CN103167547A - Ultra-short wave radio set radio wave coverage area calculation method - Google Patents

Abstract

The invention discloses an ultra-short wave radio set radio wave coverage area calculation method and belongs to the technical field of wireless communication. The ultra-short wave radio set radio wave coverage area computing method comprises: step one, establishing an ultra-short wave radio set propagation loss calculation model; step two, calculating radio wave propagation loss; step three, establishing a ultra-short wave propagation loss calculation formula; and step four, and calculating specific communication areas of an ultra-short wave radio set by adopting an ultra-short wave radio set communication capability coverage model on the basis of a communication coverage area recursive calculation method of a geographic information system (GIS), .

Description

A kind of computational methods of ultrashort wave radio set electric wave coverage

Technical field

The present invention relates to a kind of computational methods of ultrashort wave radio set electric wave coverage, belong to wireless communication technology field.

Background technology

At present, existing communication network complexity is various, and under the particular surroundingss such as battlefield or natural calamity, wherein the ultrashort wave radio set net is most widely used.Ultra short wave communication is mainly propagated by space wave, having the advantages such as communication is stable, interference is little, communication equipment is easy to carry, and its communication distance (the about demand of 40～50km) comparison operators hop communication node deployments.When carrying out the ultrashort wave radio set network planning, need to whether can be communicated with between about communication distance anticipation two radio station according to ultrashort wave radio set.Ultrashort wave radio set is under the impact of complex environment uncertain factor, very large deviation can appear in communication range, generally, whether be communicated with personal experience's subjective judgement point-to-point transmission ultra short wave communication, there are certain risk and blindness, are unfavorable for making fast and accurately network planning decision-making in complex environment.

Summary of the invention

The present invention is directed to the proposition of above problem, and develop a kind of computational methods of ultrashort wave radio set electric wave coverage.

The technical scheme that the present invention takes is as follows:

The first step: the propagation loss computation model of setting up ultrashort wave radio set;

Second step: the calculating of radio wave propagation loss;

The 3rd step: that sets up the ultrashort wave propagation loss asks the calculation formula;

The 4th step: adopt ultrashort wave radio set communication capacity overlay model, based on the communication coverage recursive calculation method of GIS, ask the concrete communication coverage of calculating ultrashort wave radio set.

Know-why of the present invention: the communication coverage recursive calculation method that the present invention is based on GIS, ask the concrete communication coverage of calculating ultrashort wave radio set, more comprehensively consider to affect the various influencing factors of ultrashort wave propagation, based on the GIS technology, make the modeling of communication capacity overlay model and find the solution to be achieved, and communication coverage area is displayed on electronic chart.

Description of drawings

Fig. 1 free space ultra short wave communication of the present invention loss analogous diagram.

Fig. 2 atmosphere of the present invention affects analogous diagram to loss of communications.

Fig. 3 cloud and mist of the present invention affects analogous diagram to loss of communications.

Fig. 4 single-blade of the present invention peak diffraction model figure.

Fig. 5 multipath transmisstion of the present invention path schematic diagram.

Fig. 6 the present invention is based on the flow chart of the communication coverage recursive calculation method of GIS.

Embodiment

The present invention will be further described below in conjunction with accompanying drawing.

At first, consider from the characteristic angle of signal source itself, set up the propagation loss computation model of ultrashort wave radio set:

FL(dB)＝Pt(dBm)-Pr(dBm)+Gt(dB)+Gr(dB)-Ct(dB)-Cr(dB) ⑴

In formula: FL: the radio wave propagation total losses comprise free-space loss, geographical environment loss, weather loss etc.;

Pt: transmitting power;

Pr: receiving equipment sensitivity;

Gt: transmitter antenna gain (dBi);

Gr: receiving antenna gain;

Ct: emission feeder loss;

Cr: receive feeder loss.

The coverage of communication capacity or transmission range are subjected to the impact of many factors, comprise the impact of signal source self character (as the gain of transmitting power, receiving equipment sensitivity, antenna, feeder loss etc.), free-space loss, geographical environment loss (as the impact of orographic factor), atmospheric loss (decay of weather etc.), multipath loss (blocking of building, trees and wall).The radio wave propagation total losses are mainly considered free-space propagation loss, weather environment loss, geographical environment loss, multipath loss.

By this model, can calculate the admissible theoretical maximum loss of ultrashort wave radio set communication.

The second, the calculating of radio wave propagation loss.

(1) calculating of free-space propagation loss.Electric wave is when free-space propagation, and the computing formula of radio communication loss is:

$L_F\left(\mathrm{dB}\right)=10\lg \left(\frac{\mathrm{Pr}}{\mathrm{Pt}}\right)=10\lg {\left(\frac{4\mathrm{\πd}}{\mathrm{\λ}}\right)}^2=20\lg \left(\frac{4\mathrm{\πdf}}{c}\right)---\left(2\right)$

Through deriving to such an extent that the relational expression of distance, frequency and loss is:

L _F(dB)＝32.44+20lgd(km)+20lgf(MHz) ⑶

In formula: Los is the free-space propagation loss, and unit is dB;

D is distance, and unit is km;

F is operating frequency, and unit is MHz.

The loss of free space ultra short wave communication is as shown in Figure 1: as can be known from Fig. 1, and the relation between the free-space loss of ultrashort wave propagation and distance.Transmission range free-space loss far away is larger.

(2) calculating of weather environment loss.Weather environment is mainly considered Atmospheric Absorption and two factors of cloud and mist to the impact of electric wave transmission, and other factors are very little on the impact of radio wave propagation, can ignore.

1. Gaseous attenuation

Electric wave in the Atmospheric Absorption wave path, Atmospheric Absorption electric wave are continuous absorptions, are mainly that oxygen and the steam of atmosphere absorbs electric wave.

Decay near the meeting on the horizontal route of ground, due to oxygen attenuation rate γ ₀Attenuation rate γ with steam _wIt is constant on whole path of integration.So can obtain the integration of attenuation rate, obtain total path attenuation A _gt(dB) be:

A _gt＝(γ ₀+γ _w)d （4）

In formula, d is the distance (km) between the sending and receiving radio station.

Attenuation coefficient γ for air (p=1013hPa, the t=15oC) oxygen of drying ₀(dB/km) expression formula is:

${\mathrm{\γ}}_0=[7.19\×{10}^{-3}+\frac{6.09}{f^2+0.227}+\frac{4.18}{{(f-57)}^2+1.50}]f^2{10}^{-6}f\≤57000\mathrm{MHz}$

Steam attenuation coefficient γ for the following frequencies of propagation of 350000MHz _w(dB/km) expression formula is:

${\mathrm{\γ}}_w=[0.67+\frac{3}{{(f-22.3)}^2+7.3}+\frac{9}{{(f-183.3)}^2+6}+\frac{4.3}{{(f-323.8)}^2+10}]f^2{\mathrm{\ρ}}_w{10}^{-7}f\≤35000\mathrm{MHz}$

Wherein f is wave frequency (GHz), ρ _wThe superficial density (g/m of local steam ³), this expression formula is the characteristic decay of hypothesis surface temperature when being 15 degrees centigrade, in the density of steam lower than 12g/m ³The time, above result is more accurately.When the density of steam greater than 12g/m ³The time characteristic decay be:

${\mathrm{\γ}}_w=[0.050+0.0021{\mathrm{\ρ}}_w+\frac{3.6}{{(f-22.2)}^2+8.5}+\frac{10.6}{{(f-183.3)}^2+9.0}+\frac{8.9}{{(f-325.4)}^2+26.3}]f^2{\mathrm{\ρ}}_w{10}^{-7}$

f≤350000MHz

Atmosphere on the impact of ultra short wave communication loss as shown in Figure 2.

As shown in Figure 2, the loss of ultra short wave communication is very little.When water-vapour density is 40g/m ³, when the distance of line-of-sight propagation was 50km, the loss that Atmospheric Absorption causes was approximately 0.088dB; When water-vapour density is 0.1g/m ³, when the distance of line-of-sight propagation was 50km, the loss that Atmospheric Absorption causes was approximately 0.086dB.

2. cloud and mist decay

Due to the yardstick of water dust than little many of the wavelength of microwave, millimeter wave, the Extinction Cross that can utilize Rayleigh approximate calculation cloud and mist to drip, under Rayleigh is approximate, the absorption cross-section of water dust is much larger than scattering section, its body extinction coefficient is approximately equal to the body absorption coefficient, its value is all cloud particle absorption cross-section sums of unit volume, so the characteristic decay A(dB/km of cloud), can be expressed as:

$A=4.343\×{10}^3\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{Q}_a\left(r_i\right),---\left(5\right)$

In formula, N is the population of unit volume, Q _a(r _i) be the absorption cross-section of the particle of radius r.Under Rayleigh is approximate, have:

$Q_a=\frac{{8\mathrm{\π}}^2}{3\mathrm{\λ}}{r}^3{\mathrm{\ϵ}}^{\′\′}{\left|\frac{3}{\mathrm{\ϵ}}\right|}^2,$

$A=4.343\×{10}^3\frac{{8\mathrm{\π}}^2}{3\mathrm{\λ}}{\mathrm{\ϵ}}^{\′\′}{\left|\frac{3}{\mathrm{\ϵ}+2}\right|}^2\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{r}^3,$

The cumulative volume that equals the water dust of unit volume due to water content multiply by the density of water, namely

$W={10}^6\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\frac{4\mathrm{\π}}{3}{r}_i^3(g/m^3),$

Arrange at last

$K_l=\frac{0.819f}{{\mathrm{\ϵ}}^{\′\′}(1+{\mathrm{\η}}^2)}(\mathrm{dB}/\mathrm{km}/g/m^3),$

A＝K _lW (dB/km)，

η＝(2+ε')/ε"，

If the dielectric constant of water is ε _w, f is frequency (GHz).

${\mathrm{\ϵ}}^{\′}=\frac{{\mathrm{\ϵ}}_0-{\mathrm{\ϵ}}_1}{f_p[1+{(f/f_p)}^2]}+\frac{{\mathrm{\ϵ}}_1-{\mathrm{\ϵ}}_2}{1+{(f/f{f}_p)}^2}+{\mathrm{\ϵ}}_2,$

${\mathrm{\ϵ}}^{\′\′}=\frac{f({\mathrm{\ϵ}}_0-{\mathrm{\ϵ}}_1)}{f_p[1+{(f/f_p)}^2]}+\frac{f({\mathrm{\ϵ}}_1-{\mathrm{\ϵ}}_2)}{f_s[1+{(f/f_p)}^2]},$

f _p＝20.09-142.4(θ-1)+294(θ-1) ²，

f _s＝590-1500(θ-1)，

Wherein: ε ₀=77.66+103.3 (θ-1), ε ₁=5.48, ε ₂=3.51, ε _w=ε '+i ε ".K _lBe the cloud attenuation coefficient, ε ' and ε ' ' are real part and the imaginary part of the complex dielectric permittivity of water, and it is by two Debye formulas.This shows, under Rayleigh was approximate, the decay of cloud and drop-size distribution distributed irrelevant, and it is relevant with water content.In addition, because the complex dielectric permittivity of water is the function of temperature, temperature has a great impact the decay of cloud, and for cloud attenuation, the temperature of generally getting cloud is 0 ℃.

Cloud and mist is on the impact of ultra short wave communication loss as shown in Figure 3: as shown in Figure 3, and when water content density is 0.4g/m ³, when the distance of propagation was 50km, the loss that cloud and mist causes was approximately 0.08dB; When water content density is 10g/m ³, when the distance of propagation was 50km, the loss that cloud and mist causes was approximately 1.18dB.

Through simulation calculation, the computing formula that match gets the weather loss is:

$\left\{\begin{array}{cc}{L}_W=0.1+\mathrm{Bd}& \\ B=0.002,& 0.4g/m^3<W<1g/m^3\\ B=0.02,& 1g/m^3<W<10g/m^3\end{array}\right.$

D is distance, and unit is km.

(3) the geographical environment loss is calculated

China region is wide, and terrain type varies, and causes the propagation path of electric wave very complicated.When propagation path was stopped by the earth surface of projection or barrier, diffraction will occur in electric wave, if stop relatively serious (as near running into mountain range or transmitting antenna, high-lager building being arranged), acceptance point can't normally receive.To correctly calculate the diffraction loss on wave path, must first analyze the path, consider the diffraction impact of landform and various barriers, calculate diffraction loss, then according to the free-space propagation field intensity, obtain the radio wave diffraction field intensity.

Actual barrier is complex-shaped various, therefore is difficult to the radio wave diffraction loss under various actual landforms is made accurately quantitatively calculate.Find out major obstacle thing on the path according to " profiles ", the abstract object that is reduced to ideal form of concrete barrier, then select corresponding radio wave diffraction computational methods to calculate diffraction loss.

Single-blade peak diffraction:

When radio wave was propagated in the mountain area, barrier was mainly the mountain peak, and electric wave usually can be stopped by ridge and produce diffraction loss.When the predicted path loss, these barriers are regarded as pointed obstacle, therefore be referred to as " tooth shape ", also can be described as knife edge.As shown in Figure 4: in the ideal case, all geometric parameters of barrier all can be summed up as a single nondimensional parameter v, are used for the barrier with similar profile of equal value, and v is called the diffraction constant, and available following formula calculates:

$v=h\sqrt{\frac{2}{\mathrm{\&lambda;}}(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HDA00002913884800021.png"\; state="\{\{state\}\}">d</figure-callout>}}_1}+\frac{1}{d_2})}$

Wherein, h refers to the part of the connecting line at high outbound path two ends, barrier top, d ₁And d ₂Be respectively the distance of two ends, path arrival barrier, d is path.θ is diffraction angle (radian), and symbol is identical with h.

According to diffraction parameter v, can estimate the diffraction loss of electric wave.Due to the complexity of radio wave diffraction environment, not nationally different computational methods have been adopted.Commonly used is ITU-R that International Telecommunication Association proposes is model P.526, and the computing formula of its diffraction loss L (v) is

$L\left(v\right)=6.9+20\log (\sqrt{{(v-0.1)}^2+1}+v-0.1)\mathrm{dB}$

The diffraction loss L (v) of knife edge can calculate according to above-mentioned formula in v＞-0.78 o'clock, otherwise diffraction loss is 0.Point P with maximum v value is called as main knife edge, and corresponding loss is L (v _P).

The diffraction loss that terrain obstruction is total is that transmitting terminal to the diffraction loss stack of each shelter between receiving terminal is completed.A plurality of shelters are divided into several stages to be calculated respectively, calculate one by one the electromagnetic wave diffraction propagation loss of each shelter, when calculating N diffraction propagation loss, the source of the top of N-1 shelter being used as N shelter, the like, adopt the diffraction theory of single knife edge during calculating, each peak sword be to there being a diffraction loss value, total diffraction loss value L _RCan be provided by following formula:

$L_R=L\left(1\right)+L\left(2\right)+...+L\left(n\right)=\underset{K=1}{\overset{n}{\mathrm{\&Sigma;}}}L\left(K\right)$

(4) multipath fading loss L _DCalculate.Because the communication equipment antenna in movement is short, bury fully below various buildings, trees etc., the electric wave of the point of arrive collecting mail not only has ground wave, also has many reflected waves, when making synthetic signal and strengthen, the time and weaken, cause rapid fading.This is very disadvantageous to communication apparatus communication.The impact of signal multipath effect is relevant with antenna height of reflection coefficient, signal frequency, grazing angle, radiation source height and the direction-finding equipment on ground etc., and reflection coefficient depends on roughness and the factors such as dielectric constant, grazing angle, signal wavelength and polarization mode of reflecting surface, and the radar engineering handbook can provide the reflection coefficient in various situations usually.Signal multipath transmisstion path is as shown in Figure 5:

The sighting distance definition:

H ₁, H ₂That dual-mode antenna is with respect to the height of ground return point.

Closely (d＜0.4D in sighting distance _o) can be used as plane earth and treat, suppose that the earth is that plane, geology are the same, consider the uneven or trees influence of building in earth's surface, the general formulae that the acceptance point field intensity is calculated is as follows:

$E=\frac{14\sqrt{\mathrm{Pe}}}{d\&times;{10}^3}\left|\sin \frac{2\mathrm{\&pi;}{H}_1{H}_2}{\mathrm{\&lambda;}\&times;d\&times;{10}^3}\right|$

In formula: Pe(w) be Effective Radiated Power;

D(km) be the distance of receiving station and transmitting antenna;

H ₁, H ₂(m) for sending out, receive the height of the relative pip of antenna;

λ (m) is operation wavelength.

Pe＝Pt×Gt×η

In formula: Pt is transmitter power;

Gt is the gain of transmitting antenna;

η is feeder line equal loss (comprising main, minute feeder line).

Can be calculated Pt=50w, Gt=1.5dB, η=1dB, H by above-mentioned formula ₁=15m, H ₂=15m, λ=10m, during d=200m, multipath loss L _DBe about 0.804dB.

The 3rd, according to calculating and the emulation of above-mentioned ultrashort wave propagation loss, in conjunction with the frequency characteristics of ultra short wave communication, through calculation and the lot of experiment validation of deriving, that sets up the ultrashort wave propagation loss asks the calculation formula:

FL＝L _F+L _W+L _R+L _D+C (6)

In formula: C is empirical correction, and the dB of unit, C=2+0.04d, d are overall pathway length (km).

Formula (6) simultaneous is calculated in asking of ultrashort wave radio set propagation loss computation model (1) and ultrashort wave propagation loss, namely gets ultrashort wave radio set communication capacity overlay model used in the present invention.When asking the calculation formula to carry out loss calculating according to the ultrashort wave propagation loss, need to judge whether piecemeal to exist diffraction loss according to the GIS terrain data.If there is diffraction loss, use the diffraction loss model to calculate this section propagation loss; If there is not diffraction loss, judge whether to exist the multipath loss, if there is the multipath loss, this section loss is multipath loss and free-space loss sum, if there is not the multipath loss, this section loss is free-space loss.

At last, adopt ultrashort wave radio set communication capacity overlay model, based on the communication coverage recursive calculation method of GIS, ask the concrete communication coverage of calculating ultrashort wave radio set.

Utilize the terrain analysis technology of GIS that the propagation path of electric wave is analyzed, and consider the impact of landform and shelter, realize the radio wave diffraction algorithm.Utilize the spatial data visualization technique of GIS, realize the visual of radio wave propagation scope.

Communication coverage recursive calculation method based on GIS: as shown in Figure 6:

1. analyze the terrain data file, take ultrashort wave radio set as launch point as the center of circle, according to computational accuracy, angle is divided, generate the angle on target collection, for example 360 degree are divided into 12 parts.

2. choose a certain angle on target, the estimation range is divided into some equidistant target phases (is step-length this side up, choose 200m), starting point at each target phase, in terminal point and target phase, every 50m gets the altitude data of landform, choose point and the starting and terminal point of height value maximum in target phase, set up single-blade peak diffraction model, if diffraction parameter v＞-0.78, this target phase loss value calculates with the diffraction loss computation model, otherwise, the vegetation data of getting this section target phase judge whether it is forest, if, this while target phase counts the distance of free-space loss and multipath loss, if not, this target phase only counts the distance of free-space loss.

3. to this angle on target target phase data of progressively increasing, the starting point coordinate of record object section, terminal point coordinate calculate the loss value of this target phase.

4. also cumulative propagation loss as calculated, if 3. the cumulative active loss that calculates forwards to less than the theoretical maximum loss (being asked by formula (1)) of point-to-point transmission communication, otherwise execution 5..

5. adopt dichotomy, in the end search impact point according to computational accuracy in a target phase, stop calculating, between launch point and impact point, distance is the maximum communication distance that this side up, the geographical coordinate of record object point at this moment.

6. successively other angle on targets of angle on target collection are called this algorithm, obtain several coordinate of ground points, the point that will obtain on map connects successively, the enclosed region of formation, the communication coverage of the ultrashort wave radio set that namely finally obtains.

According to the said method step, solve ultrashort wave radio set communication capacity coverage problems by example.

The ultra short wave communication analysis example is as follows:

Embodiment 1:

Starting point longitude and latitude (112.253,37.637)

Starting point elevation: 400m

Terminal point longitude and latitude (112.303,37.637)

Terminal point elevation: 440m

Sampling point highest elevation: 420m

Starting point antenna height (h _te)=12m

Terminal point antenna height (h _re)=12m

Starting point transmitting power (Pt)=50W

Terminal point receiving sensitivity (Pr)=-116dBm

Step-length=the 50m that arranges

Starting point antenna gain (Gt)=1dB

Terminal point antenna gain (Gr)=1dB

Emission feeder loss (Ct)=0dB

Receive feeder loss (Cr)=0dB

Conclusion: this target phase diffraction constant v=-2.828＜-0.78 does not consist of diffraction loss.Vegetation belongs to forest cover, L _F=52.205dB, L _W=0.5dB, L _R=0dB, L _D=0.804dB, C=2.08dB.Cumulative actual propagation loss 55.589dB＜theory is propagated maximum loss 149.699dB, can communicate by letter.

Illustrate: be launch point with point (112.253,37.637), along continuous straight runs is asked communication distance farthest.

Example 2:

Starting point longitude and latitude (112.303,37.637)

Starting point elevation: 440m

Terminal point longitude and latitude (112.305,37.637)

Terminal point elevation: 420m

Sampling point highest elevation: 420m

Starting point antenna height (h _te)=12m

Terminal point antenna height (h _re)=12m

Starting point transmitting power (Pt)=50W

Terminal point receiving sensitivity (Pr)=-116dBm

Step-length=the 50m that arranges

Starting point antenna gain (Gt)=1dB

Terminal point antenna gain (Gr)=1dB

Emission feeder loss (Ct)=0dB

Receive feeder loss (Cr)=0dB

Conclusion: this target phase diffraction constant v＜-0.78 does not consist of diffraction loss.Vegetation belongs to forest cover, L _F=53.712dB, L _W=0.5dB, L _R=0dB, L _D=1.608dB, C=2.08dB.Cumulative actual propagation loss 57.900dB＜theory is propagated maximum loss 149.699dB, can communicate by letter.

Illustrate: the communication distance of the 200m that progressively increases, the cumulative loss of generation need to continue cumulative less than theoretical maximum loss.

Example 3:

Starting point longitude and latitude (112.385,37.637)

Starting point elevation: 180m

Terminal point longitude and latitude (112.387,37.637)

Terminal point elevation: 160m

Sampling point highest elevation: 190m

Starting point antenna height (h _te)=12m

Terminal point antenna height (h _re)=12m

Starting point transmitting power (Pt)=50W

Terminal point receiving sensitivity (Pr)=-116dBm

Step-length=the 50m that arranges

Starting point antenna gain (Gt)=1dB

Terminal point antenna gain (Gr)=1dB

Emission feeder loss (Ct)=0dB

Receive feeder loss (Cr)=0dB

Conclusion: this target phase diffraction constant v＞-0.78 consists of diffraction loss.

L _F＝134.681dB,L _W＝0.5dB,L _R＝0dB,L _D＝10.324dB,C＝2.08dB。Cumulative actual propagation loss 147.585dB＜theory is propagated maximum loss 149.699dB, can communicate by letter.

Illustrate: the communication distance of the 200m that progressively increases, the cumulative loss of generation need to continue cumulative less than theoretical maximum loss.

Example 4:

Starting point longitude and latitude (112.387,37.637)

Starting point elevation: 160m

Terminal point longitude and latitude (112.389,37.637)

Terminal point elevation: 182m

Sampling point highest elevation: 190m

Starting point antenna height (h _te)=12m

Terminal point antenna height (h _re)=12m

Starting point transmitting power (Pt)=50W

Terminal point receiving sensitivity (Pr)=-116dBm

Step-length=the 50m that arranges

Starting point antenna gain (Gt)=1dB

Terminal point antenna gain (Gr)=1dB

Emission feeder loss (Ct)=0dB

Receive feeder loss (Cr)=0dB

Conclusion: this target phase diffraction constant v＞-0.78 consists of diffraction loss.

L _F＝137.828dB,L _W＝0.5dB,L _R＝0dB,L _D＝10.324dB,C＝2.08dB。Actual propagation loss 150.732dB〉the theoretical maximum loss 149.699dB that propagates, can not communicate by letter.

Illustrate: active loss greater than theoretical loss, needs the in the end interior dichotomy that adopts of step-length of a 200m at this moment, seeks according to computational accuracy and satisfies active loss less than or equal to the point of theoretical loss.

Example 5:

Starting point longitude and latitude (112.387,37.637)

Starting point elevation: 160m

Terminal point longitude and latitude (112.388,37.637)

Terminal point elevation: 180m

Sampling point highest elevation: 190m

Starting point antenna height (h _te)=12m

Terminal point antenna height (h _re)=12m

Starting point transmitting power (Pt)=50W

Terminal point receiving sensitivity (Pr)=-116dBm

Step-length=the 50m that arranges

Starting point antenna gain (Gt)=1dB

Terminal point antenna gain (Gr)=1dB

Emission feeder loss (Ct)=0dB

Receive feeder loss (Cr)=0dB

Conclusion: this target phase diffraction constant v＞-0.78 consists of diffraction loss.

L _F＝136.992dB,L _W＝0.5dB,L _R＝0dB,L _D＝10.324dB,C＝2.08dB。Actual propagation loss 149.896dB〉the theoretical maximum loss 149.699dB that propagates, can not communicate by letter.

Illustrate: remembering that last can lead to a little is terminal point, and the geographic distance of starting and terminal point is got in the position of recording this point, is namely ultrashort wave maximum propagation distance on this launch point horizontal direction.

The above; only be the better embodiment of the present invention; but protection scope of the present invention is not limited to this; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to replacement or changed according to technical scheme of the present invention and inventive concept thereof, within all should being encompassed in protection scope of the present invention.

Claims (6)

1. the computational methods of a ultrashort wave radio set electric wave coverage is characterized in that:

The first step: the propagation loss computation model of setting up ultrashort wave radio set:

Second step: the calculating of radio wave propagation loss;

The 3rd step: that sets up the ultrashort wave propagation loss asks the calculation formula;

The 4th step: adopt ultrashort wave radio set communication capacity overlay model;

The propagation loss computation model of the ultrashort wave radio set of the described first step is as follows:

FL(dB)＝Pt(dBm)-Pr(dBm)+Gt(dB)+Gr(dB)-Ct(dB)-Cr(dB)，

In formula: FL: the radio wave propagation total losses, it comprises free-space loss, geographical environment loss, weather loss; Pt: transmitting power; Pr: receiving equipment sensitivity; Gt: transmitter antenna gain (dBi); Gr: receiving antenna gain; Ct: emission feeder loss; Cr: receive feeder loss.

Described the 4th step is adopted ultrashort wave radio set communication capacity overlay model, asks the concrete communication coverage of calculating ultrashort wave radio set based on the communication coverage recursive calculation method of GIS.

2. the computational methods of a kind of ultrashort wave radio set electric wave coverage according to claim 1 is characterized in that:

Communication coverage recursive calculation method based on GIS is as follows:

1. analyze the terrain data file, take ultrashort wave radio set as launch point as the center of circle, according to computational accuracy, angle is divided, generate the angle on target collection,

2. choose a certain angle on target, the estimation range is divided into some equidistant target phases this side up, gets at a certain distance the altitude data of landform in starting point, terminal point and the target phase of each target phase, choose point and the starting and terminal point of height value maximum in target phase, set up single-blade peak diffraction model

3. to this angle on target target phase data of progressively increasing, the starting point coordinate of record object section, terminal point coordinate calculate the loss value of this target phase,

4. also cumulative propagation loss as calculated,

5. adopt dichotomy, in the end search impact point according to computational accuracy in a target phase, stop calculating, between launch point and impact point, distance is the maximum communication distance that this side up at this moment, the geographical coordinate of record object point,

6. successively other angle on targets of angle on target collection are called this algorithm, obtain several coordinate of ground points, the enclosed region that the point that will obtain is in turn connected to form, the communication coverage of the ultrashort wave radio set that namely finally obtains on map.

3. the computational methods of a kind of ultrashort wave radio set electric wave coverage according to claim 2 is characterized in that: if in setting up single-blade peak diffraction model diffraction parameter v＞-0.78, this target phase loss value calculates with diffraction loss computation model.

4. the computational methods of a kind of ultrashort wave radio set electric wave coverage according to claim 2, it is characterized in that: if in setting up single-blade peak diffraction model diffraction parameter v＜-0.78, if the vegetation data judgement forest of getting this section target phase this simultaneously target phase count the distance of free-space loss and multipath loss; Get the vegetation data judgement of this section target phase if not this target phase of forest only counts the distance of free-space loss.

5. the computational methods of a kind of ultrashort wave radio set electric wave coverage according to claim 2, it is characterized in that: as calculated and cumulative propagation loss adopt to this angle on target target phase data of progressively increasing less than the theoretical maximum loss of point-to-point transmission communication, the starting point coordinate of record object section, terminal point coordinate calculate the loss value of this target phase.

6. the computational methods of a kind of ultrashort wave radio set electric wave coverage according to claim 2, is characterized in that: the theoretical maximum loss employing dichotomy that the propagation loss that also adds up is as calculated communicated by letter greater than point-to-point transmission.

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