RU2486676C2 - Method of merging satellite communication systems - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: disclosed is merging low and medium orbital satellite communication systems with a communication system based on communication satellites located on a high subsynchronous orbit. Systems communicate in a frequency band higher than 20 GHz. Satellites on low or medium orbits are fitted with receiving antennae directed upwards towards a communication satellite on a high orbit.

EFFECT: merging existing satellite systems.

2 cl, 2 dwg

Description

The present invention is directed to the formation of integrated satellite communications systems (CCC), capable of real-time expansion of zones on Earth while providing them with daily communication.

SSSs are known [1, 2, 3, 4], which communicate both in low orbits up to 2000 km (LEO-Low-Earth-Orbit, low Earth orbit), medium orbits up to 20,000 km (MEO-Medium-Earth-Orbit, medium near-Earth orbit) and high subsynchronous orbits, which include both the geostationary equatorial orbit (36,000 km) and high elliptical orbits (~ 40,000 km at the peak) from the series of satellites in the USSR “Lightning”.

Noting the high demand for the indicated MSS by the Earth's population, their shortcomings should be noted:

- the high cost of launching and operating SSS with a high mass of satellites and their large number;

- the need for inter-satellite communication in one CCC when relaying messages over long distances and long delay times at these distances.

This proposal is aimed at partial elimination of these shortcomings by combining well-known existing MSS in high subsynchronous orbits with MSS located in low or medium orbits.

Such a combination, according to the authors, will significantly reduce the mass of satellites launched into high orbits, which will practically reduce the energy and financial costs when launching a satellite and maintaining it in orbit. Also, in a single time scale, relaying messages to large areas on Earth with a minimum time delay is possible. These winnings of the invention should be considered a technical solution. As a prototype in its physical essence can be taken CCC in a high subsynchronous orbit.

A method is proposed for combining CCCs, which are located in low or medium Earth orbits with a communication satellite, which are located in a high subsynchronous orbit, including the operation of one-way active relaying of radiation received from terrestrial transmitters in the direction of the Earth, in accordance with which active relaying of radiation , which is received at the satellite’s receiving antenna in a high subsynchronous orbit, a transmit antenna is implemented, the axis of which is directed to the center of the Earth in the frequency range above 20 GHz, while the emitting antenna is made such that the radiating spot of the transmitter power at the height of the low or medium orbits of the CCC forms the area S of the _RLS , on the axis of which in the direction of the mentioned orbits at least three satellites in low orbits and at least one in medium orbits CCC, and each satellite of this CCC is additionally equipped with a receiver with an antenna aimed at the satellite to receive radiation at a specified frequency, the axis of the antenna pattern of the earth transmitters stationary pointing to the center of the hour and orbits, which are in communication with the Earth, and the solid angle of the radiation pattern set ± 8,5 °.

A variant of the method is proposed in which the mirror of the satellite’s transmitting antenna in high orbit is made spherical, and the emitter or reflector of the emitter is placed on the axis of the antenna below the plane passing through the edges of the antenna by an amount Δ that is set above the focus of the sphere so that the angle α from vertical, passing from the edge of the antenna and parallel to the axis, and the direction of radiation is established from the equality

$$\alpha =\frac{R_{\mathrm{AND}3L.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\cdot 180}{\left(H-H_{\mathrm{ABOUT}RB.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\right)\cdot \pi }gR\mathrm{but}d\mathrm{.,}$$

where R _ISL.SSS is the radius of the radiation zone of the radiation from the satellite transmitter in high orbit H; N _ORB.SSS - the height of the low or medium orbit of the CCC.

The invention is further explained by reference to the drawings:

Figure 1 - conditional image of the union of two CCC, where 1 is a communication satellite in a high subsynchronous orbit at a height H; 2 - a receiving antenna of satellite 1 for receiving radiation from an earth transmitter; 3 - antenna of the active repeater of satellite 1 at a frequency of more than 20 GHz; 4 - satellites in low or medium orbits of the CCC; 5 - receiving antennas of satellites 4, aimed at satellite 1; 6 - service area on Earth of satellite 4 in orbit of height H _ORB.SSS ; 7 - a zone of radiation exposure by satellite 1 at a height of H _ORB.SSS ; 8 - earth transmitter.

Figure 2 - conditional image of the spherical transmitting antenna of satellite 1, where 9 is the axis of the antenna 10, aimed at the center of the Earth; 11 - sphere of a ball centered in T. O, of which the antenna 10 is a part; 12 - emitter, offset by a value of Δ 13 down the axis 9 relative to the plane passing through the edges of the antenna; 14 - angle α, which provides the formation of the area of radiation S _LFL at a height H _ORB.SSS ; 15 - diameter of the antenna 10.

The proposed method for combining CCC is presented in figure 1. Communication satellite 1 is placed in a high subsynchronous orbit at a height of H. The receiving antenna 2 of satellite 1 is directed down to Earth to receive the radiation from the earth transmitter. The axis of the transmitting antenna 3 with active relaying is directed to the center of the Earth, while the relaying is carried out at a frequency of electromagnetic radiation (EMP) above 20 GHz. Antenna 3 is proposed to be made in the form of a spherical mirror so that at the low or middle orbit H _ORB.SSS SSS form a circle of electromagnetic radiation, in the area of which at least three satellites 4 simultaneously _{receive radiation S.} Satellite 4 is _received by satellites 5, additionally included in their composition. The antennas of the additional receivers are directed to satellite 1. Active relay from satellites 4 to the Earth is carried out in accordance with the current regulations of these CCCs. Moreover, service areas 6 on Earth by satellites 4 are kept unchanged. In particular, the diameter of the service area of 6 low-orbit CCCs can be up to 5800 km [3]. The presence of three satellites 4 in zone S of _IZL 7 can provide communications in fairly large areas of the Earth. The stationary direction of the antenna of the terrestrial transmitter 8 to the middle of the high-orbit portion with which satellite 1 receives and then relays emissions to satellites 4 is important. This position of the antenna of transmitter 6, on the one hand, eliminates the need for automatic tracking of the antenna of transmitter 8 over the movement of satellite 1 in orbit during communication, and on the other hand, requires that the radiation pattern of transmitter 8 be at least ± 8.5 °.

It should be noted that daily communication from high subsynchronous orbits is provided by placing, for example, four satellites in this orbit evenly located in the orbit with a rotation period of each close to half the duration of an earth day (see [2, 3]). In this case, each satellite entering the apogee of the orbit is switched on only for a period of 6 hours, and after leaving the apogee, the next satellite leaves the place of the departed one without interruption of communication.

Further, energy calculations will be carried out using the example of combining low high-speed CCC orbits with low-speed CCC on subsynchronous elliptical orbits of the Lightning series [2, 3, 4].

The low-speed CCC, called the Polar Star, from the Lightning series [3] has an orbit height of 40,600 km, the number of satellites in orbit is four, the orbit tilt is 62 °, the orbital time is ~ 710 min, the frequency range of reception / transmission is 5/6 GHz , average elevation angle ~ 50 °, weight 2100 kg.

Let us find the radius that irradiates the Earth, R _{FRP of} the coverage area at a known elevation angle from the expression:

, откуда $$R_{ИЗЛ}=\frac{25{\text{}}^{\circ }\cdot H}{{\mathrm{57,3}}^{\circ }}=\mathrm{1,77}\cdot {10}^4км$$

. $${25}^{\circ }=\frac{R_{\mathrm{AND}3L}\cdot 180}{H\cdot \pi }$$

from where $$R_{\mathrm{AND}3L}=\frac{25{\text{A.}}^{\circ }\cdot H}{{57.3}^{\circ }}=1.77\cdot {10}^{\mathrm{four}}\mathrm{to}m$$

.

мощности на антенну диаметром R_ПР=1 м будет определяться выражением:The required power of the transmitter of the repeater on the satellite R _IZL for reliable reception on Earth in an area of $$\pi \cdot R_{\mathrm{AND}3L}^2$$

power to the antenna with a diameter of R _PR = 1 m will be determined by the expression:

$$\Delta P_{PR.3}=\frac{R_{\mathrm{AND}3L}\cdot K_{ATM}\cdot \pi \cdot {\left(R_{PR}\right)}^2}{\pi \cdot {\left(R_{\mathrm{AND}3L}\right)}^2},\begin{array}{cccc}& & & \end{array}\left(\mathrm{one}\right)$$

where K _ATM = 0.05 the coefficient of loss of electromagnetic radiation in the atmosphere [2].

And, substituting in (1) the values of R _PR = 1 m and P _REF = 1.77 · 10 ⁴ km, we obtain the dependence:

$$\Delta R_{PR.3}=R_{\mathrm{AND}3L}\cdot 1.77\cdot {10}^{-16}\mathrm{AT}t.\begin{array}{cccc}& & & \end{array}\left(2\right)$$

If we take the noise level of the receivers on Earth equal to ~ 2 · 10 ^-16 W (see [5]), then reliable reception is possible if the signal exceeds the noise level by three orders of magnitude, i.e. _{ΔР PR.Z} should be equal to ≥10 ^-13 W. Substituting this value _{ΔР PR.Z} in (2), the radiation power on the Polar Star satellite should be at least 1000 watts. A decrease in the calculated value of P _{REF is} possible only by reducing the signal-to-noise ratio requirements, for example, by three times. Then P _RL can be reduced to 330 W, however, even with such a transmitter radiation power, the weight and dimensions of the satellite turn out to be significant (satellite weight ~ 2100 kg).

This proposal is aimed at a significant reduction in satellite weight due to both a decrease in radiation power during active relaying in the direction of the Earth, and due to the transition to a higher frequency communication range (above 20 GHz). At these frequencies, the mass and size characteristics of the transmitters are most promising for use in space technology.

As shown in [2], a satellite in a high elliptical orbit of the Lightning series communicates only when it reaches the apogee of the orbit, which is observed from the Earth at a solid angle of ± 10 °. If there are four satellites in this orbit, evenly spaced relative to each other, the angle of observation of the satellite’s movement during communication with the Earth decreases to ± 8 °. Therefore, it was proposed to exclude the automatic tracking of the satellite’s earth transmitter in orbit at the apogee by the antenna axis stationary to the upper point of the orbit apogee, and set the antenna radiation pattern to ± 8.5 °. In the case of an elliptical orbit, the axis of the antenna of the earth transmitter is stationary at the highest point of the apogee, and in the case of a circular subsynchronous orbit, the antenna is directed to the middle of the part of the orbit that communicates with the Earth. Moreover, the most favorable position of the Earth transmitter on Earth is its location on the axis of the satellite’s transmitting antenna in high orbit.

By analogy with the previous calculation, we calculate the power of the terrestrial transmitter 6, at which a power of at least 10 ^-13 W would arrive at the receiving antenna of satellite 1 with a radius of the receiving antenna R _PR.SP = 1 m. We again use the expression (1).

$$\Delta P_{PR.\mathrm{FROM}P}\ge {10}^{-13}\mathrm{AT}t=\frac{R_{\mathrm{AND}3L.3.P}\cdot K_{ATM}\cdot \pi \cdot {\left(R_{PR.\mathrm{FROM}P}\right)}^2}{\pi \cdot {\left(R_{\mathrm{AND}3L.3.P}\right)}^2},\begin{array}{cccc}& & & \end{array}\left(3\right)$$

where _{ΔР PR.SP} - power received by the antenna on the satellite, the radius of which R _PR.SP = 1 m; R _LB.Z.P - radius of the cross-sectional radiation power of the earth transmitter in the satellite zone with the antenna radiation pattern of at least ± 8.5 °.

Define R _EX.Z.P from the obvious expression:

, откуда $$R_{ИЗЛ.З.П}=\frac{{\mathrm{8,5}}^{\circ }\cdot \mathrm{4,06}\cdot {10}^4}{{\mathrm{57,3}}^{\circ }}=6000км$$

, и из (3) находим: $${8.5}^{\circ }\ge \frac{R_{\mathrm{AND}3L.3.P}\cdot {57.3}^{\circ }}{H}$$

from where $$R_{\mathrm{AND}3L.3.P}=\frac{{8.5}^{\circ }\cdot 4.06\cdot {10}^{\mathrm{four}}}{{57.3}^{\circ }}=6000\mathrm{to}m$$

, and from (3) we find:

. $$R_{\mathrm{AND}3L.3.P.}=\frac{{10}^{-13}\cdot 36\cdot {10}^{12}}{5\cdot {10}^{-2}\cdot \mathrm{one}}=72\mathrm{AT}t$$

.

Next, we will calculate the power of the satellite transmitter 1 R _REF.SP with active relay of electromagnetic _radiation in the direction of satellites 4 at low or medium orbits of the CCC. This relay, as already indicated, is carried out at EMP frequencies above 20 GHz. Consider the case of relaying to satellites 4 located in low orbits. In particular, in the USSR, in the low LEO orbits, satellites of the Cosmos series were launched in the interest of servicing communications in the Northern Hemisphere:

- "Cosmos-80", launch 03.09.65; perigee / apogee - 1500/1500 km; 56 ° orbital inclination; circulation time 116 min;

- "Cosmos-367" - 03.10.70, 922/1024; 65.28 °; 104 min;

- "Cosmos-967" - 12/13/77; 973/1013; 66.08 °; 105 minutes

Satellites of the Cosmos series were also launched into the mid-altitude orbits of MEO in the USSR:

- “Cosmos-482” - 03/31/72; 210/9813; 52 °; 201.4 min;

- "Cosmos-839" - 09.07.76; 984/2100; 65.9 °; 117 min;

- "Cosmos-1413" - 12.10.82; 19100/19100; 64.8 °; 673 minutes

As shown in [3, 4], orbits with inclination of the orbital planes from 50 ° to 75 ° are recommended for CCC orbital groups. It is the orbits with such inclination angles that are recommended by the authors for combining with CCC in the high elliptical orbit of the Lightning series, i.e. φ ° ± 10 °, where φ ° is the inclination angle of the high subsynchronous orbit.

For calculations, we take the altitude of the low orbits of the CVS equal to 1500 km. The number of satellites (spacecraft (SC) in this orbit) for all-day and global communications (see [3]) is set equal to 48 if they are evenly located in orbit. If you save the already specified reception conditions, i.e. when the signal-to-noise ratio is ~ 10 ³ and the signal level at the receiving antenna of satellite 4 with a radius R _PR = 1 m of at least 10 ^-13 W, the radiation power of the satellite repeater 1 is determined from the expression:

$$R_{\mathrm{AND}3L.\mathrm{FROM}P}\ge \frac{{10}^{-13}\cdot {\left(R_{\mathrm{AND}3L.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\right)}^2}{{\mathrm{one}}^2},$$

where R _ISL.SSS is the radius of the spot of radiation from satellite 1 at a height of H _ORB.SSS (the height of the low orbit of the CCC). The distance between satellites 4 in orbit can be estimated by dividing the length of the circular orbit 2π (N _ORB.LOW + -R _ZEM ) by the number of satellites. With the radius of the earth R ₃ ≈6400 km, N _ORB.SSS = 1500 km and the number of satellites 48, the distance between neighboring satellites 4 is 1033 km.

Since the authors proposed to form a radiating area at an altitude of H _ORB.SSS S _RL = π (R _RL ) ² such that at least three satellites fit along this axis along its axis, the size R _RL.SSS should be set equal to 2500 km. Then the radiation power P _REF.SP is equal to:

P _OBS.SP = 10 ^-13 · (2.5 · 10 ⁶ m) ² = 6.25 · 10 ^-1 ≈0.6 W.

It is clear that with an increase in P _REF.SP , for example, up to 6 W, the reception of this radiation on all three satellites 4 in the low orbits of the CCC will be even more reliable.

Reducing the power of the transmitter on satellite 1 by almost 10 ² times compared with the prototype will significantly reduce the size and weight of both the transmitter and the satellite as a whole and, therefore, provides an economic effect when starting and operating the satellite.

For the formation at a height of H _ORB.SSS , the radiation power area S _RL with a radius R _RL.SSC = 2500 km, the authors proposed a spherical antenna, shown in _figure 2. The axis 9 of the antenna 10 is directed to the center of the earth. Antenna 10 is part of ball 11 centered in T.O. To form at the desired height R _{RED.SSC, the} emitter 12 is displaced along the axis 9 by a value of Δ 13 down from the plane passing through the edges of the antenna. The angle α 14 set from the vertical parallel to the axis of the antenna and going from its edge, and its value is determined from the equality:

$$\alpha =\frac{R_{\mathrm{AND}3L.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\cdot 180}{\left(H-N_{\mathrm{ABOUT}RB.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\right)\cdot \pi },\begin{array}{cccc}& & & \end{array}\left(\mathrm{four}\right)$$

where R _ISL.SSS is the radius of the irradiation zone by the satellite transmitter in high orbit H; N _ORB.SSS - the height of the low or medium orbits of the CCC.

The offset value Δ 13 is determined from the condition under which the angle between the straight line connecting t.C on the axis of the antenna (the location of the emitter) and the edge of the antenna and the radius from t.O to the same point of the edge of the antenna is equal to the angle between the same radius and the direction of the straight line deviated from the aforementioned vertical, forming an angle α with it.

It should be noted that the emitter shifted by Δ can be replaced by a reflector (mirror) of the emitter, and the emitter itself is placed on the axis of the antenna in the plane of the mirror. Such an arrangement of the emitter and its reflector (mirror) is referred to in the literature as the Cassergen two-mirror antenna [6].

Since all the calculations performed above were performed at R _ZER = 1 m, then at R _OVER.SSS = 2500 km, H = 40600 km and N _ORB.SSS = 1500 km, the angle α turns out to be ~ 3.7 °. The obtained value of α makes it possible to use a parabolic mirror as an antenna, since at such a small angle the foci of the sphere and the parabola coincide. Therefore, the authors recommended the use of only a spherical shape of the antenna.

It should be noted that an increase in the radiation power P _{ILL.SP of} satellite 1 allows the axis of the receiving antennas on satellites 4 to be set parallel to the direction to the center of the Earth, i.e. Do not orient them to satellite 1 due to the small angle α.

It is also possible to reduce the number of earth stations serving low or medium high-speed CCCs by transferring some of the relay functions to a satellite in high orbit, capable of relaying on a single time scale to the territory covered by at least three satellites in low orbits. Such territories may turn out to be equal to the territories of Russia and their closest neighbors. This conclusion can be made on the basis that the satellite coverage area 4 in low orbits is a circle with a diameter of at least 5800 km [3].

The number of satellites in the CCC group, as is known [3], decreases with the orbit altitude while expanding the coverage area on Earth, therefore, the number of satellites located at the average altitudes of the CCC orbits and falling into zone S of the _RL (with radius R _RL.CSS ) can limit to one satellite. This is due to the fact that mid-altitude CCS with an orbit height of 10390 km (for example, located between the 1st and 2nd Van Allen radiation belts) have 10 satellites in the constellation and a coverage area of up to 11,000 km.

Thus, a method is proposed for connecting SSS at low and medium orbits of the location of satellites with the SSS system, in which the satellite is placed in a high subsynchronous orbit, which allows:

- to provide relaying of emissions (messages) in a single time scale to large areas on Earth, while relaying messages from a high orbit to low or medium orbits of existing CCCs is carried out at a frequency above 20 GHz;

- significantly reduce the power of radiation from satellites in high orbits to units of W and, therefore, can significantly reduce the mass and dimensions of the satellite, which leads to lower costs when launching and controlling the satellite;

- a possible decrease in the number of terrestrial transmitting stations participating in the process of one-way relay of messages in the CCC at low or medium altitude orbits;

- energy and operational benefits associated with the proposal to exclude during the operation of automatic tracking systems of the earth transmitter antenna for moving a high-altitude satellite in orbit at the apogee and satellite antennas in low or medium orbits that receive radiation at frequencies above 20 GHz;

- the possible exclusion of inter-satellite communications in the aforementioned low-orbit SSS due to the use of messages from a high subsynchronous orbit.

References:

1. Abolits A.I. Satellite communications system. M .: ITIS, 2004 (ISBN-5-87484-085-0).

2. Handbook of satellite communications and broadcasting, ed. Cantora L.Ya. M: "Radio and communications", 1983.

3. Gornostaev Yu.M., Sokolov VV, Nevdyaev L.M. Promising satellite communications systems. M .: “Hot line - Telecom”, 2000.

4. "Cosmonautics", encyclopedia. M .: “Owls. Encyclopedia ", 1985.

5. Gusyatnikov I.I., Weissburg G.M., Zilberman A.R. and others. The transmission of telegraph messages using reflection from the moon. M .: Energosvyaz, 1977, No. 4. - S.26-28.

6. "Antennas and microwave devices." Designing phased array antennas. - p / ed. D.I. Voskresensky. M .: "Radio and communications", 1994.

Claims (2)

1. The method of combining satellite communication systems (CCC), which are located in low or medium Earth orbits with communication satellites, which are located in high subsynchronous orbits and provide daily communication, includes the operation of a one-way active relay of radiation that is received from terrestrial transmitters into the Earth’s direction, characterized in that the active relay of the radiation that is fed to the satellite’s receiving antenna in high subsynchronous orbit by the earth transmitters is carried out by the transmitting antenna constant, whose axis is directed at the center of the earth in the frequency range above 20 GHz, wherein the transmitter antenna is manufactured such that the emitting transmitter spot power is formed at a height low or medium orbit CAS circle area S _ILD at which the axis in the direction of said orbits CAS simultaneously adjudged not less than three satellites in low orbits and at least one satellite in the middle orbits of the CCC, and each satellite of these CCCs is additionally equipped with a receiver with an antenna, which are stationary directed to the center of the part of the high-altitude orbit for ma radiation at the frequency, the axis of antenna patterns terrestrial transmitter also suggest stationary center portion altitude orbits, which are in communication with the Earth, and the solid angle of the directional pattern of terrestrial transmitters mounted ± 8,5 °. 2. The method according to claim 1, characterized in that the mirror of the transmitting antenna at a radiation frequency above 20 GHz is made spherical, and the emitter or reflector of the emitter is placed on the axis of the antenna below the plane passing through the edges of the antenna by a value Δ, which is set above the focus of the sphere so that the angle α from the vertical passing from the edge of the antenna and parallel to the axis, and the direction of radiation is established from the equality:
$$\alpha =\frac{R_{\mathrm{AND}3L.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\cdot 180}{\left(H-H_{\mathrm{ABOUT}RB.\mathrm{FROM}\mathrm{FROM}\mathrm{FROM}}\right)\cdot \pi },$$

where R _ISL.SSS is the radius of the radiation zone of the radiation from the satellite transmitter in high orbit H;
N _ORB.SSS - the height of the low or medium orbit of the CCC.

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