Ka-band Doppler Polarimetric Radar (MRIAN-Ka-1.0)

Meteorological radar placed in a car trailer

The radar (produced in cooperation with METEK, Germany) is designed for unattended long-term operation to provide real-time permanent measurements of vertical profiles of cloud reflectivity, mean velocity, velocity variance, and velocity spectrum. A possibility of raw data saving is also introduced. A permanent calibration system is included in the radar. The radar contains a server to provide remote control and data receiving. The server provides the possibility for a number of clients to get simultaneously real time radar data in a convenient form. A remote control of the radar operation is also made possible. Any network supporting the TCP/IP protocol, including the Internet, can be used to provide the above services.

The Radar Features

  • Real-time measurements, imaging, and storing of reflectivity profiles, velocity profiles, velocity variance, linear depolarization ratio (LDR), and Doppler spectrum,
  • Raw data storing,
  • High spatial and time resolution,
  • Unattended long-term operation,
  • Permanent calibration system,
  • Network capabilities allowing for remote radar control and data receiving

The radar characteristics

The radar is intended for real time measurements, imaging, and storing of

  • reflectivity profile,
  • linear depolarization ratio (LDR) profile,
  • velocity profile,
  • velocity variance, and
  • Doppler spectrum.

These quantities are accessible in real time in various graphical and map forms on computer displays of local and remote users. The complete raw data, which are digitized signals from the I and Q receiver channels, collected simultaneously from all heights can also be stored for a following analysis.

The radar measurements are performed with the following characteristics:

Minimum Height 200 m
Measuring Range 15 km
Range Resolution 15, 30, 45 and 60 m/sec
Doppler Velocity Resolution 0.05 m/sec
Maximal Unambiguous Velocity +/-15 m/sec
Number of Gates (max) 500
FFT Length 128, 256 and 512
Minimum Dwell Time 0.1 sec
Antenna Beam Width 0.6° x 0.6°
Sensitivity at 5 km (with the integration time of 0.1 sec) -45 dBz

The described radar operates in pulsed mode and utilizes a coherent-on-receiver technique for Doppler measurements. The main technical parameters of the radar are as following:

Frequency 36.5+/-0.5 GHz
Peak Power (max) 30 kW
Tube Type magnetron
Pulse Width 100-400 ns
Pulse Repetition Frequency 2.5, 5, and 7.5 kHz
Minimum Detectable Signal -104 dBm
Polarization Decoupling -40dB
Sampling Rate 50 MHz
Sampling Resolution 14 bit
Type of Bus for the Signal Processing Board PCI
Operation System of the Host Computer Linux or MS Windows
Network Protocol TCP/IP
Antenna Diameter 1 m
Sidelobe Level -20dB
Power Supply 230V+/-10% AC
Watt consumption 1.3 kW
Weight 140 kg

The radar has a built-in permanent calibration system. The radar calibration is based on independent measurements of the transmitter and receiver parameters. For these purposes, the transmitter output power and receiver sensitivity are continuously measured.

A possibility of the measurements of the linear depolarization ratio (LDR) and the intensity and the Doppler spectrum of both co- and cross-polarized components of backscattered signals is introduced in the radar. The cross-polarization isolation is better than 40 dB.

The radar has network capabilities to allow for remote radar control and data receiving through any network supporting the TCP/IP protocol, including the Internet. In order to provide the network services, a special radar server is developed and introduced. The server is working on the radar host computer under control of the Linux operating system. There is also a software package of Windows programs for obtaining and visualising radar data via the Internet. Remote control and diagnostics of the radar operation from any network computer is made possible as well.

Example of configuration of the radar user display.Real time profiles of reflectivity, velocity, and Doppler spectrum are shown.

An example of configuration of the Image control page on the user display is shown in the figure above. The page includes a control panel and a data image panel. The control panel allows controlling radar operation in real time. On the data image panel, there are intensity, velocity, and spectrum windows. Each of these windows is divided into two subwindows. The upper part reflects the height-time map of intensity and velocity in the case of intensity and velocity windows, respectively. The lower part of these windows shows instant oscilloscope plots of the incoming data. The instant oscilloscope plots can display either the horizontal or the vertical cut of the upper maps. For example, such cut may show the intensity versus time at some selected height (horizontal plot), or the intensity versus height (vertical plot). The upper plot of the spectrum window is the dynamical spectrum, where vertical axis corresponds to time and horizontal one is the Doppler frequency (or corresponding velocity). The lower plot is an instant spectrum.