Advanced propagation model improvement method considering free space propagation in evaporation waveguide environment

Abstract

The invention discloses an advanced propagation model improvement method considering free space propagation in an evaporation waveguide environment. The method comprises the following steps: utilizing a free space propagation model to calculate radio wave propagation loss in an offshore sight distance range; and translating the advanced propagation model based on the radio wave propagation attenuation difference value to obtain an improved advanced propagation model, and when the radio wave propagation target distance is greater than the radio wave propagation limit distance under the marine sight distance condition, substituting the radio wave propagation target distance into the improved advanced propagation model to obtain a radio wave propagation target distance. And obtaining radio wave propagation loss corresponding to the radio wave propagation target distance. According to the method, the technical problem that the predicted path loss is larger than the actually measured path loss due to the fact that the existing APM model in the evaporation waveguide environment does not fully consider the free space propagation in the marine sight distance range is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore radio wave propagation, and in particular to a method for improving an advanced propagation model taking into account free space propagation in an evaporative waveguide environment. Background Art

[0002] Free space refers to a space without any obstruction for radio wave propagation. The space that plays a major role in the process of radio wave propagation is the Fresnel zone, and in engineering calculations, the main spaces that affect radio wave propagation are the first Fresnel zone and the minimum Fresnel zone. As long as they are not obstructed, the conditions of approximate free space can be obtained. In practical applications, as long as the radio wave propagation meets the free space propagation conditions within the first Fresnel radius, it can be considered that the radio wave propagates in free space.

[0003] Line-of-sight propagation refers to a propagation mode in which radio waves propagate directly from the transmitter to the receiver without any obstacles (excluding the possibility of reflected waves on the ground or sea surface). Assuming that the maximum distance that line-of-sight propagation can reach is l, when the distance between the receiver and the transmitter is d≤l, it is line-of-sight propagation. Since conditions close to free space can be obtained within the line-of-sight range, the propagation of radio waves within the line-of-sight range can be approximately considered as free space propagation.

[0004] Evaporation duct is a type of atmospheric duct. Its formation mechanism is as follows: as the sea surface water vapor evaporates and diffuses, the atmospheric humidity within a few tens of meters above the sea surface decreases sharply with increasing altitude, which will cause the atmospheric refractive index to decrease, presenting a negative gradient change, thus causing microwaves to refract downward and propagate; when the refractive curvature is greater than the curvature of the sea surface, the radio waves are trapped in the evaporation duct layer, which greatly reduces the propagation path loss, and ultimately achieves over-the-horizon propagation of hundreds of kilometers, breaking through the earth's curvature limit. Therefore, using the evaporation duct as a natural channel for communication has the advantages of high reliability, long transmission distance, low path loss, high data rate (up to tens of Mbps), and strong anti-interception.

[0005] At present, the most commonly used model for calculating the attenuation of radio wave propagation in the evaporative duct environment is the Advanced Propagation Model (APM). The APM model is a hybrid model of the ray tracing model and the parabolic equation model. The model divides the radio wave propagation area into four regions: flat earth, ray optics, parabolic equations, and hyper-optics, and uses different models to calculate the propagation loss in different propagation regions. However, the APM model does not fully consider the free space propagation within the line-of-sight range at sea, which makes the predicted path loss larger than the measured path loss.

[0006] Based on the above-mentioned shortcomings of the APM model, the present invention establishes an improved APM model, which calculates the radio wave propagation loss using a free space propagation model within the sea line-of-sight range, and improves the APM model based on the calculation results to calculate the radio wave propagation loss under beyond-line-of-sight conditions.

[0007] Considering the free space propagation within the line-of-sight range at sea in an evaporative duct environment, an improved APM model was established, which can more accurately calculate and simulate the path loss of radio wave propagation, and provide a more accurate theoretical basis for applications such as marine communications and radar detection. Summary of the invention

[0008] The embodiment of the present invention provides a method for improving an advanced propagation model that considers free space propagation in an evaporative duct environment, so as to at least solve the technical problem that the existing APM model in an evaporative duct environment does not fully consider the free space propagation within the line-of-sight range at sea, resulting in the predicted path loss being larger than the measured path loss.

[0009] According to one aspect of an embodiment of the present invention, a method for improving an advanced propagation model considering free space propagation in an evaporation duct environment is provided. The method may include: when radio waves propagate in an evaporation duct environment with an evaporation duct height at sea, obtaining the height of the transmitting antenna, the height of the receiving antenna and the target distance of radio wave propagation; determining the limit distance of radio wave propagation under the line-of-sight condition at sea based on the height of the transmitting antenna and the height of the receiving antenna; obtaining the free space propagation loss at the limit distance of radio wave propagation based on the radio wave propagation frequency and the radio wave propagation distance under the limit distance of radio wave propagation; substituting the limit distance of radio wave propagation into the advanced propagation model to obtain the propagation attenuation of the evaporation wave at the limit distance of radio wave propagation; obtaining the difference of radio wave propagation attenuation based on the propagation attenuation of the evaporation wave at the limit distance of radio wave propagation and the free space propagation loss; translating the advanced propagation model based on the difference of radio wave propagation attenuation to obtain an improved advanced propagation model, and when the target distance of radio wave propagation is greater than the limit distance of radio wave propagation under the line-of-sight condition at sea, substituting the target distance of radio wave propagation into the improved advanced propagation model to obtain the radio wave propagation loss corresponding to the target distance of radio wave propagation.

[0010] Optionally, the process of determining the evaporation duct height is: obtaining meteorological data at the center point of the offshore test link, wherein the meteorological data include: relative humidity, sea surface pressure, sea surface temperature, air temperature 2m above the sea surface, and wind speed component 10m above the sea surface; inputting the meteorological data at the center point of the offshore test link into the evaporation duct prediction model to obtain the atmospheric corrected refractive index profile within a fixed range at the center point of the offshore test link; and determining the height corresponding to the minimum corrected refractive index in the atmospheric corrected refractive index profile as the evaporation duct height.

[0011] Optionally, the expression for determining the limit distance of radio wave propagation under the condition of line-of-sight at sea based on the height of the transmitting antenna and the height of the receiving antenna is:

[0012]

[0013] Among them, l is the limit distance of radio wave propagation under the condition of line of sight at sea, h t is the height of the transmitting antenna, h r is the height of the receiving antenna.

[0014] Optionally, after determining the limit distance of radio wave propagation under line-of-sight conditions at sea based on the height of the transmitting antenna and the height of the receiving antenna, the method also includes: when the target distance of radio wave propagation is greater than the limit distance of radio wave propagation under line-of-sight conditions at sea, substituting the target distance of radio wave propagation into the advanced propagation model to obtain the evaporative waveguide propagation loss corresponding to the target distance of radio wave propagation; when the target distance of radio wave propagation is less than or equal to the limit distance of radio wave propagation under line-of-sight conditions at sea, obtaining the free space radio wave propagation attenuation corresponding to the target distance of radio wave propagation based on the radio wave propagation frequency and the radio wave propagation distance of the target distance of radio wave propagation.

[0015] Optionally, when the radio wave propagation target distance is less than or equal to the radio wave propagation limit distance under the line-of-sight condition at sea, the expression of the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance is obtained based on the radio wave propagation frequency and the radio wave propagation distance of the radio wave propagation target distance:

[0016] Lbf(dB)=32.5+20lgf+20lgd,d≤l

[0017] Wherein, Lbf represents the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance, f represents the radio wave propagation frequency of the radio wave propagation target distance, and d represents the radio wave propagation distance of the radio wave propagation target distance.

[0018] Optionally, the expression for the difference in radio wave propagation attenuation based on the evaporation waveguide electric wave propagation at the limit distance of radio wave propagation and the free space propagation loss is:

[0019] Δh=L d_min -Lbf max

[0020] Among them, Δh is the difference in radio wave propagation attenuation, L d_min is the propagation attenuation of the evaporation wave at the limit distance of the wave propagation, Lbf max is the free space propagation loss at the extreme distance of radio wave propagation.

[0021] Beneficial effects of the present invention:

[0022] The present invention proposes an improved method for an advanced propagation model that considers free space propagation in an evaporative duct environment. The method uses a free space propagation model to calculate the radio wave propagation loss within the line-of-sight range at sea, and improves the APM model based on the calculation result to calculate the radio wave propagation loss under beyond-line-of-sight conditions. The atmospheric corrected refractive index profile is calculated using reanalyzed meteorological data and the evaporative duct calculation model, and is input into the radio wave propagation model to calculate the radio wave propagation path loss. Compared with the APM model, the improved APM model has a smaller absolute error with the measured path loss in the C and X bands, thereby having a higher prediction accuracy, and can be used to accurately predict the attenuation of radio wave propagation in an offshore evaporative duct environment, further providing technical support for the design and accurate performance evaluation of marine communications, radar and other systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a flow chart of a method for improving an advanced propagation model considering free space propagation in an evaporative waveguide environment according to an embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of an improved advanced propagation model according to an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of free space radio wave propagation attenuation corresponding to the radio wave propagation target distance according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of an improved APM model according to an embodiment of the present invention and path losses at different frequency points in the C band predicted by the APM model;

[0028] Figure 5 is a schematic diagram of an improved APM model according to an embodiment of the present invention and path losses at different frequency points in the X-band predicted by the APM model;

[0029] Figure 6 This is a distribution diagram of absolute errors between the path loss calculated by the APM model according to the embodiment of the present invention and the improved APM model and the measured path loss DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] Example 1

[0033] According to an embodiment of the present invention, a method for improving an advanced propagation model considering free space propagation in an evaporation waveguide environment is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system comprising at least one set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0034] Figure 1 FIG. 4 is a flow chart of a method for improving an advanced propagation model considering free space propagation in an evaporation duct environment according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps:

[0035] Step S101 , when radio waves propagate in an environment of an evaporation duct having an evaporation duct height at sea, the height of a transmitting antenna, the height of a receiving antenna, and a target distance for radio wave propagation are obtained.

[0036] In the technical solution provided in the above step S101 of the present invention, in a scenario where radio waves propagate in an offshore evaporation duct environment, the height of the transmitting antenna, the height of the receiving antenna and the target distance d of radio wave propagation are obtained.

[0037] Step S102, based on the height of the transmitting antenna and the height of the receiving antenna, determine the limit distance of radio wave propagation under the condition of line of sight at sea.

[0038] In the technical solution provided in the above step S102 of the present invention, the height of the transmitting antenna and the height of the receiving antenna are calculated to obtain the limit distance of radio wave propagation under the line-of-sight condition at sea.

[0039] Step S103, obtaining the free space propagation loss at the limit distance of radio wave propagation based on the radio wave propagation frequency and the radio wave propagation distance at the limit distance of radio wave propagation.

[0040] In the technical solution provided in step S103 of the present invention, the radio wave propagation frequency and the radio wave propagation distance at the radio wave propagation limit distance are substituted into the formula for calculating the free space propagation loss to obtain the free space propagation loss Lbf at the radio wave propagation limit distance. max , the formula for free space propagation loss is: Lbf (dB) = 32.5 + 20lgf 1 +20lgd 1 , where Lbf is the free space propagation loss at the extreme distance of radio wave propagation, f 1 is the frequency of radio wave propagation at the limit distance of radio wave propagation, d 1 It is the distance of radio wave propagation at the limit distance of radio wave propagation.

[0041] Step S104, substituting the limit distance of radio wave propagation into the advanced propagation model to obtain the propagation attenuation of the evaporation wave conductive wave at the limit distance of radio wave propagation.

[0042] In the technical solution provided in the above step S104 of the present invention, the limit distance of radio wave propagation is substituted into the advanced propagation model to determine the propagation attenuation of the evaporation waveguide at the limit distance of radio wave propagation, wherein the advanced propagation model is defined as follows: Since the trapping angle of electromagnetic waves usually does not exceed 1° during the propagation of atmospheric waveguides. Therefore, the narrow-angle parabolic equation is selected here as the propagation model of electromagnetic waves in the evaporation waveguide. The narrow-angle parabolic equation is obtained by applying the scalar wave equation to the case of narrow-angle propagation, and approximating and simplifying it. Its standard narrow-angle parabolic equation is:

[0043]

[0044] Among them, u(x,z) is the complex amplitude of the wave field, k0=ω / c is the free space wave number of the electromagnetic wave, n=n(x,z) is the refractive index of the medium, and x and z represent the horizontal distance and height from the ground surface, respectively.

[0045] The parabolic equation is solved by discrete matching Fourier method (IDMFT), and the spatial field quantity u(x,z) is obtained recursively. The path propagation loss L is obtained from the field strength according to the following formula: d (dB):

[0046] L d (x,z)=20lgf+10lgd-20lgu(x,z)-27.6

[0047] Where f is the frequency (MHz) and d is the distance (km).

[0048] Step S105, obtaining the radio wave propagation attenuation difference based on the evaporation waveguide electric wave propagation at the radio wave propagation limit distance and the free space propagation loss.

[0049] In the technical solution provided in the above step S105 of the present invention, the propagation attenuation of the evaporation waveguide electric wave and the propagation loss in free space at the extreme distance of the electric wave propagation are subtracted to obtain the difference of the electric wave propagation attenuation.

[0050] Step S106, based on the radio wave propagation attenuation difference, the advanced propagation model is translated to obtain an improved advanced propagation model. When the radio wave propagation target distance is greater than the radio wave propagation limit distance under the line-of-sight condition at sea, the radio wave propagation target distance is substituted into the improved advanced propagation model to obtain the radio wave propagation loss corresponding to the radio wave propagation target distance.

[0051] In the technical solution provided in the above step S106 of the present invention, the high-level propagation model is translated by the radio wave propagation attenuation difference to obtain an improved high-level propagation model. When the radio wave propagation target distance is greater than the radio wave propagation limit distance under the line-of-sight condition at sea, the radio wave propagation target distance is substituted into the improved high-level propagation model to obtain the radio wave propagation loss corresponding to the radio wave propagation target distance; the radio wave propagation target distance is substituted into the translated high-level propagation model to obtain the expression of the radio wave propagation loss corresponding to the radio wave propagation target distance: PL (dB) = L d -Δh,d>l, PL represents the radio wave propagation loss corresponding to the radio wave propagation target distance, L d Indicates the path transmission loss of the radio wave propagation target distance, Figure 2 is a schematic diagram of an improved high-level propagation model according to an embodiment of the present invention.

[0052] The above method of this embodiment is further introduced below.

[0053] As an optional implementation method, step S101, the process of determining the evaporation duct height is: obtaining meteorological data at the center point of the offshore test link, wherein the meteorological data includes: relative humidity, sea surface pressure, sea surface temperature, air temperature 2m above the sea surface, and wind speed component 10m above the sea surface; inputting the meteorological data at the center point of the offshore test link into the evaporation duct prediction model to obtain the atmospheric corrected refractive index profile within a fixed range at the center point of the offshore test link; and determining the height corresponding to the minimum corrected refractive index in the atmospheric corrected refractive index profile as the evaporation duct height.

[0054] In this embodiment, the climate system of the European Centre for Medium-Term Weather Forecasts is logged in, the global meteorological data at the required time is downloaded and the meteorological data is reanalyzed to obtain the meteorological data at the midpoint of the offshore test link, including relative humidity, sea surface pressure, sea surface temperature, air temperature 2 m above the sea surface and wind speed component 10 m above the sea surface. The meteorological data at the center point of the offshore test link is input into the evaporation duct prediction model to obtain the atmospheric corrected refractive index profile within the range of 0-50 m at the center point of the offshore test link, where the calculation step is 0.1 m; the height corresponding to the minimum corrected refractive index in the corrected refractive index profile is the evaporation duct height.

[0055] As an optional implementation mode, in step S102, based on the height of the transmitting antenna and the height of the receiving antenna, the expression for determining the limit distance of radio wave propagation under the condition of line of sight at sea is:

[0056]

[0057] Among them, l is the limit distance of radio wave propagation under the condition of line of sight at sea, h t is the height of the transmitting antenna, h r is the height of the receiving antenna.

[0058] In this embodiment, the height of the transmitting antenna and the height of the receiving antenna are substituted into the above formula for calculation to obtain the limit distance of radio wave propagation under the line-of-sight condition at sea.

[0059] As an optional implementation manner, step S102, after determining the limit distance of radio wave propagation under the condition of line of sight at sea based on the height of the transmitting antenna and the height of the receiving antenna, the method also includes: when the radio wave propagation target distance is greater than the limit distance of radio wave propagation under the condition of line of sight at sea, substituting the radio wave propagation target distance into the advanced propagation model to obtain the evaporative waveguide wave propagation loss corresponding to the radio wave propagation target distance; when the radio wave propagation target distance is less than or equal to the limit distance of radio wave propagation under the condition of line of sight at sea, obtaining the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance based on the radio wave propagation frequency and the radio wave propagation distance of the radio wave propagation target distance.

[0060] In this embodiment, when the target distance for radio wave propagation is greater than the limit distance for radio wave propagation under the condition of line of sight at sea, the target distance for radio wave propagation is substituted into the advanced propagation model to obtain the evaporative waveguide propagation loss corresponding to the target distance for radio wave propagation; when the target distance for radio wave propagation is less than or equal to the limit distance for radio wave propagation under the condition of line of sight at sea, the radio wave propagation frequency and the radio wave propagation distance of the target distance for radio wave propagation are substituted into the formula for calculation to obtain the free space radio wave propagation attenuation corresponding to the target distance for radio wave propagation.

[0061] As an optional embodiment, when the radio wave propagation target distance is less than or equal to the radio wave propagation limit distance under the sea line of sight condition, based on the radio wave propagation frequency and the radio wave propagation distance of the radio wave propagation target distance, the expression of the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance is obtained as follows:

[0062] lbf(dB)=32.5+20lgf+20lgd,d≤l

[0063] Among them, lbf represents the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance, f represents the radio wave propagation frequency of the radio wave propagation target distance, and d represents the radio wave propagation distance of the radio wave propagation target distance.

[0064] In this embodiment, the radio wave propagation frequency and the radio wave propagation distance based on the radio wave propagation target distance are substituted into the above formula for calculation to obtain the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance. Figure 3 It is a schematic diagram of free space radio wave propagation attenuation corresponding to the radio wave propagation target distance according to an embodiment of the present invention.

[0065] As an optional embodiment, in step S105, based on the propagation attenuation of the evaporation waveguide electric wave at the limit distance of the electric wave propagation and the free space propagation loss, the expression of the difference of the electric wave propagation attenuation is obtained as follows:

[0066] Δh=L d_min -Lbf max

[0067] Among them, Δh is the difference in radio wave propagation attenuation, L d_min is the propagation attenuation of the evaporation wave at the limit distance of the wave propagation, Lbf max is the free space propagation loss at the extreme distance of radio wave propagation.

[0068] In this embodiment, the propagation attenuation of the evaporation waveguide electric wave at the limit distance of the electric wave propagation is subtracted from the propagation loss in free space to obtain the difference in the electric wave propagation attenuation.

[0069] Experimental part.

[0070] The accuracy of the improved APM model was verified by the measured path loss data in the C-band evaporative waveguide offshore test in the selected sea area. The transmitting end is located on the first sea island. At the transmitting site, the signal generator feeds the transmitting antenna with a continuous wave signal of 3.9 to 4.8 GHz through the power amplifier. The receiving end is located on the second sea island, and the link length from the first sea island to the second sea island is 53.435 kilometers. At the receiving terminal, the received signal is sampled at a frequency of 1 Hz. The obtained evaporative waveguide height value and electromagnetic propagation parameters are input into the improved radio wave propagation attenuation model and compared with the traditional APM model. Figure 4 1 is a schematic diagram of the improved APM model according to an embodiment of the present invention and the path loss at different frequencies in the C band predicted by the APM model. To further verify the accuracy of the improved APM model, the measured path loss in the X band on the link between the first sea island and the second sea island was selected. Figure 5 is a schematic diagram of the improved APM model according to an embodiment of the present invention and the path loss at different frequency points in the X-band predicted by the APM model. It can be seen that in the C-band, the calculation result of the improved APM model is closer to the measured path loss than the calculation result of the APM model; similarly, in the X-band, the calculation result of the improved APM model is closer to the measured path loss than the calculation result of the APM model;

[0071] The absolute error between the output results of the APM model and the improved APM model and the measured path loss is calculated. The path loss data collected on the first sea island-second sea island test link is selected as the measured path loss. Figure 6 This is a distribution diagram of the absolute errors of the path loss calculated by the APM model and the improved APM model according to the embodiment of the present invention and the measured path loss. The number of samples of the measured path loss is 51560. The results show that the absolute errors between the improved APM model and the measured path loss do not exceed 5dB and 10dB, accounting for 62.18% and 89.41% respectively, while the absolute errors between the APM model and the measured path loss do not exceed 5dB and 10dB, accounting for only 14.73% and 54.86%. Therefore, the improved APM model is more accurate than the APM model in predicting.

[0072] In an embodiment of the present invention, when radio waves propagate in an environment of an evaporation waveguide with an evaporation waveguide height at sea, the height of the transmitting antenna, the height of the receiving antenna, and the target distance of radio wave propagation are obtained; based on the height of the transmitting antenna and the height of the receiving antenna, the limit distance of radio wave propagation under the line-of-sight condition at sea is determined; based on the radio wave propagation frequency and the radio wave propagation distance at the limit distance of radio wave propagation, the free space propagation loss at the limit distance of radio wave propagation is obtained; the limit distance of radio wave propagation is substituted into an advanced propagation model to obtain the propagation attenuation of the evaporation waveguide at the limit distance of radio wave propagation; based on the propagation attenuation of the evaporation waveguide at the limit distance of radio wave propagation and the free space propagation loss, the radio wave propagation attenuation difference is obtained; based on the radio wave propagation attenuation and the free space propagation loss, the height of the receiving antenna is converted into the free space propagation loss at the limit distance of radio wave propagation. The advanced propagation model is translated to obtain an improved advanced propagation model. When the target distance of radio wave propagation is greater than the limit distance of radio wave propagation under the condition of line of sight at sea, the target distance of radio wave propagation is substituted into the improved advanced propagation model to obtain the radio wave propagation loss corresponding to the target distance of radio wave propagation. The existing APM model in the evaporation duct environment does not fully consider the free space propagation within the line of sight at sea, which makes the predicted path loss larger than the measured path loss. The free space propagation within the line of sight at sea in the evaporation duct environment is considered, and an improved APM model is established, which can more accurately calculate and simulate the path loss of radio wave propagation, and provide a more accurate theoretical basis for applications such as marine communications and radar detection.

[0073] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0074] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0076] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0077] In addition, each functional unit in each embodiment of the present invention may be integrated into a first processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0078] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving an advanced propagation model considering free space propagation in an evaporative waveguide environment, characterized in that: include: When radio waves propagate in an environment of an evaporation duct having an evaporation duct height at sea, the height of the transmitting antenna, the height of the receiving antenna, and the target distance of radio wave propagation are obtained; Based on the height of the transmitting antenna and the height of the receiving antenna, determine the limit distance of radio wave propagation under the condition of line of sight at sea; Based on the radio wave propagation frequency and the radio wave propagation distance at the radio wave propagation limit distance, the free space propagation loss at the radio wave propagation limit distance is obtained; Substituting the limit distance of radio wave propagation into the advanced propagation model, the propagation attenuation of evaporation wave and conductive wave at the limit distance of radio wave propagation is obtained; Based on the propagation attenuation of the evaporation wave and the propagation loss in free space at the limit distance of the propagation of the electric wave, the difference of the propagation attenuation of the electric wave is obtained; The advanced propagation model is translated based on the difference in radio wave propagation attenuation to obtain an improved advanced propagation model. When the radio wave propagation target distance is greater than the limit distance of radio wave propagation under line-of-sight conditions at sea, the radio wave propagation target distance is substituted into the improved advanced propagation model to obtain the radio wave propagation loss corresponding to the radio wave propagation target distance.

2. The method according to claim 1, characterized in that The process of determining the evaporation waveguide height is as follows: Obtain meteorological data at the center point of the offshore test link, where the meteorological data include: relative humidity, sea surface pressure, sea surface temperature, air temperature 2 meters above the sea surface, and wind speed component 10 meters above the sea surface; The meteorological data at the center point of the offshore test link is input into the evaporation duct prediction model to obtain the atmospheric correction refractive index profile within a fixed range at the center point of the offshore test link; The height corresponding to the minimum corrected refractive index in the atmospheric corrected refractive index profile is determined as the evaporation duct height.

3. The method according to claim 1, characterized in that The expression for determining the limit distance of radio wave propagation under the condition of line of sight at sea based on the height of the transmitting antenna and the height of the receiving antenna is: Among them, l is the limit distance of radio wave propagation under the condition of line of sight at sea, h t is the height of the transmitting antenna, h r is the height of the receiving antenna.

4. The method according to claim 1, characterized in that After determining the limit distance of radio wave propagation under the line-of-sight condition at sea based on the height of the transmitting antenna and the height of the receiving antenna, the method further includes: When the radio wave propagation target distance is greater than the radio wave propagation limit distance under the condition of line of sight at sea, the radio wave propagation target distance is substituted into the advanced propagation model to obtain the evaporation wave conduction wave propagation loss corresponding to the radio wave propagation target distance; When the radio wave propagation target distance is less than or equal to the radio wave propagation limit distance under the line-of-sight condition at sea, the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance is obtained based on the radio wave propagation frequency and the radio wave propagation distance of the radio wave propagation target distance.

5. The method according to claim 4, characterized in that When the radio wave propagation target distance is less than or equal to the radio wave propagation limit distance under the sea line of sight condition, the expression of the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance is obtained based on the radio wave propagation frequency and the radio wave propagation distance of the radio wave propagation target distance: Lbf(dB)=32.5+20lgf+20lgd,d≤l Wherein, Lbf represents the free space radio wave propagation attenuation corresponding to the radio wave propagation target distance, f represents the radio wave propagation frequency of the radio wave propagation target distance, and d represents the radio wave propagation distance of the radio wave propagation target distance.

6. The method according to claim 1, characterized in that The expression for the difference in radio wave propagation attenuation based on the evaporation wave conductive wave propagation at the limit distance of radio wave propagation and the free space propagation loss is: Δh=L d_min -Lbf max Among them, Δh is the difference in radio wave propagation attenuation, L d_min is the propagation attenuation of the evaporation wave at the limit distance of the wave propagation, Lbf max is the free space propagation loss at the extreme distance of radio wave propagation.

7. A computer system, characterized in that include: One or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the method of claim 1.

8. A computer-readable storage medium, characterized in that Computer executable instructions are stored, and when the instructions are executed, they are used to implement the method of claim 1.

9. A computer program product, characterized in that The invention comprises computer executable instructions, which are used to implement the method of claim 1 when being executed.

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