JP3552206B2 - Doppler radar equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a Doppler radar device that contributes to weather disaster prevention.
[0002]
[Prior art]
As is well known, for example, in a Doppler radar device that contributes to weather disaster prevention such as downburst / microburst detection at an airport and cell tracking in lightning prediction, a staggered trigger system is employed. In this method, several types of the pulse repetition period are generated by increasing and shortening by a fixed time, and these periods are switched and used in a predetermined order for each pulse repetition.
[0003]
According to such a stagger trigger method, by calculating speed data in a plurality of staggers for each sector, it is possible to perform speed turnaround correction by a combination of adjacent sectors having different pulse repetition frequencies (hereinafter, referred to as PRF). However, since the weather echo has a spread in the velocity region and the calculated speed of each sector varies, there is a problem in that if the speed aliasing correction is performed between adjacent sectors, the possibility of a correction error increases. is there.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional Doppler radar system based on the staggered trigger method, especially in the case of weather, the speed range of the weather echo is wide, so that the calculation speed for each sector varies, and the comparison between adjacent sectors is performed. When the speed aliasing correction is performed in this manner, there is a problem that an error in the correction is likely to occur.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problem and to provide a Doppler radar device capable of performing favorable velocity return correction even when a velocity region to be observed has a wide area.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a Doppler radar device which calculates velocity data in a plurality of staggers for each sector, and performs velocity aliasing correction by a combination of adjacent sectors having different pulse repetition frequencies. When there is a spread, the range in which the average change of the target echo is considered to be small is defined as the unit area, and the speed aliasing correction is performed based on the average speed of multiple sectors and multiple ranges within this range. And
[0007]
Specifically, a first step of calculating the speed in units of a prescribed range for each sector, and a second step of calculating an average speed for each transmission repetition pulse in a range of (m sectors) × (n range) located around the target selection. Two steps, a third step of calculating a velocity reference V0 after the return correction based on the average velocity for each transmission repetition pulse calculated in the second step, and a velocity candidate Vi after the return correction by the target sector and the adjacent sector. A fourth step of calculating (1 ≦ i ≦ k) and a fifth step of setting a speed candidate Vi in which a speed difference between the speed candidate value Vi and the speed reference value V0 is within the reference value as a speed after loopback correction. It is characterized by having.
[0008]
According to the above processing procedure, even when the variation is large in the sector unit and the frequency of occurrence of the speed return correction error increases, the speed reference value after the return correction is calculated in units of plural sectors × multiple ranges. Since the correction is performed so as not to largely deviate from the value, the frequency of the speed aliasing correction error decreases.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 shows a configuration of a Doppler radar apparatus according to the present invention, in which an intermediate frequency signal having a frequency fi generated by a COHO oscillator 11 and a local oscillation signal having a frequency fLo generated by a local oscillator 12 are mixed by a mixer 13. Then, a transmission signal of the frequency f0 is generated and sent to the transmitter 14. The transmission signal input to the transmitter 14 is power-amplified by the power amplifier 141 and then sent to a klystron or magnetron modulator 142 where it is pulsed based on a repetitive transmission pulse from the high voltage modulation circuit 143.
[0011]
Here, in the high-voltage modulation circuit 143, a staggered trigger method is adopted, and for example, two staggered PRFs of 720 Hz and 900 Hz are used. The transmission pulse signal generated by the transmitter 13 in this way is supplied to the antenna device 16 via the circulator 15 and sent out to space.
[0012]
The transmission wave of the frequency f0 transmitted from the antenna device 16 returns upon hitting a target (raindrops or the like), but is accompanied by the Doppler frequency fd due to the movement of the target.
[0013]
The received signal (frequency fr = f0 + fd) received by the antenna device 16 is amplified by the high-frequency amplifier 17 via the circulator 15, mixed with the local oscillation signal by the mixer 18, and converted into an intermediate frequency (frequency fi + fd). After being amplified by the intermediate frequency amplifier 19, the signals are mixed by the phase detectors 22 and 21 with the intermediate frequency signals (fi) having a phase difference of 90 ° by the mixers 20 and 21 so that the signals are subjected to quadrature detection. The signal is sent to the signal processing device 23. The signal processing device 25 performs a rainfall conversion process by obtaining a Doppler speed in sector units during reception.
[0014]
In the above configuration, the processing content of the signal processing device 23 which is a feature of the present invention will be described.
[0015]
As described above, since the weather echo has a spread in the speed domain, the calculated speed for each sector varies, so if speed loopback correction is performed only from comparison of adjacent sectors, a correction error may occur. Get higher. Therefore, in the present embodiment, in the signal processing device 23, a range in which the average speed change of the weather echo is considered to be small is defined as a unit area, and the speed is determined based on the average speed of a plurality of sectors and a plurality of ranges within the range. By performing the aliasing correction, the speed aliasing error is reduced.
[0016]
FIG. 2 shows the procedure of the speed return correction in this case, and will be described with reference to FIG.
[0017]
(1) First, a Doppler velocity is calculated for each sector in a specified range unit (S1).
(2) As shown in FIG. 3, an average speed is calculated for each PRF in a range of (m sectors) × (n range) located around the target selection (S2).
(3) Next, a speed reference V0 after aliasing correction is calculated based on the average speed for each PRF calculated in (2) (S3).
(4) A speed candidate Vi (1 ≦ i ≦ k) after aliasing correction is calculated by the target sector and the adjacent sector (S4).
(5) A candidate Vi in which the speed difference between Vi and V0 is within the reference value is set as the speed after loopback correction (S5).
[0018]
Here, in (4), a plurality of speed candidates Viy after aliasing correction are calculated, but the number of candidates depends on the stagger ratio. For example, when the PRF is two staggers of 720 Hz and 900 Hz, the stagger ratio is 4: 5, so that there are five candidates at 720 Hz and four candidates at 900 Hz. These speed candidates exist from the first candidate to the k-th candidate in descending order of possibility from the difference in speed calculated for each PRF. The candidate selected in (5) means the most likely candidate among the candidates in which the speed difference between Vi and V0 is within the reference value.
[0019]
As a result of the above processing, even when the variation is large in the sector unit and the frequency of occurrence of the speed return correction error increases, the speed reference value after the return correction is calculated in units of plural sectors × multiple ranges, and from this value. Since the correction is performed so as not to be largely deviated, the frequency of the speed aliasing correction error decreases.
[0020]
Therefore, the Doppler radar device having the above-described configuration can perform favorable velocity aliasing correction even when the velocity range of the observation target is wide.
[0021]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a Doppler radar device that can perform favorable velocity aliasing correction even when the velocity range of the observation target is wide.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a Doppler radar device according to an embodiment of the present invention.
FIG. 2 is an exemplary flowchart illustrating the aliasing correction procedure of the embodiment.
FIG. 3 is a diagram showing a range of (m sectors) × (n range) located around a target selection when an average speed is calculated for each PRF in the loopback correction of the embodiment.
[Explanation of symbols]
11 COHO oscillator 12 Local oscillator 13 Mixer 14 Transmitter 141 Power amplifier 142 Modulator 143 High voltage modulation circuit 15 Circulator 16 Antenna device 17 High frequency amplifier 18 Mixer 19 Intermediate frequency amplifier 20 ... Mixer 21 ... Mixer 22 ... Phase detector 23 ... Signal processing device

Claims (2)

In a Doppler radar device which calculates speed data in a plurality of staggers for each sector and performs speed return correction by a combination of adjacent sectors having different pulse repetition frequencies,
When the target echo has a spread in the velocity region, the area where the average change in the average velocity of the target echo is considered to be small is defined as the unit area, and the speed is looped back based on the average velocity of multiple sectors and multiple ranges within this range A Doppler radar device that performs correction. In a Doppler radar device which calculates speed data in a plurality of staggers for each sector and performs speed return correction by a combination of adjacent sectors having different pulse repetition frequencies,
A first step of calculating a speed in a specified range unit for each sector;
A second step of calculating an average speed for each transmission repetition pulse in a range of (m sectors) × (n range) located around the target selection;
A third step of calculating a velocity reference V0 after aliasing correction based on the average velocity for each transmission repetition pulse calculated in the second step;
A fourth step of calculating a velocity candidate Vi (1 ≦ i ≦ k) after aliasing correction by the target sector and the adjacent sector;
A Doppler radar apparatus, comprising: setting a speed candidate Vi in which a speed difference between the speed candidate value Vi and the speed reference value V0 is within the reference value as a speed after loopback correction.

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