CN102340343B - 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, according to the situation of electron distributions, is divided into three layers usually, by highly from bottom to top, is called D layer, E layer, F layer (being divided in the daytime F1 and F2 layer).Because the ionosphere variation is irregular, easily cause the short wave communication link unstable.Wish is set up reliable short wave communication, can not in the shortwave frequency range, select arbitrarily a frequency.On the path of giving set a distance and direction, short wave communication can only be with a limited frequency band (Xu Yijun etc., the sky wave propagation decay forecast model based on shortwave is studied, " microcomputer and application " the 29th the 18th phase of volume in 2010) within a certain period of time.So need be selected the short wave communication frequency.

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 relatively simple; And the F2 layer is ionospheric high ionization zone, it also is subject to the strong effect of the kinetic effects such as wind, diffusion, drift except being subject to 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.Once its advantage is just can use for a long time after setting up, and parameter can be solidificated in equipment, does not need frequent updating.According to this model, the channel calculation method of a lot of maturations and experience (Feng Xiaozhe etc., the accurate parabolic Ionospheric Parameters that the shortwave list is stood firm in position is revised in real time, electronic information countermeasure techniques, the 5th phase of September in 2008) have been arranged.

But what provide due to IRI is ionospheric average mode, it can not to ionospheric in real time or the short-term state forecast.Because the ionospheric factor of impact is a lot, many factors are again with larger randomness, and at present correlation, Changing Pattern and the internal mechanism etc. of various factors are not got clear fully, and a lot " irregular " variation is arranged.So the Ionospheric Parameters precision of utilizing this model to obtain is generally all not so good.(Liu Jingnan, Chen Junyong, WADGPS principle and method, Mapping Press, 1997) and, due to the data that does not adopt CHINESE REGION, the result that IRI calculates certain departing from occur in China; And the method amount of calculation and data volume are very large, are not suitable for embedded device and use.

The GNSS WAAS is constantly broadcast global longitude and latitude graticule mesh crosspoint, and (grid points, 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 precision, the advantage on real-time.But these data are never for the selection to the short wave communication frequency.

Summary of the invention

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

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 comprises the following 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 wide area enhancing 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 ionosphere vertical transfer length of delay corresponding to above-mentioned ionosphere grid points;

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

Above-mentioned weighting ionosphere vertical transfer length of delay is converted to ionospheric electron density total content value (TEC);

Above-mentioned ionospheric electron density total content value is converted to the value (f of the critical frequency of Ionospheric F_2-layer ₀F2);

Critical frequency (f according to the Ionospheric F_2-layer of above-mentioned calculating ₀F2) calculate corresponding short wave communication frequency.

An 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 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 formula _midFor 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 ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to.

According to an embodiment of the short frequency system of selection based on the satellite navigation WAAS of the present invention, above-mentioned weighting ionosphere vertical transfer length of delay is converted in the step of ionospheric electron density total content value, use formula:

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

In formula, TEC is ionospheric electron density total content value, 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 ionospheric electron density total content value is converted in the step of value of critical frequency of Ionospheric F_2-layer, use formula:

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

F0F wherein ₂For the critical frequency of Ionospheric F_2-layer, H ₀For 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 the critical frequency (f of the Ionospheric F_2-layer according to above-mentioned calculating 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 be calculated, 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, ionospheric electron density total content value modular converter, ionospheric F 2 layer critical frequency value modular converter, short wave communication frequency selection module, wherein:

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

Described ionosphere grid points sequencing information acquisition module, navigation neceiver receives wide area enhancing information via satellite, obtains ionosphere grid points sequencing information;

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

Described ionosphere vertical transfer postpones acquisition module, in the wide area enhancing information received at satellite navigation receiver, obtains ionosphere vertical transfer length of delay corresponding to above-mentioned at least one ionosphere grid points;

Described 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;

Described ionospheric electron density total content value modular converter, be converted to ionospheric electron density total content value by above-mentioned weighting ionosphere vertical transfer length of delay;

Described ionospheric F 2 layer critical frequency value modular converter, be converted to above-mentioned ionospheric electron density total content value the value of the critical frequency of Ionospheric F_2-layer;

Described short wave communication frequency is selected module, according to the critical frequency (f of the Ionospheric F_2-layer of above-mentioned calculating ₀F2) calculate corresponding short wave communication frequency.

An 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 described path, longitude and latitude according to 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; In described ionosphere grid points is searched module, 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 described weighting ionosphere, use formula:

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

D in formula _midFor 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 ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to.

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

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

In formula, TEC is ionospheric electron density total content value, 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 described ionospheric F 2 layer critical frequency value modular converter, use formula:

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

FoF in formula ₂For the critical frequency of Ionospheric F_2-layer, H ₀For 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, in described short wave communication frequency, select in module, according to the critical frequency (f of the Ionospheric F_2-layer of above-mentioned calculating 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 be calculated, obtain optimum traffic frequency (OWF).

The present invention contrasts prior art following beneficial effect: the present invention adopts the GNSS wide area to strengthen information, immediate several ionosphere grid points of the path intermediate point of communication link are calculated to weighting ionosphere vertical transfer length of delay, thereby acquisition optimum traffic frequency, compare that traditional method has on precision, the advantage on real-time, amount of calculation and data volume greatly reduce, and can overcome the difficulty of CHINESE REGION ionosphere data deficiency.

The accompanying drawing explanation

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 relationship schematic diagram of immediate ionosphere grid points.

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 drawings and Examples, the invention will be further described.

The embodiment of the short frequency system of selection based on the 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, refers to Fig. 1, is below the detailed description to each step of the short frequency system of selection of the present embodiment.

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 base station.

Longitude and latitude according to 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, and the second place is that the position of building berth is obtained by the satellite navigation location.

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

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

WAAS is defined 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 °.Refer to Table A-14 and the figure A-14 of RTCA DO-229D " GPS WAAS airborne equipment minimum performance requirement ".

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

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

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

Step S105: navigation neceiver receives wide area enhancing information via satellite, obtains ionosphere vertical transfer length of delay corresponding to above-mentioned 4 ionosphere grid points.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 formula _midFor the weighting ionosphere vertical transfer length of delay of the path intermediate point of communication link, k ₁～k ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to, air line distance more is worth less.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, have:

$k_i=\frac{{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4-l_i}{3({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4)}$

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

Step S108: weighting ionosphere vertical transfer length of delay is converted to ionospheric electron density total content value.

Use formula:

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

Wherein TEC is ionospheric electron density total content value, and c is the light velocity, and f is the navigation signal frequency.

Step S110: the value that above-mentioned ionospheric electron density total content value is converted to the critical frequency of Ionospheric F_2-layer.

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 formula, H ₀For the oxygen atom absolute altitude, it is set-point.

Therefore:

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

F0F wherein ₂For the critical frequency of Ionospheric F_2-layer, H ₀For the oxygen atom absolute altitude.

Step S112: according to the critical frequency (f of the Ionospheric F_2-layer of above-mentioned calculating 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 be calculated, can obtain optimum traffic frequency (OWF).

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

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 embodiment of the short frequency selective system based on the 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, refer to Fig. 3, the short frequency selective system of the present embodiment comprises: path intermediate point computing module 10, ionosphere grid points sequencing information acquisition module 11, the ionosphere grid points is searched module 12, the ionosphere vertical transfer postpones acquisition module 13, weighting ionosphere vertical transfer length of delay computing module 14, ionospheric electron density total content value modular converter 15, ionospheric F 2 layer critical frequency value modular converter 16, the short wave communication frequency is selected module 17.

Path intermediate point computing module 10 calculates the path intermediate point of the communication link between primary importance and the second place.Path intermediate point computing module 10 is according to the longitude and latitude of 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 the satellite navigation location.

Ionosphere grid points sequencing information acquisition module 11 navigation neceiver via satellite receives wide area enhancing information, obtains ionosphere grid points sequencing information.WAAS is defined 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 °.Refer to Table A-14 and the figure A-14 of RTCA DO-229D " GPS WAAS airborne equipment minimum performance requirement ".

Above-mentioned information is play in the message of ionosphere grid points sequencing information, after receiving IGP position table, the IGP position is kept in 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 position relationship, search the several IGP points nearest with the path intermediate point, the present embodiment is selected four, is respectively IGP ₁, IGP ₂, IGP ₃, IGP ₄.As shown in Figure 2, wherein Mid represents the path intermediate point of communication link, with immediate four the IGP points of Mid, is respectively the IGP shown in Fig. 2 ₁, IGP ₂, IGP ₃, IGP ₄.

The ionosphere vertical transfer postpones acquisition module 13 navigation neceiver reception via satellite wide area and strengthens information, obtains ionosphere vertical transfer length of delay corresponding to 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 formula _midFor 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 ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to, air line distance more is worth less.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, have:

$k_i=\frac{{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4-l_i}{3({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2+{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA0000075595200000021.png"\; state="\{\{state\}\}">l</figure-callout>}}_3+l_4)}$

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

Ionospheric electron density total content value modular converter 15 is converted to ionospheric electron density total content value by above-mentioned weighting ionosphere vertical transfer length of delay.In ionospheric electron density total content value modular converter 15, use formula:

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

Wherein TEC is ionospheric electron density total content value, and c is the light velocity, and f is the navigation signal frequency.

Ionospheric F 2 layer critical frequency value modular converter 16 is converted to above-mentioned ionospheric electron density total content value the value of the critical frequency of Ionospheric F_2-layer.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 formula, H ₀For the oxygen atom absolute altitude, it is set-point.

Therefore:

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

FoF wherein ₂For the critical frequency of Ionospheric F_2-layer, H ₀For the oxygen atom absolute altitude.

The short wave communication frequency is selected the critical frequency (f of module 17 according to the Ionospheric F_2-layer of above-mentioned calculating 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 be calculated, can obtain optimum traffic frequency (OWF).

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

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.

Above-described embodiment is to provide to those of ordinary skills and realizes and use of the present invention, those of ordinary skills can be without departing from the present invention in the case of the inventive idea, above-described embodiment is made to various modifications or variation, thereby invention scope of the present invention do not limit by above-described embodiment, and it 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, comprises the following steps:

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

(2) navigation neceiver receives wide area enhancing 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) ionosphere vertical transfer length of delay corresponding to the described ionosphere of finding step (3) grid points;

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

(6) the described weighting of step (5) ionosphere vertical transfer length of delay is converted to ionospheric electron density total content value TEC;

(7) the described ionospheric electron density total content of step (6) value is converted to the value f of the critical frequency of Ionospheric F_2-layer ₀F2;

(8) according to the critical frequency f of the Ionospheric F_2-layer of above-mentioned calculating ₀F2 calculates 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 described step (1), longitude and latitude according to 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; In described 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 2, is characterized in that, in described step (5), uses formula:

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

D in formula _midFor 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 ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to; In described step (6), use formula:

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

In formula, TEC is ionospheric electron density total content value, and c is the light velocity, and f is the navigation signal frequency.

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

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

FoF in formula ₂For the critical frequency of Ionospheric F_2-layer, H ₀For the oxygen atom absolute altitude.

5. according to the described short frequency system of selection based on the satellite navigation WAAS of claim 1 or 3, it is characterized in that, in described step (8), the method of using ITU-R P.1240-1 to provide in recommendation " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " is calculated, and obtains optimum traffic frequency (OWF).

6. the 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, ionospheric electron density total content value modular converter, ionospheric F 2 layer critical frequency value modular converter, short wave communication frequency selection module, wherein:

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

Described ionosphere grid points sequencing information acquisition module, navigation neceiver receives wide area enhancing information via satellite, obtains ionosphere grid points sequencing information;

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

Described ionosphere vertical transfer postpones acquisition module, in the wide area enhancing information received at satellite navigation receiver, obtains ionosphere vertical transfer length of delay corresponding to above-mentioned at least one ionosphere grid points;

Described 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;

Described ionospheric electron density total content value modular converter, be converted to ionospheric electron density total content value by above-mentioned weighting ionosphere vertical transfer length of delay;

Described ionospheric F 2 layer critical frequency value modular converter, be converted to above-mentioned ionospheric electron density total content value the value of the critical frequency of Ionospheric F_2-layer;

Described short wave communication frequency is selected module, according to the critical frequency f of the Ionospheric F_2-layer of above-mentioned calculating ₀F2 calculates 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 described path, longitude and latitude according to 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; In described ionosphere grid points is searched module, the quantity of ionosphere grid points is 4.

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

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

D in formula _midFor 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 ₄For weighted value, its span 0～1 and k ₁+ k ₂+ k ₃+ k ₄=1, and k ₁～k ₄With the path intermediate point of communication link and the air line distance of described four ionosphere grid points, be inversely proportional to; In described ionospheric electron density total content value modular converter, use formula:

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

In formula, TEC is ionospheric electron density total content value, and c is the light velocity, and f is the navigation signal frequency.

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

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

FoF in formula ₂For the critical frequency of Ionospheric F_2-layer, H ₀For the oxygen atom absolute altitude.

10. according to the described short frequency selective system based on the satellite navigation WAAS of claim 6 or 8, it is characterized in that, in described short wave communication frequency, select in module, the method of using ITU-R P.1240-1 to provide in recommendation " basic maximun usable frequency (MUF), actual MUF and ray Forecasting Methodology " is calculated, and obtains optimum traffic frequency (OWF).

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