Waveguide / scattering mode discrimination method based on evaporation waveguide height

Abstract

The invention discloses a waveguide / scattering mode discrimination method based on an evaporation waveguide height, and the method comprises the steps: setting an interval to which an evaporation waveguide height critical value belongs when an electric wave communication mode is switched, and setting a threshold value of the interval length; taking the midpoint of the interval as an initial value of an evaporation waveguide height critical value; whether the interval length exceeds a threshold value or not is judged; if the interval length is larger than the threshold value, iterative calculation is carried out; calculating the abscissa of the intersection point of the evaporation waveguide and the radio wave propagation loss in the troposphere scattering mode; the final value of the critical value is obtained through iterative calculation; and obtaining a predicted evaporation waveguide height value, comparing the predicted evaporation waveguide height value with the final value, if the predicted evaporation waveguide height value is smaller than the final value, determining troposphere scattering, otherwise, determining evaporation waveguide. The maritime beyond visual range communication mode is judged according to the evaporation waveguide height critical value, continuous switching of the communication mode is better adapted, guidance is provided for adjustment and optimization of communication system parameters, and the performance of the communication system is improved.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of wireless communication technologies, and in particular, to a method for discriminating waveguide / scattering modes based on the height of an evaporation duct. Background Art

[0002] Except for satellite communication, evaporation ducts and tropospheric scatterings are two main ways to achieve over-the-horizon (OTH) communication at sea. Making full use of evaporation ducts and tropospheric scatterings can adjust and optimize the parameters of an OTH communication system at sea, and thus improve the communication rate of the OTH communication system at high speed at sea.

[0003] An evaporation duct is formed due to the evaporation and diffusion of water vapor on the sea surface. The atmospheric humidity above the sea surface decreases sharply with height, causing radio waves to refract downward and be trapped in the evaporation duct layer, greatly reducing the path loss of radio wave propagation and ultimately achieving OTH communication at sea.

[0004] Tropospheric scattering refers to another way to achieve OTH communication at sea by using a large number of scatterers (mainly various vortex air masses, clouds, warm fronts, cold fronts, horizontal stratifications, etc.) in the troposphere to refract and re-radiate microwaves and millimeter waves.

[0005] Affected by the complex marine weather, the OTH communication mode at sea will continuously switch between evaporation ducts and tropospheric scatterings: when the height of the evaporation duct is high and the communication distance is short, OTH communication at sea is achieved through the evaporation duct; when the height of the evaporation duct is low and the communication distance is long, OTH communication at sea is achieved through tropospheric scattering. Currently, existing models can only calculate the radio wave propagation loss in the evaporation duct or tropospheric scattering mode, and cannot directly discriminate the current radio wave propagation mode based on the height of the evaporation duct, so that parameters such as the operating frequency and antenna height of the OTH communication system at sea cannot be adjusted and optimized in a timely manner according to the height of the evaporation duct, thereby affecting the communication rate of the system.

[0006] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0007] It should be noted that this part is intended to provide background or context for the technical solutions of the present disclosure stated in the claims. The description herein is not admitted to be prior art merely because it is included in this part. Summary of the Invention

[0008] The purpose of the embodiments of the present disclosure is to provide a method for discriminating waveguide / scattering modes based on the height of an evaporation duct, so as to at least overcome one or more problems caused by the limitations and defects of the related technologies to a certain extent.

[0009] An embodiment of the present disclosure provides a method for discriminating waveguide / scattering modes based on the height of evaporation ducts, including: Set the interval to which the critical value of the evaporation duct height belongs when the radio communication mode switches, and set the threshold value for the interval length of the critical value of the evaporation duct height; Take the midpoint of the interval to which the critical value of the evaporation duct height belongs as the initial value of the critical value of the evaporation duct height; Determine whether the interval length of the critical value of the evaporation duct height exceeds the threshold value: if the interval length of the critical value of the evaporation duct height is less than or equal to the threshold value, take the initial value as the final value of the critical value of the evaporation duct height; if the interval length of the critical value of the evaporation duct height is greater than the threshold value, perform iterative calculation on the critical value of the evaporation duct height; When the marine communication distance is greater than the radio wave propagation limit distance, use the iteratively calculated critical value of the evaporation duct height and communication system parameters to calculate the abscissa of the intersection coordinates of the radio wave propagation loss in the evaporation duct mode and the radio wave propagation loss in the tropospheric scattering mode; According to the magnitude relationship between the abscissa and the marine communication distance, obtain the final value of the critical value of the evaporation duct height when the radio communication mode switches at the marine communication distance through iterative calculation; Obtain the meteorological data in the radio communication area, input the meteorological data into the evaporation duct height prediction model to obtain the predicted evaporation duct height value, compare the predicted evaporation duct height value with the final value, if the predicted evaporation duct height value is less than the final value, determine that the current radio communication mode is the tropospheric scattering mode, otherwise it is the evaporation duct mode.

[0010] In an embodiment of the present disclosure, the value range of the threshold value is: less than or equal to 0.01.

[0011] In an embodiment of the present disclosure, the iterative calculation of the critical value of the evaporation duct height is performed using the bisection method.

[0012] In an embodiment of the present disclosure, the step of obtaining the final value of the critical value of the evaporation duct height when the radio communication mode switches at the marine communication distance through iterative calculation according to the magnitude relationship between the abscissa and the marine communication distance includes: When the abscissa is greater than the marine communication distance, set the maximum value within the interval to which the critical value of the evaporation duct height belongs equal to the critical value of the evaporation duct height to narrow the upper limit of the critical value of the evaporation duct height; When the abscissa is less than the marine communication distance, set the minimum value within the interval to which the critical value of the evaporation duct height belongs equal to the critical value of the evaporation duct height to increase the lower limit of the critical value of the evaporation duct height; When the abscissa is equal to the maritime communication distance, the midpoint of the interval where the critical value of the evaporation duct height is located is used as the final value of the critical value of the evaporation duct height.

[0013] In an embodiment of the present disclosure, the communication system parameters include: the operating frequency of the communication system, the height of the transmitting antenna, and the height of the receiving antenna.

[0014] In an embodiment of the present disclosure, the meteorological data includes: relative humidity, sea surface atmospheric pressure, sea surface temperature, air temperature above the sea surface, and wind speed component above the sea surface.

[0015] In an embodiment of the present disclosure, the discrimination method further includes: Comparing the propagation loss with the measured loss value to verify the discrimination accuracy of the discrimination method.

[0016] In an embodiment of the present disclosure, the discrimination method further includes: Comparing the predicted evaporation duct height value with the final value of the critical value of the evaporation duct height to verify the discrimination accuracy of the discrimination method.

[0017] The technical solution provided by the embodiment of the present disclosure may include the following beneficial effects: A waveguide / scattering mode discrimination method based on the evaporation duct height in an embodiment of the present disclosure calculates the critical value of the evaporation duct height when the waveguide / scattering mode switches by using communication system parameters, etc., and then discriminates the mode of over-the-horizon communication at sea according to this critical value. The discrimination method of the present application can better adapt to the continuous switching between the evaporation duct and tropospheric scattering in the over-the-horizon communication mode at sea by using the calculated critical value of the evaporation duct height, and provides guidance for the adjustment and optimization of parameters such as the transmission power, operating frequency, and the height of the transmitting and receiving antennas of the over-the-horizon communication system at sea, so that it can make more full use of the evaporation duct to improve performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0019] Figure 1 A flowchart showing a waveguide / scattering mode discrimination method based on the evaporation duct height in an exemplary embodiment of the present disclosure; Figure 2 A flowchart showing a waveguide / scattering mode discrimination method based on the evaporation duct height in another exemplary embodiment of the present disclosure; Figure 3 Schematic diagram showing the iterative process of the critical value EDH at different communication distances in the 7960 MHz frequency band in an exemplary embodiment of the present disclosure; Figure 4 Effect diagram of the application in the measured data of a 188 km link on June 16, 2024 in an exemplary embodiment of the present disclosure; Figure 5 Effect diagram of the application in the measured data of a 188 km link on June 18, 2024 in an exemplary embodiment of the present disclosure; Figure 6 Effect diagram of the application in the measured data of a 188 km link on June 19, 2024 in an exemplary embodiment of the present disclosure. Detailed implementation manners

[0020] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments.

[0021] In addition, the accompanying drawings are only schematic illustrations of the embodiments of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0022] In this example embodiment, a waveguide / scattering mode discrimination method based on the evaporation duct height is provided. Please refer to Figure 1 , and this method includes: S101 - S106. Specifically as follows: S101, set the interval to which the critical value of the evaporation duct height belongs when the radio communication mode switches, and set the threshold value of the interval length of the critical value of the evaporation duct height. The two endpoints of the interval to which the critical value of the evaporation duct height belongs are respectively the minimum value and the maximum value of the critical value of the evaporation duct height. Setting the threshold value of the interval length of the critical value of the evaporation duct height means setting the threshold value for the difference between the maximum value and the minimum value of the interval. Among them, the value range of the threshold value is: less than or equal to 0.01.

[0023] S102, use the midpoint of the interval to which the critical value of the evaporation duct height belongs as the initial value of the critical value of the evaporation duct height. This initial value serves as the starting value for the iterative calculation of the critical value of the evaporation duct height in the subsequent process.

[0024] S103. Determine whether the interval length of the evaporation duct height critical value exceeds the threshold value: If the interval length of the evaporation duct height critical value is less than or equal to the threshold value, use the initial value as the final value of the evaporation duct height critical value; if the interval length of the evaporation duct height critical value is greater than the threshold value, perform iterative calculation on the evaporation duct height critical value.

[0025] S104. When the maritime communication distance is greater than the radio wave propagation limit distance, use the iteratively calculated evaporation duct height critical value and communication system parameters to calculate the abscissa of the intersection coordinate of the radio wave propagation loss in the evaporation duct mode and the radio wave propagation loss in the tropospheric scattering mode. Among them, the communication system parameters include: the operating frequency of the communication system, the height of the transmitting antenna and the height of the receiving antenna, etc.

[0026] S105. According to the magnitude relationship between the abscissa and the maritime communication distance, obtain the final value of the evaporation duct height critical value when the radio wave communication mode switches under the maritime communication distance through iterative calculation. The final value is such that the difference between the maximum value and the minimum value of the interval to which it finally belongs is less than or equal to the threshold value.

[0027] S106. Obtain the meteorological data in the radio wave communication area, input the meteorological data into the evaporation duct height prediction model to obtain the predicted evaporation duct height value, and compare the predicted evaporation duct height value with the final value. If the predicted evaporation duct height value is less than the final value, determine that the current radio wave communication mode is the tropospheric scattering mode, otherwise it is the evaporation duct mode. Among them, the meteorological data includes: relative humidity, sea surface atmospheric pressure, sea surface temperature, air temperature above the sea surface, and wind speed component above the sea surface, etc.

[0028] In this embodiment, the evaporation duct height critical value at which the waveguide / scattering mode switches is calculated using communication system parameters, etc., and then the mode of maritime over-the-horizon communication is discriminated based on this critical value. The discrimination method of this application can more adapt to the continuous switching between the evaporation duct and tropospheric scattering of the maritime over-the-horizon communication mode by using the calculated evaporation duct height critical value, and provides guidance for the adjustment and optimization of parameters such as the transmit power, operating frequency, and the height of the transmitting and receiving antennas of the maritime over-the-horizon communication system, enabling it to make better use of the evaporation duct to improve performance.

[0029] The following explains the specific solutions of each step in the above embodiments.

[0030] Please refer to Figure 1 and Figure 2 , in S101, set the range of the evaporation duct height critical value when the waveguide / scattering mode switches , , where and are the minimum and maximum critical values of the evaporation duct height, respectively. Set the threshold value of .

[0031] In S102, the critical value of the evaporation duct height is updated using the bisection method. The midpoint of the interval , is used as the initial value of the critical value of the evaporation duct height. The calculation formula is as follows: (1) In S103, it is judged whether does not exceed the given threshold value , that is: (2) If formula (2) holds, the loop is exited, and the initial value obtained in step S102 is output as the final value of the critical value of the evaporation duct height. If formula (2) does not hold, iterative calculation is performed on the critical value of the evaporation duct height, and the subsequent steps are continued.

[0032] In S104, first, the radio wave propagation loss in the evaporation duct mode and the radio wave propagation loss in the tropospheric scatter mode are calculated.

[0033] When calculating the radio wave propagation loss, the radio wave propagation model of the mixed mode of evaporation duct and tropospheric scatter under over-the-horizon conditions (please refer to CN119312581A) is used for calculation. In this model, when the maritime communication distance d exceeds the radio wave propagation limit distance under the line-of-sight condition l , the above radio wave propagation loss is calculated using the following expression: (3) In formula (3), is the radio wave propagation loss in the evaporation duct mode , the radio wave propagation loss in the tropospheric scatter mode or within the line-of-sight range, the free space radio wave propagation loss is calculated using the free space propagation model ; is the operating frequency of the communication system, in MHz; is the maritime communication distance; is the radio wave propagation loss calculated using the APM model (Advanced Propagation Model, a commonly used model for calculating the radio wave propagation path loss in the evaporation duct environment) under the evaporation duct condition; and are the radio wave propagation limit distances lThe maximum value of the free-space radio wave propagation loss at [location] and the minimum value of the radio wave propagation loss calculated using the APM model in an evaporation duct environment, both in dB; is the meteorological factor (dB); is the minimum scattering angle (mrad); is the exponential decay coefficient of the tropospheric inhomogeneity intensity with height ( ; is the height (km) from the lowest scattering point to the line connecting the receiving antenna and the transmitting antenna; is the height (km) of the lowest scattering point from the ground; is the aperture-medium coupling loss (dB); and are the transmitting antenna gain and the receiving antenna gain (dB), respectively.

[0034] Among them, in this model, the radio wave propagation limit distance l (in km) is calculated as follows: (4) Among them, and represent the transmitting antenna height and the receiving antenna height, respectively, both in m.

[0035] The calculation formula of (5) Among them, is the spatial field quantity of the wave field, and represent the horizontal distance on the ground surface and the height from the ground surface, respectively, both in m.

[0036] Secondly, input the evaporation duct height critical value EDH updated each time and the parameters of the over-the-horizon communication system at sea (including the operating frequency, transmitting and receiving antenna heights, etc.) into the radio wave propagation model of the mixed mode of evaporation duct and tropospheric scattering under over-the-horizon conditions, and obtain the current and abscissa of the intersection point . Then, enter S105.

[0037] S105 specifically includes the following steps S201~S203: S201, when the abscissa is greater than the over-the-horizon communication distance , make the maximum value within the interval of the evaporation duct height critical value equal to the evaporation duct height critical value to narrow the upper limit of the evaporation duct height critical value. That is, when , in order to make the abscissa of the intersection point approachd , make , so as to reduce the upper limit of the critical value of the evaporation duct height, thereby reducing the critical value of the evaporation duct height.

[0038] S202. When the abscissa is less than the marine communication distance , make the minimum value within the interval to which the critical value of the evaporation duct height belongs equal to the critical value of the evaporation duct height, so as to increase the lower limit of the critical value of the evaporation duct height. That is, when , in order to make the abscissa of the intersection point close to d , make , so as to increase the lower limit of the critical value of the evaporation duct height, thereby increasing the critical value of the evaporation duct height.

[0039] S203. When the abscissa is equal to the marine communication distance , take the midpoint of the interval to which the critical value of the evaporation duct height belongs as the final value of the critical value of the evaporation duct height. That is, when , the final value of the critical value EDH when the waveguide / scattering mode switches at a given communication distance is calculated by formula (2), and the iteration is stopped.

[0040] In S106, first, log in to the Global Forecast System (GFS), download the meteorological data at the required forecast time, extract the meteorological data at the point closest to the link by setting the longitude and latitude of the sea area where the marine test link is located, including parameters such as relative humidity, sea surface atmospheric pressure, sea surface temperature, air temperature at 2 m above the sea surface, and wind speed component at 10 m above the sea surface, and input the extracted meteorological data into the evaporation duct height prediction model (Naval Postgraduate School model, NPS model) to calculate the atmospheric modified refractive index profile within 0 - 50 m at the point closest to the marine test link, and the height corresponding to the minimum modified refractive index is the predicted evaporation duct height value at the required forecast time.

[0041] Secondly, compare the predicted evaporation duct height value with the final value. If the predicted evaporation duct height value is less than the final value, it is determined that the current radio wave communication mode is the tropospheric scattering mode, otherwise it is the evaporation duct mode.

[0042] In addition, the propagation loss can also be compared with the measured loss value, and the predicted evaporation duct height value can be compared with the final value of the critical value of the evaporation duct height to verify the discrimination accuracy of the discrimination method.

[0043] The waveguide / scattering mode discrimination method based on the evaporation duct height of the present application will be further described below through specific test examples.

[0044] 1. Set the critical value range of the evaporation duct height when the waveguide / scattering mode switches to [8, 13]. Set the threshold value .

[0045] 2. Take 10.5, the midpoint of the interval [8, 13], as the initial value of the evaporation duct height critical value.

[0046] 3. Since the interval length of 5 exceeds the threshold value, continue with the subsequent steps.

[0047] 4. Input the evaporation duct height critical value EDH updated iteratively each time and the over-the-horizon communication system parameters (including operating frequency, transmitting and receiving antenna heights, etc.) of the over-the-horizon communication system into the radio wave propagation model of the mixed mode of evaporation duct and tropospheric scattering under over-the-horizon conditions to obtain the current and abscissa of the intersection point , and compare it with the over-the-horizon communication distance d . In this embodiment, the over-the-horizon communication distance d is 188 km.

[0048] Please refer to Figure 3 , and through iterative calculation, obtain the final values of the critical value EDH at different communication distances ( Figure 3 in (a) is 150 km, Figure 3 in (b) is 188 km) in the 7960 MHz frequency band. When the communication distance is 150 km, the critical value EDH is 9.07812 m, and when the communication distance is 188 km, the critical value EDH is 9.82297 m.

[0049] 5. Log in to the Global Forecast System GFS, download the meteorological forecast data from June 16th to 19th, 2024, select the analysis area , extract the meteorological data in this area, including parameters such as relative humidity, sea surface atmospheric pressure, sea surface temperature, air temperature at 2 m above the sea surface, and wind speed component at 10 m above the sea surface, and input the extracted meteorological data into the evaporation duct height prediction model (NPS model) to calculate the atmospheric modified refractive index profile within the range of 0 - 50 m at the point closest to the sea trial link, and the height corresponding to the minimum modified refractive index is the predicted evaporation duct height value at the required forecast time.

[0050] Select the measured path loss data in the 7960 MHz frequency band obtained on the 188 km cross-sea trial link from Yangxi, Guangdong to Wenchang, Hainan from June 16th to 19th, 2024 to verify the accuracy and applicability of the discrimination method described in the present invention. Figures 4 to 6The application effect diagram of the discrimination method of the present invention in the measured data of a 188 km link is given. Among them, Figures 4 to 6 The numbers of measured path loss samples are 60,614, 27,150, and 162,152 respectively, and the total number of valid measured path loss samples is 249,916.

[0051] 6. From Figure 4 It can be seen that in the 7960 MHz frequency band, when the length of the over-the-horizon communication link at sea is 188 km, the critical value EDH of waveguide / scattering switching calculated by the discrimination method of the present application is 9.82297 m. When the predicted evaporation duct height value is less than the critical value of 9.82297 m, the over-the-horizon communication mode at sea is the tropospheric scatter communication mode, and the predicted path loss does not change with the change of the evaporation duct height value, showing a gentle and stable trend.

[0052] When the predicted evaporation duct height value is greater than the critical value of 9.82297 m, the over-the-horizon communication mode at sea is the evaporation duct communication mode, and the predicted path loss gradually decreases with the increase of the evaporation duct height value. This simulation result is consistent with the change trend of the measured path loss, verifying the accuracy and applicability of the discrimination method of the present invention.

[0053] Similarly, Figure 5 and Figure 6 also verify the accuracy of the discrimination method of the present invention. At the moment of 12:00 in Figure 5 , the predicted evaporation duct height value is 9.74 m at this time, which is lower than the critical value of 9.82297 m. The over-the-horizon communication mode at sea changes from the evaporation duct to the tropospheric scatter, and the predicted path loss gradually increases with the decrease of the evaporation duct height value, gradually showing a stable trend, which is consistent with the change trend of the measured path loss; while at the moment of 09:30 in Figure 6 , the predicted evaporation duct height value is 10 m at this time, which exceeds the critical value of 9.82297 m. The over-the-horizon communication mode at sea changes from the tropospheric scatter to the evaporation duct, and the predicted path loss gradually decreases with the increase of the evaporation duct height value, which is also consistent with the change trend of the measured path loss, both verifying the accuracy of the discrimination method of the present invention.

[0054] Compared with the prior art, the present application only needs to calculate a height parameter, that is, the critical value of the evaporation duct height when the radio wave communication mode switches, and then the radio wave communication mode can be determined, improving the efficiency of adjusting and optimizing the communication system parameters, and thus improving the communication rate.

[0055] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention. All of these fall within the protection scope of the present invention.

Claims

1. A waveguide / scattering mode discrimination method based on the height of evaporation duct, characterized in that The discrimination method includes: Setting the interval to which the critical value of the evaporation duct height belongs when the radio wave communication mode switches, and setting the threshold value of the interval length of the critical value of the evaporation duct height; Taking the midpoint of the interval to which the critical value of the evaporation duct height belongs as the initial value of the critical value of the evaporation duct height; Judging whether the interval length of the critical value of the evaporation duct height exceeds the threshold value: if the interval length of the critical value of the evaporation duct height is less than or equal to the threshold value, taking the initial value as the final value of the critical value of the evaporation duct height; if the interval length of the critical value of the evaporation duct height is greater than the threshold value, performing iterative calculation on the critical value of the evaporation duct height; When the maritime communication distance is greater than the radio wave propagation limit distance, using the iteratively calculated critical value of the evaporation duct height and communication system parameters to calculate the abscissa of the intersection coordinate of the radio wave propagation loss in the evaporation duct mode and the radio wave propagation loss in the tropospheric scatter mode; According to the magnitude relationship between the abscissa and the maritime communication distance, obtaining the final value of the critical value of the evaporation duct height when the radio wave communication mode switches at the maritime communication distance through iterative calculation; Obtaining the meteorological data within the radio wave communication area, inputting the meteorological data into the evaporation duct height prediction model to obtain the predicted evaporation duct height value, comparing the predicted evaporation duct height value with the final value, and if the predicted evaporation duct height value is less than the final value, determining that the current radio wave communication mode is the tropospheric scatter mode, otherwise it is the evaporation duct mode.

2. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein The value range of the threshold value is: less than or equal to 0.

01.

3. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein Using the bisection method to perform iterative calculation on the critical value of the evaporation duct height.

4. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein The step of obtaining the final value of the critical value of the evaporation duct height when the radio wave communication mode switches at the maritime communication distance through iterative calculation according to the magnitude relationship between the abscissa and the maritime communication distance includes: When the abscissa is greater than the maritime communication distance, making the maximum value within the interval to which the critical value of the evaporation duct height belongs equal to the critical value of the evaporation duct height to narrow the upper limit of the critical value of the evaporation duct height; When the abscissa is less than the maritime communication distance, making the minimum value within the interval to which the critical value of the evaporation duct height belongs equal to the critical value of the evaporation duct height to increase the lower limit of the critical value of the evaporation duct height; When the abscissa is equal to the maritime communication distance, taking the midpoint of the interval to which the critical value of the evaporation duct height belongs as the final value of the critical value of the evaporation duct height.

5. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, characterized in that The communication system parameters include: the operating frequency of the communication system, the height of the transmitting antenna and the height of the receiving antenna.

6. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein The meteorological data includes: relative humidity, sea surface atmospheric pressure, sea surface temperature, air temperature above the sea surface and wind speed component above the sea surface.

7. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein The discrimination method further includes: Comparing the propagation loss with the measured loss value to verify the discrimination accuracy of the discrimination method.

8. The waveguide / scattering mode discrimination method based on the evaporation duct height according to claim 1, wherein The discrimination method further includes: Comparing the predicted evaporation duct height value with the final value of the critical value of the evaporation duct height to verify the discrimination accuracy of the discrimination method.

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