RU2299837C1 - Method of construction of low-orbital satellite navigation system - Google Patents

Abstract

FIELD: information satellite systems; forming global radio-navigational field for sea-going ships, ground, air and space vehicles.

SUBSTANCE: proposed system includes many low-orbit spacecraft whose number depends on conditions of global covering of access areas of users. Each spacecraft contains communication unit in addition to navigational equipment for communication of this spacecraft with two other spacecraft in its orbital plane and two spacecraft from adjacent orbital planes. Communication is performed in millimetric wave band absorbed by Earth atmosphere. At least one spacecraft is provided with high-accuracy synch generator. Thus spacecraft group is formed which is provided with noise immunity system of relaying and measuring radio lines connecting all spacecraft groups and navigational radio line covering upper hemisphere.

EFFECT: enhanced reliability and accuracy; enhanced noise immunity of data fed to users of satellite system.

1 dwg

Description

The invention relates to satellite navigation systems and can be used to create a global radio navigation field for navigating marine, land, air, as well as low orbit and high orbit space consumers.

Known satellite navigation systems (RU 2001109386, B64G 1/00, 2003, RU 2181927, H04B 7/185, 2002, US 51129095 Н04В 1/185, 1992, RU 2118055, Н04В 7/185, 1998).

Glonass and GPS satellite navigation systems developed in the mid-eighties of the twentieth century, and Glonass-K and Galileo are currently being developed are known. The orbital constellation of each of these systems consists of 24 spacecraft (SC) launched into orbits about 20,000 km above the surface of the Earth (Yu.A. Stepanov. Satellite navigation and its application. Moscow: Eco-Trends, 2003, p. 35 -54).

Such an orbit altitude was chosen mainly from the convenience of reconciling the frequency of the onboard cesium standards with the frequency of the ground hydrogen frequency standard, since the spacecraft of these systems pass above the ground control point at the same time every day, and from the condition of reducing the influence of inhomogeneities of the Earth's gravitational field. However, the construction of a group of navigation spacecraft was carried out in the absence of inter-satellite systems covering the entire spacecraft group of relay and measuring radio lines, and is not optimal in terms of the cost of forming a spacecraft group and maintaining its quantitative composition, therefore, a method is proposed that is optimal in terms of the cost of building a system.

The technical result of the implementation of the proposed method is to create a low-orbit grouping of navigation satellites, which, in combination with a noise-free network of relay and measuring radio links connecting all the satellites of the constellation, with a navigation radio line illuminating the upper hemisphere, allows for much lower costs than existing and developing navigation systems provide more reliable and high-precision navigation definitions of land, sea, air and space low orbit high-orbit consumers.

To achieve the specified result, it is proposed:

Low-orbit network navigation system containing N spacecraft (SC), the number of which is determined from the expression

N = mn

m is the number of spacecraft in one orbital plane,

n is the number of orbital planes in the system.

Where

[] - the integer part of number,

i is the inclination of the orbit of the spacecraft,

α is the angular radius of visibility of the spacecraft from the Earth’s surface,

R ₃ is the radius of the Earth,

N is the spacecraft orbit,

β is the smallest permissible elevation angle of the spacecraft’s visibility by the ground consumer, and each spacecraft, in addition to navigation equipment, contains a communication node that provides communication in the Earth’s atmosphere absorbed by a part of the millimeter wave range of this spacecraft with two spacecraft in its orbital plane and two spacecraft from neighboring orbital planes, with at least one spacecraft containing a high-precision synchro-generator.

Specifically, the following is proposed:

- create a low-orbit spacecraft grouping with spacecraft orbits ranging from 6,000 km to 9,000 km.

- to provide stabilization of the frequency and time on the spacecraft using radio links protected from Earth interference.

- assign to these lines the functions of measuring the relative position of the spacecraft.

- provide each spacecraft with an antenna to create a radio navigation field in the upper hemisphere with respect to the spacecraft.

If stabilization of the onboard frequency of the spacecraft is carried out not from atomic frequency standards, but with the help of relay and measuring radio links connecting all the spacecraft, it becomes possible to optimize the height of the spacecraft's orbit according to the cost of forming the spacecraft grouping. In this case, the number of spacecraft for each height of the orbit is calculated by the formula:

where p is the spacecraft head in one plane of the orbit;

m is the number of orbits

Where:

[] is the integer part of the number, 1 is the inclination of the orbit of the spacecraft,

α is the angular radius of visibility of the spacecraft from the Earth’s surface,

R ₃ is the radius of the Earth,

N is the spacecraft orbit,

β is the smallest allowable elevation angle of the spacecraft visibility by the ground consumer.

The costs L for the derivation of the spacecraft grouping into orbits can be estimated using the expression:

where M is the mass of the spacecraft,

- отношение стартовой массы ракеты к массе полезной нагрузки.

может быть получен расчетным путем или из многочисленных данных, полученных при выводах полезных нагрузок на орбиты разных высот.

- the ratio of the starting mass of the rocket to the mass of the payload.

can be obtained by calculation or from numerous data obtained by deriving payloads into orbits of different heights.

Taking the ratio L corresponding to an altitude of 20,000 km to L corresponding to a desired orbit height, we obtain a coefficient B characterizing the gain in forming a grouping of navigation spacecraft at the required spacecraft orbit compared with the cost of forming a grouping of spacecraft having orbit heights of 20,000 km. The values of B calculated for the altitudes of the orbits from 20,000 to 5,000 km and β _min = 5 ° are shown in the graph (drawing)

Row 1 - β _min = 0 °, row 2 - β _min = 5 °, row 3 - β _min = 10 °

The broken nature of the graph of B values and maxima in the regions of 7000 km and 14000 km are determined by the change in the number of spacecraft in the group at these altitudes.

The maximum of coefficient B in the range of orbit heights from 5000 to 20,000 km falls on H = 7000 km, and at this altitude the costs of forming a grouping of navigation spacecraft will be minimal.

However, the accuracy of predicting the spacecraft’s orbit at such a low altitude will be lower, therefore, the accuracy of the navigation determination of system consumers will also be lower. But having equipped the SC of a low-orbit group with a network of inter-satellite satellite position meters, we will not only get a reduction in the cost of forming a group, but also a high accuracy in knowing the position of the SC, and, consequently, a higher accuracy in the navigation determination of consumers. Such a solution to the problem will be especially advantageous if the measuring network is built in the part of the millimeter-wave range of radio waves protected from interference from the Earth's surface.

At the same time, a relay of synchronization of frequencies of navigation signals between the spacecraft constellations can be assigned to the millimeter-wave radio network. Studies have shown that replacing cesium frequency standards with repeaters will reduce the mass of each spacecraft, which will give an additional gain in the cost of putting it into orbit.

Thus, having created a grouping of navigation satellites at an altitude of 7000 km in combination with providing these satellites with inter-satellite millimeter-band radio links for relaying synchronizing signals and measuring the distance between the satellites, eliminating cesium frequency standards from the spacecraft, adding additional navigation transmitters with antennas to the satellite’s equipment, looking up, we get a new quality - improving the accuracy of the navigation definition of consumers of the system, an additional continuous radio navigation This field for navigation of high-orbit spacecraft at more than 2 times less cost for the formation of the constellation. Inter-satellite radio links should operate in the part of the millimeter wave range absorbed by the Earth’s atmosphere. This will make them resistant to interference from the surface of the Earth.

Claims (1)

Low-orbit network navigation system containing spacecraft (SC), the number N of which is determined from the expressions N = mn

, where m is the number of spacecraft in one orbital plane; n is the number of orbital planes in the system; [] - the integer part of number; i is the inclination of the orbit of the spacecraft,

α is the angular radius of visibility of the spacecraft from the Earth's surface; R ₃ is the radius of the Earth; H is the spacecraft orbit; β is the smallest allowable elevation angle of the spacecraft visibility by the ground consumer, in addition, each satellite, in addition to navigation equipment, contains a communication node that provides the connection of this satellite in the Earth’s absorbed part of the millimeter wave range with two spacecraft in its orbital plane and two spacecraft from neighboring orbital planes, at least one spacecraft contains a high-precision clock generator.

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