Effective Signal Conditioning
Signal Conditioning for Strain Gauges, Load Cells, RTDs, and other Resistive Sensors
Bellevue, WA, March 9, 2006 -- Microstar Laboratories, Inc., maker of Data Acquisition Processor (DAP) boards, today announced the newest two members of a new family of signal-conditioning expansion boards that make it easy to implement signal conditioning in data acquisition systems. The new boards, MSXB 066 and MSXB 067, provide analog signal conditioning for strain gauges, load cells, RTDs, and other resistive sensors. They provide a flexible interface for quarter-bridge, half-bridge, and full-bridge sensors, with voltage excitation, gain, simultaneous sampling, and voltage sense feedback. MSXB 067 includes anti-alias filters. On each board, eight 8-wire connectors, one for each sensor, support a wide variety of connections with two to six wires per sensor. Users supply bridge completion resistors, and place them on small daughterboards.
For applications with unwanted frequencies above Nyquist, 8 fourth-order lowpass filters on MSXB 067 – one for each channel – eliminate alias errors. Customers can choose from cutoff frequencies of 100Hz, 250Hz, 500Hz, 1kHz, 2.5kHz, 5kHz, 10kHz, 25kHz, and 50kHz.
Customers also can choose from two gain ranges. MSXB 066-01 and MSXB 067-01 have gains of 20, 40, 100, 200, 500, and 1000 – for strain gauges and load cells. MSXB 066-02 and MSXB 067-02 have gains of 1, 2, 5, 10, 25, and 50 – for RTDs.
Bridge-completion resistors and anti-alias filters on quick-swap daughterboards allow for easy configuration of a variety of applications. On MSXB 067, different daughterboards have different cutoff frequencies.
Multichannel spectral analysis and other applications that acquire data from several channels simultaneously need products like MSXB 066 and MSXB 067. Any application that requires accurate interchannel phase measurements – any application that computes transfer functions, for example – needs signal-conditioning expansion boards like these. These products eliminate the phase error that sequential sampling introduces.
Sampling any signal introduces alias errors when the input contains energy at frequencies above half the sampling rate: the Nyquist frequency. Only analog filters can remove these frequencies. The MSXB 067 board includes a fourth-order lowpass filter on each channel to ensure that sampled data contains no alias errors.
The MSXB 066 and MSXB 067 boards slot into a backplane in a standard industrial enclosure like other products that conform to the channel architecture that Microstar Laboratories uses: signal connectors on 3U (100mm high) Eurocard B (220mm deep) boards – Eurocards – that often pre-process a signal. The new MSXB 066 and MSXB 067 boards each have eight differential input channels and 16 differential outputs on a backplane connector: eight for signals and eight to sense the excitation voltage. Conditioned signals pass through the backplane and an interface board and cable to a DAP board in a PC.
Range of Filter Responses
DAPL, the onboard real-time operating system that controls every DAP board (and that the user controls through PC software like DAPstudio or LabVIEW from the PC), includes over a hundred data-acquisition specific commands – among them several built-in filtering commands. Applying these onboard digital filters to the output data from MSXB 067 boards produces a wide range of filter responses, including very sharp lowpass filters.
Conclusion and Next Step
MSXB 066 and MSXB 067 boards are available now. With eight differential channels each, and up to 15 boards allowed to connect to a single DAP board in a PC for a total of 120 channels of resistive sensor input, MSXB 066 and MSXB 067 provide effective signal conditioning at a low cost per channel. Contact Microstar Laboratories for more information.
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Microstar Laboratories, Inc., maker of Data Acquisition Processor (DAP) boards, today announced the newest two members of a new family of signal-conditioning expansion boards for its DAP boards. The new expansion boards, model numbers MSXB 066 and MSXB 067, provide analog signal conditioning for strain gauges, load cells, RTDs, and other resistive sensors. They provide a flexible interface for quarter-bridge, half-bridge, and full-bridge sensors, with two to six wires for each sensor, with or without voltage sense feedback. For applications with unwanted frequencies above Nyquist, fourth-order lowpass filters on MSXB 067 daughterboards eliminate alias errors from the simultaneous samples on all channels. Systems using these boards can scale up for applications with hundreds of resistive sensor inputs at a low cost per channel. The boards are available now. Contact Microstar Laboratories for more information.
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The MSXB 067 provides analog signal conditioning for strain gauges, load cells, RTDs, and other resistive sensors with fourth-order lowpass filters on the additional daughterboards, installed in the center, to eliminate alias errors.
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