83rd Annual

Monday, 10 February 2003
A new data acquisition system for the U.S. Army FM-CW radar: still a great way to see half-meter resolution
Scott A. McLaughlin, DeTect, Inc., Longmont, CO
Poster PDF (1.4 MB)
The U.S. Army has been operating a high-resolution turbulence profiling radar since 1990. The frequency-modulated continuous-wave (FM-CW) radar has been used in various atmospheric research studies, and currently resides at Dugway Proving Ground, Utah. Although the FM-CW has a steerable antenna mount, it is normally operated vertically to profile clear-air turbulence or hydrometeors. Its spatial resolution is selectable depending on the maximum height desired, from 0.5 to 10 meters. The maximum height depends on atmospheric conditions, but is usually set to approximately 4 km for clear-air backscatter measurements, resulting in 1024 4-meter resolution range cells. The temporally averaging interval is also user selectable and is usually set to 3-5 seconds.

Recently the data acquisition system was completely refurbished allowing the use of modern PC architecture, data acquisition boards, and communications. The previous data system was comprised of a HP-1000 real-time computer, a 9-track tape system, several large external 20 MB disk drives, a custom built timing board, an Analogic 16-bit analog-to-digital converter (ADC), an Analogic parallel-processing array processor, and code written in FORTRAN and assembly language. The new data system utilizes an industrial PC, a commercially available graphical programming language, and one internal 16-bit ADC.

In this paper the new data system will be described and new data presented. The FM-CW radar is quite sensitive and due to its high spatial and temporal resolution allows researchers to identify and measure thin turbulence layers, hydrometeor backscatter, the melting layer, and point targets such as insects and birds. With the new data system, the FM-CW should have many years of use with both the U.S. Army and other researchers in the atmospheric community.

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