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A government agency that conducts test associated with the effects of weaponry on human hearing contacted SDS to update their existing data acquisition platform. Previously digital storage scopes were used to perform this task. The scopes lacked some of the necessary features needed for this type of testing, and were not very flexible in the manner which they could display and save the data. The system needs to measure the time pressure history of the soundwaves emitted from weapons at various locations nearby.
The desired data acquisition system had the following requirements:
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PC based - Battery powered operation -
including printer Portable with ruggedized shipping case Able to withstand large vibrations 40 KHz analog bandwidth per channel 1 MHz aggregate sample rate Anti-aliasing filters to ensure spectral
integrity Ability to display in time and frequency
domain very large data setsOne of the primary requirements of the system was that it could take the abuse associated with testing at various military locations. The PC had to be able to withstand the harsh field conditions that it would encounter regularly. A FieldWorks 7000 series ruggedized PC was chosen. FieldWorks PCs meet the tough military standards for shock and vibration (Mil Stds 810C 516.2 & 514.2). The 7000 series also features 3 ISA & 3 PCI expansion slots so additional hardware could be installed in the future if necessary.
The IOtech WaveBook/512 was chosen for the data acquisition system. It is a compact (8.4" x 11" x 1.375") data acquisition unit that connects to a PCs parallel port and can be run with the DBK30A rechargable battery of about the same size. The WaveBook/512 has 8 differential inputs (expandable to 72), a 1MHz sample rate, and the optional WBK 12 programmable anti-aliasing filter card installs in side the unit so it does not take up any additional space.The WaveBook/512 includes WaveView software that allows the user to easily configure the data acquisition unit and save or display the data. The WaveView software can also save data directly in DaDisp format, which is the analysis package used for this system.
The DaDisp software package was chosen for the data analysis package. DaDisp is an interactive data analysis and display package. It is especially good at analyzing and displaying large data sets (several hundred thousand points). DaDisp operations can be automated by use of the Signal Processing Language (SPL) that is part of the package. SDS wrote custom SPL routines that automated the task of reading the data files, performing FFTs and displaying the data in time and frequency format, so the user simply selected the desired data file and all the analysis and display was done automatically.
A HP-340 color portable printer is powered by a rechargeable battery pack, allowing color printouts in the field as the data is being collected.
A ruggedized carrying case with custom fitted compartments for the WaveBook, FieldWorks PC, printer and additional storage completes the system and allows for easy setup/takedown and transport.