JP4746436B2 - Radar apparatus and signal processing method thereof - Google Patents

Description

  The present invention relates to a radar apparatus used in a Doppler weather radar that captures dynamic conditions of rain and clouds, for example, and a signal processing method thereof.

In general, in Doppler radar, the speed calculation accuracy deteriorates for a target having a large variation in speed distribution. This tendency is particularly significant in radar devices that observe natural phenomena, such as weather radar. In order to cope with this, it is effective to average the variation by increasing the number of observation data, that is, the number of pulse hits.
Toshiba Review, Volume 55, Issue 5, May 1, 2000, “Doppler Weather Radar”, p. 28-30

  However, in existing radar devices, there are limits to increasing the pulse repetition frequency (PRF) of the radar pulse and increasing the number of pulse hits at the expense of azimuth resolution. In addition, in the conventional Doppler radar signal processing method, data between different scans cannot be handled at a time to calculate the Doppler velocity. When the target observed by the radar is a weather echo, it is necessary to handle a lot of data at one time and calculate the speed because the variation is large. When only the data of the same scan (data of continuous pulse hits) can be handled, the number of pulse hits obtained from the relationship of the azimuth resolution is inevitably determined, and a lot of data cannot be used to suppress the variation.

  The present invention has been made paying attention to the above circumstances, and its object is to provide a radar apparatus capable of calculating the speed of an observation target with high accuracy even when there is a large variation in the speed distribution of the observation target, and its signal processing method Is to provide.

In order to achieve the above object, a radar apparatus according to the present invention includes a transmission / reception unit that repeatedly transmits a radar pulse toward a target and receives a radar echo while scanning a radar coverage, and a received signal of the radar echo for each scan. A means for extracting pulse hit data in the same azimuth area, and setting one of a plurality of scans as a reference scan, and averaging the phase difference between the pulse hits between the reference scan and each scan . Means for calculating one average value, first correction means for correcting the phase of the pulse hit of each scan to a phase corresponding to the reference scan based on the first average value, and adjacent in the plurality of scans means for calculating a second mean value by averaging the phase difference between the pulses hit fit, on the basis of the second average value, corrected by the first correcting means A second correction means for correcting the pulse hits the phase of each scan phase continuous pulse hits the reference scan, the target based on the data of the pulse hits the corrected plurality of scanning by said second correcting means And a means for calculating the Doppler speed.

The signal processing method according to the present invention, in the signal processing method for use in the radar system for scanning a radar cover area while receiving the repeating radar echoes transmitted radar pulses toward the target, receiving the radar return for each of the scan Extracting pulse hit data in the same azimuth region from the signal, and setting one of a plurality of scans as a reference scan, and a first phase difference between the pulse hits between the reference scan and each scan . A step of calculating an average value, a first correction step of correcting a phase of a pulse hit of each scan to a phase corresponding to the reference scan based on the first average value, and an adjacent in the plurality of scans Calculating a second average value of a phase difference between pulse hits; and, based on the second average value, the first correction value. A second step of correcting the phase of the Tsu pulse hits each scan corrected by up phase continuous pulse hits the reference scan, a plurality of scan pulses hit data corrected by said second correction step which is a shall which have a calculating a Doppler velocity of the target based on.

The radar device and its signal processing method with the above configuration can handle pulse hits from multiple scans that are different from each other as phased data , and handle the data between multiple scans at one time to calculate the Doppler velocity. Will be able to.

  Therefore, according to the present invention, it is possible to provide a radar apparatus and its signal processing method capable of calculating the speed of the observation target with high accuracy even when the variation in the speed distribution of the observation target is large.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of the configuration of a radar apparatus according to the present invention. A digital value of an intermediate frequency signal of a specified modulation method is created by a modulation unit 12 in accordance with control from a signal processing apparatus 11, and D / Analogized by the A converter 13. The created intermediate frequency signal is up-converted by the transmission / reception device 14, power amplified, supplied to the antenna device 15, and sent to the space.

  The transmission wave of the frequency f0 transmitted from the antenna device 15 returns upon hitting a target (raindrops, etc.), but is accompanied by a Doppler frequency due to the movement of the target. The reception signal (frequency f0 + fd) received by the antenna device 15 is amplified and down-converted by the transmission / reception device 14 and converted into a digital value by the A / D conversion unit 16 and subjected to quadrature detection. The quadrature-detected signal is demodulated by the demodulator 17 using a plurality of modulation schemes, sent to the signal processing device 11, and subjected to calculation processing such as intensity, speed, and speed width. However, in the present invention, the D / A conversion unit 13 and the A / D conversion unit 16 are not indispensable devices, and other devices can have the same function. The operation of the above configuration will be described below.

  The features of the present invention are summarized in the signal processing device 11. FIG. 2 is a flowchart showing the Doppler velocity calculation processing procedure and its contents in the signal processing device 11. FIG. 3 is a schematic diagram showing a phase correction of data received between different scans. In the present invention, as shown in FIG. 3, phase correction is performed using data of a plurality of scans in the same region, and the Doppler velocity is calculated.

First, in step S2a, a phase difference is obtained for each pulse hit from the data (IQ data) of each scan to the reference scan (first scan). As shown in FIG. 3, for example, the phase difference between corresponding ones such as P1 and P6 and P1 and P11 is obtained. It is desirable that the pulse hits for obtaining the phase difference are closer to each other. Next, in step S2b, the average of the obtained phase differences is taken, and the phase difference θn (first average value) for each scan is calculated. In FIG. 3, the average phase difference between the first and second scans is θ1, and the average phase difference between the first and third scans is θ2. In step S2c, the average θn of each phase difference is used to correct the phase of each scan data to match the reference scan.
(Each phase of P6 to P10) −θ1
(Each phase of P11 to P15) −θ2
Further, in step S2d, a phase difference between adjacent hits is obtained, and an average θave is calculated. In step S2e, the phase of each hit is corrected by the following equation using the calculated θave (second average value) .
(Phase after correction of each of P6 to P10) + θave × ( 5 × 1 ) ( number of hits of each scan × number of scans from the reference scan )
(Phase after correction of each of P11 to P15) + θave × ( 5 × 2 ) ( number of hits of each scan × number of scans from the reference scan )
In this way, pulse hits can be handled as continuous data from the first scan to the third scan. In step S2f, the Doppler velocity is calculated using the data of each pulse hit corrected in this way.

  As described above, according to the present invention, the Doppler velocity can be calculated using more pulse hit data by using data of a plurality of scans in the same region. By doing so, even when the variation in the velocity distribution of the observation target is large, the Doppler velocity of the observation target can be calculated with high accuracy using a lot of data.

  The present invention is not limited to the above embodiment. For example, in FIG. 1, the functions of the D / A conversion unit 13 and the A / D conversion unit 16 can be combined with other functional blocks. In addition, the present invention is not limited to the weather radar but can be applied to other Doppler radars. The reference scan is not limited to the first scan, and other scans such as the second scan and the third scan may be used as reference values. The number of scans used for the calculation is not limited to three scans, and can be applied to a larger number of scans. Furthermore, the present invention can be applied not only to a plurality of scan data in a single radar apparatus, but also to a so-called radar system in which a plurality of radar apparatuses having different PRFs in the same region are combined.

  Further, as an application example of the present invention, it can be applied to terrain echo removal (MTI: Moving Target Indicator) processing. By using the present invention, a large amount of data can be handled, and terrain echoes can be efficiently removed.

  In short, 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. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

The block diagram which shows the function structure of one Embodiment of the radar apparatus concerning this invention. The flowchart which shows the signal processing procedure of the radar apparatus of FIG. The schematic diagram which shows a mode that the data received between different scans are phase-corrected.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Signal processing part, 12 ... Modulation part, 13 ... D / A conversion part, 14 ... Transmission / reception part, 15 ... Antenna, 16 ... A / D conversion part, 17 ... Demodulation part

Claims (2)

A transmitter / receiver that repeatedly transmits radar pulses toward the target and receives radar echoes while scanning the radar coverage;
Means for extracting pulse hit data in the same azimuth region from the radar echo received signal for each scan ;
Means for calculating a first average value by averaging one of a plurality of scans as a reference scan and averaging a phase difference between pulse hits between the reference scan and each scan ;
First correcting means for correcting the phase of the pulse hit of each scan to a phase corresponding to the reference scan based on the first average value ;
Means for averaging the phase difference between adjacent pulse hits in the plurality of scans to calculate a second average value;
Second correction means for correcting the phase of the pulse hit of each scan corrected by the first correction means to a phase continuous with the pulse hit of the reference scan based on the second average value ;
A radar apparatus comprising: means for calculating a Doppler velocity of the target based on pulse hit data of a plurality of scans corrected by the second correction means . In a signal processing method used in a radar apparatus that scans a radar coverage area while repeatedly transmitting radar pulses to a target and receiving radar echoes,
Extracting pulse hit data in the same azimuth region from the received signal of the radar echo for each scan ;
Setting one of a plurality of scans as a reference scan, and calculating a first average value of phase differences between pulse hits between the reference scan and each scan ;
A first correction step of correcting the phase of the pulse hit of each scan to a phase corresponding to the reference scan based on the first average value ;
Calculating a second average value of phase differences between adjacent pulse hits in the plurality of scans;
A second correction step of correcting the phase of the pulse hit of each scan corrected in the first correction step based on the second average value to a phase continuous with the pulse hit of the reference scan;
Signal processing method comprising Rukoto that having a calculating a Doppler velocity of the target based on the data of the pulse hits plurality of scan corrected by the second correcting step.

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