Lexington, MA--Oxford Instruments is using a PCI-based digital signal processor board in Synergy, a non-imaging diagnostic system used to study how nerve cells receive and transmit information. The PCI/C44S DSP board enables Blue Wave Systems (Leicestershire, England) to create an open, modular system that accommodates tests of varying complexity.
"The PCI board offers sufficient performance to enable real-time processing of incoming test signals," says Dr. Martin Nichols, principal engineer on the Synergy project, "and thereby provides clinicians with a much more effective diagnostic tool than previously available."
In designing Synergy, the company concluded that a system based on PC technology would be user-friendly and easily accommodate add-on features such as multimedia and networking. Oxford Instruments also wanted to allow for future I/O expansion and the option to extend the number of processors from one to a maximum of four.
Blue Wave Systems' PCI/C44S board meets these requirements. "It allows one to four DSPs, dependent upon the instrument's configuration, and offers flexibility, matching of processing performance to different product configurations, and off-the-shelf availability," says Nichols.
In use, the Synergy system applies an electrical stimulus to the patient's skin and measures the electrical response of the muscles. These patient analog signals are digitized in the headbox, a specialized digital-to-analog converter and amplifier unit, at sample rates up to 200 KHz. The signals are then transferred to the PCI/C44S DSP board, which analyzes the data and passes the results to the PC for real-time display and archiving.
says Nichols. "In achieving this, it becomes much easier to relate what's happening physically to the patient, to what's happening on the screen."
Blue Wave Systems created a workable interface and replaced a standard I/O which would not connect with the DSPLINK2 connector, a 32-bit interface that provides expansion capabilities to a range of peripheral modules. The DSPLINK2 connector was replaced with two connectors--one provides the DSPLINK2 functionality, the other provides access to COM ports, controls and gathers data from the daughterboard.
The PCI/C44S takes advantage of Texas Instrument's floating-point TMS320C4x parallel DSP chip for fast parallel DSP processing and real-time embedded applications. It can be populated with up to four 50- or 60-MHz TMS320C44 processors, and provides a PCI interface and shared memory accessible by the host PC.
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