Technic Defination

 

 

 

 

 

 

X-Band：

Low-altitude wind shear, microburst and other medium and small-scale hazardous weather events around the airport are the major threats to the safety of aircrafts during takeoff and landing. Once formed, these events develop very fast, but the echoes are relatively weak. Prompt detection, real-time monitor and accurate forecast of this type of weather event require radar to have good ground clutter reduction capability and very high system sensitivity.

Selecting X-band  —— Stronger backscatter power can be obtained from the meteorological target:

The diameters of the particles that reflect in the atmosphere are far shorter than the working wavelength of the radar and the effective reflection area is inversely proportional to  of the wavelength used. For a given antenna beam width, the effective reception area of the antenna is proportional to  of the wavelength. Although the intensity of reflection for objects on the ground and the noise coefficient of the receiver will become slightly worse as the frequency increases, they will not change much in the wavelength range of 3~10 cm. Therefore, the ratio of useful meteorological signal power and noise power is inversely proportional to.

Selecting X-band  —— The required system sensitivity and relatively high signal-to-noise ratio can be reached and performance equivalent to C-band and S-band can be obtained with smaller equipments:

It can guarantee effective detection of medium and small-scale weather events such as low altitude wind shear and microburst.

Selecting X-band  —— Narrower beam width can be obtained with the same antenna aperture plane:

The main lobe width of ADWR-X weather radar is 0.55°, so space filtering is well performed on the noises from objects on the ground, providing the real guarantee for detecting low altitude wind shear and microburst. In addition, it relatively reduced the infrastructure engineering volume for building a radar station, which helps users to cut down investments.

Selecting X-band —— Also avoid the mutual interference with the widely used S-band and C-band radars and other equipments.

 

Adjustable pulse width and PRF combination well resolved the conflict between distance-measurement ambiguity and velocity-measurement ambiguity normally existing for X-band:

Generally speaking, selecting X-band reduces unambiguous velocity measurement range and makes the velocity-measurement ambiguity problem more prominent. Therefore, we formulated a set of scanning strategies for low level observation. Taking advantage of the continuity of meteorological targets, in other words, the characters of body targets, we use the combination of different radar PRFs and the combination of the intensity mode and the velocity mode to expand the range of distance measurement and velocity measurement. These strategies well resolved the conflict between distance-measurement ambiguity and velocity-measurement ambiguity.

Reasonably selecting and allocating technical requirements for each subsystem of the radar and adopting the“penetration compensation” technology at the same time effectively reduced the degeneration on the way to the effective distance of the radar:

In signal processing, according to the rule of electromagnetic wave degeneration by different weather targets, compensation correction is performed on the intensity of the echoes that have penetrated the cloud and rain areas to improve the accuracy of intensity measurement.

 

Antenna subsystem with high performance —- High gain, Narrow beam, Low sidelobe level

The angular resolution of this radar is no greater than 0.55°and the position accuracy is no greater than 0.1°. More significantly, the gain is as high as 50 dB, 24 dB higher than any other domestic X-band weather radar (round-trip). Therefore, theoretically its system detection capacity is 24 dB higher than other radars of the same band. Conventionally, it is believed that X-band weather radars are easily affected by the precipitations on the way and the degeneration is severe. The application limitation caused by this problem hasbeen well compensated by antenna gain. Its strong detection capacity benefits from the high performance antenna subsystem. It provided important technical support to the functions of airport terminal weather radar.

 

The antenna servo control system enables both online control by the“signal processing / control terminal”and offline self-controlled movement, facilitating maintenance and checkup. In order to ensure the safe operation of the antenna, multiple limits and as many as 26 monitoring sites were set up to monitor the operation of antenna servo subsystem. In structural design, the single units of the reflection surface can be randomly exchanged without affecting the performance of the antenna.

 

 

	High stability transmitter  î

 

 

Solid state amplifier and klystron were selected to form the high power RF power amplification chain of the full-coherent transmitter.   Klystron——It works stably and reliably, with compact and simple structure and long lifetime.   Scanning-back charging circuit——It provides modulating pulse with stable amplitude，ensuring the stability of the transmitter.   Real-time monitoring and checkup——Real-time monitoring and checkup are performed on as many as 8 working modes and 14 failure monitoring sites. Once any failure or abnormal condition is detected, the transmitter initiates self-protection immediately through the hardware, ensuring the safe operation and convenient maintenance of equipments.

The transmitter of ADWR-X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Performance specification of similar products abroad

		ADWR-X	TDWR	WSR-88D
Band		X	C	S
Pulse power	kW	75	250	750
Pulse width	μs	0.83，3.4	1.1	15.7，4.71
PRF	Hz	420~2500	1060~2000	318~1304
Antenna		Paraboloid reflector
Feeding		Central feeding
Polarization		Horizontal polarization
Diameter	m	4.5	7.62	8.5
Beam width	º	0.55	0.55	0.99
Gain	dB	≥50	≥50	≥45
First sidelobe level	dB	≤-29	≤-27	≤-27
Positioning accuracy	º	0.1	0.05	0.2
Repetition accuracy	º	0.1	0.024	0.1
Radome	m	7.2	11	12
Receiver		Linear Digital Intermediate Frequency	Linear	Linear/ Logarithm
Dynamic range	dB	LIN 90	STC 26 AGC 42 LIN 61	LIN+AGC=93 LOG 94
Noise coefficient	dB	≤4	2.3	4.3
Intensity processing precision	dB	≤1	≤1  Linear average	≤1  Statistical average
Velocity processing		PPP/FFT	PPP	PPP / FFT
Ground clutter filter	dB	47	55	50
Producer		Beijing Shoulder Electronic	Raytheon(U.S.A)	Lockheed · Martin(U.S.A)