CN1270190C - Movable satellite ground station system - Google Patents

Abstract

The present invention solves the problem that an earth station antenna of a mobile satellite aligns the satellite with a gradient method and overcomes the defects of the prior art, a vehicular mobile satellite communication system of which the patent number is 99118037.2, for example, the vehicular mobile satellite communication system can only communicate with still satellites, is not adaptable to sudden jobs, is not adaptable to jobs on a light vehicle, is high in cost, etc. The technology of the present invention calculates the azimuth A and the elevation E of an observation satellite of the earth station antenna based on the rough longitude lambdaG and the rough latitude phiG of the ground station, the height h of the satellite to be observed and the longitude lambdaG and the latitude phiG of a sub-satellite point, wherein the rough longitude lambdaG and the rough latitude phiG of the ground station can be looked up from a map or measured by a minitype GPS receiver, etc. A servo system drives the antenna to perform searching, such as N-shaped searching or helical searching, around the estimated A and E. When the output level U of the receiver is judged to be higher than V<TH>, a relay operates and begins to track the satellite with gradient method. In the gradient method, the satellite is tracked according to the gradient of a beam from the earth station antenna, when the antenna beam aligns the satellite, the gradient is zero; when the antenna beam deviates to one side of the satellite, the gradient is positive; when the antenna beam deviates to the other side of the satellite, the gradient is negative; thereby, a user can use gradient signals to drive the servo system so as to cause the earth station antenna of the mobile satellite to align the satellite.

Description

The Search/Track method of movable satellite ground station system and use thereof

The technical field movable satellite ground station

The technology of background technology fixed satellite communication land station is known.Existing many customer requirements are placed on land station on the high speed vehicles such as ship, vehicle, aircraft, low orbit satellite.Key issue be how to make the mobile ground station antenna under high-speed motion to satelloid.The Bashan Mountain, Chongqing instrument plant utilizes laser gyro to point to this performance that remains unchanged and has realized mobile earth station antenna alignment synchronous satellite, and obtains patent of invention (vehicle-mounted mobile satellite communication system, the patent No.: 99118037.2).Theory and practice proves that " 99118037.2 " patented technology has following problem: 1. laser gyro can only keep pointing to the stationary satellite on the synchronous orbit, the mobile-satellite in can not following the tracks of on the low orbit.And medium and low earth orbit satellites communication at present and remote sensing development are very fast, use more and more wider.2. laser gyro work needs preheating, and incompatible burst work is the laser gyro Heavy Weight 3., and incompatible going up at light-duty vehicle (driving an airplane moonlet etc. as miniature self-service) used.4. laser gyro costs an arm and a leg, and also needs import at present.We propose with " gradient method " design movable satellite ground station for this reason.Present technique has abandoned following the tracks of with laser gyro the notion of synchronous satellite, and comes tracking satellite with the gradient of single-chip microcomputer calculating earth station antenna receiving satellite signal, has overcome the above-mentioned shortcoming of " 99118037.2 " patents.

Summary of the invention mobile earth station antenna alignment satellite divides Search/Track two stages:

(1), the search phase:

Roughly longitude and latitude λ according to land station _GΦ _G(as checking in by map or record etc.) with simple and easy small-sized GPS receiver, desire the longitude and latitude λ of observation satellite height h and substar _GΦ _GCalculate the position angle A and the elevation angle E (A is counted from positive north, and E is counted from ground level) of earth station antenna observation satellite.

$A={\mathrm{Sin}}^{-1}\frac{\mathrm{Sin\&Delta;\&lambda;Cos}{\mathrm{\&Phi;}}_S}{\sqrt{1-{(\mathrm{Sin}{\mathrm{\&Phi;}}_G\mathrm{Sin}{\mathrm{\&Phi;}}_S+\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos}{\mathrm{\&Phi;}}_S\mathrm{Cos\&Delta;\&lambda;})}^2}}$

$E={\mathrm{Tan}}^{-1}\frac{\mathrm{Sin}{\mathrm{\&Phi;}}_G\mathrm{Sin}{\mathrm{\&Phi;}}_S+\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos}{\mathrm{\&Phi;}}_S\mathrm{Cos\&Delta;\&lambda;}-r/R}{\sqrt{1-{(\mathrm{Sin}{\mathrm{\&Phi;}}_G\mathrm{Sin}{\mathrm{\&Phi;}}_S+\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos}{\mathrm{\&Phi;}}_S\mathrm{Cos\&Delta;\&lambda;})}^2}}$

To synchronous satellite Φ _S=0, then have:

$A={\mathrm{Sin}}^{-1}\frac{\mathrm{Sin\&Delta;\&lambda;}}{\sqrt{1-{\left(\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos\&Delta;\&lambda;}\right)}^2}}$

$E={\mathrm{Tan}}^{-1}\frac{\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos\&Delta;\&lambda;}-r/R}{\sqrt{1-{\left(\mathrm{Cos}{\mathrm{\&Phi;}}_G\mathrm{Cos\&Delta;\&lambda;}\right)}^2}}$

In the formula Δ λ=land station be observed the longitude and latitude of satellite poor=λ _s-Φ _GR=6378Km=terrestrial equator radius.R＝r+h。To synchronous stationary satellite R=42166Km.

The servo subsystem of scanning search driven of search processor output makes antenna calculate near search of satellite A, the E; Write down receiver output level U ₁, when the ground station antenna to satelloid U when (comprising that antenna scanned satellite with certain speed) ₁Increase; The judgement comparer is receiver output level U ₁With threshold voltage V _mRelatively, work as U ₁Greater than V _mThe time, relay is delivered to servo subsystem to the gun parallax signal delta VA and the trim signal delta VE of the output of gradient tracking processor, and system enters tracking phase; Work as U ₁Less than V _mThe time, relay is then delivered to servo subsystem to the scanning search voltage of search processor output, and system keeps the search phase.

(2), tracking phase:

Tracking phase adopts gradient method to follow the tracks of.It is to come tracking satellite according to the gradient of movable satellite ground station antenna beam that gradient method is followed the tracks of.Gradient is zero when the antenna beam satellite, on one side when the antenna wave beam when departing from satellite gradient for just, when antenna wave beam gradient when another side departs from satellite is to bear.So available gradient signal drives servo subsystem and makes movable satellite ground station antenna alignment satellite.

The description of drawings total system as shown in Figure 1.The 1st, determine roughly longitude and latitude of land station with GPS or additive method.The 2nd, the land station that estimates is longitude and latitude λ roughly _GΦ _GThe 3rd, calculate position angle A, the angle of pitch E of land station to satelloid.The 4th, the result of calculation of position angle A, angle of pitch E.The 5th, search processor.The 6th, near the scanning search voltage of exporting when search processor is searched for (for example by N font or spiral search) target the A, the E that calculate.The 7th, antenna-receiver.The 8th, receiver output level U ₁When the ground station antenna to satelloid U when (comprising that antenna scanned satellite with certain speed) ₁Increase.The 9th, the gradient tracking processor.The 10th, the gun parallax signal delta VA and the trim signal delta VE of 9 outputs of gradient tracking processor.The 11st, the judgement comparer.The 12nd, threshold voltage V _mThe 13rd, servo subsystem.The 14th, relay.Work as U ₁Greater than V _mThe time, relay 14 is delivered to servo subsystem 13 to the gun parallax signal delta VA and the trim signal delta VE of 9 outputs of gradient tracking processor; System is in tracking phase.Work as U ₁Less than V _mThe time, 14 scanning search voltages search processor 5 outputs of relay are delivered to servo subsystem 13; System is in the search phase.The 15th, antenna rotating platform.

The embodiment search phase is as shown in Figure 1: the earth station antenna that calculates earlier is to position angle A, the angle of pitch E of satelloid.Search processor 5 produces N font or spiral search voltage, delivers to servo subsystem 13, makes near the antenna-receiver 7 search of satellite position angle A, the angle of pitch E that calculate; Write down receiver output level U ₁As 7 pairs of satelloids of ground station antenna-receiver U when (comprising that antenna scanned satellite with certain speed) ₁Increase.Judgement comparer 11 is receiver output level U ₁With threshold voltage V _mRelatively, work as U ₁Greater than V _mThe time, relay 14 is delivered to servo subsystem 13 to the gun parallax signal delta VA and the trim signal delta VE of 9 outputs of gradient tracking processor, and system enters tracking phase; Work as U ₁Less than V _mThe time, 14 scanning search voltages search processor 5 outputs of relay are delivered to servo subsystem 13, and system keeps the search phase.

The tracking error signal of tracking phase is produced by software by single-chip microcomputer.The gradient tracking processor is handled orientation and following in elevation respectively, establishes and does following in elevation earlier.The process flow diagram of trace routine as shown in Figure 2.

1. suppose initial elevation angle E=E ₀, note receiver output level U at this moment ₁=U ₁₀The initial value Δ E of one little elevation angle increment Delta E is set ₀, the Δ E=Δ E of this moment ₀

2. make antenna elevation angle E stepping Δ E ₀, Δ E ₀After executing, antenna elevation angle is E=E ₂=E ₀+ Δ E ₀, record and E ₂Corresponding receiver output level U ₂

3. calculate gradient ${\&dtri;}_E=\left(\frac{U_2-U_1}{\mathrm{\&Delta;E}}\right).$

4. calculate Δ E= _Ek _E(k _EBe a suitable constant, got greatly to follow the tracks of and dispersed that it is too slow to get convergence little, influences tracking velocity), make U ₁=U ₂

5. order about antenna and change Δ E.After Δ E executed, noting incoming level was U ₂, again by 3. calculating gradient _E, iteration like this is up to _E＜ε (ε=selected in advance arbitrary small number).

6. change the orientation over to and follow the tracks of, program and following in elevation are together.

Claims (3)

1, the Search/Track method of using in a kind of mobile satellite communication earth station system; System realizes the Search/Track of earth station antenna to satellite; Adopt the gradient tracing to make the earth station antenna tracking satellite; Gradient is zero when the antenna beam satellite; When the antenna wave beam when satellite is departed from one side gradient for just; When antenna wave beam gradient when another side departs from satellite is negative; So available gradient signal drives servo subsystem and makes movable satellite ground station antenna alignment satellite; To the search of satellite and search satellite backward and follow the tracks of the step of switching and be: the roughly longitude and latitude λ that estimates land station with GPS or additive method _GΦ _GCalculate position angle A, the angle of pitch E of land station to satelloid; Search processor drives servo subsystem, makes near the antenna ferret out A, the E that calculate; Write down receiver output level U ₁, as ground station antenna U during to satelloid ₁Increase; The judgement comparer is receiver output level U ₁With threshold voltage V _THRelatively, work as U ₁Greater than V _THThe time, relay is delivered to servo subsystem to the gun parallax signal delta VA and the trim signal delta VE of the output of gradient tracking processor, and the mobile satellite communication earth station system enters tracking phase; Work as U ₁Less than V _THThe time, relay is then delivered to servo subsystem to the scanning search voltage of search processor output, and the mobile satellite communication earth station system keeps the search phase.

2, according to the mobile satellite communication earth station system of the Search/Track method of claim 1 design, it is characterized in that: system is formed by connecting by interface circuit by search processor, gradient tracking processor, logical decision circuit and conventional receiver, antenna, turntable, servo subsystem; The work of mobile satellite communication earth station system divides search and follows the tracks of two stages; According to the output of judgement comparer, two stages automatically switch.

3, employed gradient tracing in the Search/Track method of claim 1 is characterized in that: compute gradient during tracking, and gradient is zero when the antenna beam satellite; When the antenna wave beam when satellite is departed from one side gradient for just; Gradient is for negative when another side departs from satellite when the antenna wave beam, and gradient signal drives servo subsystem and makes movable satellite ground station antenna alignment satellite.

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