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INSU/Météo VHF Radar locations

The INSU/Météo ST (called Stratosphere-Troposphere radar) wind profiler radars are semi-mobile clear air Doppler radars which are generally situated at these locations :

Map © 1986 Michelin (click on the image to obtain a full scale GIF image of 440 kb)

==========================================================================
Location (freq.)   Geographic Coordinates                   Date		
==========================================================================
CLERMONT-FERRAND - latitude  :  45 45 52 N =  45.764   Dec. 1990-Dec. 1995
  (45 MHz)       - longitude :   3  6 45 E =   3.112
                 - altitude  :                   394 m
CLERMONT-FERRAND - latitude  :  45 43 00 N =  45.717   Oct. 1998 - present 
  (45 MHz)       - longitude :   3  5 30 E =   3.085
                 - altitude  :                   660 m
--------------------------------------------------------------------------
TOULOUSE         - latitude  :  43 34    N =  43.566   Feb. 1991 - present
  (45 MHz)       - longitude :   1 22    E =   1.366
                 - altitude  :                   158 m
--------------------------------------------------------------------------
TOULON           - latitude  :  43  7    N =  43.116   From 1985 
  (45 MHz)       - longitude :   5 55    E =   5.919   Feb. 1993 - present
--------------------------------------------------------------------------
LANNEMEZAN       - latitude  :  43  7 59 N =  43.133   Oct. 1990-Dec. 1990
  (45 MHz)       - longitude :   0 22  1 E =   0.367   Feb. 1993 - present
                 - altitude  :                   600 m
--------------------------------------------------------------------------
SAINT-MICHEL     - latitude  :  43 56 46 N =  43.946   Feb. 1993 - present
L'OBSERVATOIRE   - longitude :   5 42 45 E =   5.713
  (72.5 MHz)
--------------------------------------------------------------------------
SAINT-SANTIN     - latitude  :  44 39    N =  44.650   Feb. 1988 - present
   (961 MHz)     - longitude :   2 12    E =   2.200
==========================================================================

45 MHz INSU/Météo VHF Radar Specifications

Transmitter:
------------
Frequency ........................... 45.0 MHz
Pulse Peak Power .................... 4.5 kW
Pulse Repetition Frequency .......... 6.4 kHz
Pulse Length ........................ 2.5,  15  or  25 (coded pulse) 10-6 s
Height Resolution ................... 375, 2250 or 375 (coded pulse) m
Duty Cycle .......................... 1.6,  9.6 or  16 (coded pulse) %

Receiver:
---------
Linearity ........................... 112 dB
Bandwidth ........................... 2 MHz

Antenna:
--------
Single Element ...................... Co-Co (Coaxial-Colinear) line 
Number of Elements .................. 16 lines of 26 elements
Beamwidth ........................... 5.6 degrees
Gain ................................ 30 dB
Effective Area ...................... 3500 m2
Steerability ........................ vertical, 15 degrees North, 15 degrees East,
                                      15 degrees South and 15 degrees West 
Polarisation ........................ linear
Power Aperature Product ............. 2.52 x 106 Wm2

(click on the image to obtain a full scale JPEG image of 110 kb)

The antenna field of the 45 MHz INSU/Météo VHF Radar near CLERMONT-FERRAND is made of 2 perpendicular sets of 60 m Co-Co (Coaxial-Colinear) lines feeded without or with fixed delay, enabling the radar beam to be successively pointed vertically, and at 15 degrees off the vertical in the North, East, South and West directions, depending of a control sequence :

(click on the image to obtain a full scale JPEG image of 130 kb)


SIGNAL PROCESSING CHARACTERISTICS:
----------------------------------
Wind Measurement Technics ........... Doppler Beam Swinging Mode 
Number of Radial Gates .............. 1 to 48  (computer setting)
Practical Measurement Range ......... 1.9 to 7-8 km (1.9 to 12-15 km for the coded mode)
Number of Points for FFT ............ 256
Number of Coherent Integrations ..... 128    256     512     1024     2048
Maximum Radial Velocity (m.s-1 ) .... 83.2   41.6    20.8     10.4      5.2
Radial Velocity Resolution (m.s-1 ) . 0.65   0.33    0.16     0.08     0.04
Maximum Horiz. Velocity (m.s-1 ) .... 320.   160.     79.      39.      20.
Acquisition Duration (s) ........... 5.2   10.2    20.5     41.0     81.9
  (for 1 incoherent integration)
Time Resolution (1 Windprofile) .... 1 to 3 min

(click on the image to obtain a full scale JPEG image of 140 kb)

In Clermont-Ferrand and Toulouse, a RASS (Radio-Acoustic Souding System) is coupled to the wind profiler radar. A step-frequency modulated sound wave, generated by a coninuous acoustic source and propagating upward in the troposphere, is tracked by a Doppler radar (VHF profiler in our case). In Clermont-Ferrand, a frequency shift of the received signal brings the speed of this sound wave (around 300 m/s) within the radial velocity range (see the above Table) of the measurements made by the Doppler radar. The acoustic temperature, whose value lies between that of the real temperature and that of the virtual temperature, is deduced from the value of the measured speed of this sound wave.


Clermont-Ferrand RASS CHARACTERISTICS:
--------------------------------------
Acoustic Transmitter:
---------------------
Frequency ........................... modulated by DDS aroud 100 Hz
                                      (Direct Digital Synthesis)
Modulation .......................... linear or random by steps 
Power ............................... 100 W (electric), 10 W (acoustic)
Pulse Repetition Frequency .......... 0,05-0,2 Hz

Antenna:
--------
Type ................................ woofer-speaker and acoustic horn
Beamwidth ........................... around 50 degrees
Geometric Area ...................... 2.2 m2


Voldorad (Volcanic Doppler radar) UHF Radar Specifications

A UHF radar is fonctionnally identical to a VHF radar, except that the electromagnetic wavelength is smaller (0,24 m instead of 6,66 m). Its vertical range is smaller, but its antenna is much smaller for the same beamwidth.
Transmitter:
------------
Frequency ........................... 1,238 GHz
Pulse Peak Power .................... 1 kW
Pulse Repetition Frequency .......... 10 kHz
Pulse Length ........................ 0,75 or 1 10-6 s
Height Resolution ................... 112  or 150 m

Receiver:
---------
Linearity ........................... 100, 110 ou 120 dB
Bandwidth ........................... 1 or 2 MHz

Antenna:
--------
Single Element ...................... Yagi (24 éléments) antenna 
Number of Elements .................. 4 
Beamwidth ........................... 9 degrees
Gain ................................ 24 dB
Steerability ........................ azimuth and elevation orientable 

SIGNAL PROCESSING CHARACTERISTICS:
----------------------------------
Wind Measurement Technics ........... Doppler 
Number of Radial Gates .............. 1 to 40
Corresponding Measurement Range ..... 0.3 to 6   km
Practical Measurement Range ......... 0.3 to 1.5 km
Number of Points for FFT ............ 64
Number of Coherent Integrations ..... 10   to 100
Maximum Radial Velocity (m.s-1 ) ...... 60.5 to 6  
Radial Velocity Resolution (m.s-1 ) ... 1.87 to 0.19


Specifications of the Sodar next to the 45 MHz INSU/Météo VHF Radar in Clermont-Ferrand

A Sodar is fonctionnally identical to a VHF radar, except that it emits acoustic soundwaves with a loud-speaker which also serves as microphone during the reception of the return sound signals.
Transmitter:
------------
Frequency ........................... 2,0 kHz
Pulse Peak Power .................... 150 W (electric)
Pulse Repetition Frequency .......... 0.25 Hz
Pulse Length ........................ 100 ms
Height Resolution ................... 17 m

Receiver:
---------
Linearity ........................... 82 dB
Bandwidth ........................... 100 Hz

Antenna:
--------
Single Element ...................... parabola (1.5 m diameter) 
Beamwidth ........................... 9.5 degrees
Gain ................................ 23 dB
Steerability ........................ vertical, 30 degrees North and 30 degrees East 

SIGNAL PROCESSING CHARACTERISTICS:
----------------------------------
Wind Measurement Technics ........... Doppler Beam Swinging Mode 
Number of Radial Gates .............. 35
Practical Measurement Range ......... 50 to 600 m
Number of Points for FFT ............ 64
Maximum Radial Velocity (m.s-1 ) ...... 27.2
Radial Velocity Resolution (m.s-1 ) ... 0.65
Time Resolution (1 Windprofile) ..... 4 s


Y.Pointin@opgc.univ-bpclermont.fr
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