Each of six analog input channels contains a lowpass image filter and a delta-sigma A/D converter that provides digital antialias filtering. A linear-phase digital antialiasing filter rejects out-of-band signals, and a lowpass analog filter reject those interference signals that fall within the harmonic images of the digital filter. Input response can be selected as DC coupled for response down to DC, or as AC-coupled for maximum dynamic range.
An internal sample-rate generator is adjustable over a 2:1 frequency range, and is divided down within the local controller to provide individual channel sample rates from 2KSPS to 200KSPS. Conversion data from all active channels is transferred to the PCI bus through a 256K-sample data buffer that is supported by two DMA channels. Multiple channels can be synchronized to perform sampling in “lockstep”, either by a software command, or by external hardware sync and clock input signals.
