Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/12/1998
Publication Date: N/A
Technical Abstract: The TACQ computer program, a program for Time domain reflectometry (TDR) data ACQuisition, allows control of multiplexed systems supporting up to 256 TDR probes. The program is DOS-based in order to ease creation of low-power, embedded computer systems; and, to avoid resource conflicts and timing difficulties inherent to Windows-based operating systems. It runs on IBM PC/XT or AT compatible computing platforms with 640 kbytes of RAM and 1 Mbyte of expanded memory, and with Hercules, ATT, EGA, or VGA graphics. Embedded computer systems based on the PC-104 specification have been implemented using TACQ. The program controls multiplexers from both Campbell Scientific, Inc. and Dynamax, Inc. The user has complete control over multiplexer address assignments, interconnection of multiplexers, and probe locations on each multiplexer; including individual settings for probe length, window width, averaging, distance to each probe, gain, and kind of data acquired (wave form, travel time, apparent permittivity, wate content, BEC, or a combination of these). Interfaces to TDR instruments including Tektronix 1502 (modified), 1502B, and 1502C cable testers are implemented through an RS-232 port. System power control is implemented through the computer's own power management capabilities, and through direct control of power to the TDR instrument and video subsystem where applicable, thus allowing creation of very low-power systems. Wave form interpretation methods are user-controlled, and include various methods from the literature or methods available only in TACQ.