JP4592506B2 - Uplink interference source locating apparatus and method - Google Patents

Description

  The present invention relates to an uplink interference source position identifying apparatus and method for estimating the position of a launch source that uplinks an interference wave and displaying the position so that the position can be identified in satellite communication or the like.

  In the uplink that emits radio waves from the ground station to the satellite by satellite communication etc., it may interfere with other broadcasting / communications that are operating by erroneously transmitting the transmission direction, frequency, time, etc. It often happens to give.

  To solve this problem, there is no technology for easily identifying the position of the ground station that is uplinked to the satellite, but the position can be identified only when the uplink wave from the ground station can be received via two satellites. I know. By receiving the downlink from two satellites that are distantly located, measuring the difference in arrival time, the difference in Doppler frequency due to satellite movement, and considering the satellite position / velocity at the time of measurement, the position of the ground station can be identified. .

  However, this method has the following technical problems. First, the downlink from the two satellites is received, but the beam pattern of the transmitting antenna used in satellite communication becomes narrower as the aperture of the parabolic antenna becomes larger. At least one of them becomes very weak radio waves. The two satellites always move even if they are geostationary satellites, and the Doppler shift amount of the received signal is different, so that a difference occurs in the reception frequency. Furthermore, the installation locations of the two antennas are separated, and the length of the transmission line may not be the same.

  Thus, since the received signals via the two satellites have different frequencies and one of them is a very weak signal, it is impossible to detect the arrival time difference with a simple correlation process. In addition, a delay time is generated depending on the length of the transmission line, which becomes an error factor in calculating the arrival time difference. In particular, the arrival time difference and the Doppler frequency difference can be calculated by performing a correlation process in consideration of the frequency difference. However, in order to calculate the arrival time difference by a correlation process with a weak received signal, the processing AD is processed. It is necessary to increase the number of sample data and increase the processing gain. For this reason, there is a problem that the amount of calculation for the correlation processing increases and the processing time is very long.

Patent Documents 1 and 2 describe a method and apparatus for specifying the position of a launch source by receiving the downlink of two satellites, but speeding up the processing targeted by the present invention. A method and apparatus for correcting the arrival time difference is not disclosed.
JP 2000-512380 gazette Special table 2003-507747

  As described above, it has been extremely difficult to estimate the position of a launch source that uplinks interference waves in satellite communications or the like.

  An object of the present invention is to solve the above-described problems and to provide an uplink interference source position identifying apparatus and method that can easily and accurately identify the position of an uplink interference source in a short time.

  In order to solve the above problem, an uplink interference source location apparatus according to the present invention includes first and second receiving antennas for receiving downlinks via first and second satellites, and the first and second receiving antennas. Analog-to-digital conversion means for obtaining first and second received data by simultaneously analog-to-digital conversion of received signals of the two receiving antennas, and performing correlation processing on the first and second received data, Correlation processing means for calculating the arrival time difference and Doppler frequency difference of the downlink via the first and second satellites, calculation range control means for gradually narrowing down the calculation range for the correlation processing, and the downlink radio wave Satellite position calculation processing means for calculating the position at the measured time of the two satellites receiving the signal, the arrival time difference obtained by the correlation processing means, Doppler The source position estimation processing means for estimating the position of the ground station using the information on the frequency difference and the satellite position and speed information at the measurement time obtained by the satellite position calculation processing means, and the position of the ground station Display means for plotting the coordinates of the intersection of the trajectory of the arrival time difference and the trajectory of the Doppler frequency difference on the map from the estimation result of the above, and displaying the position estimation result of the radio wave emission source.

  The correlation processing means divides a calculation range for correlation processing by a plurality of computers instead of the calculation range control means, and performs parallel processing.

  The emission source position estimation processing means executes the estimation process after correcting an error when calculating the arrival time difference obtained by the correlation processing means.

  In addition, the uplink interference source location method according to the present invention receives the first and second downlink data via the first and second satellites by two receiving antennas and simultaneously performs analog / digital conversion to obtain the first and second received data. A correlation process for calculating a difference in arrival time and a Doppler frequency difference between the first and second satellites by performing a correlation process on the first and second received data, and the correlation A calculation range control process for gradually narrowing down a calculation range for correlation processing, a satellite position calculation process for calculating the positions of the two satellites receiving the downlink radio wave at the measured time, and the correlation process Using the obtained arrival time difference and Doppler shift frequency difference information and the satellite position and velocity information at the measurement time obtained in the satellite position calculation process Plot the coordinates of the intersection of the arrival time difference trajectory and the Doppler frequency difference trajectory on the map from the ground source position estimation process to estimate the ground station position and the ground station position estimation result. And a display process for displaying the position estimation result.

  That is, the uplink interference source localization apparatus and method according to the present invention are configured by using two receiving antennas for a downlink of a radio wave uplinked to a certain satellite and a downlink of the same radio wave of another satellite in the vicinity. By receiving and processing, when estimating the position of the emission source, the correlation processing for calculating the arrival time difference and the Doppler frequency difference is executed, and the calculation time is shortened by gradually narrowing down the range of calculation for correlation processing. Features.

  In the system that estimates the position of the emission source by receiving and processing the downlink of the radio wave uplinked to a certain satellite and the downlink of the same radio wave of another satellite in the vicinity by two receiving antennas And a correlation processing unit for calculating the arrival time difference and the Doppler frequency difference, and the calculation range to be correlated is shared by a plurality of computers, and the calculation time is shortened by parallel processing.

  In the system that estimates the position of the emission source by receiving and processing the downlink of the radio wave uplinked to a certain satellite and the downlink of the same radio wave of another satellite in the vicinity by two receiving antennas An error at the time of arrival time difference calculation is corrected by receiving the same radio wave of the same satellite by two receiving antennas.

  ADVANTAGE OF THE INVENTION According to this invention, the uplink interference source position identification apparatus and its method which can identify the position of an uplink interference source easily in a short time can be provided.

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

(First embodiment)
FIG. 1 is a block diagram schematically showing the configuration of an uplink interference source location apparatus according to the first embodiment of the present invention. This apparatus includes receiving antennas 10 to 11, a frequency conversion unit 20, an AD conversion unit 30, a correlation processing unit 40, a satellite position calculation processing unit 50, a launch source position estimation processing unit 60, and a display unit 70.

  The receiving antennas 10 to 11 are receiving antennas that can measure the same frequency band. The shape and type of the antenna, the interval for placing the antenna, etc. are arbitrary depending on the object to be measured and the purpose of measurement, but a parabolic antenna with a sufficient aperture size that can receive weak radio waves from the satellite. desirable.

  The frequency converter 20 converts the received signal from the satellite into an intermediate frequency that can be AD converted. It is desirable to use a common local signal in the two reception systems.

  The AD conversion unit 30 uses one that can sample two received signals simultaneously. The sampling frequency, dynamic range, etc. need to be appropriately selected according to the received signal.

  The overall processing flow is shown in FIG.

  In FIG. 2, in step 11, two receiving antennas 10 to 11 receive downlinks via two satellites, and simultaneously AD-sample received signals in two systems to obtain digital data.

In step 12, the correlation processing unit 40 performs correlation processing for calculating the arrival time difference and the Doppler frequency difference.

Here, s ₁ and s ₂ indicate received signals with two antennas. T indicates the measurement time. Τ and ν are parameters indicating arrival time difference and frequency difference, respectively. The arrival time difference and the Doppler shift frequency difference are obtained by estimating τ and ν that maximize | F (τ, ν) |.

  Since the processing gain by the correlation processing is proportional to the number N of AD sampling data used for the correlation processing, in order to obtain a processing gain of 50 dB, 100,000 points of AD sampling data are required. However, since the calculation amount is proportional to the square of the AD sampling number N, when the AD sampling number is doubled, the calculation amount and calculation time are four times.

  Further, in the equation (1), the parameter ν of the frequency difference is considered. Considering the case where the frequency range to be calculated for ν is calculated at M points, the amount of calculation is proportional to M.

  Therefore, the correlation processing F is proportional to the square of the AD sampling number N and the calculation number M of the parameter ν of the frequency difference. If N and M are increased and an attempt is made to calculate with good accuracy, the calculation amount becomes enormous. Processing time will take tens of hours.

  The correlation process F responds very sensitively to the time parameter τ, but responds slowly to the parameter of the frequency f. Therefore, data cannot be thinned out for the parameter τ, but can be thinned out to some extent for the parameter ν. Regarding the parameter τ, it is conceivable to lose sight of the correlation peak by thinning out the data. However, even if the parameter ν is thinned out to some extent, the correlation peak is not lost.

  FIG. 3 shows the correlation processing flow.

In step 101, the calculation range of the time parameter τ and the frequency parameter is determined as follows.
For τ, n samples are calculated from τmin to τmax.
For ν, m samples are calculated from νmin to νmax.

In step 102, the correlation process F is calculated for the calculation range determined in step 101. Τ is τ _p and ν is ν _p when the correlation value | F | is the maximum value.

In step 103, the range of ν is narrowed, and correlation processing F is calculated with τ = τ _p fixed.

The calculation range of ν is determined as follows.

A new νmax, decide to _{ν p + (νmax-νmin)} / α and the larger νmax.

A new νmin, ν _p - decide to (νmax-νmin) / α and the smaller of νmin.

α is a parameter that determines the speed of narrowing the range of ν as a number larger than one.

  By repeating step 103 as many times as necessary, the range of ν can be exponentially narrowed and converges quickly.

  Returning to FIG. 2, in step 13, the satellite position calculation processing unit 50 calculates the position at the measured time of the two satellites receiving radio waves as accurately as possible. It is necessary to obtain accurate orbital elements and orbit information, or to measure the position and velocity of the satellite at the time of AD data acquisition using another measurement system.

  In step 14, the launch position estimation processing unit 60 obtains the arrival time difference and Doppler shift frequency difference information obtained by the correlation processing unit 40 and the satellite position and velocity information at the measurement time obtained by the satellite position calculation processing unit 50. To estimate the position of the ground station.

  FIG. 4 shows an algorithm of the emission source position estimation process.

  In step 201, a locus based on the arrival time difference is calculated.

When the position vector of the radio wave emission source X is x ^→ ( ^→ represents a vector), the position vectors of the two satellites A and B are p _A ^→ and p _B ^→ , respectively, and the position vector of the reception point Q is q ^→ In addition,

Find the trajectory of x that satisfies ΔT represents the arrival time difference, and c represents the speed of light. The sign of the arrival time difference ΔT is based on the time when the radio wave via the satellite B arrived.

In step 202, a locus based on the Doppler frequency difference is calculated. As described above, the position vector of the radio wave emission source X is x˜, the position vectors of the two satellites A and B are respectively p _A ^→ , p _B ^→, and the position vector of the reception point Q is q ^→ 2 satellites A, V _a ^→ respectively the velocity vector of B, and when the V _B ^→, calculates a Doppler frequency at which radio waves emitted from radio wave source X is received satellites a, in B.

  Further, consider the frequency of the local signal that is converted from uplink frequency to downlink frequency in the satellite. Further, consider the Doppler frequency when radio waves emitted as downlinks from satellites A and B are received at the reception point Q.

  In consideration of the above, the trajectory of the radio wave emission source X that becomes the Doppler frequency difference measured at the reception point Q via the Doppler frequency difference via the two satellites is calculated.

  In step 203, the coordinates of the intersection of the trajectory of the arrival time difference calculated in step 201 and step 202 and the trajectory of the Doppler frequency difference are calculated.

  Returning to FIG. 2, in step 15, the display unit 70 plots the coordinates of the intersection of the arrival time difference locus and the Doppler frequency difference locus calculated in step 203 on the map, and the position estimation result of the radio wave emission source Is displayed. The trajectory of the arrival time difference and the trajectory of the Doppler frequency difference are also displayed together.

  As described above, according to the uplink interference source position specifying apparatus configured as described above, the position of the uplink interference source can be easily specified in a short time.

(Second Embodiment)
In the configuration apparatus according to the first embodiment, the correlation processing F is proportional to the square of the AD sampling number N and the calculation number M of the parameter ν of the frequency difference, and increases N and M so as to calculate with high accuracy. Then, the amount of calculation becomes enormous, and it takes tens of hours of processing time.

  However, since the correlation process F repeatedly performs simple calculations, it takes a long time. Therefore, if the range to be calculated is shared by a plurality of computers and parallel processing can be performed, the calculation time decreases in inverse proportion to the number of computers.

  The correlation processing F can easily determine the range to be shared for the time parameter τ and the frequency parameter ν, and the data to be distributed only needs to be AD sampling data for two systems, which is suitable for parallel processing. .

  Thus, as a second embodiment according to the present invention, an uplink interference source location apparatus including hardware for processing the correlation processing unit 40 shown in FIG. 1 in parallel with a plurality of computers is proposed.

  FIG. 6 is a block diagram showing the internal configuration of the correlation processing unit 40 to which the present invention is applied. It comprises a digital data distribution unit 401, correlation processing sharing units 1 to M (4021 to 402M), and a correlation processing result synthesis processing unit 403.

FIG. 7 shows a correlation processing flow.

  In step 301, the digital data distribution unit 401 distributes the AD sampling data of the two received signals to the correlation processing shares 1 to M (4021 to 402M). The data to be distributed is the same data for each division. In each assignment, the range for performing the correlation process is clear.

  In step 302, the correlation process is calculated for the range in charge of each of the correlation process shares 1 to M (4021 to 402M). The correlation processing result is delivered to the subsequent correlation processing result synthesis processing unit 403.

  In step 303, the correlation processing result synthesis processing unit 403 collects the correlation processing results from the respective assignments and synthesizes them to create correlation processing results for all ranges.

  In the present embodiment, the algorithm of the emission source position estimation process is the same as that of the first embodiment described above, and thus the description thereof is omitted.

  According to the above configuration, since the processing of the correlation processing unit can be calculated at higher speed, the position of the uplink interference source can be specified in a shorter time.

(Third embodiment)
By the way, in both the devices of the first and second embodiments, radio waves passing through two satellites are received by two receiving antennas, but the installation locations of the two antennas are separated, and the length of the transmission line is reduced. If they cannot be the same, a delay time is generated depending on the length of the transmission line, which becomes an error factor in calculating the arrival time difference. For this reason, the accuracy of the process of estimating the emission source position is reduced.

  Therefore, as a third embodiment according to the present invention, as shown in FIG. 7, a function for calculating a correction value for the arrival time difference is added to the emission source position estimation processing unit 60 shown in FIG.

  As shown in FIG. 8, the entire processing flow is the same as the flow shown in FIG. 2 up to step 13. The two receiving antennas 10 and 11 receive the same downlink via one satellite, and 2 The received signal in the system is simultaneously AD-sampled to obtain digital data, the correlation processing unit 40 performs correlation processing for calculating the arrival time difference and the Doppler frequency difference, and the satellite position calculation processing unit 50 generates radio waves. The position at the measured time of one receiving satellite is calculated.

  In the launch source position estimation process 60, first, in step 141, using the arrival time difference information obtained by the correlation processing unit 40 and the satellite position information at the measurement time obtained by the satellite position calculation processing unit 50, the receiving antenna 10. , 11 to obtain a correction value for the arrival time difference due to the difference in the path length of the transmission lines. Subsequently, in step 142, the arrival time difference obtained by the correlation processing unit 40 is corrected by the correction value of the arrival time difference, and then the emission source position estimation process described in the previous embodiment is performed.

The correction value is obtained by the following process. That is, the position vector of the radio wave emission source X is set as x ^→, and the position vector of the satellite is set as p ^→ . When the position vector of the reception point is q ₁ ^→ and q ₂ ^→ ,

A correction value δ satisfying the above is obtained. ΔT represents the arrival time difference, and c represents the speed of light.

  By correcting the arrival time difference of the satellites using the correction value δ, it is possible to estimate the emission source more accurately. Therefore, according to this embodiment, the arrival time difference correction value can be calculated, and by using this value, the uplink interference source position can be specified more accurately.

  The present invention can be applied in various fields such as the field of radio wave monitoring for the purpose of finding the emission source of interference waves.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a block diagram which shows roughly the structure of the uplink interference source position identification apparatus in connection with the 1st Embodiment of this invention. It is a flowchart which shows the flow of the whole process of the apparatus shown in FIG. It is a flowchart which shows the flow of the correlation process of the apparatus shown in FIG. It is a flowchart which shows the flow of the launch source position estimation process of the apparatus shown in FIG. FIG. 5 is a block diagram showing an internal block configuration of a correlation processing unit shown in FIG. 1 as a second embodiment of the present invention. It is a flowchart which shows the flow of the correlation process of the correlation process part shown in FIG. FIG. 10 is a block diagram schematically showing a configuration in which arrival time difference correction value calculation processing is added to the apparatus shown in FIG. 1 as a third embodiment of the present invention. It is a flowchart which shows the flow of the whole process of the apparatus shown in FIG.

Explanation of symbols

10, 11 ... receiving antenna,
20: Frequency converter,
30 ... AD converter,
40 ... correlation processing unit,
50 ... satellite position calculation processing unit,
60 ... Launch source position estimation processing unit,
70: Display section.

Claims (4)

First and second receive antennas for receiving downlinks via the first and second satellites;
Analog / digital conversion means for simultaneously performing analog / digital conversion on the received signals of the first and second receiving antennas to obtain first and second received data; and
Correlation processing means for performing correlation processing on the first and second received data to calculate a difference in arrival time of a downlink via the first and second satellites, and a Doppler frequency difference ;
Satellite position calculation processing means for calculating the positions of the two satellites receiving the downlink radio waves at the measured time;
The launch that estimates the position of the ground station using the arrival time difference and Doppler shift frequency difference information obtained by the correlation processing means and the satellite position and velocity information at the measurement time obtained by the satellite position calculation processing means. Source position estimation processing means;
Plotting the coordinates of the intersection of the trajectory of the arrival time difference and the trajectory of the Doppler frequency difference from the estimation result of the position of the ground station on a map, and display means for displaying the position estimation result of the radio wave emission source ,
The correlation processing means includes
For each of the arrival time difference and the Doppler frequency difference, calculate a correlation value of a specified sample in a preset calculation range,
Obtaining the arrival time difference and Doppler frequency difference when the calculated correlation value is the maximum value,
The arrival time difference is fixed to a value when the correlation value becomes the maximum value, and the calculation range of the Doppler frequency difference is set based on the value of the Doppler shift frequency difference when the correlation value becomes the maximum value. Recalculate the correlation value narrower than the calculation range
By repeating the above process, the calculation range of the Doppler frequency difference is converged . 2. The uplink interference source position identifying apparatus according to claim 1, wherein the correlation processing unit shares the calculation range with a plurality of computers and performs parallel processing.   2. The uplink interference source position specifying apparatus according to claim 1, wherein the emission source position estimation processing means executes estimation processing after correcting an error in calculating the arrival time difference obtained by the correlation processing means. . A receiving process of receiving downlinks via the first and second satellites by two receiving antennas and simultaneously performing analog-to-digital conversion to obtain first and second received data;
A correlation process for performing a correlation process on the first and second received data to calculate a downlink arrival time difference and a Doppler frequency difference via the first and second satellites ;
A satellite position calculation process for calculating the positions of the two satellites receiving the downlink radio wave at the measured time;
A launch that estimates the position of the ground station using the information on the arrival time difference and Doppler shift frequency difference obtained in the correlation process and the satellite position and velocity information at the measurement time obtained in the satellite position calculation process. Source location estimation process,
Plotting the coordinates of the intersection of the trajectory of the arrival time difference and the trajectory of the Doppler frequency difference from the estimation result of the position of the ground station on a map, and displaying the position estimation result of the radio wave emission source ,
The correlation process is as follows:
For each of the arrival time difference and the Doppler frequency difference, calculate a correlation value of a specified sample in a preset calculation range,
Obtaining the arrival time difference and Doppler frequency difference when the calculated correlation value is the maximum value,
The arrival time difference is fixed to a value when the correlation value becomes the maximum value, and the calculation range of the Doppler frequency difference is set based on the value of the Doppler shift frequency difference when the correlation value becomes the maximum value. Recalculate the correlation value narrower than the calculation range
An uplink interference source position specifying method characterized in that the calculation range of the Doppler frequency difference is converged by repeating the process.

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