Among the four elements, air is by far the least understood. A major concern for sailing
and trade in the old days ( trade winds ), the study of wind fell into neglect when steam power appeared.Nuclear power plant and industrial site monitoring, airport safety requirements and
intensive agriculture have created an urgent need for the study of air masses . Totally accurate and reliable instrumentation was needed which could operate continuously in
order to assess statistical and climatological models and which could also be used in real time.After years of intensive research in cooperation with various governments and military agencies in both Europe and in the U.S. , REMTECH is especially proud of its third generation DOPPLER SODAR.
Universally acknowledged, it is the most versatile system for measuring wind, wind turbulence and the temperature structure in the planetary boundary layer. It is what the scientific community has been waiting for.
The REMTECH DOPPLER SODAR processes the echo of an acoustic pulse which is directed into the atmosphere. The frequency shift of the echo varies according to the wind speed (this is the DOPPLER effect ) while the echo intensity varies according to thermal turbulence and structure. Each REMTECH DOPPLER SODAR uses a single, multicellular antenna whose beam is steered electronically. The basic antenna is composed of 52 elements, is only 40 cm x 40 cm x 15 cm in size, and weighs, with its electronics and computer, less than 20 kg, which makes it the first portable Sodar in the world. Despite its size, however, it is capable of measuring up to 600 m and beyond. By using more powerful acoustic emitters, larger dimensions and lower acoustic frequencies, we are able to reach altitudes of up to 5,000 meters.
A Fast Fourier Transform application has been chosen by REMTECH to process the received signal. The system's hardware is simply comprised of a personal computer, a transceiver board and power amplifiers, all of which is mounted in an electronics case.
The REMTECH DOPPLER SODAR is presently the only Sodar which outputs real-time data of guaranteed precision without any human intervention. This is made possible primarily by a pulse-coding technique and a fixed echo detection subroutine.
In order to respond to the various requests of our clients, REMTECH has developed a whole family of DOPPLER SODARS. It ranges from the portable PA0 model, which weighs around 20 kg, to tropospheric profilers such as the PA5, whose antenna measures 1.8 m x 1.8 m and whose range reaches as high as 5,000 meters. Numerous other options are available, such as software for climatological and rnicrometeorological applications.
Due to the software-oriented policy REMTECH has adopted which has allowed the systems' hardware to be reduced to a minimum, it is possible to monitor the Sodar via a simple modem link.
The applications for the REMTECH DOPPLER SODAR are numerous. Some examples include
- environmental impact studies
- elevated stable layer characterization
- prediction of the consequences of nuclear accidents or toxic chemical spills
- consideration of wind fields in studies of the trajectory of flying objects
- quantifying the effects of atmospheric turbulence on the propagation of light and radio waves
- airport measurement of windshear and radio wake turbulence created by large airplanes
- wind energy siting
- etc...
