Overview

The SCS-812 amplifier/filter module provides eight 8-pole low-pass filters that can be individually configured for a cutoff-frequency from 0.5Hz to 100kHz(elliptic mode) and 0.5Hz to 50kHz(linear phase mode). Each of the SCS-812's eight channels features an instrumentation amplifier with software-selectable gains of 1 to 1000 in 1-2-5 steps.

The output of the gain stage is followed by separate low-pass filter stages. One-pole filters reduce clock feed through. Each channel's -3 dB corner frequency is independently software controlled, selectable from any of eight internal or four external sources.

Automatic offset compensation nulls errors due to drift and aging.

A proprietary DC transformer circuit provides true differential outputs, with very low 10 ohm impedance. This circuit guarantees that common-mode noise will not effect the signal at the receiving end. This circuit also allows for use of single ended inputs on the A/D converter, effectively doubling the number of A/D channels without sacrificing common-mode rejection. Outputs are scaled to provide ±10V. Each channel output is available as a differential signal on the output connector and can be wired to the data acquisition receiver as either a single-ended or differential input.

The SCS-800/801 system provides a variety of methods for bringing outputs to the data acquisition host:

• All output signals can be wired in parallel to the host for simultaneous sampling.
• All output signals can be time-multiplexed onto one set of analog output lines via the SCS-812's front-panel output connector.
• All output signals can be time-multiplexed with all other module outputs via the SCS-800 back plane to one connector on the SCS-804 System Controller Module. This method provides channel multiplexing, or channel and module multiplexing.

The connection methods are independent. Some modules may be multiplexed onto the back plane, and others multiplexed out their own front panel, while other modules can have all channels as independent outputs.