ARC-X250P – X-band Polarimetric Doppler Weather Radar

The ARC X250P radar is designed for high quality data acquisition and analysis in both research and operational settings. ARC utilizes the NCAR-developed TITAN/CIDD radar product generation and display software, which has been refined through decades of research and operational use around the planet, for both standard and polarimetric radar products. The ARC X250P has been implemented for studying wind shear around airports and Quantitative Precipitation Estimation (QPE). It is an ideal operational system for local monitoring of weather impacts on aviation and severe and hazardous weather in real-time. Research regarding advanced detection of wind shear events and water resource management have been conducted with the ARC X250P.

The X250P radar utilizes an Antenna Mounted Receiver to increase the system sensitivity and to eliminate the requirement for a dual rotary joint. Using this design, data are passed to the product generator computer via a gigabit ethernet slip ring. Built-in calibration equipment can be programmed to calibrate the entire radar’s front end with the ultra-low phase noise signal generator. The electronically configurable waveguide network permits automatic polarity mode switching. Critical elements in the antenna head are housed in a climate controlled enclosure.

Antenna / Pedestal Specifications

  • Dish Diameter: 2.44 meters (Beamwidth: 0.95 degrees)
  • Polarization:
    • Simultaneous Horizontal and Vertical, Horizontal, Vertical
  • Long-life, powerful, brushless AC servo motors
  • Maintenance free,sealed, low backlash gearboxes
  • Fabricated using COTS products to ensure parts support into the future
  • Azimuth range 360 degrees
  • Elevation Range -5 to 95 degrees
  • Pointing accuracy .05 degrees
  • Velocity accuracy .05 degrees/ second
  • Scan types:
    • Surveillance (360 degrees) with elevation step
    • PPI sector scan with elevation step
    • RHI scan with azimuth step
    • Raster scan around the sun
    • Sun tracking
Transmitter Specifications

  • Magnetron transmitter
  • Peak Power: 250 kW
  • Frequency: 9.3 – 9.5 GHz
  • PRF: 160 to 3.0 kHz
Polarimetric Radar Variables

  • Z (Equivalent radar reflectivity factor, dBZ)
  • V (Doppler radial velocity, m/s)
  •  W (Velocity spectrum width, m/s)
  • P (Power received, dBm)
  • Zdr (Differential reflectivity)
  • Phi-dp (Differential phase)
  • Kdp (Specific differential phase)
  • Rho-hv (Co-polar correlation)
  • NCP/SQI (Normalized Coherent Power/Signal Quality Index)
  • Zcoh (Coherent equivalent radar reflectivity factor, dBZ)
  • Phase (Differential and Absolute phase)