JP2021081328A - Communication source estimation system and communication source estimation method - Google Patents

Abstract

To correctly estimate a position of a communication source without using two satellites even when position information of a satellite to be up-linked is not open or the position information is not correct.SOLUTION: A communication source estimation system of an embodiment collects, by a receiving antenna, radio waves of an uplink signal transmitted from the communication source toward a satellite and scattered by each of a plurality of scattering bodies, acquires, by a signal processing device, the position information of each of the plurality of scattering bodies, confirms, by correlation processing, that the scattered radio wave of each of the plurality of scattering bodies is from the same communication source, detects time of arrival of the received signal of the collected scattered radio wave of each of the plurality of scattering bodies, and estimates the position of the communication source.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a communication source position estimation system and a communication source position estimation method.

Conventionally, a communication source position estimation system that estimates the position of a communication source that uplinks a signal to a satellite has been proposed. This system consists of two receiving antennas and two satellites. The two satellites are adjacent to each other, receive signals that are uplinked from the target communication source, and send the signals as downlinks to the ground station. At the ground station, each downlink signal is received by two receiving antennas directed to each satellite. At this time, since the two satellites and the two receiving antennas are located at known positions, a time difference of arrival (TDOA) occurs between the signals received by the respective receiving antennas. On the other hand, although the satellite is orbiting on the equator, it moves up and down in the north-south direction, so a frequency difference FDOA (Frequency Difference Of Arrival) occurs due to the Doppler shift. Therefore, in the conventional system, the uplink generation position (communication source) is estimated by the intersection of the lines drawn by TDOA and FDOA.

However, in the conventional communication source position estimation system, it is necessary for two satellites to be adjacent to each other in a positional relationship in which one uplink signal can be received, and it is an essential condition that their positions are known. There is. Therefore, if the location information is not disclosed or the location information is not accurate, the location of the communication source cannot be estimated correctly.

Takeshi Amishima, Nobuhiro Suzuki, “TDOA / FDOA geolocation in space radio monitoring using RLMS and gating,” IEICE Communications Express, Vol.1, P1-6

As described above, in the conventional communication source position estimation system, it is necessary that two satellites are adjacent to each other in a positional relationship in which one uplink signal can be received, and it is an essential condition that their positions are known. Therefore, there is a problem that the position of the communication source cannot be estimated correctly when the position information is not disclosed or the position information is not accurate.

In the embodiment of the present invention, the position of the communication source is correctly estimated even when the position information of the satellites to be uplinked is not disclosed or the position information is not accurate without using two satellites. It is an object of the present invention to provide a communication source position estimation system and a communication source position estimation method which can be performed.

The communication source position estimation system according to one embodiment collects radio waves of uplink signals transmitted from a communication source to a satellite, which are scattered by a plurality of scatterers by a receiving antenna, and is a signal processing device. Premise The position information of each of the plurality of scattering bodies is acquired, it is confirmed that the scattered radio waves of each of the plurality of scattering bodies are radio waves from the same communication source by correlation processing, and the collected scattering by the plurality of scattering bodies is performed. The arrival time of the received signal of the radio wave is detected to estimate the position of the communication source.

FIG. 1 is a conceptual diagram showing an outline of a communication source position estimation system according to the present embodiment. FIG. 2 is a block diagram showing a configuration of a signal processing device of the system shown in FIG. FIG. 3 is a diagram showing reception timing of a plurality of reflected waves received by the receiving antenna of the system shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing an outline of a communication source position estimation system according to the present embodiment. In FIG. 1, T is a target communication source, S is a satellite that receives a radio wave (communication wave) of a signal uplinked from the communication source T and transmits it to a base station, and A1 to An are radio waves of an uplink signal. A high-rise building, a fixed object such as a mountain, or an aircraft (hereinafter referred to as a scatterer) whose position is known to scatter. On the other hand, in the system according to the present embodiment, the receiving antenna 11 that receives the radio waves scattered by the scatterers A1 to An and the signal processing device 12 that estimates the position of the communication source T from the received signal of the receiving antenna 11 And.

FIG. 2 is a block diagram showing a specific configuration of the signal processing device 12. In FIG. 2, the receiving antenna 11 collects radio waves of uplink signals transmitted from the communication sources T scattered by the scatterers A1 to An toward the satellite S, respectively. The received signal of the radio wave collected by the receiving antenna 11 is sent to the signal processing device 12. The signal processing device 12 includes a detection processing unit 121, a correlation processing unit 122, a communication source estimation processing unit 123, and a scatterer position information acquisition processing unit 124. The detection processing element unit 121 detects the appearance time and frequency of the signal whose received power becomes large with respect to the collected scattered radio wave reception signal. The correlation processing unit 122 performs cross-correlation processing between the received signals at the appearance time and frequency of the signal detected by the detection processing unit 121, and calculates the peak value (hereinafter, referred to as a pulse) of the correlation value obtained by the cross-correlation processing. To do. The communication source estimation processing unit 123 estimates the signal reception time assumed to be a signal transmitted from the same communication source T based on the pulse calculated by the correlation processing unit 122. The scatterer position information acquisition processing unit 124 measures the position information in advance when the scatterer is a fixed object, and when the scatterer is an aircraft, the position information of each target aircraft is obtained through a communication system prepared separately. get.

In the above configuration, the processing contents will be described below.

The communication source position estimation system according to the present embodiment assumes that the radio waves of the uplink signal transmitted from the communication source T toward the satellite S are scattered by the scatterers A1 to An whose position information is known, and each of them. Radio waves scattered by the scatterers A1 to An are collected by the receiving antenna 11, and the signal processing device 12 uses the arrival time of the signal received from each of the scatterers A1 to An as a communication source (position information where the uplink occurs). Estimate T. As a precondition at this time, the position information of each scatterer A1 to An is known, and it can be confirmed that the communication wave scattered from the scatterers A1 to An is a radio wave of the same communication source by correlation processing. ..

In the signal processing device 12, the detection processing unit 121 detects the appearance time and frequency of the signal whose received power increases with respect to the received signal. At this time, in order to improve the accuracy of the correlation processing and the pulse-to-pulse time difference estimation processing of the subsequent processing, the receiving antennas may be increased and installed for each of the plurality of scatterers to improve the receiving sensitivity. In this case, it is assumed that the receiving systems are synchronized in time.

The correlation processing unit 122 is assumed to be the same communication source T by calculating the pulse obtained by the cross-correlation processing between the received signals at the appearance time and frequency of the signal detected by the detection processing unit 121. Estimate the signal reception time _Ti (i = 1, 2, ..., N). N is the maximum number of samples assumed to be the same communication source. FIG. 3 shows a pulse detection example (N = 4) of the received signal that has been correlated. In the cross-correlation process, if the communication specifications are known, the process may be performed by using the specifications as a reference pattern.

The position information and signal transmission time of the communication source T to be determined (x, y, z, t ), the position information and the scattering time when reception of the scatterer _{A1~An (x i, y i,} z i, t _{If i} ), then those relationships are given by the following equation.

ｃは光速である。なお、散乱時刻ｔ_ｉと受信アンテナ１１における信号受信時刻Ｔ_ｉとの関係は、受信アンテナ１１の位置情報を（Ｘ，Ｙ，Ｚ）とすると、次式で与えられる。

c is the speed of light. The relationship between the signal reception time T _i in the scattering time t _i and the receiving antenna 11, the position information of the receiving antenna 11 (X, Y, Z) When given by the following equation.

通信源推定処理部１２３では、同時に受信可能な散乱体Ａ１〜Ａｎからの電波の数Ｎに合わせて処理するものとする。なお、通信源推定処理では、変数ｘ，ｙ，ｚ，ｔを算出する必要があるため、地球表面上での発生という条件を含めて、Ｎは少なくとも３以上である必要がある。また、これらを組み合わせて実施できるものとする。

It is assumed that the communication source estimation processing unit 123 processes according to the number N of radio waves from the scatterers A1 to An that can be received at the same time. Since it is necessary to calculate the variables x, y, z, and t in the communication source estimation process, N must be at least 3 or more, including the condition that it occurs on the earth's surface. In addition, these can be combined and implemented.

(A) When N = 3
In the case of simultaneous three-wave reception, the simultaneous equations are three equations, whereas the variables are x, y, z, and t, so the condition that they occur on the earth's surface is added, and the simultaneous equations of four equations are added. Therefore, the position information of the communication source T can be obtained. As an example of the condition on the surface of the earth

このとき、Ｒ_Ｅは地球半径とする。

At this time, _RE is the radius of the earth.

(B) When N ≧ 4
In the case of simultaneous reception of four or more waves, the simultaneous equations are four or more equations, whereas the four variables are x, y, z, and t, so that the position information of the communication source T can be obtained. It is also possible to add the condition that it occurs on the surface of the earth. Further, the position information of the scatterers A1 to An required for the communication source estimation process is obtained by the scatterer position information acquisition processing unit 124 through a communication path prepared separately.

As described above, according to the communication source position estimation system according to the present embodiment, when two satellites are not used and the position information of the uplink satellite is not disclosed or the position information is not accurate. However, the position of the communication source T can be estimated correctly.

The present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

T ... communication source, S ... satellite, A1 to An ... scatterer, 11 ... receiving antenna, 12 ... signal processing device, 121 ... detection processing unit, 122 ... correlation processing unit, 123 ... communication source estimation processing unit, 124 ... scattering Body position information acquisition processing unit.

Claims (4)

A receiving antenna that collects the radio waves of the uplink signal transmitted from the communication source to the satellite, which are scattered by multiple scatterers, respectively.
It is provided with a signal processing device that detects the arrival time of the received signal of the scattered radio wave by the plurality of scatterers collected by the receiving antenna and estimates the position of the communication source.
The signal processing device is a communication source position estimation system that acquires position information of each of the plurality of scatterers and confirms that the scattered radio waves of each of the plurality of scatterers are radio waves from the same communication source by correlation processing. .. The signal processing device is
A detection processing unit that detects the appearance time and frequency of a signal whose received power increases with respect to the scattered radio wave reception signal collected by the receiving antenna.
A correlation processing unit that performs cross-correlation processing between received signals at the appearance time and frequency of the signal detected by the detection processing unit and calculates the peak value of the correlation value obtained by the cross-correlation processing.
Based on the position information of each of the plurality of scatterers and the peak value of the correlation value calculated by the correlation processing unit, the signal reception time assumed to be a signal transmitted from the same communication source is estimated and estimated. A communication source estimation processing unit that estimates the position of the communication source from the signal reception time,
The communication source position estimation system according to claim 1, further comprising a position information acquisition unit that acquires position information of each of the plurality of scatterers used in the estimation process of the communication source estimation processing unit. When the scatterer is a fixed object, the position information acquisition unit measures the position information in advance, and when the scatterer is a flying object, the position information of each target flying object is obtained through a communication system prepared separately. 2. The communication source location estimation system according to claim 2. Collects the radio waves of the uplink signal transmitted from the communication source to the satellite, which are scattered by multiple scatterers.
Obtaining the position information of each of the plurality of scatterers,
After confirming that the scattered radio waves of each of the plurality of scattering bodies are radio waves from the same communication source by correlation processing,
A communication source position estimation method for estimating the position of the communication source by detecting the arrival time of the received signals of the collected radio waves scattered by the plurality of scatterers.

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