of phase information obtained is calculated, and the phase difference data described above is calculated from the phase information based on the calculation result.

[0029] 1 and 2, when a terrestrial digital broadcast signal, which is a direct wave received by first antenna 21, and a terrestrial digital broadcast signal, which is a reflected wave received by second antenna 22, are input to observation device 20, the complex delay profile data input from receiving unit 54 to communication unit 55 is, for example, a complex delay profile as shown in FIG. 23, and phase difference data calculation unit 151 performs the calculation shown in equation (8) above to obtain τ as phase difference data. Phase difference data calculation unit 151 passes phase difference data τ to various calculation units (water vapor amount) 152, which then performs calculations based on the phase difference data τ to calculate data on the amount of water vapor in the atmosphere between the installation position of observation device 20, which is the position of first antenna 21, and the reflector from which the reflected wave is reflected. In this case, various calculation units (water vapor amount) 152 perform calculations to calculate the following water vapor amount data. In the phase difference data τM, if the wavelength of the terrestrial digital broadcasting wave is λ, the propagation delay amount Δ is Δ=λ τM If the distance between the observation device 20 and the reflector is DR, the propagation delay τP per unit distance obtained from the phase difference data τM is expressed as shown in equation (9-1). τP=Δ / DR=(λ·τM) / DR (9-1) Here, the refractive index of radio waves, N, is the atmospheric refractive index, n, incremented by 10. 6Since it is defined as a factor of 1 / 2, if the partial pressure of dry air is Pd, the partial pressure of water vapor is Pv, and the air temperature (absolute temperature) is T, then the refraction index of radio waves, N, can be approximately expressed as shown in equation (9-2). N=10 6 [n-1]=k1·(Pd / T)+k2·(Pv / T) +k3·(Pv / T 2 ) (9-2) In equation (9-2), k1=77.60 [K hPa -1 ] k2=70.4 [K hPa -1 ] k3=3.739×10 5 [K 2 hPa -1 ]] (Bevis et al. 1994). The absolute temperature T is T[K] = t[℃]+273.15 It is expressed as: And the speed v of the electromagnetic wave in the atmosphere with refractive index n is v = c / n Therefore, the propagation delay ΔD when propagating the distance L is ΔD=(L / v)-(L / c)=(L / c)·(n-1) where c is the speed of light. Then, the propagation delay τZ per unit distance expressed using the radio wave refraction index N can be expressed as shown in equation (9-3). τZ=ΔD / L=(N / c)·10 6 (9-3) Assuming that the propagation delay amount τP shown in equation (9-1) is equal to the propagation delay amount τZ shown in equation (9-3), and assuming the temperature T and the partial pressure of dry air Pd, the partial pressure of water vapor Pv can be calculated. Since the partial pressure of water vapor Pv is proportional to the amount of water vapor, it corresponds to data on the amount of water vapor, and the data on the amount of water vapor can be calculated using the calculations described above. The data on the amount of water vapor calculated by the various calculation units (amount of water vapor) 152 is sent to the wireless communication unit 160 . Furthermore, by utilizing the fact that the propagation time of radio waves is slightly delayed when the amount of water vapor in the atmosphere increases, for example, when the propagation path is 5 km, the ground pressure is 20°C, and the humidity increases by 1%, the propagation time is delayed by approximately 17 picoseconds, i.e., the propagation delay time is 17 picoseconds, the humidity can be calculated from the obtained phase difference data τM, and the amount of water vapor in the atmosphere between the installation position of the observation device 20, which is the position of the first antenna 21, and the reflector from which the reflected wave is reflected can be calculated from the calculated humidity.

[0030] Incidentally, if (n-1) input terminals INa to IN(n-1) of type 1 input are provided, the amount of water vapor in a plurality of different spaces can be observed by the observation device 20. That is, there are multiple broadcasting stations that transmit terrestrial digital broadcasts. By installing multiple antennas on the observation device 20 and pointing each antenna toward a respective one of the multiple broadcasting stations, terrestrial digital broadcasts transmitted from each of the multiple broadcasting stations can be received. In this case, since the broadcasting stations are generally located in different directions from the observation device 20, received signals of direct waves and reflected waves of terrestrial digital broadcasts transmitted from broadcasting stations in different directions are input to the type 1 inputs INa to IN(n-1), respectively. The received signals of direct waves and reflected waves input to each of INa to IN(n-1) are input to the corresponding receiving units 54a to 54(n-1) via the signal distribution unit 53. Then, the receiving units 54a to 54(n-1) generate complex delay profile data corresponding to the different directions. The phase difference data processing unit 151 calculates water vapor amount data based on the complex delay profile data as described above. However, if complex delay profile data corresponding to the different directions is used, the water vapor amount for each space corresponding to the different directions can be calculated. This allows the observation device 20 to observe the amount of water vapor in each space corresponding to the different directions.

[0031] Furthermore, by providing an input terminal INn for type 2 input, direct waves and their reflected waves of terrestrial digital broadcasting transmitted from one broadcast station can be received by an antenna and input to the type 2 input INn. The received signals of the direct waves and reflected waves input to INn can be distributed by the signal distributor 53 and input to multiple receiving units 54a to 54(n-1). The receiving units 54a to 54(n-1) then select different channels and generate complex delay profile data for each different channel. The phase difference data processor 151 calculates phase information of the direct waves and reflected waves based on the data of the multiple complex delay profiles and calculates the average of the calculated phase information. Phase difference data is calculated from the phase information based on the calculation results, and the various calculation units (water vapor amount) 152 calculate water vapor amount data. This allows the observation device 20 to observe the water vapor amount in the space corresponding to the direction of the one broadcast station with guaranteed reliability and quality.

[0032] 2, weather data is input to the observation device 20 from the ground meteorological instrument 92 via the cable introduction hole 40c, and the weather data from the ground meteorological instrument 92 is input to the I / F port 161 of the communication unit 55 and then input to the wireless communication unit 160. In this case, the weather data from the ground meteorological instrument 92 is temperature, pressure, wind direction, and other weather data, and this weather data may be input to the various calculation unit 152, where it is subjected to various data processing before being input to the wireless communication unit 160. The wireless communication unit 160 modulates the sent water vapor amount data and the weather data from the ground meteorological instruments 92 or the weather data from the ground meteorological instruments 92 processed by the various calculation units 152, and outputs the modulated data as a high-frequency communication signal from RFOUT. The communication signal output from RFOUT is radiated from a communication antenna 91 as shown in Fig. 2, and is transmitted to a cloud 90 on the Internet. This makes it possible to easily provide data via the cloud 90 to relevant organizations that require water vapor amount data, etc.

[0033] Next, a functional block diagram showing the configuration of the power supply unit 57 is shown in FIG. As shown in FIG. 7, the power supply unit 57 includes a rectifier circuit section 183 and a transformer section 184. The rectifier circuit section 183 receives either AC from a commercial power supply or AC from the transformer section 184, selected by a switch 181. The transformer section 184 receives either AC 60V or AC 30V AC1 supplied to an AC1 receiving terminal 145. The transformer section 184 converts the input AC1 to the commercial power supply voltage and supplies it to the switch 181, while outputting AC 30V as drive power AC2 to the power supply superimposition section 52. The rectifier circuit section 183 rectifies the supplied AC and converts it to DC of a predetermined voltage, which is then supplied to each unit of the observation device 20 as operating power. The AC from the commercial power supply is supplied to the power supply unit 57 via a power cable introduced via the power supply input 40b of the housing 40 shown in FIG. 2, and the AC1 receiving terminal 145 is provided to the power supply input 40b.

[0034] <Connection mode of the observation device according to the first embodiment of the present invention> Next, FIG. 8 is a perspective view showing the connection state of various lines connected to the observation device 20 of the first embodiment of the present invention, and FIG. 9 is another perspective view showing the connection state. The connection modes shown in these figures are shown in two figures because it is not possible to show the entire configuration in one figure, and the actual connection mode combines the connection modes shown in Figures 8 and 9. The observation device 20 according to the present invention includes a housing 40 composed of a rectangular box-shaped main body 141 with an open front and a lid 142 rotatably attached to the front of the main body 141 so as to close the front opening of the main body 141. One long side edge of the lid 142 facing the side edge of one long side of the main body 141 is rotatably fixed, for example, by a hinge, and the other long side edge of the lid 142 facing the side edge of the other long side of the main body 141 is fixed by a fastener that can be fastened and detached. By rotating the lid 142 to cover the front of the main body 141 and fastening the fastener, the housing 40 becomes watertight when the front of the main body 141 is closed by the lid 142. The main body 141 houses a lightning protection circuit section 51, a power supply superimposition section 52, a signal distribution section 53, and a relay board 56 (not shown), as well as up to four receiving units 54, communication units 55, and power supply units 57, which are detachable from the main body 141 so that these units can be easily replaced. On the underside of the main body 141, there are provided three input terminals 143 that serve as input terminals IN, an inlet for AC cables, a cable inlet 144 through which interface cables and communication cables are introduced, and an AC1 receiving terminal 145.

[0035] In the illustrated example, a received signal obtained by mixing a received signal from a first antenna 21 for receiving direct terrestrial digital broadcast waves and a received signal from a second antenna 22 for receiving terrestrial digital broadcast waves reflected by a reflector in a mixer (MIX) 41 is input to one of the input terminals 143, and this mixed received signal is finally input to a receiving unit 54. Commercial power is supplied to a power supply unit 57 through an AC cable introduction hole, and operating power is supplied from the power supply unit 57 to each unit. Alternatively, when AC1 from a community receiving power supply 93 is connected to an AC1 receiving terminal 145 as shown, AC1 is supplied to the power supply unit 57, and operating power is supplied from the power supply unit 57 to each unit. In addition, a cable extending from a ground-based meteorological instrument 92 is introduced through a cable introduction port 144, and weather data is input to the communication unit 55. Furthermore, a communication cable extending from an RFOUT of the communication unit 55 is introduced through the cable introduction port 144 and connected to the communication antenna 91. The communication antenna 91 transmits the above-mentioned water vapor data and meteorological data from the ground meteorological instruments 92 to a cloud 90 on the Internet.

[0036] <Communication unit processing> Next, a flowchart of the water vapor amount calculation process executed by the phase difference data processing unit 151 and the various calculation units (water vapor amount) 152 of the microcomputer processing unit 150 in the communication unit 55 of the observation device 20 of the first embodiment of the present invention is shown in Figure 10. The water vapor amount calculation process shown in FIG. 10 starts when the observation device 20 is powered on, and in step S10, it is determined whether complex delay profile data has been received from the receiving unit 54. If complex delay profile data has not been received, the process determines "NO" and waits in step S10 until complex delay profile data is received. If complex delay profile data is received, the process determines "YES" and proceeds to step S11. In step S11, a peak is searched for in the complex delay profile data, and the process proceeds to step S12. In this case, since the complex delay profile is a combination of intensity (logarithmic expression) and phase (angle) discretely on the time axis (= delay time), in step S11, it is detected whether the intensity signal forms an upwardly convex quadratic function within a predetermined delay time interval. If the detection result is upwardly convex, it is determined that a normal peak position (= delay time) has been detected. On the other hand, if the detection result is downwardly convex, it is determined that peak detection has failed. As a result, in step S11, peaks of the direct wave and the reflected wave are searched for as shown in FIG. 23. Next, the phase information of the peaks of the direct wave and the reflected wave found in step S11 is calculated in step S12, and the process proceeds to step S13. In step S12, the phase information at the peak position is obtained by linearly interpolating the phase (angle) data before and after the peak position. The complex delay profile may change over the short term due to the condition of the reflector or the influence of other reflectors (for example, an aircraft passing overhead), and in such cases the intensity and phase of the peak obtained as the detection result will fluctuate. Therefore, by calculating the average and standard deviation of these in step S12, it becomes possible to determine that the quality of the observation data is good if the standard deviation is sufficiently small, and that the quality of the observation data is poor if the standard deviation is large.

[0037] In step S13, the average of multiple pieces of phase information from the same source is calculated, and the phase information is averaged, and the process proceeds to step S14. Since the receiving unit 54 sequentially outputs complex delay profile data from the receiving units 54a to 54(n-1) at predetermined intervals, phase information calculated based on the complex delay profile data output from the same receiving units 54a to 54(n-1) is phase information from the same source. In step S14, phase difference data is calculated from the phase information of the direct wave and the reflected wave. The phase difference data corresponds to the difference in propagation time between the direct wave and the reflected wave, and can also be expressed as a phase rotation amount (angle). Once the phase difference data is generated in step S14, the phase difference data is averaged and the standard deviation is calculated in step S15, and the process proceeds to step S16. In step S15, the phase difference data can be converted into angle units and averaged. Furthermore, by detecting variations in the phase difference data from the standard deviation, abnormal data such as sudden bursts or data acquisition errors can be detected, thereby ensuring the reliability and quality of the phase difference data.

[0038] In step S16, as shown in the above-mentioned equations (9-1) to (9-3), the partial pressure of water vapor corresponding to the water vapor amount data can be obtained by assuming that the propagation delay amount represented by the phase difference data obtained in step S15 is equal to the propagation delay amount per unit distance represented using the refraction index of radio waves. Furthermore, in calculating the water vapor amount in step S16, humidity may be obtained from the phase difference data, and the water vapor amount data may be calculated from the obtained humidity, taking into account the fact that an increase in the amount of water vapor in the atmosphere slightly delays the propagation time of radio waves. For example, under conditions of a propagation path of 5 km, ground pressure, and a temperature of 20°C, a 1% increase in humidity results in a delay of approximately 17 picoseconds in propagation time, i.e., the propagation delay time becomes 17 picoseconds. The propagation time of the reflected wave is affected by the propagation delay time depending on the amount of water vapor in the atmosphere between the installation position of the observation device 20 and the reflector, and since the phase difference data is the phase difference data between the peak of the received signal of the direct wave received by the first antenna 21 and the peak of the reflected wave received by the second antenna 22, data on the amount of water vapor in the atmosphere between the installation position of the observation device 20 and the reflector can be obtained. The data on the standard deviation calculated in step S15 may be sent to the wireless communication unit 160 together with the data on the amount of water vapor.

[0039] When the receiving units 54a to 54(n-1) sequentially input complex delay profile data of direct and reflected waves of terrestrial digital broadcasting transmitted from broadcasting stations in different directions to the communication unit 55 using Type 1 input, the processes of steps S10 to S17 search for peaks of the direct and reflected waves from the complex delay profile data corresponding to the different directions, and calculate phase information for the peaks. Then, phase difference data between the direct and reflected waves is calculated from the peak phase information, and data on the amount of water vapor in the atmosphere in the spaces corresponding to the different directions is obtained. As a result, when the observation device 20 receives multiple received signals of direct and reflected waves of terrestrial digital broadcasting transmitted from broadcasting stations in different directions to the observation device 20 using Type 1 input, it becomes possible to obtain data on the amount of water vapor in the atmosphere in multiple spaces corresponding to the directions of the installation position of the observation device 20 and different reflectors. Furthermore, when a plurality of data sets of complex delay profiles in which the direct wave and its reflected wave of terrestrial digital broadcasting transmitted from a broadcasting station by receiving units 54a to 54(n-1) have the same source are input to communication unit 55, steps S10 to S17 are performed to search for peaks of the direct wave and its reflected wave from each of the plurality of complex delay profile data sets, calculate phase information for the searched peaks, and calculate water vapor amount data from the plurality of phase information obtained from the same calculated peaks, and then calculate an average value, thereby obtaining data on the amount of water vapor in the atmosphere in the space corresponding to the direction from the installation position of observation device 20 to the reflector. This makes it possible to observe data on the amount of water vapor in the atmosphere in the space corresponding to the direction from the installation position of observation device 20 to the reflector with guaranteed reliability and quality.

[0040] Next, a flowchart of the external meteorological instrument data processing executed by the microcomputer processing unit 150 in the communication unit 55 of the observation device 20 according to the first embodiment of the present invention is shown in FIG. The external meteorological instrument data processing shown in FIG. 11 starts when the observation device 20 is powered on, and serial communication is set up in step S20. This setting configures serial communication so that weather data is acquired from the ground-based meteorological instrument 92, which is an external meteorological instrument, via the I / F port 161. Next, in step S21, time synchronization processing for the ground-based meteorological instrument 92 is performed. Once the time synchronization processing is complete, the process proceeds to step S22. In step S22, the process waits for weather data from the ground-based meteorological instrument 92. When weather data is received via the I / F port 161, the process proceeds to step S23, where the meteorological instrument data is acquired and temporarily stored, and then to step S24. In step S24, a determination is made as to whether it is time to transmit the weather data from the observation device 20 to the cloud 90 on the Internet. If the time to transmit the weather data has not yet arrived, a NO determination is made and the process returns to step S21. Steps S21 through S23 are performed, and the next weather data is acquired and temporarily stored. If it is determined in step S24 that the time to transmit the weather data has arrived, the process proceeds to step S25, where the multiple temporarily stored weather data are averaged, and the averaged weather data is sent to the wireless communication unit 160 in step S26.

[0041] FIG. 12 shows a flowchart of the external meteorological instrument time synchronization processing subroutine performed in step S21. When the processing in step S21 starts, the process proceeds to the external meteorological instrument time synchronization processing shown in FIG. 12, where step S30 determines whether the external meteorological instrument time synchronization processing will be performed for the first time since the external meteorological instrument data processing was started, and also determines whether the designated time for performing the synchronization processing has arrived. If both of these determinations are negative, a NO judgment is made, the subroutine ends, and the process returns to step S22. If either of the two determinations in step S30 is positive, a YES judgment is made, and the process proceeds to step S31. In step S31, the time of the ground meteorological instrument 92, which is the external meteorological instrument, is updated to the current time, the subroutine ends, and the process returns to step S22.

[0042] Next, a flowchart of the communication processing executed by the wireless communication section 160 in the communication unit 55 of the observation device 20 according to the first embodiment of the present invention is shown in FIG. The communication process shown in FIG. 13 starts when the observation device 20 is powered on, and in step S40, a process is performed to connect the observation device 20 to the cloud 90 via the Internet. Once communication between the observation device 20 and the cloud 90 is established, the process proceeds to step S41, in which it is determined whether the wireless communication unit 160 has received water vapor amount data from the microcomputer processing unit 150. If water vapor amount data has not been received, the process determines NO and proceeds to step S43. If water vapor amount data has been received, the process determines YES and proceeds to step S42. In step S42, the received water vapor amount data is uploaded to the connected cloud 90. In step S43, it is determined whether weather data has been received from the microcomputer processing unit 150. If weather data has not been received, the process determines NO and returns to step S41. In this case, the processes of steps S41 and S43 are repeated. If weather data has been received in step S43, the process determines YES and proceeds to step S44. In step S44, the received weather data is uploaded to the connected cloud 90. If the data on the standard deviation calculated in the water vapor amount calculation process is sent to the wireless communication unit 160 together with the water vapor amount data, the standard deviation data is also uploaded to the cloud 90 in addition to the water vapor amount data. By executing the communication process, the water vapor amount data, standard deviation data, and weather data received by the wireless communication unit 160 are successively uploaded to the cloud 90 on the Internet and stored in the cloud 90.

[0043] <Water vapor observation system to which the observation device according to the first embodiment of the present invention is applied> FIG. 14(a) is a block diagram showing the configuration of a water vapor observation system to which the observation device of the first embodiment of the present invention is applied, and FIG. 14(b) shows a schematic configuration of a cloud 90. The water vapor observation system 120 shown in Figure 14(a) includes multiple observation devices 20a-20p according to the first embodiment of the present invention, and each of the observation devices 20a-20p observes the water vapor amount in at least one space as described above and uploads the water vapor amount data to a cloud 90 on the Internet 190. As shown in Figure 14(b), the cloud 90 is composed of a database (DB) 90a and an API connection service unit 90b, and DB 90a stores water vapor amount data uploaded from the multiple observation devices 20a-20p and weather data observed by a ground-based meteorological instrument 92. In DB 90a, each piece of water vapor amount data is assigned location information (ID1) indicating the location of the space for which the water vapor amount data is located, and each piece of weather data is assigned location information (ID2) where the weather data was observed. When related organizations 191, 192, 193, 194 such as universities, meteorological research institutes, and forecasting companies access the cloud 90, the API connection service unit 90b can provide the related organizations 191 to 194 with the necessary data, such as water vapor data and weather data, in a timely manner via an API (Application Programming Interface).

[0044] <Application of the observation device according to the first embodiment of the present invention> The observation device 20 of the first embodiment of the present invention described above is based on the premise that the amount of water vapor between the observation point where the observation device 20 is installed and a reflector is observed using direct and reflected waves of terrestrial digital broadcasting waves. This requires a reflector to sandwich the location where the amount of water vapor is to be observed between the observation point and the observation point. However, in areas such as low mountainous regions or vast grain-producing areas behind mountains where radio waves are blocked, there are cases where there are no structures such as high-rise buildings or apartment buildings, making it difficult to obtain a usable reflector. The observation device 20 of the first embodiment of the present invention can also observe the amount of water vapor without requiring a reflector. In this case, the observation device 20 of the first embodiment of the present invention can be applied to a gap filler system. Therefore, first, a gap filler system to which the observation device 20 of the first embodiment of the present invention can be applied will be described with reference to FIG. 15. FIG. 15 is a block diagram showing the configuration of a general gap filler system 200.

[0045] <General Gap Filler System> The gap filler system is installed so that when there is an obstacle S, such as a mountain, that impedes the propagation of terrestrial digital broadcast waves, the terrestrial digital broadcast waves can be received well on the side beyond the obstacle S. In the gap filler system 200 shown in FIG. 15, there is an obstacle S, such as a mountain, that impedes the propagation of terrestrial digital broadcast waves between a broadcast station 500 (or relay station) that transmits the terrestrial digital broadcast waves and a residence H that receives the terrestrial digital broadcast waves. Therefore, a gap filler receiving station Rx is installed near the top of the mountain, which is the obstacle S, where the terrestrial digital broadcast waves can be received well. The gap filler receiving station Rx receives the terrestrial digital broadcast signals transmitted from the broadcast station 500 using an antenna 411 and a receiving unit 410. The received terrestrial digital broadcast signals are sent from the receiving unit 410 to a transmission line T made up of an optical fiber or a coaxial cable, and transmitted to a transmitting unit 530 of the gap filler transmitting station Tx. The gap filler transmitting station Tx is installed in a location that overlooks multiple residences H that are scattered beyond the obstacle S. The transmitting unit 530 of the gap filler transmitting station T distributes the terrestrial digital broadcast signal transmitted from the gap filler receiving station Rx via the transmission line T using a distributor 533, amplifies each distributed signal, and transmits it from a first transmitting antenna 531 and a second transmitting antenna 532. As a result, the terrestrial digital broadcast waves are retransmitted from the first transmitting antenna 531 and the second transmitting antenna 532, respectively, and the retransmitted terrestrial digital broadcast waves are received by each of a plurality of houses H located on the side beyond the obstacle S as viewed from the broadcasting station 500. In this case, since the gap filler transmitting station Tx is installed in a location overlooking the houses H, the houses H can receive the terrestrial digital broadcast waves well.

[0046] <Another water vapor observation system to which the observation device according to the first embodiment of the present invention is applied> The observation device 20 of the first embodiment of the present invention described in Figures 1 to 13 is applied to a gap filler system 200 shown in Figure 15. The configuration of a water vapor observation system in which the observation device 20 of the first embodiment of the present invention is applied to the gap filler system 200 is shown in Figure 16. The water vapor observation system 1 shown in FIG. 16 is configured by applying the observation device 20 of the present invention to a gap filler system 200. The gap filler system 200 is usually already installed, and the observation device 20 of the present invention is installed at a point beyond the gap filler system 200 as viewed from the broadcast station BR. The installation point of the observation device 20 of the first embodiment of the present invention is observation point M. In FIG. 16, the gap filler system 200 is shown as comprising a receiving antenna 01 and a gap filler receiving station Rx that receive terrestrial digital broadcast waves emitted from the broadcast station BR, and a gap filler transmitting station Tx and a transmitting antenna 02 that retransmit the terrestrial digital broadcast signal transmitted from the gap filler receiving station Rx via an optical line 13 as terrestrial digital broadcast waves. The observation device 20 of the first embodiment of the present invention is installed on an extension of the straight line connecting the broadcast station BR and the gap filler system 200, and receives the terrestrial digital broadcast waves emitted from the broadcast station BR and the terrestrial digital broadcast waves retransmitted from the gap filler transmitting station Tx with an antenna 21. The water vapor observation system 1 observes the amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx by taking advantage of the fact that an increase in the amount of water vapor in the atmosphere causes a slight delay in the propagation time of radio waves - for example, under conditions of a 5 km propagation path, ground pressure, and a temperature of 20°C, a 1% increase in humidity will delay the propagation time by approximately 17 picoseconds, i.e., the propagation delay time will be 17 picoseconds. In this case, the observation device 20 of the present invention obtains water vapor amount data by using terrestrial digital broadcast waves retransmitted from the gap filler transmitting station Tx instead of reflected waves to accurately observe the propagation time from the gap filler transmitting station Tx to the observation device 20 of the present invention.

[0047] To explain the water vapor observation system 1 shown in FIG. 16 in more detail, the gap filler receiving station Rx is equipped with a receiving antenna 01 and receives a terrestrial digital broadcast signal of a terrestrial digital broadcast wave transmitted from a broadcast station BR. The terrestrial digital broadcast signal received by the gap filler receiving station Rx is converted into an optical signal and transmitted to the gap filler transmitting station Tx via an optical line 03. At the gap filler transmitting station Tx, the transmitted optical signal of the terrestrial digital broadcast signal is restored to a high-frequency signal, and the terrestrial digital broadcast wave is retransmitted from the transmitting antenna 02 to an area where the terrestrial digital broadcast wave from the broadcast station BR cannot be received well. In the observation device 20 of the first embodiment of the present invention, which is installed at an observation point M on an extension of the straight line connecting the broadcast station BR and the gap filler system 200, the direct wave of the terrestrial digital broadcast signal transmitted from the broadcast station BR is received by the antenna 21, and the terrestrial digital broadcast wave retransmitted from the gap filler transmitting station Tx is also received by the antenna 21. The observation device 20 of the first embodiment of the present invention, installed at the observation point M, observes the complex delay profile of the direct wave from the broadcasting station BR and the retransmitted wave from the gap filler transmitting station Tx, and calculates the phase difference data between the direct wave from the broadcasting station BR and the retransmitted wave from the gap filler transmitting station Tx from the observed complex delay profile.

[0048] Here, an example of a complex delay profile observed by the observation device 20 of the first embodiment of the present invention installed at the observation point M is shown in FIG. In the complex delay profile shown in Fig. 17, the phase information corresponding to the propagation time from the terrestrial digital broadcasting wave transmitted from the broadcasting station BR to the gap filler receiving station Rx is τ A The phase information corresponding to the propagation time from the gap filler receiving station Rx to the gap filler transmitting station Tx when the terrestrial digital broadcasting wave transmitted from the broadcasting station BR propagates through space is τ B The phase information corresponding to the propagation time until the terrestrial digital broadcasting wave retransmitted from the gap filler transmitting station Tx propagates through space and reaches the observation point M is τ CThe phase information corresponding to the propagation time from the gap filler receiving station Rx to the gap filler transmitting station Tx after being transmitted from the gap filler receiving station Rx through the optical line 03 and then retransmitted from the gap filler transmitting station Tx is expressed as τ GF As shown in FIG. 16, the phase noise of the local oscillator of the transmitter in the broadcasting station BR is φ T , the phase noise of the observation device 20 of the first embodiment of the present invention at the observation point M is φ R It is shown as follows. Note that τ B is affected by the propagation delay time depending on the amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx.

[0049] In the complex delay profile shown in FIG. 17, if the above notation is used, the terrestrial digital broadcasting wave transmitted from the broadcasting station BR at time t10 propagates through space and arrives at the observation point M as a direct wave at time t13, and is observed as a complex delay profile. The phase information G1 corresponding to the propagation time (t13-t10) is G1=φ T +τ A +τ B +τ C +φ R (10) Furthermore, if the phase information corresponding to the propagation time (t14-t10) from when the terrestrial digital broadcasting wave transmitted from the broadcasting station BR at time t10 is received by the gap filler receiving station Rx at time t11 and transmitted to the gap filler transmitting station Tx via the optical line 03, and when the terrestrial digital broadcasting wave is retransmitted from the gap filler transmitting station Tx at time t12 and reaches the observation point M at time t14, is denoted as G2, then G2=φ T +τ A +τ GF +τ C +φ R (11) Here, the phase information G1 and G2 are expressed as peaks in the complex delay profile at the observation point M, as shown in FIG.

[0050] The water vapor amount observation system 1 can observe the amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx based on the phase difference data, which is the difference between the phase information G1 and the phase information G2. GF The propagation time can be accurately estimated and is not affected by the propagation delay time depending on the amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx. Here, when the phase difference data H of the difference between the phase information G1 and the phase information G2 is calculated, H=G2-G1=τ GF -τ B (12) In this case, the phase noise φ of the broadcasting station BR that causes the error T and the phase noise φ of the observation device 20 of the first embodiment of the present invention at the observation point M. R It can be seen that the phase difference data H is removed from the phase difference data H. From the above equation (12), the phase information τ B When we ask for τ B =τ GF -H (13) The phase difference data H is calculated as the difference between two peaks in the complex delay profile shown in FIG. 17, for example, and is phase information that is affected by the propagation delay time depending on the amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx. Then, the phase difference data H calculated from the complex delay profile and τ that can be accurately estimated are calculated. GF From the propagation time of B Calculate the speed of radio waves in a vacuum (2.99792458×10 8 The amount of water vapor in the atmosphere between the gap filler receiving station Rx and the gap filler transmitting station Tx can be observed based on the propagation delay time, which is the difference between the propagation time for the terrestrial digital broadcasting wave, calculated based on the propagation time (m / s), and the propagation time from the gap filler receiving station Rx to the gap filler transmitting station Tx.

[0051] In this case, as shown in the above equations (9-1) to (9-3), the partial pressure of water vapor corresponding to the water vapor amount data can be calculated by equating the propagation delay amount expressed by the calculated phase difference data H with the propagation delay amount per unit distance expressed using the refraction index of radio waves. Note that when radio waves propagate over a distance of 5 km, under conditions of ground pressure and a temperature of 20°C, a 1% increase in humidity results in a propagation delay time of approximately 17 ps (picoseconds), which corresponds to a propagation time of approximately 5 mm. Because the propagation delay time caused by the amount of water vapor is so small, highly accurate measurements (on the order of at least several tens of ps) are required for effective observation. In the water vapor amount observation system 1, the phase noise φ of the broadcasting station BR, which causes errors, is used. T and the phase noise φ of the observation device 20 of the first embodiment of the present invention. R and are removed, and τ GF Since the propagation time can be accurately estimated, very accurate observations of water vapor content can be made. In the observation device 20 of the first embodiment of the present invention, a complex delay profile is measured to observe phase rotation from the in-phase component I signal and the quadrature component Q signal. However, in the observation device 20 of the first embodiment of the present invention, a delay profile may be measured instead of the complex delay profile, and the peak positions of the direct wave and the retransmitted wave may be searched for from the amplitude information to observe phase rotation.

[0052] <Second embodiment of the present invention> A functional block diagram showing the configuration of an observation device 20B for observing the amount of water vapor according to a second embodiment of the present invention is shown in Fig. 18. The observation device 20B according to the second embodiment of the present invention shown in this figure is applied to a gap filler system to observe the amount of water vapor. The observation device 20B of the second embodiment shown in Figure 18 differs from the observation device 20 of the first embodiment in that it further comprises a mixing unit (MIX) 45 and a photodetector (PD) 47, but otherwise has the same configuration as the observation device 20 of the first embodiment. That is, the observation device 20B of the second embodiment also comprises a housing 40, which detachably houses a lightning protection circuit unit 51, a power supply superposition unit 52, a signal distribution unit 53, a receiving unit 54 consisting of a desired number of receiving units 54a to 54(n-1), a communication unit 55, a relay board 56, and a power supply unit 57. The housing 40 is made of metal, but can also be made of synthetic resin. The housing 40 is provided with an input terminal IN, which has a plurality of input terminals, one of which receives the received signal of the direct wave received by the first antenna 21 and mixed by MIX 45, the received signal of the retransmitted wave received by the second antenna 22 and retransmitted from the gap filler system, and a retransmitted signal from PD 47, which will be described later.

[0053] In the observation device 20B of the second embodiment, a complex delay profile is generated in the receiving unit 54, and this complex delay profile contains peaks of the retransmitted signal in addition to the peaks of the direct wave and retransmitted wave. The complex delay profile data output from the receiving unit 54 is input to the communication unit 55, which generates first phase difference data between the peak of the direct wave and the peak of the retransmitted wave, and second phase difference data between the peak of the direct wave and the peak of the retransmitted signal. The generated first phase difference data and second phase difference data can be used to determine data on the amount of water vapor between the receiving antenna and the retransmitting antenna in the gap filler system. The observation device 20B of the second embodiment is installed in the same position as the receiving antenna in the gap filler system.

[0054] <Water vapor observation system to which the observation device according to the second embodiment of the present invention is applied> FIG. 19 is a block diagram showing the configuration of a water vapor observation system 2 to which an observation device 20B according to a second embodiment of the present invention is applied. The water vapor observation system 2 shown in Figure 19 utilizes the gap filler system 200 shown in Figure 15 described above, and is configured by installing an observation device 20B of the second embodiment of the present invention in the existing gap filler system 200. The water vapor observation system 2 includes a broadcasting station BR that transmits terrestrial digital broadcast waves in all directions in the horizontal plane, a gap filler receiving station GRx that receives the terrestrial digital broadcast waves emitted from the broadcasting station BR, a gap filler transmitting station GTx that retransmits the terrestrial digital broadcast signals transmitted from the gap filler receiving station GRx via a first optical line 12 as terrestrial digital broadcast waves, and an observation device 20B of the second embodiment of the present invention that is installed at the same location as the gap filler receiving station GRx and receives the terrestrial digital broadcast waves emitted from the broadcasting station BR and the terrestrial digital broadcast waves retransmitted from the gap filler transmitting station GTx and propagating through space, and receives the terrestrial digital broadcast signals transmitted from the gap filler transmitting station GTx via a second optical line 13. The location where the observation device 20B of the second embodiment of the present invention is installed is observation point M. The water vapor observation system 2 observes the amount of water vapor in the atmosphere between observation point M and gap filler transmitting station GTx by taking advantage of the fact that an increase in the amount of water vapor in the atmosphere causes a slight delay in the propagation time of radio waves - for example, under conditions of a 5 km propagation path, ground pressure, and temperature of 20°C, a 1% increase in humidity will cause a delay of approximately 17 picoseconds in propagation time, i.e., a propagation delay time of 17 picoseconds. In this case, the observation device 20B of the second embodiment of the present invention obtains information on the amount of water vapor by measuring the propagation delay time with high precision using terrestrial digital broadcasting waves retransmitted from gap filler transmitting station GTx.

[0055] The water vapor observation system 2 will be described with reference to Figures 18 and 19. The gap filler receiving station GRx has at least an antenna 11 and a receiving unit 10 for receiving terrestrial digital broadcast waves transmitted from the broadcasting station BR. The receiving unit 10 adjusts the gain of the terrestrial digital broadcast signal received by the antenna 11 so that it is output at a predetermined level, and restores it to a baseband terrestrial digital broadcast signal. The baseband terrestrial digital broadcast signal is supplied to a laser diode (LD) 48, where it is converted into an optical signal, and then sent to a first optical line 12 and transmitted to the gap filler transmitting station GTx. The gap filler transmitting station GTx includes a transmitting unit 30, a first transmitting antenna 31, and a second transmitting antenna 32. The transmitting unit 30 receives an optical terrestrial digital broadcast signal transmitted from the gap filler receiving station GRx via a first optical line 12. The input optical terrestrial digital broadcast signal is split into two, and one optical terrestrial digital broadcast signal is sent to a second optical line 13 and transmitted to an observation device 20B of a second embodiment of the present invention. The other optical terrestrial digital broadcast signal is converted back into an electrical terrestrial digital broadcast signal by a photodiode and output from a transmitter in the transmitting unit 30. The terrestrial digital broadcast signal output from the transmitter is split into two, and one of the split terrestrial digital broadcast signals is supplied to a first transmitting antenna 31, and the other split terrestrial digital broadcast signal is supplied to a second transmitting antenna 32. As a result, terrestrial digital broadcast waves are retransmitted from the first transmitting antenna 31 and the second transmitting antenna 32. The first optical line 12 and the second optical line 13 are configured by a single optical fiber cable having multiple optical fibers, and each optical fiber of the multiple optical fibers is assigned to the first optical line 12 and the second optical line 13. Therefore, the first optical line 12 and the second optical line 13 have the same length and almost the same transmission characteristics.

[0056] 18, the observation device 20B of the second embodiment of the present invention receives as input a terrestrial digital broadcast signal M1', a direct wave from broadcast station BR received by a first antenna 21, and a terrestrial digital broadcast signal M2', a retransmitted wave from gap filler transmitting station GTx received by a second antenna 22. Furthermore, a terrestrial digital broadcast signal R2', which is an optical signal transmitted from gap filler transmitting station GTx via a second optical line 13, is input and converted into an electrical signal by a PD 47. The terrestrial digital broadcast signal M1', terrestrial digital broadcast signal M2', and terrestrial digital broadcast signal R2' are mixed by a mixer (MIX) 45 and input to a receiving unit 54. Then, complex delay profiles of the terrestrial digital broadcast signal M1', terrestrial digital broadcast signal M2', and terrestrial digital broadcast signal R2' are generated in the receiving unit 54, and data of the generated complex delay profile is output to a communication unit 55. The communication unit 55 calculates phase information M1 of terrestrial digital broadcast signal M1', phase information M2 of terrestrial digital broadcast signal M2', and phase information R2 of terrestrial digital broadcast signal R2' based on the complex delay profile data, and generates phase difference data D1 between phase information M1 and phase information M2, and phase difference data D2 between phase information M1 and phase information R2. Then, water vapor amount data is calculated based on the phase difference data D1 and phase difference data D2, and the calculated water vapor amount data is uploaded from the communication antenna 91 to a cloud 90 on the Internet. The water vapor amount data is taken as the amount of water vapor in the space between observation point M, where observation device 20B of the second embodiment of the present invention is installed, and gap filler transmitting station GTx.

[0057] As described above, the terrestrial digital broadcast signal received by the receiving unit 10 of the gap filler receiving station GRx is transmitted to the gap filler transmitting station GTx via the first optical line 12, and the terrestrial digital broadcast signal in the form of an optical signal distributed at the gap filler transmitting station GTx is transmitted to the observation device 20B of the second embodiment of the present invention via the second optical line 13. In this case, one optical fiber of the optical fiber cable with a multi-core structure is assigned to each of the first optical line 12 and the second optical line 13 as described above, and they are made to have the same line length and to exhibit the same transmission characteristics. An example of a complex delay profile output from the receiving unit 54 is shown in Fig. 20. Referring to the complex delay profile shown in Fig. 20, it can be seen that the peak of the direct wave terrestrial digital broadcast signal M1' appears at time t21, the peak of the retransmitted wave terrestrial digital broadcast signal M2' appears at time t23, and the peak of the optical signal terrestrial digital broadcast signal R2' appears at time t24.

[0058] Let τ1 be the phase information corresponding to the propagation time for the terrestrial digital broadcasting wave transmitted from the broadcasting station BR to reach the gap filler receiving station GRx installed at the same location and the observation device 20B (observation point M) of the second embodiment of the present invention, let τa be the phase information corresponding to the propagation time for the terrestrial digital broadcasting wave retransmitted from the gap filler transmitting station GTx to reach the observation point M, let (τb+τc) be the phase information corresponding to the propagation time for the terrestrial digital broadcasting signal to be transmitted on the first optical line 12 from the gap filler receiving station GRx to reach the gap filler transmitting station GTx, and let (τb+τc) be the phase information corresponding to the propagation time for the terrestrial digital broadcasting signal to be transmitted on the second optical line 13 from the gap filler transmitting station GTx to reach the gap filler receiving station GRx. Also, let φ be the phase noise of the local oscillator of the transmitting section in the broadcasting station BR. T , the phase noise of the local oscillator in the receiving unit 54 of the observation device 20B of the second embodiment of the present invention at the observation point M is φ MThe first optical line 12 and the second optical line 13 have the same line length and exhibit the same transmission characteristics, so their propagation times are equal, but the phase information is expressed as (τb + τc) because the optical fiber lines in the first optical line 12 and the second optical line 13 generally use silica-based glass fiber, which has an extremely small expansion coefficient but can cause errors as the length of the optical line increases. Therefore, the phase information corresponding to the propagation time of the expansion / contraction length based on the expansion coefficient is expressed as τc. In other words, since the propagation time changes depending on the temperature, the phase information corresponding to the propagation time of the first optical line 12 and the second optical line 13 is expressed by the sum of the phase information τb corresponding to the fixed propagation time and the phase information τc corresponding to the propagation time that changes depending on the temperature.

[0059] In the above notation, the phase information M1 corresponding to the propagation delay time (t21) until the terrestrial digital broadcasting wave transmitted from the broadcasting station BR reaches the observation point M is M1=τ1+φ T +φ M (14) Furthermore, if R1 is phase information corresponding to the propagation time (t22) of the terrestrial digital broadcasting signal received by the gap filler receiving station GRx installed at the same point as the observation point M until it reaches the gap filler transmitting station GTx via the first optical line 12, then R1=τ1+τb+τc+φ T (15) However, the phase information R1 is used for the purpose of explanation, and the phase information R1 is not actually calculated in the gap filler transmitting station GTx. Then, when the terrestrial digital broadcasting wave is retransmitted from the gap filler transmitting station GTx, the retransmitted terrestrial digital broadcasting wave is received at the observation point M. The phase information M2, which corresponds to the propagation time (t23) required for the terrestrial digital broadcasting wave retransmitted from the gap filler transmitting station GTx to reach the observation point M, is M2=R1+τa+φ M =τ1+τa+τb+τc+φ T +φ M (16) Furthermore, phase information R2 corresponding to the propagation time (t24) required for the terrestrial digital broadcasting signal transmitted from the gap filler transmitting station GTx via the second optical line 13 to reach the observation point M is given by R2=R1+τb+τc+φ M =(τ1+τb+τc+φ T )+τb+τc+φ M =τ1+2(τb+τc)+φ T +φ M (17) 20 shows an example of a complex delay profile generated by the receiving unit 54 in the observation device 20B according to the second embodiment of the present invention, and phase information M1, M2, and R2 is calculated from the complex delay profile data in the communication unit 55.

[0060] As shown in Fig. 20, the complex delay profile has a horizontal axis representing the time axis and a vertical axis representing the amplitude axis, with the horizontal axis representing the propagation time. The terrestrial digital broadcasting signal received by the gap filler receiving station GRx is transmitted to the gap filler transmitting station GTx via the first optical line 12, and the terrestrial digital broadcasting wave is further retransmitted from the gap filler transmitting station GTx and reaches the observation point M. Phase difference data D1 corresponding to the propagation time (t23-t21) is calculated as (M2-M1). That is, D1=(M2-M1)=(τ1+τa+τb+τc+φ T +φ M )-(τ1+φ T +φ M ) =τa+τb+τc (18) In this case, the phase noise φ of the broadcasting station BR that causes the error T and the phase noise φ of the observation device 20B of the second embodiment of the present invention. MIt can be seen that these are removed in the phase difference data D1. Furthermore, the phase difference data D2, which corresponds to the propagation time (t24-t21) taken for the terrestrial digital broadcasting signal transmitted from the broadcasting station BR and received by the gap filler receiving station GRx to be transmitted to the gap filler transmitting station GTx via the first optical line 12, then turned back from the gap filler transmitting station GTx via the second optical line 13 and reach the observation point M, can be calculated as (R2-M1). That is, D2=(R2-M1)={τ1+2(τb+τc)+φ T +φ M}-(τ1+φ T +φ M ) =2(τb+τc) (19) In this case, the phase noise φ of the broadcasting station BR that causes the error T and the phase noise φ of the observation device 20B of the second embodiment of the present invention. M It can be seen that these factors have been removed in the phase difference data D2. Furthermore, since D2 corresponds to the propagation time of the round trip on the optical path between the gap filler receiving station GRx and the gap filler transmitting station GTx, it is not affected by the propagation delay time depending on the amount of water vapor in the atmosphere between the gap filler receiving station GRx and the gap filler transmitting station GTx, and it is clear that the phase information corresponding to the one-way propagation time on the optical path between the gap filler receiving station GRx and the gap filler transmitting station GTx is (D2 / 2). Then, the phase difference data D3 corresponding to the propagation time until the terrestrial digital broadcasting wave retransmitted from the gap filler transmitting station GTx reaches the observation point M can be calculated as (D1 - D2 / 2), and therefore, D3=D1-D2 / 2=(τa+τb+τc)-(τb+τc)=τa (20) and the phase information corresponding to the propagation time until the terrestrial digital broadcasting wave retransmitted from the gap filler transmitting station GTx reaches the observation point M is obtained as τa. In this case, it can be seen that the delay times in the first optical line 12 and the second optical line 13 are canceled out, and the influence of the expansion coefficient of the optical fiber is eliminated. Furthermore, τa is phase information that is influenced by the propagation delay time depending on the amount of water vapor in the atmosphere between the gap filler receiving station GRx and the gap filler transmitting station GTx. The communication unit 55 calculates the phase difference data D1 and D2 from the complex delay profile data shown in FIG. 20, and can calculate the phase difference data D3 (= τa) from equation (20).

[0061] As described above, the observation device 20B of the second embodiment of the present invention utilizes the fact that the terrestrial digital broadcast wave from the broadcast station BR and the terrestrial digital broadcast wave retransmitted from the gap filler transmitting station GTx are phase-synchronized, thereby making it possible to remove phase noise between the broadcast station BR and the observation point M without requiring any synchronization means. The observation device 20B of the second embodiment of the present invention calculates the phase difference data D3 (=τa) corresponding to the propagation time until the terrestrial digital broadcast wave retransmitted from the gap filler transmitting station GTx reaches the observation point M, and the speed of radio waves in a vacuum (2.99792458×10 8 The amount of water vapor in the atmosphere between the gap filler transmitting station GTx and the observation point M can be calculated based on the propagation delay time, which is the difference between the phase information corresponding to the propagation time it takes for the terrestrial digital broadcasting wave, calculated based on the propagation time (m / s), to reach the observation point M from the gap filler transmitting station GTx. In this case, as shown in the above equations (9-1) to (9-3), the partial pressure of water vapor corresponding to the water vapor content data can be calculated by equating the propagation delay expressed by the calculated phase difference data D3 (=τa) with the propagation delay per unit distance expressed using the refraction index of radio waves. Note that when radio waves propagate over a distance of 5 km, under conditions of ground pressure and a temperature of 20°C, a 1% increase in humidity results in a propagation delay of approximately 17 ps (picoseconds), which corresponds to a propagation time of approximately 5 mm. Because the propagation delay time caused by the amount of water vapor is so small, highly accurate measurements (on the order of at least several tens of ps) are required for effective observation. In the water vapor content observation system 2, the phase noise φ of the broadcasting station BR, which causes errors, is used. T and the phase noise φ of the observation device 20B of the second embodiment of the present invention. M Since the delay times in the first optical path 12 and the second optical path 13 are eliminated and the delay times in the first optical path 12 and the second optical path 13 are cancelled out, the amount of water vapor can be observed very accurately. In the observation device 20B of the second embodiment of the present invention, a complex delay profile is measured and phase information is generated from the I signal, which is the in-phase component, and the Q signal, which is the quadrature component. However, in the observation device 20B of the second embodiment of the present invention, a delay profile may be generated instead of the complex delay profile, and the phase information may be calculated from the amplitude information of the generated delay profile. [Industrial Applicability]

[0062] By installing the water vapor observation device according to the present invention described above at an observation point between a broadcast station and a reflector, the amount of water vapor in the atmosphere between the reflector and the observation point can be observed. Furthermore, by installing the water vapor observation device according to the present invention at an observation point on an extension of a line connecting a broadcast station with a gap filler receiving station and a gap filler transmitting station, the amount of water vapor in the atmosphere between the gap filler receiving station and the gap filler transmitting station can be observed. Furthermore, by installing the water vapor observation device according to the present invention at an observation point at the same location as the gap filler receiving station, the amount of water vapor in the atmosphere between the gap filler receiving station and the gap filler transmitting station can be observed. Note that, since gap filler systems comprising gap filler receiving stations and gap filler transmitting stations are generally already installed, if there is spare capacity in the gap filler receiving station building, the water vapor observation device according to the present invention may be installed in the gap filler receiving station building. Furthermore, when a new gap filler system is being installed, the gap filler receiving station and the water vapor observation device according to the present invention can be integrated into one facility. The water vapor observation device according to the present invention described above utilizes the phase synchronization between terrestrial digital broadcast waves from a broadcast station and the reflected waves of terrestrial digital broadcast waves reflected by a reflector or terrestrial digital broadcast waves retransmitted from a gap filler transmitting station. Simply by installing a water vapor observation device according to the present invention equipped with an antenna at an observation point, it is possible to observe the water vapor amount between the observation point and the reflector or gap filler transmitting station. Therefore, only one observation point is required, and two observation points are not required, eliminating the need to synchronize the two observation points. Furthermore, if the gap filler transmitting station is installed at the same location as the gap filler receiving station, there is no need to place the gap filler transmitting station on a straight line connecting the broadcast station and the observation point. Furthermore, when the water vapor observation device according to the present invention is installed at the same location as a gap filler receiving station, the multi-core optical fiber cable constituting the first optical line is already installed because the gap filler system is already in place. Therefore, unused optical fibers in the multi-core optical fiber cable constituting the existing first optical line can be used as the second optical line connecting the gap filler transmitting station and the observation point. In this way, the work of laying a new optical line can be eliminated. While coaxial lines can be used instead of the first and second optical lines, if the gap filler transmitting station is installed far away from the gap filler receiving station, coaxial lines are not suitable due to the large transmission loss. Therefore, using the first and second optical lines is preferred. Furthermore, the water vapor observation device of the present invention can eliminate phase noise from the transmitting station and the water vapor observation device of the present invention, which can cause measurement errors, and can also offset changes in delay time due to expansion and contraction of the optical path, which can cause measurement errors when installed at the same location as the gap filler receiving station. Furthermore, it has been explained that the water vapor amount observation device of the present invention generates a complex delay profile and calculates the phase rotation, which is phase information, from the in-phase component I signal and the quadrature component Q signal. However, the water vapor amount observation device of the present invention may generate a delay profile instead of a complex delay profile and calculate the phase rotation from amplitude information. Furthermore, in the water vapor observation device according to the present invention, water vapor amount data is calculated based on phase difference data, but the phase difference data may be uploaded to a cloud on the Internet, and the water vapor amount data may be calculated in the cloud based on the phase difference data. [Explanation of symbols]

[0063] 1,2 Water vapor observation system, 01 Receiving antenna, 02 Transmitting antenna, 03 Optical line, 10 Receiving unit, 11 Antenna, 12 First optical line, 13 Second optical line, 20, 20B, 20a to 20p Observation equipment, 21 First antenna, 22 Second antenna, 30 Transmitting unit, 31 First transmitting antenna, 32 Second transmitting antenna, 40 Housing, 40b Power supply input, 40c Cable entry hole, 42 Preamplifier, 51 Lightning protection circuit unit, 52 Power supply superposition unit, 53 Signal distribution unit, 54, 54-1, 54-2 Receiving unit, 54a to 54(n-1) Receiving unit, 55 Communication unit, 56 Relay board, 56a Bus, 57 Power supply unit, 90 Cloud, 90b API connection service unit, 91 Communication antenna, 92 Ground meteorological instrument, 93 Community receiving power supply unit, 101, 101a to 101m tuner unit, 102, 102-2 complex delay profile generation unit, 103 distributor, 120 water vapor observation system, 141 main body unit, 142 lid unit, 143 input terminal, 144 cable inlet, 145 power receiving terminal, 150 microcomputer processing unit, 151 phase difference data processing unit, 151 phase difference data calculation unit, 152 various calculation units, 160 wireless communication unit, 161 I / F port, 162 LAN port, 170 distributor, 190 Internet, 191 to 194 related organizations, 183 rectifier circuit unit, 184 transformer unit, 200 gap filler system, 410 receiving unit, 411 antenna, 500 broadcasting station, 530 transmitting unit, 531 transmitting antenna, 532 transmitting antenna, 533 Distributor, AC2 drive power supply, BR broadcast station, Ca~Cn capacitors, GRx gap filler receiving station, GTx gap filler transmitting station, H house, IN input terminal, INa~INn input terminals, La~Ln choke coils, M observation point, R reflector, Rx gap filler receiving station, S obstacle, T transmission line, Tx gap filler transmitting station

Claims

1. a plurality of receiving units each receiving a received signal input from a plurality of input terminals, generating a complex delay profile of the received signal, and outputting data of the complex delay profile; a communication unit that searches for peaks from the complex delay profile data output from the receiving unit, generates phase difference data between phase information of a first peak at the earliest time among the searched peaks and phase information of the other peaks excluding the first peak, and calculates and transmits data on the amount of water vapor based on the phase difference data, When the device is installed at an observation point beyond a gap filler system comprising a gap filler receiving station and a gap filler transmitting station as seen from a broadcasting station, and when a received signal of a direct wave of a terrestrial digital broadcasting wave from the broadcasting station and a retransmitted wave of the terrestrial digital broadcasting wave received by the gap filler receiving station and transmitted over a transmission line and retransmitted from the gap filler transmitting station is input to the input terminal, In the communication unit, the peak of the direct wave is searched for as a first peak, and the peak of the retransmitted wave is searched for, and data on the amount of water vapor in the atmosphere in the space between the gap filler receiving station and the gap filler transmitting station is obtained based on phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the retransmitted wave.

2. a plurality of receiving units each receiving a received signal input from a plurality of input terminals, generating a complex delay profile of the received signal, and outputting data of the complex delay profile; a communication unit that searches for peaks from the complex delay profile data output from the receiving unit, generates phase difference data between phase information of a first peak at the earliest time among the searched peaks and phase information of the other peaks excluding the first peak, and calculates and transmits data on the amount of water vapor based on the phase difference data, In a gap filler system including a gap filler receiving station and a gap filler transmitting station, the gap filler receiving station is installed at an observation point at the same position as the gap filler receiving station, and when received signals of a direct wave of a terrestrial digital broadcast wave from a broadcast station, a retransmission wave of the terrestrial digital broadcast wave received by the gap filler receiving station and transmitted over a first transmission line and retransmitted from the gap filler transmitting station, and a terrestrial digital broadcast signal of the terrestrial digital broadcast signal retransmitted from the gap filler transmitting station and transmitted over a second transmission line are input to the input terminal, In the communication unit, the peak of the direct wave is searched for as a first peak, and the peak of the retransmitted wave and the peak of the terrestrial digital broadcasting signal are searched for, and data on the amount of water vapor in the atmosphere in the space between the observation point and a gap filler transmitting station is obtained based on first phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the retransmitted wave, and second phase difference data between the phase information of the peak of the direct wave and the phase information of the peak of the terrestrial digital broadcasting signal.

3. 3. The water vapor amount observation device according to claim 1, wherein the communication unit uploads the calculated water vapor amount data to a cloud on the Internet.

4. The water vapor observation device described in claim 1 or claim 2, characterized in that the communication unit receives weather data from an externally installed ground meteorological instrument, and the communication unit uploads the calculated water vapor amount data and the weather data to a cloud on the Internet.

5. A water vapor observation device as described in any one of claims 1 to 4, characterized in that the multiple receiving units, the communication unit, and a power supply unit capable of supplying power to the multiple receiving units and the communication unit are housed in a housing, and the housing is installed at the observation point.

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