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1、P12.163 Solid-state weather radar which reached the practical use stage Masakazu Wada (1) and Hiroshi Ueda (2) (1) Defense 32 sec 200W or more (horizontal polarization) 200W or more (vertical polarization) Receiver dynamic range95 dB or more Radome diameter4.5 m or less Antenna diameter2.2 m or less
2、 Antenna gain41 dB or more Beam width1.2 deg or less Range resolution150 m or less Elimination of ground clutterCoherent MTI system Received signal power (Ph, Pv) (dB) Doppler velocity V (m/s) Spectrum width W (m/s) Differential phase DP (deg) Correlation coefficient ( HV)Peak powerOutput dataB. Fre
3、quency separation of short and long pulses The pulse compression is performed by giving linear FM modulation to the long transmitting pulse of 32s in this weather radar to achieve the range resolution of 150 m. As radars cannot transmit while receiving, the observation in a short range is not possib
4、le while transmitting long pulses. To solve this problem and to enable full coverage from short range to long range, the observation by short pulse for short range observation is also performed. Figure 4 shows the time sequence of transmitting pulse. According to this system, the reflection wave of
5、long pulse from precipitation area which is outside the observation range is also received at the same time and the reflection waves of short and long pulses are mixed in the radar of its own station. To avoid this problem, the frequencies of short and long pulses are detuned in this radar as shown
6、in Figure 5. Transmission of long pulseReceiving of long pulseTransmission of short pulse Receiving of short pulsef1f2f1f2Figure 4. Transmission and receiving schedule of solid-state radar Figure 5. Separation of frequencies of long and short pulses Figure 6 shows the calculation result of received
7、level when the frequencies of transmitting and receiving waves of long and short pulses are detuned (when the frequencies are separated). For example, if the frequencies of transmitting and receiving waves are detuned by 2.5 MHz, the received level is reduced by 35 dB for short pulse and the receive
8、d level is reduced by 50 dB for long pulse. Transmitting/Receiving frequency difference and received level-70-60-50-40-30-20-1000.01.02.03.04.05.0Detuned frequency (MHz)BLong pulseShort pulseFigure 6. Suppression of received level by frequency detuning Figure 7 shows the relationship between the int
9、ensity of the mutually interfered secondary echo and the intensity of the primary echo. If the frequency is not detuned, it is observed that the received power is reduced approximately by 15 dB when the secondary echo of long pulse interfered in the short pulse area. The received power is reduced by
10、 approximately 35 dB when the short pulse interfered in the long pulse area. As the received level is further reduced by 50 dB for long pulse and by 35 dB for short pulse when the long and short pulses are detuned by 2.5 MHz, the precipitation intensity of the secondary echo is reduced to 0.01 mm/h
11、which is a negligible level. Figure 7. Effect of interference suppression IV. OBSERVATION DATA A X-band MP Radar of Kinki area network(MLIT) As shown in Figure 8, Ministry of Land, Infrastructure, Transport and Tourism has installed 4 units of X-band MP radars in Kinki Area. The one installed in Jyu
12、busan is a solid- state radar while the other three are Klystron radars. Figure 8. X-band MP radar of Kinki area network (MLIT） B Observation examples by X-band MP Radar Figure 9 shows the result of two observation examples by these 4 radars. As shown in Figure 9, the results of radar observation ar
13、e very similar and no conspicuous difference is found among the radars. Rokko(Klystron) Tanokuchi(Klystron) -80-60-40-20020406080-80-60-40-20020406080kmkmRokko(2010/07/07 15:00)mm/h1234567891020304050100Inf-80-60-40-20020406080-80-60-40-20020406080kmkmTanokuchi(2010/07/07 15:00)mm/h12345678910203040
14、50100InfKatsuragi(Klystron) Jyuubusan(Solid-state) -80-60-40-20020406080-80-60-40-20020406080kmkmKatsuragi(2010/07/07 15:00)mm/h1234567891020304050100Inf-80-60-40-20020406080-80-60-40-20020406080kmkmJuubusan(2010/07/07 15:00)mm/h1234567891020304050100Inf(a) 2010/07/07 15:00 Rokko(Klystron) Tanokuchi
15、(Klystron) -80-60-40-20020406080-80-60-40-20020406080kmkmRokko(2010/07/13 06:56)mm/h1234567891020304050100Inf-80-60-40-20020406080-80-60-40-20020406080kmkmTanokuchi(2010/07/13 06:56)mm/h1234567891020304050100InfKatsuragi(Klystron) Jyuubusan(Solid-state) -80-60-40-20020406080-80-60-40-20020406080kmkm
16、Katsuragi(2010/07/13 06:56)mm/h1234567891020304050100Inf-80-60-40-20020406080-80-60-40-20020406080kmkmJuubusan(2010/07/13 06:56)mm/h1234567891020304050100Inf(b) 2010/07/13 06:56 Figure 9. Radar echo observed by the solid MP radar and Klystron MP radars C Comparison of observation data among the radars. Figure 10 shows the scatter diagram of precipitation intensity observed by each radar and T
