RU113022U1 - LAND-SPACE RADAR SYSTEM - Google Patents

Abstract

 1. Terrestrial-space radar system containing a space-based or air-based transmitter, the carrier of which is a satellite or flight-lifting means, and spaced-apart radar receiving devices located on cell towers and connected via cellular communication channels to cellular cellular communication stations, each of which contains a nodal calculator of target coordinates connected via a cellular communication channel to a central cellular communication station on which a central calculator is located to the coordinate of the target, the output of which is connected to the control center of the ground-space system, which is connected through the satellite control station to the specified transmitter. ! 2. The ground-based space radar system according to claim 1, characterized in that the radar receiving device contains two antennas, one of which is designed to receive a direct signal from a space or air-based transmitter, and the other to receive a signal reflected from a target, connected respectively with digital radios for receiving direct and reflected signals, which are connected to the meter of the parameters of the signal reflected from the target, relative to the parameters of the direct signal.

Description

A utility model relates to the field of radar, specifically to diversity radar systems.

Known terrestrial-space radar system (patent No. 36147, 2003), containing a space-based transmitter and spaced receiving devices that are connected to the Central processing station via a space communication line. Diversity receiving devices contain a series-connected antenna, a digital radio receiver and a radar information transmission unit.

A disadvantage of the known solution is its technical complexity and low reliability due to the presence of a special communication system (space or relay) between the receiving devices and the central station, as well as the complexity of the receiving devices, each of which contains a computer and must determine the distance to the target and the direction to it at the same time. These receiving devices are in fact separate radars operating on a radio illumination signal from a satellite. The presence of computing devices on each receiving device reduces the reliability of the system as a whole.

The utility model is based on combining a network of simple radar receivers with a network of cellular transceivers.

The technical result of the proposed solution is to simplify the radar system while improving the reliability and accuracy of determining the location of the target.

The specified technical result is achieved by the fact that the ground-space radar system contains a space-based or air-based transmitter and spaced radar receiving devices. Diversity radar receiving devices are installed on the same towers on which cellular communication transceivers are installed and connected via a cellular communication channel to cellular cellular communication stations, each of which contains a nodal target coordinate calculator connected via a cellular communication channel to a central cellular communication station, which houses the central calculator of the coordinates of the target, the output of which is connected to the control center of the ground-space system, which through the satellite control station connected to the transmitter spaceborne or airborne.

The radar receiving device contains two antennas, one of which is designed to receive a direct signal from a space or air-based transmitter, and the other is used to receive a signal reflected from a target, connected respectively to digital radios to receive direct and reflected signals, which are connected to a signal parameter meter, reflected from the target relative to the direct signal parameters.

This allows you to simultaneously solve two problems: firstly, using at least three non-directional receivers to remotely accurately determine the coordinates of the target in the triangle of cell towers, and secondly, to remove the problem of creating a special space communication system between radar receivers and the central station through the use of channels the same cellular network. At the same time, the transmitters are located on one or more spacecraft or airborne aircraft (aerostats, airships, etc.). The transmitter operates in several ranges of electromagnetic waves.

Figure 1 presents the functional diagram of the ground-space radar system

Figure 2 - presents a diagram of the mutual placement of receivers on the towers of cellular communications and radar targets

Figure 3 - presents the line position of the target relative to the three receivers on the towers of cellular communication

Figure 4 - shows the placement of the target between the areas of action of neighboring node cellular stations.

The ground-space radar system contains a space-based or air-based transmitter 1, diversity radar receiving devices 2 located on the cell towers and connected via the cellular communication channel 3 to the cellular communication stations 4 and 5, each of which contains a node computer 6 of the target coordinates, connected via a cellular communication channel to a central cellular communication station 7, on which a central calculator 8 of the target coordinates is located. The output of the computer 8 is connected to the control center of the ground-space system 9, which is connected to the transmitter 1 through the satellite control station 10. The diversity radar receivers 2 contain two antennas: one for receiving a direct signal from a space or air-based transmitter, and the other for receiving a signal reflected from the target, which are connected respectively to digital radios for receiving direct and reflected signals, which are connected to a meter of parameters of the signal reflected from the target ( delay time and Doppler frequency shift) relative to the direct signal parameters. The signal parameter meters are connected via cellular communication channels 3 with the corresponding node computers 6 of the node stations 4 and 5. The transmitter 1 is equipped with a transmitting device 11 operating in different ranges, as well as several antennas 12 for generating sounding signals.

The system operates as follows.

The transmitter 1 generates sounding signals (pulsed or complex phase-shift), irradiating a given region of the near-Earth airspace of the Earth. These signals are directly received on the direct signal antennas of the radar receiving devices 2 located on the cell towers (Fig. 2) under the numbers 4.1, 4.2 and 4.3 (or 5.1, 5.2 and 5.3, respectively).

The transmitter signals reflected from the target are received at the reflected signal antennas of the same receiving devices 2 located on the corresponding towers 4.1, 4.2 and 4.3 (or 5.1, 5.2 and 5.3, respectively). Next, in each receiving device, the difference Δt of the arrival time of the direct signal and the signal reflected from the target is measured:

where C is the propagation velocity of radio waves;

R _C is the distance between the space transmitter and the target;

R ₀ is the distance between the receiving device (tower) and the space-based transmitter;

R is the distance between the target and the receiving device (tower).

Information about the arrival time difference is transmitted via the cellular channel 3 available on each tower to the nodal calculator 6 of the nodal station 4 or 5, where a system of three quadratic equations is generated and solved with respect to the desired coordinates of the target:

Where

X _C , Y _C , Z _C - current coordinates of a space or air-based transmitter (ephemeris);

X _i , Y _i , Z _i - the coordinates of the respective towers with receiving devices;

X _C , Y _C , Z _C - the desired current coordinates of the target.

The system of equations (2) is difficult to see and therefore, to simplify the principle of determining the coordinates of the target, we simplify it. Assume that the target is low-altitude (Z _C = Z _i ), the height of the space-based transmitter is significantly greater than the height of the target and it is located above the head, i.e. R _C = R _0i

In this case, the system of equations (2) takes the form:

This system is a system of equations of circles with centers at the points of placement of towers and intersecting at the point of placement of the target with coordinates X _C , Y _C (figure 3)

It is important to note that system (3) is redundant, therefore, any pair of equations can be left if there is additional crude information about the target's motion area. However, any redundant measurement improves the accuracy of determining coordinates.

Thus, by measuring only the difference between the direct and reflected from the target signal Δt _i , it is possible to very accurately determine the coordinates of the target in the system of cell towers

As for the Doppler shift, under the same conditions we obtain a system of equations:

F _gi = f ₀ i / c

where F _gi - measured in the receiving device 2 on each tower the difference of the Doppler shifts of the direct and reflected signals,

f ₀ - carrier frequency of the radiation of the transmitter,

Ri is the radial velocity of the target relative to each of the three towers.

In the system of equations (3) there are three unknown coordinates of the target: X _C , Y _C , Z _C. Therefore, the number of measured values of Δt must be at least three relative to three towers. With large target sizes, and, accordingly, a high level of the reflected signal, signals can be received not only at the nearest towers, but also at remote ones. The total number of receiving towers is increasing towers. This improves the accuracy of determining the coordinates of the target.

The measurement results of the Doppler shift from the receiving devices 2 are transmitted via channel 3 to the nodal computer 6.

According to the results of calculating the coordinates of the target (X _C , Y _C ) and the received information about the Doppler shifts F _gi in the calculator 6, the current target velocity vector is determined. This information is transmitted directly to the control center 9 through the central cellular communication station, where the control signals of transmitter 1 are generated and transmitted via satellite control station 10.

A situation is possible when the target flies between towers belonging to different nodal cellular stations and it is difficult to determine the coordinates of the target within the same nodal station. This situation is illustrated in figure 4, where the flags 4 and 5 indicate two nodal stations, double numbers 4.1-4.6 and 5.1-5.6 - their cell towers. If the target C (X _C , Y _C ) is between the zones of two nodal stations, as shown in figure 4, then the strongest reflected signal will be for the minimum ranges: R ₄₅ and R ₄₆ in the tower system of stations 4 and R ₅₂ and R ₅₃ in the tower system of station 5. With this composition of measurements, it is better to combine them into a system of four equations in calculator 8 at the central station. In this case, incomplete information from both neighboring node stations is transmitted to the computer 8 of the central cellular communication station 7, where the same equations (2) (3) and (4) are solved for the corresponding tower numbers. The calculated current coordinates of the target and the value of the velocity vector from the computers 6 and 8 are transmitted via a cellular channel to the control center of the system 9, where signals from air targets are identified and control signals are generated for the operating modes of the space-based or air-based transmitter 1. At a high signal level, all calculators 6 and 8 work in normal mode, which increases the accuracy and reliability of determining the coordinates of the target. Indeed, with a good signal in the station 4 system, measurements of distances up to 5 stations are possible: R ₄₅ , R ₄₆ , R ₄₄ , R ₄₁ and R ₄ , and in station 5 system there are also 5 stations: R ₅₂ , R ₅₃ , R ₅₁ and R ₅ . Processing an excessive number of measurements relative to 10 towers allows to increase the accuracy of determining the coordinates of the target in 1.5-2 times.

When a small target is detected by the command of the satellite control station 10, the transmitter either switches to high-potential target tracking mode with a narrowed radiation pattern, or switches to another carrier frequency in a different wavelength range. At the same time, on a command from the transmitter, all terrestrial receivers also switch to a different carrier frequency.

As carriers of probing signal transmitters, it is possible to use geostationary satellites, mid-orbit (such as Glonass), as well as low-orbit satellites. In addition, it is possible to use aerial equipment such as balloons, airships, etc.

As cellular systems it is possible to use all existing systems: Megaphone, Beeline, MTS.

With existing types of radionavigation sounding signals, both pulsed and continuous ultra-wideband, the expected error in determining the coordinates in this system is 10-15 m, and for speed - no more than 5 cm / s.

The proposed system is simpler than the known and has higher reliability for two reasons:

- receivers located on the towers are simpler and more reliable since do not contain calculators;

- the communication system does not contain special elements of space communication systems or relay systems (special antenna systems and special transmitters);

In addition, the proposed system has a higher accuracy in determining the coordinates of the target with the same accuracy as a prototype of single measurements, because with an excessive number of measurements of distances to a larger number of towers (up to 10), the error in determining the coordinates of the target as a result of the joint processing of all measurements is reduced by 1.5-2 times.

Claims (2)

1. Terrestrial-space radar system containing a space-based or air-based transmitter, the carrier of which is a satellite or flight-lifting means, and spaced-apart radar receiving devices located on cell towers and connected via cellular communication channels to cellular cellular communication stations, each of which contains a nodal calculator of target coordinates, connected via a cellular communication channel to a central cellular communication station, on which a central calculator is located to the coordinate of the target, the output of which is connected to the control center of the ground-space system, which is connected to the specified transmitter through the satellite control station. 2. The ground-based space radar system according to claim 1, characterized in that the radar receiving device contains two antennas, one of which is designed to receive a direct signal from a space or air-based transmitter, and the other to receive a signal reflected from a target, connected respectively with digital radios for receiving direct and reflected signals, which are connected to the meter of the parameters of the signal reflected from the target, relative to the parameters of the direct signal.