Doppler Velocity Measurement of Portable X-Band Weather Radar Equipped with Magnetron Transmitter and IF Digital Receiver

Masayuki K. YAMAMOTO  Tomoaki MEGA  Nobuyuki IKENO  Toyoshi SHIMOMAI  Hiroyuki HASHIGUCHI  Mamoru YAMAMOTO  Masahisa NAKAZATO  Takuya TAJIRI  Takashi ICHIYAMA  

IEICE TRANSACTIONS on Communications   Vol.E94-B   No.6   pp.1716-1724
Publication Date: 2011/06/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E94.B.1716
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Sensing
weather radar,  Doppler radar,  magnetron,  IF digital receiver,  Micro Rain Radar,  

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This study demonstrates the ability of a portable X-band Doppler weather radar (XDR) to measure Doppler velocity (Vd). Existing portable X-band weather radars are housed in a container and hence have to be carried by a truck. Therefore they have limitations in their installation places. For installations at small areas where the existing X-band weather radars cannot be installed (e.g., rooftop area of small building), XDR is designed to be carried by a cart. Components of the outdoor unit (a parabolic antenna with a diameter of 1.2 m, magnetron transmitter, and radio frequency (RF) and intermediate frequency (IF) analog components) are housed in a compact body with a weight less than 300 kg. The radar operation, IF digital processing, and data storage are carried out by a desktop computer having a commercial IF digital receiver. In order to attain the required portability and reduced purchase and running costs, XDR uses a magnetron transmitter. Because XDR is the first that utilizes an IF digital receiver for the signal processing specific to magnetron transmitters (i.e., the phase correction of received signals due to the randomness of the transmitted pulse phase), Vd measured by XDR (hereafter VdXDR) was assessed. Using the dataset collected from 25 to 26 October 2009 at the Shigaraki MU Observatory (3451'N, 13606'E), the equivalent radar reflectivity factor (Ze) and VdXDR were assessed using Ze and Vd measured by a Micro Rain Radar and a L-band Doppler radar named LQ-7. The results using correlation coefficients and regression lines demonstrate that XDR measured Ze and Vd accurately. The results also show that IF digital receivers are useful for providing magnetron weather radars with the function of Vd measurement, and further suggest that a combination of IF digital receiver and magnetron transmitter contributes to future development of Doppler weather radars, because high cost performance is strongly required for a precipitation monitoring radar network.