Water vapor observation device, water vapor observation system, water vapor observation method, and water vapor observation program

Abstract

This water vapor observation device (10) comprises an antenna (40), an RF amplifier (30), a frequency setting unit (21), and a water vapor index calculation unit (22). The antenna (40) receives radio waves radiated from an atmosphere including water vapor. The RF amplifier (30) amplifies the received radio waves and generates an observation signal. The frequency setting unit (21) uses the observation signal to set a plurality of observation frequencies excluding an accuracy degradation frequency. The water vapor index calculation unit (22) calculates a water vapor index using the spectral intensity of the plurality of observation frequencies. This configuration makes it possible to accurately observe a water vapor amount.

Description

[Technical field]

[0001] The present invention relates to a technique for observing water vapor. [Background technology]

[0002] Conventionally, a water vapor observation device as shown in Patent Document 1 has been devised. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-224884 A Summary of the Invention [Problem to be solved by the invention]

[0004] As a method for observing water vapor, in addition to the method using radio waves as disclosed in Patent Document 1, a method using radio waves generated by water vapor has also been considered.

[0005] However, when using radio waves generated from water vapor, the signal strength of the object being observed is small, making it difficult to accurately observe the amount of water vapor.

[0006] Therefore, an object of the present invention is to observe the amount of water vapor with high accuracy. [Means for solving the problem]

[0007] The water vapor observation device of the present invention includes an antenna, an RF amplifier, a frequency setting unit, and a water vapor index calculation unit. The antenna receives radio waves emitted from the atmosphere containing water vapor. The RF amplifier amplifies the received radio waves to generate an observation signal. The frequency setting unit sets a plurality of observation frequencies excluding accuracy-deteriorating frequencies based on the observation signal. The water vapor index calculation unit calculates the water vapor index using the spectral intensities of the plurality of observation frequencies.

[0008] In this configuration, the spectral intensities of a plurality of observation frequencies required for calculating the water vapor index can be obtained with high accuracy. Effect of the Invention

[0009] According to the present invention, the amount of water vapor can be observed with high accuracy. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a functional block diagram showing the configuration of a water vapor observation device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a functional block diagram showing the configuration of the frequency setting unit. [Diagram 3] FIG. 3 is a diagram showing an example of the concept of calculating the water vapor index. [Figure 4] FIG. 4 is a flowchart of the water vapor index calculation process. [Diagram 5] FIG. 5 is a flowchart of a process for setting the precision degradation frequency. [Figure 6] FIG. 6 is a flowchart showing the main steps of the abnormal value detection method. [Figure 7] FIG. 7 is a spectrum characteristic diagram illustrating the detection concept of the first abnormal value detection method. [Figure 8] FIG. 8 is a flowchart showing a second method for detecting an abnormal value. [Figure 9] In FIG. 9, the horizontal axis indicates the frequency of the observed signal, and the vertical axis indicates the spectral intensity. [Figure 10] FIG. 10 is a flowchart showing a third method for detecting an abnormal value. [Figure 11] FIG. 11 is a spectrum characteristic diagram illustrating the detection concept of the third method for detecting an abnormal value. [Figure 12] FIG. 12 is a flowchart showing a fourth method for detecting an abnormal value. [Figure 13] FIG. 13 is a spectrum characteristic diagram illustrating the detection concept of the fourth abnormal value detection method. [Figure 14]FIG. 14 is a flowchart showing a fifth method for detecting an abnormal value. [Figure 15] 15(A) and 15(B) are spectral characteristic diagrams illustrating the detection concept of the fifth method for detecting abnormal values. [Figure 16] FIG. 16 is a flowchart showing a method for switching the observation frequency. [Figure 17] FIG. 17 is a spectrum characteristic diagram for explaining the concept of the observation frequency switching method. [Figure 18] FIG. 18 is a flowchart showing a method for interpolating the spectral intensity of observed frequencies. [Figure 19] FIG. 19 is a spectrum characteristic diagram for explaining the concept of the method of interpolating the spectrum intensity of the observed frequency. [Figure 20] Figure 20(A) is a functional block diagram showing the configuration of a water vapor observation device in a water vapor observation system related to the second embodiment of the present invention, and Figure 20(B) is a functional block diagram showing the configuration of an observation frequency setting device in the water vapor observation system related to the second embodiment of the present invention. [Figure 21] FIG. 21 is a graph showing an example of the NF characteristic of an RF amplifier. [Figure 22] FIG. 22 is a flowchart of the precision degraded frequency processing. [Figure 23] FIG. 23 is a flowchart of the water vapor observation process. [Figure 24] FIG. 24 is a functional block diagram showing the configuration of a water vapor observation system according to the third embodiment. [Diagram 25] FIG. 25 is a functional block diagram showing the configuration of a water vapor observation system according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) A water vapor observation device, a water vapor observation method, and a water vapor observation program according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a functional block diagram showing the configuration of the water vapor observation device according to the first embodiment of the present invention. Fig. 2 is a functional block diagram showing the configuration of a frequency setting unit.

[0012] (Water Vapor Observation Device 10) 1, the water vapor observation device 10 includes a calculation unit 20, an RF amplifier 30, and an antenna 40. The antenna 40 is connected to the RF amplifier 30, and the RF amplifier 30 is connected to the calculation unit 20.

[0013] The antenna 40 has a certain sensitivity to high frequency signals (RF signals) in the gigahertz band (GHz band). The antenna 40 receives the high frequency signals radiated from the atmosphere and outputs them to the RF amplifier 30. The high frequency signals radiated from the atmosphere include radio waves radiated from water vapor. The frequency spectrum of water vapor has characteristics according to the state of the water vapor, such as the amount of water vapor.

[0014] The RF amplifier 30 is a so-called LNA (low noise amplifier) ​​and has a predetermined amplification characteristic for high-frequency signals in the gigahertz band. The RF amplifier 30 is realized by a predetermined electronic circuit. The RF amplifier 30 amplifies the high-frequency signal input from the antenna 40 and outputs it as an observation signal in the RF band.

[0015] The calculation unit 20 is realized by a predetermined electronic circuit, an arithmetic processing device such as a computer, an IC, etc. The calculation unit 20 includes a frequency setting unit 21, a water vapor index calculation unit 22, and an intermediate signal processing unit .

[0016] The intermediate signal processing unit 23 includes a down-converter, an IF amplifier, etc. An observation signal in the RF band is input to the intermediate signal processing unit 23.

[0017] The intermediate signal processing unit 23 down-converts the RF band observation signal to the IF band, amplifies it, and outputs the processed observation signal. At this time, the intermediate signal processing unit 23 may include a filter circuit and perform filter processing on the down-converted observation signal. In this case, for example, the intermediate signal processing unit 23 performs filter processing so as to suppress frequency components other than the frequency band required for water vapor observation.

[0018] As shown in FIG. 2, frequency setting section 21 includes abnormal value detection section 211, accuracy degradation frequency setting section 212, and observation frequency setting section 213.

[0019] The abnormal value detection unit 211 receives an observation signal from the intermediate signal processing unit 23. The abnormal value detection unit 211 detects an abnormal value in the frequency spectrum of the observation signal. An example of a specific method for detecting an abnormal value will be described later. Here, in the present invention, an abnormal value in the frequency spectrum of the observation signal is not caused by the water vapor of the observation target, but is caused by the configuration, specifications, and external radio wave environment of the device, that is, the observation environment. For example, when an inexpensive RF amplifier 30 is used to reduce the cost of the device, the amplification factor of the RF amplifier 30 may vary due to temperature or individual differences, or the amplification factor may differ for each frequency. In such a case, an abnormal value occurs. In addition, the frequency of the water vapor spectrum may overlap with the frequency band of a specific communication system such as 5G. For this reason, when a communication signal of this communication system is included in the observation signal, an abnormal value occurs.

[0020] The precision deteriorating frequency setting unit 212 sets the frequency of the abnormal value as the precision deteriorating frequency.

[0021] The observation frequency setting unit 213 sets a plurality of observation frequencies other than the accuracy-degraded frequency from the accuracy-degraded frequency. A specific example of a method for setting the plurality of observation frequencies will be described later. The frequency setting unit 21 outputs the plurality of observation frequencies to the water vapor index calculation unit 22.

[0022] An observation signal is input to the water vapor index calculation unit 22. The water vapor index calculation unit 22 detects, from the observation signal, the spectral intensities of a plurality of observation frequencies set by the frequency setting unit 21. The water vapor index calculation unit 22 calculates a water vapor index having a high correlation with the amount of water vapor from the spectral intensities of the plurality of observation frequencies.

[0023] (Example of water vapor index calculation) 3 is a diagram showing an example of the concept of calculation of the water vapor index. The observation frequency setting unit 213 sets an observation frequency f1 and an observation frequency f2 as a plurality of observation frequencies. For example, the observation frequency f1 is generally set near the peak frequency of the frequency spectrum of water vapor (for example, near about 22 GHz). Also, for example, the observation frequency f2 is set to a frequency higher than the observation frequency f1.

[0024] The settings of the observation frequency f1 and the observation frequency f2 are not limited to this. The observation frequency f1 may be a frequency higher than the observation frequency f2. Also, the observation frequency f1 and the observation frequency f2 may be appropriately set depending on the method of calculating the water vapor index.

[0025] The water vapor index calculation unit 22 detects a spectral intensity Df1 of the observation frequency f1 and a spectral intensity Df2 of the observation frequency f2. The water vapor index calculation unit 22 calculates the water vapor index using the spectral intensity Df1 and the spectral intensity Df2.

[0026] For example, when the spectrum intensity Df1 of the observation frequency f1 and the spectrum intensity Df2 of the observation frequency f2, which are respectively set as described above, are used, it is known that a water vapor index having a high correlation with the water vapor amount can be obtained by the applicant's past inventions (for example, see the specification of U.S. Patent Application Publication No. 2014 / 0035779). The water vapor index calculation unit 22 uses this content to calculate the water vapor index using the spectrum intensity Df1 and the spectrum intensity Df2.

[0027] (Actions and Effects of the Configuration of the Water Vapor Observation Device 10) With the above-mentioned configuration, the water vapor observation device 10 detects a frequency with degraded accuracy and sets multiple observation frequencies excluding the frequency with degraded accuracy. This allows the water vapor observation device 10 to detect the spectral intensities of multiple observation frequencies that accurately reflect the amount of water vapor. The water vapor observation device 10 can then calculate the water vapor index using these spectral intensities, thereby accurately calculating the water vapor index. By using the accurately calculated water vapor index, for example, the water vapor observation device 10 can accurately observe the amount of water vapor, etc.

[0028] (Water vapor observation method according to the first embodiment) In the above description, the water vapor observation processes are performed by different functional units. However, the processes in the calculation unit 20 can be programmed and stored in a storage medium or the like, and the water vapor observation can be achieved by executing the program using a calculation processing device. In this case, the calculation processing device can execute the processes according to the flowcharts shown in Figures 4 and 5, for example. Figure 4 is a flowchart of the water vapor index calculation process. Figure 5 is a flowchart of the process of setting the accuracy degradation frequency.

[0029] The arithmetic processing device sets a precision degradation frequency using an observed signal (S11). More specifically, the arithmetic processing device generates a frequency spectrum of the observed signal (S21). The arithmetic processing device detects an abnormal value of the spectrum intensity from the frequency spectrum (S22). The arithmetic processing device sets the frequency of the abnormal value as the precision degradation frequency (S23).

[0030] The arithmetic processing device sets a plurality of observation frequencies different from the accuracy degradation frequency (S12). The arithmetic processing device detects the spectral intensities of the plurality of observation frequencies from the observation signal (S13). The arithmetic processing device calculates a water vapor index from the spectral intensities of the plurality of observation frequencies (S14).

[0031] (Example of a specific method for detecting abnormal values) In the water vapor observation device 10 of the present invention, the following multiple methods can be used to detect abnormal values. Therefore, each abnormal value detection method will be explained in order below. Note that each of these abnormal value detection methods may be performed independently, or abnormal values ​​may be detected from the results of combining multiple methods.

[0032] 6 is a flowchart showing the main processing steps in the method for detecting abnormal values. In the following, the explanation will be mainly focused on abnormal value detection section 211, but if the abnormal value detection processing is programmed, this processing is executed by the arithmetic processing device.

[0033] The abnormal value detection unit 211 sets a normal range of the spectral intensity of each frequency (frequency-specific normal range) according to the waveform of the frequency spectrum of the observed signal (S221). The abnormal value detection unit 211 uses the frequency-specific normal range to determine whether each frequency spectral intensity is within or outside the normal range.

[0034] If the spectral intensity is outside the normal range (S222: YES), abnormal value detection section 211 determines that the spectral intensity of this frequency is an abnormal value (S223). Then, accuracy-deteriorating frequency setting section 212 sets the frequency detected as the abnormal value as an accuracy-deteriorating frequency.

[0035] If the spectral intensity is within the normal range (S222: NO), abnormal value detection section 221 determines that the spectral intensity of this frequency is a normal value (S224).

[0036] (First detection method) 7 is a spectrum characteristic diagram illustrating the detection concept of the first abnormal value detection method, in which the horizontal axis indicates the frequency of the observed signal, and the vertical axis indicates the spectral intensity.

[0037] In the first detection method, the abnormal value detection unit 211 detects abnormal values ​​using a spectrum setting region ZRn. The spectrum setting region ZRn is a range in which normal spectrum intensity can be set in the frequency band of the observation signal. The spectrum setting region ZRn can be set by referring to, for example, past measurement results obtained in a noise-free state for water vapor observation, simulations, and the like.

[0038] The abnormal value detection unit 211 judges whether the spectral intensity of each frequency is abnormal or normal depending on whether it is within the spectrum setting region ZRn. More specifically, the abnormal value detection unit 211 acquires the normal range of the spectral intensity of the frequency to be judged from the spectrum setting region ZRn. If the spectral intensity of the observed signal is outside the normal range, the abnormal value detection unit 211 detects that this spectral intensity is an abnormal value.

[0039] 7, the abnormal value detection unit 211 acquires a normal range ZNna of the observation frequency fa from the spectrum setting region ZRn. The abnormal value detection unit 211 detects a spectral intensity Dfa of the observation frequency fa in the observation signal. The abnormal value detection unit 211 detects that the spectral intensity Dfa is outside the normal range ZNna, thereby detecting that the spectral intensity Dfa is an abnormal value. Then, the accuracy-deteriorating frequency setting unit 212 detects that this observation frequency fa is an accuracy-deteriorating frequency.

[0040] (Second detection method) Fig. 8 is a flowchart showing a second method for detecting an abnormal value. Fig. 9 is a spectrum characteristic diagram explaining the detection concept of the second method for detecting an abnormal value. In Fig. 9, the horizontal axis indicates the frequency of the observed signal, and the vertical axis indicates the spectral intensity.

[0041] In the second detection method, abnormal value detection unit 211 detects abnormal values ​​using approximation characteristics of spectral intensity. The approximation characteristics are set by coefficients of an approximation function calculated using spectral intensity at multiple frequencies aligned on the frequency axis. The approximation function may be a linear function or a quadratic function, but using a linear function reduces the calculation load.

[0042] Abnormal value detection section 211 shifts a plurality of frequency groups for which approximate characteristics are to be calculated on the frequency axis, and calculates approximate characteristics for each frequency group (S231). Abnormal value detection section 211 calculates the amount of change in the approximate characteristics along the frequency axis (S232).

[0043] Abnormal value detection unit 211 sets a threshold value for the amount of change in advance. If the amount of change is equal to or greater than the threshold value, abnormal value detection unit 211 determines that the amount of change is outside the normal range (S233: YES) and judges that there is an abnormality (S234). If the amount of change is equal to or less than the threshold value, abnormal value detection unit 211 determines that the amount of change is within the normal range (S233: NO) and judges that there is a normality (S235).

[0044] For example, in the example of FIG. 9, the abnormal value detection unit 211 approximates the spectral intensities of the frequencies fd3, fd2, and fd1 arranged on the frequency axis with a linear function, and the coefficient is set as the approximate characteristic Kd321. The abnormal value detection unit 211 approximates the spectral intensities of the frequencies fd2, fd1, and fa arranged on the frequency axis with a linear function, and the coefficient is set as the approximate characteristic Kd21a. The abnormal value detection unit 211 approximates the spectral intensities of the frequencies fd1, fa, and fe1 arranged on the frequency axis with a linear function, and the coefficient is set as the approximate characteristic Kdae. The abnormal value detection unit 211 approximates the spectral intensities of the frequencies fa, fe1, and fe2 arranged on the frequency axis with a linear function, and the coefficient is set as the approximate characteristic Kae12. The abnormal value detection unit 211 approximates the spectral intensities of the frequencies fe1, fe2, and fe3 arranged on the frequency axis with a linear function, and the coefficient is set as the approximate characteristic Ke123.

[0045] Next, abnormal value detection unit 211 calculates the amount of change between adjacent approximate characteristics on the frequency axis. For example, abnormal value detection unit 211 calculates the amount of change between approximate characteristic Kd321 and approximate characteristic Kd21a, and calculates the amount of change between approximate characteristic Kd21a and approximate characteristic Kdae. Abnormal value detection unit 211 calculates the amount of change between approximate characteristic Kdae and approximate characteristic Kae12, and calculates the amount of change between approximate characteristic Kae12 and approximate characteristic Ke123.

[0046] 9, when an abnormal value (spectral intensity Dfa) is included, the approximation characteristic including this spectral intensity Dfa changes significantly with respect to the approximation characteristics before and after it. Therefore, by setting a threshold value for this amount of change and detecting that it is equal to or greater than the threshold value, abnormal value detection section 211 can detect the abnormal value.

[0047] 9, the approximation characteristic including the spectral intensity Dfa, which is an abnormal value, changes significantly compared to the approximation characteristic not including the spectral intensity Dfa. Therefore, the abnormal value detection unit 211 can determine and detect that the spectral intensity Dfa is an abnormal value by detecting this. Then, the accuracy-deteriorating frequency setting unit 212 detects that the observation frequency fa having this abnormal value is an accuracy-deteriorating frequency.

[0048] (Third detection method) Fig. 10 is a flowchart showing the third method for detecting abnormal values. Fig. 11 is a spectrum characteristic diagram explaining the detection concept of the third method for detecting abnormal values. In Fig. 11, the horizontal axis indicates the frequency of the observed signal, and the vertical axis indicates the spectral intensity.

[0049] In the third detection method, as in the second detection method, the abnormal value detection unit 211 detects abnormal values ​​using the approximation characteristic of the spectral intensity. However, in the third detection method, the abnormal value detection unit 211 calculates the approximation characteristic from the spectral intensity of the entire frequency band of the observation frequency. In this case, the approximation function indicating the approximation characteristic is set by a predetermined function or the like whose waveform is similar to the water vapor spectrum. This function can be appropriately set, for example, from past observation results of water vapor.

[0050] The outlier detection unit 211 calculates an approximate characteristic from the spectral intensity of the entire frequency band of the observed frequency (S241). The outlier detection unit 211 sets a normal range that takes into account the observation error for the spectral intensity (estimated spectral intensity) of each frequency of the approximate characteristic (S242).

[0051] If the spectral intensity is outside the normal range (S243: YES), abnormal value detection section 211 determines that the spectral intensity is abnormal (S244). If the spectral intensity is within the normal range (S243: NO), abnormal value detection section 211 determines that the spectral intensity is normal (S245).

[0052] For example, in the example of FIG. 11, abnormal value detection section 211 calculates approximate characteristic REF from the spectrum intensity of the entire frequency band of observed frequencies.

[0053] Next, the abnormal value detection unit 211 sets an upper threshold THmax and a lower threshold THmin for the approximate characteristic REF. The abnormal value detection unit 211 sets the intensity range between the upper threshold THmax and the lower threshold THmin as a normal range ZNn. The abnormal value detection unit 211 compares the spectrum intensity with the normal range ZNn for each observation frequency.

[0054] 11, at the observation frequency fa, the spectral intensity Dfa is outside the normal range ZNn. Therefore, the abnormal value detection unit 211 can determine and detect that the spectral intensity Dfa is an abnormal value by detecting this. Then, the accuracy-deteriorating frequency setting unit 212 detects that the observation frequency fa having this abnormal value is an accuracy-deteriorating frequency.

[0055] Such detection of abnormal values ​​may be performed, for example, in a predetermined frequency range FROB including the peak frequency of the water vapor spectrum or in a specific frequency range of interference waves, as shown in Fig. 11. This reduces the computation load without reducing the accuracy of water vapor observation. Note that setting such a frequency range FROB for judgment is also applicable to the first and second detection methods.

[0056] (Fourth detection method) Fig. 12 is a flowchart showing a fourth method for detecting abnormal values. Fig. 13 is a spectrum characteristic diagram explaining the detection concept of the fourth method for detecting abnormal values. In Fig. 13, the horizontal axis shows the frequency of the observed signal, and the vertical axis shows the spectrum intensity.

[0057] In the fourth detection method, abnormal value detection section 211 detects abnormal values ​​using the difference in spectral intensity between adjacent frequencies.

[0058] Abnormal value detection section 211 calculates the amount of change between the spectral intensities of adjacent frequencies (S251).

[0059] If the amount of change in the spectral intensity is outside the normal range (S252: YES), abnormal value detection section 211 determines an abnormality (S253). If the amount of change in the spectral intensity is within the normal range (S252: NO), abnormal value detection section 211 determines a normality (S254).

[0060] 13, the abnormal value detection unit 211 calculates the amount of change ΔDab between the spectral intensity Dfa of the observation frequency fa and the spectral intensity Dfb of the observation frequency fb. The abnormal value detection unit 211 calculates the amount of change ΔDbc between the spectral intensity Dfb of the observation frequency fb and the spectral intensity Dfc of the observation frequency fc.

[0061] An abnormal value detection unit 211 sets a threshold value for the amount of change in advance. The threshold value is set based on the amount of change when no abnormal value exists, and can be set appropriately based on past observation results, etc.

[0062] The abnormal value detection unit 211 detects that the amount of change ΔDab is larger than the threshold value and detects that there is an abnormal value. The abnormal value detection unit 211 also detects that the amount of change ΔDbc is smaller than the threshold value and detects that there is no abnormal value. From these results, the abnormal value detection unit 211 determines and detects that the spectral intensity Dfa of the observation frequency fa included only in the amount of change ΔDab is an abnormal value, not the spectral intensity Dfb of the observation frequency fb included in both amounts of change. Then, the accuracy-deteriorating frequency setting unit 212 detects that the observation frequency fa having this abnormal value is an accuracy-deteriorating frequency.

[0063] Such abnormal value detection may be performed, for example, only in a predetermined frequency range FROB including the peak frequency of the water vapor spectrum or in a frequency range of a specific jamming wave, as shown in Fig. 13. This makes it possible to reduce the computational load without reducing the accuracy of water vapor observation.

[0064] (Fifth detection method) Fig. 14 is a flow chart showing the fifth method for detecting abnormal values. Fig. 15(A) and Fig. 15(B) are spectral characteristic diagrams explaining the detection concept of the fifth method for detecting abnormal values. Fig. 15(A) and Fig. 15(B) show spectral characteristics at different observation times. In Fig. 15(A) and Fig. 15(B), the horizontal axis shows the frequency of the observed signal, and the vertical axis shows the spectral intensity.

[0065] In the fifth detection method, abnormal value detection section 211 detects abnormal values ​​using the time characteristic (amount of change over time) of the spectral intensity.

[0066] Outlier detection section 211 calculates the spectral intensity of each observed frequency at time t1 (S261). Outlier detection section 211 calculates the spectral intensity of each observed frequency at time t2 (a time different from time t1) (S262).

[0067] Abnormal value detection section 211 calculates the time characteristic of the frequency spectrum, specifically, the amount of change over time in the spectrum intensity at each observed frequency (S263).

[0068] If the amount of change in the spectral intensity is outside the normal range (S264: YES), abnormal value detection section 211 determines an abnormality (S265). If the amount of change in the spectral intensity is within the normal range (S264: NO), abnormal value detection section 211 determines a normality (S256).

[0069] For example, in the example of FIG. 15, abnormal value detection section 211 calculates the amount of change over time between the spectral intensity Dfd(t1) of observation frequency fd at time t1 and the spectral intensity Dfd(t2) of observation frequency fd at time t2.

[0070] Abnormal value detection section 211 sets a threshold value for the amount of change over time in advance. The threshold value is set based on the amount of change when no abnormal value exists, and can be set appropriately based on past observation results, etc.

[0071] The abnormal value detection unit 211 detects that the amount of change over time in the observation frequency fd is greater than a threshold value and detects the presence of an abnormal value. Then, the accuracy-deteriorating frequency setting unit 212 detects that the observation frequency fd having this abnormal value is an accuracy-deteriorating frequency.

[0072] (How to change the observation frequency) Fig. 16 is a flowchart showing a method for switching the observation frequency. Fig. 17 is a spectrum characteristic diagram explaining the concept of the method for switching the observation frequency. Note that, although the following mainly describes the observation frequency setting unit 213, if the observation frequency switching process is programmed, the arithmetic processing unit executes this process.

[0073] When the observation frequency setting unit 213 detects an observation frequency that has been used for water vapor observation up until now, in other words, that has been provided to the water vapor index calculation unit 22, as an accuracy-deteriorating frequency (S31: YES), it sets an adjacent frequency (one frequency in the frequency spectrum) as a new observation frequency (S32). At this time, if the observation frequency setting unit 213 determines that the adjacent frequency is also an accuracy-deteriorating frequency, it further sets the adjacent frequency as a new observation frequency.

[0074] For example, in the example of FIG. 17, the spectral intensity Dfa of the observation frequency fa is an abnormal value, and the observation frequency setting unit 213 sets the observation frequency fa as the accuracy-deteriorating frequency. The observation frequency setting unit 213 sets the frequency fb adjacent to the observation frequency fa as the new observation frequency. When such processing is performed, an error in the water vapor index may occur due to switching of the observation frequency. However, the magnitude of the error can be made sufficiently small compared to the error that occurs when an abnormal value is used. Therefore, the water vapor observation device 10 can calculate the water vapor index while suppressing accuracy deterioration.

[0075] In the above description, a frequency on the higher frequency side than the accuracy degraded frequency is set as the new observation frequency, but a frequency on the lower frequency side may be set as the new observation frequency. Also, the frequency to be switched to may not be adjacent to the accuracy degraded frequency, but may be a frequency in the vicinity.

[0076] (Interpolation method for the spectral intensity of observed frequencies) Fig. 18 is a flowchart showing a method for interpolating the spectral intensity of the observation frequency. Fig. 19 is a spectrum characteristic diagram explaining the concept of the method for interpolating the spectral intensity of the observation frequency. Note that, in the following, the observation frequency setting unit 213 and the water vapor index calculation unit 22 will be mainly described, but if the process of switching to the observation frequency is programmed, the arithmetic processing unit executes this process.

[0077] When the observation frequency setting unit 213 detects an observation frequency that has been used for water vapor observation, in other words, that has been provided to the water vapor index calculation unit 22, as an accuracy-deteriorating frequency (S41: YES), it sets adjacent frequencies on both sides of the frequency axis (one frequency in the frequency spectrum) as an interpolation frequency (S42). At this time, if the adjacent frequencies are also determined to be accuracy-deteriorating frequencies, the observation frequency setting unit 213 further sets the adjacent frequencies as interpolation frequencies.

[0078] The water vapor index calculation unit 22 detects the spectral intensity of the observation frequency for interpolation, and calculates the spectral intensity of the original observation frequency (the observation frequency determined to be the accuracy-degraded frequency) from the spectral intensity of the interpolation frequency (S43).

[0079] 19, the spectrum intensity Dfa of the observation frequency fa is an abnormal value, and the observation frequency setting unit 213 sets the observation frequency fa as the accuracy deteriorating frequency. The observation frequency setting unit 213 sets the frequencies fb1 and fb2 adjacent to both sides of the observation frequency fa as the interpolation frequencies.

[0080] The water vapor index calculation unit 22 detects a spectral intensity Dfb1 of an interpolation frequency fb1 and a spectral intensity Dfb2 of an interpolation frequency fb2. The water vapor index calculation unit 22 calculates an interpolated spectral intensity Dfac of an observation frequency fa from the spectral intensity Dfb1 and the spectral intensity Dfb2. Specifically, for example, the water vapor index calculation unit 22 calculates the interpolated spectral intensity Dfac by a weighted average value or the like according to the frequency separation amount (sampling frequency or the like).

[0081] By performing such processing, the water vapor observation device 10 can accurately calculate the water vapor index without changing the apparent observation frequency.

[0082] Second embodiment In each of the above-mentioned methods, the spectrum of the observed frequency is actually generated, and then the degraded frequency is set. However, by using the following configuration and method, the degraded frequency can be set without generating the spectrum of the observed frequency.

[0083] (Water vapor observation system configuration) Fig. 20(A) is a functional block diagram showing the configuration of a water vapor observation device in a water vapor observation system according to a second embodiment of the present invention. Fig. 20(B) is a functional block diagram showing the configuration of an observation frequency setting device in the water vapor observation system according to the second embodiment of the present invention.

[0084] The water vapor observation system includes a water vapor observation device 10A shown in FIG. 20(A) and an observation frequency setting device shown in FIG. 20(B).

[0085] 20(A), the water vapor observation device 10A according to the second embodiment includes a calculation unit 20A, an RF amplifier 30, an antenna 40, and an input unit 50. The calculation unit 20A includes a water vapor index calculation unit 22 and an intermediate signal processing unit 23. The RF amplifier 30, the antenna 40, the water vapor index calculation unit 22, and the intermediate signal processing unit 23 are similar to those of the water vapor observation device 10 according to the first embodiment, and therefore descriptions of similar parts will be omitted.

[0086] The input unit 50 accepts input of an observation frequency set by an observation frequency setting device 60 described below. The input unit 50 outputs the input observation frequency to the water vapor index calculation unit 22. The water vapor index calculation unit 22 calculates the water vapor index using this observation frequency.

[0087] As shown in FIG. 20(B), the observation frequency setting device 60 includes an NF characteristic measuring unit 61 and a frequency setting unit 62.

[0088] The NF characteristic measuring unit 61 is configured by, for example, an NF meter etc. The NF characteristic measuring unit 61 measures the NF characteristic of the RF amplifier 30. The NF characteristic measuring unit 61 outputs the measurement result of the NF characteristic to the frequency setting unit 62.

[0089] The frequency setting unit 62 uses the measurement results of the NF characteristics to set a plurality of observation frequencies excluding the accuracy degraded frequency.

[0090] Fig. 21 is a graph showing an example of NF characteristics of an RF amplifier. Generally, as shown in Fig. 21, an RF amplifier such as an LNA has a frequency band BFex with a high NF and a frequency band BFad with a low NF.

[0091] The signal strength of radio waves due to water vapor is very weak, and the impact of this NF is large, which significantly affects the calculation error of the water vapor index.

[0092] The frequency setting unit 62 sets the frequency band BFex with a high NF to the frequency band of the accuracy degraded frequency. The frequency setting unit 62 sets a plurality of observation frequencies so as to exclude the frequency band of the accuracy degraded frequency. More preferably, the frequency setting unit 62 sets a plurality of observation frequencies within the frequency band BFex with a low NF.

[0093] By performing such configuration and processing, a plurality of observation frequencies set so as to exclude the frequency band of the accuracy-deteriorating frequency are input to the water vapor index calculation unit 22. Therefore, the water vapor index calculation unit 22 can calculate the water vapor index with high accuracy. Furthermore, by setting a plurality of observation frequencies in the frequency band BFex with a low NF, that is, in the frequency band where a highly accurate spectrum intensity can be obtained, the water vapor index calculation unit 22 can calculate the water vapor index with even higher accuracy.

[0094] (Water vapor observation method according to the second embodiment) In the above description, an embodiment has been shown in which each process of water vapor observation is executed by a different functional unit for each process. However, it is also possible to realize the above-mentioned water vapor observation by programming the processes in the above-mentioned water vapor observation system and storing them in a storage medium or the like, and executing this program with a calculation processing device. In this case, the calculation processing device may execute the processes according to the flowcharts shown in Figures 22 and 23, for example. Figure 22 is a flowchart of the accuracy degradation frequency processing. Figure 23 is a flowchart of the water vapor observation processing.

[0095] 22, the arithmetic processing device measures the NF characteristics of an LNA (RF amplifier) ​​(S51). The arithmetic processing device sets a frequency band with a high NF as a frequency band of accuracy-deteriorating frequencies (S52).

[0096] As shown in Fig. 23, the arithmetic processing device detects a high-precision frequency band in the vicinity of the peak frequency of the spectral intensity of the water vapor index (S61). The peak frequency of the spectral intensity of the water vapor index can be detected from a frequency spectrum of water vapor previously acquired. In addition, the high-precision frequency band can be acquired from the NF characteristics, and is a frequency band different from the frequency band of the accuracy degraded frequency.

[0097] The calculation processing device sets an observation frequency near the peak frequency within the high-precision frequency band (S62).

[0098] The arithmetic processing device sets at least one observation frequency in addition to the observation frequency in the vicinity of the peak frequency, and detects the spectral intensities of the plurality of observation frequencies (S63).

[0099] The calculation processing device calculates the water vapor index from the spectral intensities of the multiple observed frequencies (S64).

[0100] By such processing, the arithmetic processing device can calculate the water vapor index with high accuracy. Note that the arithmetic processing device can calculate the water vapor index with high accuracy by setting the observation frequency excluding the frequency band of the accuracy-deteriorating frequency, and can calculate the water vapor index with a predetermined accuracy even if the observation frequency is set to a frequency away from the peak frequency.

[0101] However, the calculation processing device can calculate the water vapor index more accurately by setting the observation frequency in the high-precision frequency band, and can calculate the water vapor index even more accurately by setting the observation frequency in the vicinity of the peak frequency.

[0102] (Third embodiment) In the above-described first embodiment, a water vapor observation system including the calculation of the water vapor index is configured by a single water vapor observation device. However, a water vapor observation system similar to the water vapor observation device according to the first embodiment can be configured by using a data communication network.

[0103] FIG. 24 is a functional block diagram showing the configuration of a water vapor observation system according to the third embodiment.

[0104] As shown in Fig. 24, the water vapor observation system 1B includes a water vapor observation device 10B and an information processing device 80. The water vapor observation device 10B and the information processing device 80 are connected via a data communication network 90. ​​The information processing device 80 can be realized, for example, by a personal computer or the like. The data communication network 90 can be realized by the Internet, a LAN, or the like.

[0105] The water vapor observation device 10B includes a calculation unit 20B, an RF amplifier 30, an antenna 40, and a transmission / reception unit 70. The calculation unit 20B includes a water vapor index calculation unit 22 and an intermediate signal processing unit 23. The transmission / reception unit 70 is connected to the water vapor index calculation unit 22. The transmission / reception unit 70 has an interface function of the water vapor observation device 10B to the data communication network 90.

[0106] The information processing device 80 includes a CPU 81, a storage unit 82, a transmission / reception unit 83, a display unit 84, and an operation unit 85. The CPU 81, the storage unit 82, the transmission / reception unit 83, the display unit 84, and the operation unit 85 are connected by a data bus.

[0107] The CPU 81 executes each process by executing a program stored in the storage unit 82. For example, the CPU 81 functions as a frequency setting unit 811 by executing a frequency setting program stored in the storage unit 82. The frequency setting unit 811 performs the same process as the frequency setting unit 21 described above. The CPU 81 also functions as a water vapor observation unit 812 by executing a water vapor observation program stored in the storage unit. The water vapor observation unit 812 observes a water vapor index, a water vapor amount, and the like.

[0108] The storage unit 82 stores various programs executed by the CPU 81, and also stores the water vapor index from the water vapor observation device 10B. The storage unit 82 may not be included in the information processing device 80, but may be external and connected to the data communication network 90 (for example, a server, etc.).

[0109] The transmitter / receiver 83 has an interface function of the information processing device 80 with the data communication network 90. ​​The display unit 84 is realized by a liquid crystal display or the like, and can display water vapor observation results, water vapor indices, frequency spectra of observed signals, etc. The operation unit 85 is realized by a keyboard, mouse, touch panel, etc., and accepts operation inputs related to water vapor observation.

[0110] Even with this configuration, the water vapor observation system 1B can achieve the same effects as the water vapor observation device 10 described above.

[0111] (Fourth embodiment) The water vapor observation system according to the fourth embodiment differs from the observation system according to the third embodiment in that the calculation of the water vapor index is performed on the information processing device side. The other configuration of the water vapor observation system according to the fourth embodiment is the same as that of the water vapor observation system according to the third embodiment, and the description of the similar parts will be omitted.

[0112] FIG. 25 is a functional block diagram showing the configuration of a water vapor observation system according to the fourth embodiment.

[0113] 25, the water vapor observation system 1C includes a water vapor observation device 10C and an information processing device 80C. The water vapor observation device 10C and the information processing device 80C are connected via a data communication network 90.

[0114] The water vapor observation device 10C includes a calculation unit 20C. The calculation unit 20C includes a frequency spectrum generation unit 24 and an intermediate signal processing unit 23. The frequency spectrum generation unit 24 generates a frequency spectrum of the observation signal. The frequency spectrum generation unit 24 transmits the generated frequency spectrum to the information processing device 80C via the transmission / reception unit 70 and the data communication network 90.

[0115] The information processing device 80C includes a CPU 81C. In addition to the processing of the CPU 81 according to the third embodiment, the CPU 81C executes a water vapor index calculation program stored in a storage unit to function as a water vapor index calculation unit 810. The water vapor index calculation unit 810 is similar to the above-mentioned water vapor index calculation unit 22, and calculates a water vapor index from a plurality of observed frequency spectrum intensities.

[0116] Even with this configuration, the water vapor observation system 1B can achieve the same effects as the water vapor observation device 10 described above.

[0117] Furthermore, it is also possible to configure the calculation section of the water vapor observation device only with the intermediate signal processing section 23, and to provide the function of the frequency spectrum generating section 24 to an information processing device.

[0118] Furthermore, the configurations and processes of the above-described embodiments can be combined as appropriate, and effects according to each combination can be achieved. [Explanation of symbols]

[0119] 1B, 1C: Water vapor observation system 10, 10A, 10B, 10C: Water vapor observation equipment 20, 20A, 20B, 20C: Arithmetic section 21: Frequency setting section 22: Water vapor index calculation unit 23: Intermediate signal processing section 24: Frequency spectrum generation section 30: RF amplifier 40: Antenna 50: Input section 60: Observation frequency setting device 61: NF characteristic measurement section 62: Frequency setting section 70: Transmitter / receiver 80, 80C: Information processing device 81, 81C: CPU 82: Storage section 83: Transmitter / receiver 84: Display section 85:Operation unit 90: Data communication network 211: Abnormal value detection unit 212: Precision degradation frequency setting unit 213: Observation frequency setting unit 221: Abnormal value detection unit 810: Water vapor index calculation unit 811: Frequency setting unit 812: Water Vapor Observation Section

Claims

1. an antenna for receiving radio waves emitted from the atmosphere containing water vapor; an RF amplifier that amplifies the received radio waves to generate an observation signal; a frequency setting unit that sets a plurality of observation frequencies excluding a precision-degraded frequency based on the observation signal; a water vapor index calculation unit that calculates a water vapor index using the spectral intensities of the plurality of observed frequencies; Equipped with The frequency setting unit is an abnormal value detection unit that detects abnormal values ​​in a frequency spectrum of the observed signal; an accuracy degradation frequency setting unit that sets the frequency of the abnormal value as the accuracy degradation frequency; an observation frequency setting unit that sets the plurality of observation frequencies excluding the accuracy degraded frequency; Equipped with The abnormal value detection unit detecting the abnormal value by using an approximate frequency characteristic based on the spectral intensities of a plurality of frequencies arranged on a frequency axis of the frequency spectrum; Water vapor observation device.

2. An antenna for receiving radio waves emitted from the atmosphere containing water vapor; an RF amplifier that amplifies the received radio waves to generate an observation signal; a frequency setting unit that sets a plurality of observation frequencies excluding a precision-degraded frequency based on the observation signal; a water vapor index calculation unit that calculates a water vapor index using the spectral intensities of the plurality of observed frequencies; Equipped with The frequency setting unit is an abnormal value detection unit that detects abnormal values ​​in a frequency spectrum of the observed signal; an accuracy degradation frequency setting unit that sets the frequency of the abnormal value as the accuracy degradation frequency; an observation frequency setting unit that sets the plurality of observation frequencies excluding the accuracy degraded frequency; Equipped with The abnormal value detection unit detecting the abnormal value based on a difference in spectral intensity between adjacent frequencies arranged on a frequency axis of the frequency spectrum; Water vapor observation device.

3. An antenna for receiving radio waves emitted from the atmosphere containing water vapor; an RF amplifier that amplifies the received radio waves to generate an observation signal; a frequency setting unit that sets a plurality of observation frequencies excluding a precision-degraded frequency based on the observation signal; a water vapor index calculation unit that calculates a water vapor index using the spectral intensities of the plurality of observed frequencies; Equipped with The frequency setting unit is an abnormal value detection unit that detects abnormal values ​​in a frequency spectrum of the observed signal; an accuracy degradation frequency setting unit that sets the frequency of the abnormal value as the accuracy degradation frequency; an observation frequency setting unit that sets the plurality of observation frequencies excluding the accuracy degraded frequency; Equipped with The observation frequency setting unit is a frequency adjacent to the accuracy degraded frequency in the frequency spectrum of the observation signal is set to at least one of the plurality of observation frequencies; Water vapor observation device.

4. An antenna for receiving radio waves radiated from the atmosphere containing water vapor; an RF amplifier that amplifies the received radio waves to generate an observation signal; a frequency setting unit that sets a plurality of observation frequencies excluding a precision-degraded frequency based on the observation signal; a water vapor index calculation unit that calculates a water vapor index using the spectral intensities of the plurality of observed frequencies; Equipped with The frequency setting unit is an abnormal value detection unit that detects abnormal values ​​in a frequency spectrum of the observed signal; an accuracy degradation frequency setting unit that sets the frequency of the abnormal value as the accuracy degradation frequency; an observation frequency setting unit that sets the plurality of observation frequencies excluding the accuracy degraded frequency; Equipped with The observation frequency setting unit is Two frequencies sandwiching the accuracy degraded frequency on a frequency axis are set as interpolation frequencies; The water vapor index calculation unit calculating a spectral intensity of the observation frequency, which is the same frequency as the precision degraded frequency, from the spectral intensity of the interpolation frequency; Water vapor observation device.

5. A water vapor observation device comprising: an antenna for receiving radio waves radiated from the atmosphere containing water vapor; an RF amplifier for amplifying the received radio waves to generate an observation signal; a frequency setting unit for setting a plurality of observation frequencies excluding accuracy-deteriorating frequencies based on the observation signal; and a water vapor index calculation unit for calculating a water vapor index using the spectral intensities of the plurality of observation frequencies; An NF characteristic measuring unit that measures the NF characteristic of the RF amplifier; Equipped with The frequency setting unit is setting the plurality of observation frequencies using the measurement results of the NF characteristics; Water vapor observation system.

6. The water vapor observation device according to claim 1, The abnormal value detection unit Set a normal range of the spectral intensity that water vapor can exhibit for each frequency, detecting the abnormal value from a spectrum intensity of a frequency where the spectrum intensity falls outside the normal range; Water vapor observation device.

7. A water vapor observation device as claimed in claim 1, The abnormal value detection unit calculating the abnormal value using the approximate frequency characteristic obtained from the spectral intensities of three frequencies adjacent on the frequency axis; Water vapor observation device.

8. A water vapor observation device according to claim 1 or claim 7, The abnormal value detection unit A normal range for each frequency is set based on the approximate frequency characteristics, detecting the abnormal value from a spectrum intensity of a frequency where the spectrum intensity falls outside the frequency-specific normal range; Water vapor observation device.

9. A water vapor observation device according to any one of claims 1, 6, 7, and 8, The abnormal value detection unit Detecting the abnormal value from a time change of the frequency spectrum. Water vapor observation device.

10. The water vapor observation device according to claim 2, The abnormal value detection unit Detecting the abnormal value from a time change of the frequency spectrum. Water vapor observation device.

11. It receives radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the observation frequency, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; In the detection of the abnormal value, detecting the abnormal value by using an approximate frequency characteristic based on the spectral intensities of a plurality of frequencies arranged on a frequency axis of the frequency spectrum; Water vapor observation methods.

12. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; In the detection of the abnormal value, detecting the abnormal value based on a difference in spectral intensity between adjacent frequencies arranged on a frequency axis of the frequency spectrum; Water vapor observation methods.

13. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; Excluding the accuracy degradation frequency, a frequency adjacent to the accuracy degraded frequency in the frequency spectrum of the observation signal is set to at least one of the plurality of observation frequencies; Water vapor observation methods.

14. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; Two frequencies sandwiching the accuracy degraded frequency on a frequency axis are set as interpolation frequencies; In the calculation of the water vapor index, calculating a spectral intensity of the observation frequency, which is the same frequency as the precision degraded frequency, from the spectral intensity of the interpolation frequency; Water vapor observation methods.

15. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; measuring the NF characteristic of an RF amplifier that generates the observation signal; The plurality of observation frequencies are set using the measurement results of the NF characteristics. Water vapor observation methods.

16. It receives radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the observation frequency, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; In the detection of the abnormal value, detecting the abnormal value by using an approximate frequency characteristic based on the spectral intensities of a plurality of frequencies arranged on a frequency axis of the frequency spectrum; A water vapor observation program that causes a processing unit to execute the processing.

17. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; In the detection of the abnormal value, detecting the abnormal value based on a difference in spectral intensity between adjacent frequencies arranged on a frequency axis of the frequency spectrum; A water vapor observation program that causes a processing unit to execute the processing.

18. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; Excluding the accuracy degradation frequency, a frequency adjacent to the accuracy degraded frequency in the frequency spectrum of the observation signal is set to at least one of the plurality of observation frequencies; A water vapor observation program that causes a processing unit to execute the processing.

19. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; In setting the plurality of observation frequencies, Detecting an anomaly in a frequency spectrum of the observed signal; The frequency of the abnormal value is set as the precision degradation frequency; setting the plurality of observation frequencies excluding the accuracy-degraded frequency; Two frequencies sandwiching the accuracy degraded frequency on a frequency axis are set as interpolation frequencies; In the calculation of the water vapor index, calculating a spectral intensity of the observation frequency, which is the same frequency as the precision degraded frequency, from the spectral intensity of the interpolation frequency; A water vapor observation program that causes a processing unit to execute the processing.

20. A method of receiving radio waves emitted from the atmosphere containing water vapor, The received radio waves are amplified to generate an observation signal, Based on the observation signal, a plurality of observation frequencies are set excluding a precision degraded frequency in the observation signal; Calculating a water vapor index using the spectral intensities of the plurality of observed frequencies; measuring the NF characteristic of an RF amplifier that generates the observation signal; The plurality of observation frequencies are set using the measurement results of the NF characteristics. A water vapor observation program that causes a processing unit to execute the processing.

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