CN102340343A - Satellite navigation wide area augmentation system-based shortwave frequency selection method and system - Google Patents

Abstract

The invention discloses a satellite navigation wide area augmentation system-based shortwave frequency selection method and system. The shortwave frequency selection method comprises the following steps of: calculating a path intermediate point between a first position and a second position of a communication link; receiving wide area augmentation information through a satellite navigation receiver, and acquiring ionized layer grid point sequencing information and a corresponding ionized layer vertical transmission delay value; finding out a plurality of ionized layer grid points closest to the path intermediate point of the communication link; finding out the ionized layer vertical transmission delay value corresponding to the plurality of ionized layer grid points; calculating a weighted ionized layer vertical transmission delay value of the path intermediate point of the communication link; converting the weighted ionized layer vertical transmission delay value to a total ionized layer electron concentration content value; converting the total ionized layer electron concentration content value to a value of critical frequency of an F2 ionized layer; and calculating the corresponding shortwave communication frequency according to the critical frequency of the F2 ionized layer. As in comparison with the traditional method, the invention has the advantages of high precision and real time, great reduction of calculation amount and data quantity and capability of overcoming the difficulty of insufficient ionized layer reference in China.

Description

Short frequency system of selection and system based on the satellite navigation WAAS

Technical field

The present invention relates to a kind of system of selection and system of short wave communication frequency, relate in particular to a kind of system of selection and system of the short wave communication frequency based on the satellite navigation WAAS.

Background technology

Short wave communication is to utilize the ionospheric reflection in high-altitude or scattering and the communication carried out, can realize the long haul communication transmission.Ionosphere is divided into three layers usually according to the situation of electron distributions, by highly from bottom to top, is called D layer, E layer, F layer (being divided into F1 and F2 layer in the daytime) respectively.Because it is irregular that ionosphere changes, be prone to cause the short wave communication link unstable.Desire is set up reliable short wave communication, can not in the shortwave frequency range, select a frequency arbitrarily.On the path of giving set a distance and direction, short wave communication can only be used a limited frequency band (Xu Yijun etc. are based on the sky wave propagation decay forecast model research of shortwave, " microcomputer and application " 2010 the 29th the 18th phases of volume) within a certain period of time.So need the short wave communication frequency is selected.

Short wave communication mainly relies on the reflection of E layer and F2 layer to carry out, and wherein the E layer is more stable layer, and the communication frequency of E layer is selected also simple relatively; And the F2 layer is ionospheric high ionization zone, and it also receives the strong influence of kinetic effects such as wind, diffusion, drift except that receiving the solar radiation effect, and the communication frequency of F2 layer is selected comparatively complicated and difficult.

The short wave communication frequency is selected to adopt international reference ionosphere (IRI) model to carry out, and the IRI model is set up according to the observations of collecting in the long period, is a kind of predicted value that reflection ionosphere changes.In case its advantage is to set up the back just can use for a long time, can parameter be solidificated in the equipment, does not need frequent updating.Channel calculation method and experience (the accurate parabolic ionosphere parameter that Feng Xiaozhe etc., shortwave list stand firm in the position is revised electronic information countermeasure techniques, the 5th phase of September in 2008 in real time) that a lot of maturations have been arranged according to this model.

But, be ionospheric average mode because IRI provides, it can not to ionospheric in real time or the short-term state forecast.Because the ionospheric factor of influence is a lot, many factors have bigger randomness again, and at present correlation, Changing Pattern and the internal mechanism etc. of various factors are not got clear fully, have a lot " irregular " to change.So the ionosphere parameters precision that utilizes this model to obtain is generally all not so good.(Liu Jingnan, Chen Junyong, GPS wide area differential GPS GPS principle and method, Mapping Press, 1997) and, owing to do not adopt the data of CHINESE REGION, the IRI result calculated certain departing from occur in China; And this method amount of calculation and data volume are very big, are not suitable for embedded device and use.

The GNSS WAAS is constantly broadcast global longitude and latitude graticule mesh crosspoint, and (grid points is IGP) with respect to the ionosphere vertical delay corrected value of GPS L1 frequency.GNSS WAAS issue be data quasi real time, compare the ionosphere empirical value of IRI, have on the precision, the advantage on the real-time.But these data never are used for the selection to the short wave communication frequency.

Summary of the invention

The objective of the invention is to address the above problem, a kind of short frequency system of selection based on the satellite navigation WAAS be provided, can be used for communication distance at 4000km with of the selection of interior (F2 layer single-hop mode) building berth to the short wave communication frequency of base station.

Another object of the present invention is to provide a kind of short frequency selective system based on the satellite navigation WAAS.

Technical scheme of the present invention is: a kind of short frequency system of selection based on the satellite navigation WAAS may further comprise the steps:

Calculate the primary importance of communication link and the longitude and latitude of the path intermediate point point between the second place;

Navigation neceiver receives the wide area enhanced information via satellite, obtains ionosphere grid points sequencing information and corresponding ionosphere vertical transfer length of delay thereof;

Search and immediate at least one the ionosphere grid points of the path intermediate point of communication link;

Search the corresponding ionosphere vertical transfer length of delay of above-mentioned ionosphere grid points;

Calculate the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link;

Convert above-mentioned weighting ionosphere vertical transfer length of delay into ionosphere electron concentration total content value (TEC);

Above-mentioned ionosphere electron concentration total content value is converted into the value (f of the critical frequency of 2 layers of Ionospheric F ₀F2);

Critical frequency (f according to 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency.

Embodiment according to the short frequency system of selection based on the satellite navigation WAAS of the present invention; In the step of the path intermediate point that calculates communication link; Longitude and latitude according to the primary importance and the second place; Calculate the longitude and latitude of the path intermediate point of communication link, wherein primary importance is the position of coastal station and is known, and the second place is the position of building berth and is obtained by the ship satellite navigation location; Search in the step with immediate several ionosphere grid points of path intermediate point of communication link, the quantity of ionosphere grid points is 4.

According to an embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, in the step of the weighting ionosphere vertical transfer length of delay of the path intermediate point that calculates communication link, use formula:

D _mid＝k ₁·VD ₁+k ₂·VD ₂+k ₃·VD ₃+k ₄·VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, VD ₁, VD ₂, VD ₃, VD ₄Be respectively the ionosphere vertical transfer length of delay of four ionosphere grid points, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points.

Embodiment according to the short frequency system of selection based on the satellite navigation WAAS of the present invention converts above-mentioned weighting ionosphere vertical transfer length of delay in the step of ionosphere electron concentration total content value into, uses formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

TEC is an ionosphere electron concentration total content value in the formula, and c is the light velocity, and f is the navigation signal frequency.

According to an embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, above-mentioned ionosphere electron concentration total content value is converted in the step of value of critical frequency of 2 layers of Ionospheric F, use formula:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\×1.24\×{10}^{10}\×H_0}}$

F0F wherein ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

According to an embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, at critical frequency (f according to 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate in the step of corresponding short wave communication frequency, use the ITU-R method that P.1240-1 chapters and sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, obtain optimum traffic frequency (OWF).

The present invention has also disclosed a kind of short frequency selective system based on the satellite navigation WAAS; Comprise that path intermediate point computing module, ionosphere grid points sequencing information acquisition module, ionosphere grid points are searched module, the ionosphere vertical transfer postpones acquisition module, weighting ionosphere vertical transfer length of delay computing module, ionosphere electron concentration total content value modular converter, 2 layers of critical frequency value of Ionospheric F modular converter, short wave communication frequency selection module, wherein:

Said path intermediate point computing module, the path intermediate point of the communication link between the calculating primary importance and the second place;

Said ionosphere grid points sequencing information acquisition module, navigation neceiver receives the wide area enhanced information via satellite, obtains ionosphere grid points sequencing information;

Said ionosphere grid points is searched module, searches and immediate at least one the ionosphere grid points of the path intermediate point of communication link;

Said ionosphere vertical transfer postpones acquisition module, in the wide area enhanced information that satellite navigation receiver receives, obtains the corresponding ionosphere vertical transfer length of delay of above-mentioned at least one ionosphere grid points;

Said weighting ionosphere vertical transfer length of delay computing module, the weighting ionosphere vertical transfer length of delay of the path intermediate point of calculating communication link;

Said ionosphere electron concentration total content value modular converter converts above-mentioned weighting ionosphere vertical transfer length of delay into ionosphere electron concentration total content value;

2 layers of critical frequency value of said Ionospheric F modular converter converts above-mentioned ionosphere electron concentration total content value into the value of the critical frequency of 2 layers of Ionospheric F;

Said short wave communication frequency is selected module, according to the critical frequency (f of 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency.

Embodiment according to the short frequency selective system based on the satellite navigation WAAS of the present invention; In the intermediate point computing module of said path; Longitude and latitude according to the primary importance and the second place; Calculate the longitude and latitude of the path intermediate point of communication link, wherein primary importance is the position of coastal station and is known, and the second place is the position of building berth and is obtained by the satellite navigation location; Grid points is searched in the module in said ionosphere, and the quantity of ionosphere grid points is 4.

According to an embodiment of the short frequency selective system based on the satellite navigation WAAS of the present invention, in the vertical transfer length of delay computing module of said weighting ionosphere, use formula:

D _mid＝k ₁·VD ₁+k ₂·VD ₂+k ₃·VD ₃+k ₄·VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, VD ₁, VD ₂, VD ₃, VD ₄Be respectively the ionosphere vertical transfer time-delay of four ionosphere grid points, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points.

According to an embodiment of the short frequency selective system based on the satellite navigation WAAS of the present invention, in the electron concentration total content value modular converter of said ionosphere, use formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

TEC is an ionosphere electron concentration total content value in the formula, and c is the light velocity, and f is the navigation signal frequency.

According to an embodiment of the short frequency selective system based on the satellite navigation WAAS of the present invention, in 2 layers of critical frequency value of said Ionospheric F modular converter, use formula:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\×1.24\×{10}^{10}\×H_0}}$

FoF in the formula ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

According to an embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, select in the module in said short wave communication frequency, according to the critical frequency (f of 2 layers of the Ionospheric F of aforementioned calculation ₀F2), use the ITU-R method that P.1240-1 chapters and sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, obtain optimum traffic frequency (OWF).

The present invention contrasts prior art has following beneficial effect: the present invention adopts GNSS wide area enhanced information; Immediate several ionosphere grid points of the path intermediate point of communication link are calculated weighting ionosphere vertical transfer length of delay; Thereby acquisition optimum traffic frequency; Compare that traditional method has on the precision, the advantage on the real-time, amount of calculation and data volume significantly reduce, and can overcome the not enough difficulty of CHINESE REGION ionosphere data.

Description of drawings

Fig. 1 shows the flow chart of the embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention.

Fig. 2 shows the path intermediate point of communication link and the position of immediate ionosphere grid points concerns sketch map.

Fig. 3 shows the schematic diagram of the embodiment of the short frequency selective system based on the satellite navigation WAAS of the present invention.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is done further description.

Embodiment based on the short frequency system of selection of satellite navigation WAAS

Fig. 1 shows the flow process of the embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, sees also Fig. 1, is the detailed description to each step of the short frequency system of selection of present embodiment below.

Step S100: the satellite navigation positioning result that obtains building berth.

Step S101: the path intermediate point that calculates the communication link between building berth and the base station.

According to the longitude and latitude of base station (primary importance) and building berth (second place), calculate the longitude and latitude of the path intermediate point of communication link, wherein primary importance is that the position of coastal station is known, the second place is that the position of building berth is obtained by the satellite navigation location.

Step S102: navigation (GNSS) receiver receives the wide area enhanced information via satellite.

Step S103: obtain ionosphere grid points (IGP) sequencing information (IGPM).

WAAS defines and numbers ionosphere grid points (IGP) in advance; Formed the position table of IGP; Comprise 11 bands (numbering 0～10), the zone between latitude N55～S55 wherein, IGP is spaced apart 5 °; Zone between latitude N55～N85 and S55～S85, IGP is spaced apart 10 °.See the Table A-14 and figure A-14 of RTCA DO-229D " GPS WAAS airborne equipment minimum performance requirement " for details.

Above-mentioned information is play in the message of ionosphere grid points sequencing information, receive IGP position table after, the IGP position is kept in the memory.

Step S104: search and immediate several ionosphere grid points of the path intermediate point of communication link.

According to the position relation, search the several IGP points nearest with the path intermediate point, present embodiment is selected four, is respectively IGP ₁, IGP ₂, IGP ₃, IGP ₄As shown in Figure 2, wherein Mid represents the path intermediate point of communication link, is respectively the IGP shown in Fig. 2 with immediate four the IGP points of Mid ₁, IGP ₂, IGP ₃, IGP ₄

Step S105: navigation neceiver receives the wide area enhanced information via satellite, obtains above-mentioned 4 ionosphere vertical transfer length of delays that the ionosphere grid points is corresponding.Promptly obtain IGP ₁, IGP ₂, IGP ₃, IGP ₄Ionosphere vertical transfer length of delay, be respectively VD ₁, VD ₂, VD ₃, VD ₄

Step S106: the weighting ionosphere vertical transfer length of delay that calculates the path intermediate point of communication link.

The formula of wherein using is: D _Mid=k ₁VD ₁+ k ₂VD ₂+ k ₃VD ₃+ k ₄VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points, air line distance more greatly then is worth more little.Mid point and IGP ₁, IGP ₂, IGP ₃, IGP ₄The air line distance of point is respectively l ₁, l ₂, l ₃, l ₄, then have:

$k_i=\frac{l_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4-l_i}{3(l_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4)}$

In the formula: k _iBe that i ionosphere vertical transfer length of delay is the weighted value of VDi, l _iBe Mid point and i the distance that IGP is ordered.When the Mid point is positioned at IGP ₁, IGP ₂, IGP ₃, IGP ₄The point the center time, k is arranged ₁=k ₂=k ₃=k ₄=0.25.

Step S108: convert weighting ionosphere vertical transfer length of delay into ionosphere electron concentration total content value.

Use formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

Wherein TEC is an ionosphere electron concentration total content value, and c is the light velocity, and f is the navigation signal frequency.

Step S110: the value that above-mentioned ionosphere electron concentration total content value is converted into the critical frequency of 2 layers of Ionospheric F.

F2 range upon range of mountains value electron concentration (NmF ₂) with the critical frequency (foF of F2 layer ₂) relation (seeing Davies, K., and X.M.Liu, Ionospheric slab thickness in middle and low latitudes.Radio Sci, 1991,26 (4)) be:

NmF ₂＝1.24×10 ¹⁰(foF ₂) ²

And TEC and NmF ₂The empirical equation (seeing Ezquer, R.G. etc., Predicted and measured total electron content at both peaks of the equatorial anomaly, Radio Sci., 1994,29 (4)) of relation be:

TEC＝4.13×H ₀×N _mF ₂

So:

TEC＝4.13×1.24×10 ¹⁰×H ₀×(foF ₂) ²

In the formula, H ₀Be the oxygen atom absolute altitude, be set-point.

Therefore:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\&times;1.24\&times;{10}^{10}\&times;H_0}}$

F0F wherein ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

Step S112: according to the critical frequency (f of 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency, use the ITU-R method that P.1240-1 chapters and sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, can obtain optimum traffic frequency (OWF).

According to optimum traffic frequency and predetermined communication channel scope, select the real work channel.With the maritime affairs shortwave unilateral-band broadcasting-station is example; Suppose that the optimum traffic frequency that calculates is 6.52MHz; But, be at the actual spendable full duplex single-sideband voice channel of 6MHz wave band because real work channel in radio station need meet the requirement of ITU (International Telecommunications Union):

Channel number	Building berth receive frequency (MHz)	Building berth tranmitting frequency (MHz)
			601	6.501	6.200
602	6.504	6.203
			603	6.507	6.206
604	6.510	6.209
			605	6.513	6.212
606	6.516	6.215
			607	6.519	6.218
608	6.522	6.221

According to optimum traffic frequency and available channel, can select 607 or 606,608 contiguous channels, should also be noted that simultaneously avoid with base station predetermined broadcast channel confliction.

Embodiment based on the short frequency selective system of satellite navigation WAAS

Fig. 3 shows the principle of the embodiment of the short frequency selective system based on the satellite navigation WAAS of the present invention; See also Fig. 3, the short frequency selective system of present embodiment comprises: path intermediate point computing module 10, ionosphere grid points sequencing information acquisition module 11, ionosphere grid points are searched module 12, the ionosphere vertical transfer postpones acquisition module 13, weighting ionosphere vertical transfer length of delay computing module 14, ionosphere electron concentration total content value modular converter 15,2 layers of critical frequency value of Ionospheric F modular converter 16, short wave communication frequency selection module 17.

Path intermediate point computing module 10 calculates the path intermediate point of the communication link between the primary importance and the second place.Path intermediate point computing module 10 is according to the longitude and latitude of the primary importance and the second place; Calculate the longitude and latitude of the intermediate point of communication link; Wherein primary importance is the position of coastal station and is known, and the second place is the position of building berth and is obtained by satellite navigation location.

Ionosphere grid points sequencing information acquisition module 11 navigation neceiver via satellite receives the wide area enhanced information, obtains ionosphere grid points sequencing information.WAAS defines and numbers ionosphere grid points (IGP) in advance; Formed the position table of IGP; Comprise 11 bands (numbering 0～10), the zone between latitude N55～S55 wherein, IGP is spaced apart 5 °; Zone between latitude N55～N85 and S55～S85, IGP is spaced apart 10 °.See the Table A-14 and figure A-14 of RTCA DO-229D " GPS WAAS airborne equipment minimum performance requirement " for details.

Above-mentioned information is play in the message of ionosphere grid points sequencing information, receive IGP position table after, the IGP position is kept in the memory.

The ionosphere grid points is searched module 12 and is searched and immediate several ionosphere grid points of the path intermediate point of communication link.According to the position relation, search the several IGP points nearest with the path intermediate point, present embodiment is selected four, is respectively IGP ₁, IGP ₂, IGP ₃, IGP ₄As shown in Figure 2, wherein Mid represents the path intermediate point of communication link, is respectively the IGP shown in Fig. 2 with immediate four the IGP points of Mid ₁, IGP ₂, IGP ₃, IGP ₄

The ionosphere vertical transfer postpones acquisition module 13 navigation neceiver reception via satellite wide area enhanced information, obtains the corresponding ionosphere vertical transfer length of delay of above-mentioned several ionosphere grid points.

Weighting ionosphere vertical transfer length of delay computing module 14 calculates the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link.In weighting ionosphere vertical transfer length of delay computing module 14, use formula:

D _mid＝k ₁·VD ₁+k ₂·VD ₂+k ₃·VD ₃+k ₄·VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, VD ₁, VD ₂, VD ₃, VD ₄Be respectively the ionosphere vertical transfer time-delay of four ionosphere grid points, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points, air line distance more greatly then is worth more little.Mid point and IGP ₁, IGP ₂, IGP ₃, IGP ₄The geometric distance of point is respectively l ₁, l ₂, l ₃, l ₄, then have:

$k_i=\frac{l_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4-l_i}{3(l_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4)}$

In the formula: k _iBe that i ionosphere vertical transfer length of delay is the weighted value of VDi, l _iBe Mid point and i the distance that IGP is ordered.When the Mid point is positioned at IGP ₁, IGP ₂, IGP ₃, IGP ₄The point the center time, k is arranged ₁=k ₂=k ₃=k ₄=0.25.

Ionosphere electron concentration total content value modular converter 15 converts above-mentioned weighting ionosphere vertical transfer length of delay into ionosphere electron concentration total content value.In ionosphere electron concentration total content value modular converter 15, use formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

Wherein TEC is an ionosphere electron concentration total content value, and c is the light velocity, and f is the navigation signal frequency.

2 layers of critical frequency value of Ionospheric F modular converter 16 converts above-mentioned ionosphere electron concentration total content value into the value of the critical frequency of 2 layers of Ionospheric F.F2 range upon range of mountains value electron concentration (NmF ₂) with the critical frequency (foF of F2 layer ₂) relation (seeing Davies, K., and X.M.Liu, Ionospheric slab thickness in middle and low latitudes.Radio Sci, 1991,26 (4)) be:

NmF ₂＝1.24×10 ¹⁰(foF ₂) ²

And TEC and NmF ₂The empirical equation (seeing Ezquer, R.G. etc., Predicted and measured total electron content at both peaks of the equatorial anomaly, Radio Sci., 1994,29 (4)) of relation be:

TEC＝4.13×H ₀×N _mF ₂

So:

TEC＝4.13×1.24×10 ¹⁰×H ₀×(foF ₂) ²

In the formula, H ₀Be the oxygen atom absolute altitude, be set-point.

Therefore:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\&times;1.24\&times;{10}^{10}\&times;H_0}}$

FoF wherein ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

The short wave communication frequency is selected the critical frequency (f of module 17 according to 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency, use the ITU-R method that P.1240-1 chapters and sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, can obtain optimum traffic frequency (OWF).

According to optimum traffic frequency and predetermined communication channel scope, select the real work channel.With the maritime affairs shortwave unilateral-band broadcasting-station is example; Suppose that the optimum traffic frequency that calculates is 6.52MHz; But, be at the actual spendable full duplex single-sideband voice channel of 6MHz wave band because real work channel in radio station need meet the requirement of ITU (International Telecommunications Union):

Channel number	Building berth receive frequency (MHz)	Building berth tranmitting frequency (MHz)
			601	6.501	6.200
602	6.504	6.203
			603	6.507	6.206
604	6.510	6.209
			605	6.513	6.212
606	6.516	6.215
			607	6.519	6.218
608	6.522	6.221

According to optimum traffic frequency and available channel, can select 607 or 606,608 contiguous channels, should also be noted that simultaneously avoid with base station predetermined broadcast channel confliction.

The foregoing description provides to those of ordinary skills and realizes and use of the present invention; Those of ordinary skills can be under the situation that does not break away from invention thought of the present invention; The foregoing description is made various modifications or variation; Thereby invention scope of the present invention do not limit by the foregoing description, and should be the maximum magnitude that meets the inventive features that claims mention.

Claims (10)

1. the short frequency system of selection based on the satellite navigation WAAS is characterized in that, may further comprise the steps:

(1) calculates the primary importance of communication link and the longitude and latitude of the path intermediate point between the second place;

(2) navigation neceiver receives the wide area enhanced information via satellite, obtains ionosphere grid points sequencing information and corresponding ionosphere vertical transfer length of delay thereof;

(3) search and immediate at least 1 the ionosphere grid points of the path intermediate point of communication link;

(4) the corresponding ionosphere vertical transfer length of delay of the described ionosphere of finding step (3) grid points;

(5) the weighting ionosphere vertical transfer length of delay of the path intermediate point of calculating communication link;

(6) convert the described weighting of step (5) ionosphere vertical transfer length of delay into ionosphere electron concentration total content value (TEC);

(7) the described ionosphere of step (6) electron concentration total content value is converted into the value (f of the critical frequency of 2 layers of Ionospheric F ₀F2);

(8) according to the critical frequency (f of 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency.

2. the short frequency system of selection based on the satellite navigation WAAS according to claim 1; It is characterized in that; In said step (1),, calculate the longitude and latitude of the path intermediate point of communication link according to the longitude and latitude of the primary importance and the second place; Wherein primary importance is the position of coastal station and is known, and the second place is the position of building berth and is obtained by ship satellite navigation location; In said step (3), the quantity of ionosphere grid points is 4.

3. the short frequency system of selection based on the satellite navigation WAAS according to claim 1 and 2 is characterized in that, in said step (5), uses formula:

D _mid＝k ₁·VD ₁+k ₂·VD ₂+k ₃·VD ₃+k ₄·VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, VD ₁, VD ₂, VD ₃, VD ₄Be respectively the ionosphere vertical transfer length of delay of four ionosphere grid points, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points; In said step (6), use formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

TEC is an ionosphere electron concentration total content value in the formula, and c is the light velocity, and f is the navigation signal frequency.

4. according to claim 1 or 3 described short frequency systems of selection, it is characterized in that, in said step (7), use formula based on the satellite navigation WAAS:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\&times;1.24\&times;{10}^{10}\&times;H_0}}$

FoF in the formula ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

5. according to claim 1 or 4 described short frequency systems of selection based on the satellite navigation WAAS; It is characterized in that; In said step (8); Use the ITU-R method that P.1240-1 related Sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, obtain optimum traffic frequency (OWF).

6. short frequency selective system based on the satellite navigation WAAS; It is characterized in that; Comprise that path intermediate point computing module, ionosphere grid points sequencing information acquisition module, ionosphere grid points are searched module, the ionosphere vertical transfer postpones acquisition module, weighting ionosphere vertical transfer length of delay computing module, ionosphere electron concentration total content value modular converter, 2 layers of critical frequency value of Ionospheric F modular converter, short wave communication frequency selection module, wherein:

Said path intermediate point computing module, the path intermediate point of the communication link between the calculating primary importance and the second place;

Said ionosphere grid points sequencing information acquisition module, navigation neceiver receives the wide area enhanced information via satellite, obtains ionosphere grid points sequencing information;

Said ionosphere grid points is searched module, searches and immediate at least one the ionosphere grid points of the path intermediate point of communication link;

Said ionosphere vertical transfer postpones acquisition module, in the wide area enhanced information that satellite navigation receiver receives, obtains the corresponding ionosphere vertical transfer length of delay of above-mentioned at least one ionosphere grid points;

Said weighting ionosphere vertical transfer length of delay computing module, the weighting ionosphere vertical transfer length of delay of the path intermediate point of calculating communication link;

Said ionosphere electron concentration total content value modular converter converts above-mentioned weighting ionosphere vertical transfer length of delay into ionosphere electron concentration total content value;

2 layers of critical frequency value of said Ionospheric F modular converter converts above-mentioned ionosphere electron concentration total content value into the value of the critical frequency of 2 layers of Ionospheric F;

Said short wave communication frequency is selected module, according to the critical frequency (f of 2 layers of the Ionospheric F of aforementioned calculation ₀F2) calculate corresponding short wave communication frequency.

7. the short frequency selective system based on the satellite navigation WAAS according to claim 6; It is characterized in that; In the intermediate point computing module of said path,, calculate the longitude and latitude of the path intermediate point of communication link according to the longitude and latitude of the primary importance and the second place; Wherein primary importance is the position of coastal station and is known, and the second place is the position of building berth and is obtained by satellite navigation location; Grid points is searched in the module in said ionosphere, and the quantity of ionosphere grid points is 4.

8. according to claim 6 or 7 described short frequency selective systems, it is characterized in that, in the vertical transfer length of delay computing module of said weighting ionosphere, use formula based on the satellite navigation WAAS:

D _mid＝k ₁·VD ₁+k ₂·VD ₂+k ₃·VD ₃+k ₄·VD ₄

D in the formula _MidBe the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, VD ₁, VD ₂, VD ₃, VD ₄Be respectively the ionosphere vertical transfer time-delay of four ionosphere grid points, k ₁～k ₄Be weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄Be inversely proportional to the path intermediate point of communication link and the air line distance of said four ionosphere grid points; In the electron concentration total content value modular converter of said ionosphere, use formula:

$\mathrm{TEC}=\frac{{\mathrm{cf}}^2}{40.3}{D}_{\mathrm{mid}}$

TEC is an ionosphere electron concentration total content value in the formula, and c is the light velocity, and f is the navigation signal frequency.

9. according to claim 6 or 8 described short frequency selective systems, it is characterized in that, in 2 layers of critical frequency value of said Ionospheric F modular converter, use formula based on the satellite navigation WAAS:

${\mathrm{foF}}_2=\sqrt{\frac{\mathrm{TEC}}{4.13\&times;1.24\&times;{10}^{10}\&times;H_0}}$

FoF in the formula ₂Be the critical frequency of 2 layers of Ionospheric F, H ₀Be the oxygen atom absolute altitude.

10. according to claim 6 or 9 described short frequency selective systems based on the satellite navigation WAAS; It is characterized in that; Select in the module in said short wave communication frequency; Use the ITU-R method that P.1240-1 related Sections such as 3.1,6 and 7 provide in " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " to calculate, obtain optimum traffic frequency (OWF).

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