Data Acquisition (DAQ) and Control from Microstar Laboratories

Effective Signal Conditioning

Differential Instrumentation Amplifiers with Filtering and Simultaneous Sampling

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Bellevue, WA, June 23, 2005 -- Microstar Laboratories, Inc., maker of Data Acquisition Processor (DAP) boards, today announced signal-conditioning expansion boards for its DAP boards. These new expansion boards make it easy to implement signal conditioning in data acquisition systems. They can eliminate alias frequencies from acquired data and they can scale up for applications with hundreds of simultaneously sampled inputs at a very low cost per channel. The first two of a family of signal-conditioning expansion boards, part numbers MSXB 064 and MSXB 065, provide differential instrumentation amplifiers with optional sample-and-hold circuits and jumper-selectable gains of 1, 5, and 25. The MSXB 065 also includes fourth-order anti-alias filters. Future signal-conditioning expansion boards also will come in pairs: with and without built-in analog filters.

Spectral Analysis

Multichannel spectral analysis and other applications that acquire data from several channels simultaneously need products like the MSXB 064 and MSXB 065. 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.

Alias Errors

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 065 board includes a fourth-order lowpass filter on each channel to ensure that sampled data contains no alias errors.

Channel Architecture

The MSXB 064 and MSXB 065 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 064 and MSXB 065 boards each have eight differential input channels and eight differential outputs on a backplane connector. Conditioned signals pass through the backplane and an interface board and cable to a DAP board in a PC.

Different Daughterboards

On the MSXB 065, circuits on a daughterboard implement eight four-pole lowpass filters one for each channel before passing signals on to the simultaneous sampling circuits. Different daughterboards have different cutoff frequencies. Customers can choose from cutoff frequencies of 100Hz, 250Hz, 500Hz, 1kHz, 2.5kHz, 5kHz, 10kHz, 25kHz, and 50kHz.

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 065 boards produces a wide range of filter responses, including very sharp lowpass filters.

Conclusion and Next Step

MSXB 064 and MSXB 065 boards provide the signal conditioning that many applications need. Each has eight differential channels and conforms to the Microstar Laboratories Channel Architecture that allows up to 30 of these boards to connect to a single DAP board in a PC, for a total of 240 differential channels. MSXB 064 and MSXB 065 boards provide effective signal conditioning at a remarkably low cost per channel. Contact Microstar Laboratories for more information.

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Editorial Overview:

Microstar Laboratories, Inc., maker of Data Acquisition Processor (DAP) boards, today announced new signal-conditioning expansion boards for its DAP boards. Each expansion board, model numbers MSXB 064 and MSXB 065, includes eight differential amplifiers instrumentation amplifiers with user-selectable sample-and-hold circuits for each channel and jumper-selectable gains of 1, 5, and 25. Any application that requires accurate interchannel phase measurements any application that computes transfer functions, for example needs signal-conditioning expansion boards like these. For applications with unwanted frequencies above Nyquist, fourth-order lowpass filters on optional daughterboards eliminate alias errors. Systems using these boards can scale up for applications with hundreds of simultaneously sampled inputs at a very low cost per channel. Contact Microstar Laboratories for more information.

Note to the Editor:

Microstar Laboratories uses this text to go with the available image:

The MSXB 065 provides analog signal conditioning for voltage signals with fourth-order lowpass filters on the additional daughterboards, installed on the left, to eliminate alias errors.

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