Engineering Design NIDisk Guide de l'utilisateur télécharger pdf (Page 31)

NIDisk User Guide

Minimum sample rate 100 Hz

Maximum sample rate 500 kHz

Programmable gain 1, 2, 5, 10, 20, 50, 100

Impedance 100 G-ohm in parallel with 100 pF

Noise (re max signal level) n/s

THD n/s

Output characteristics

Maximum channels 2

Minimum sample rate 100 Hz

Maximum sample rate 500 kHz

Impedance < 0.1 ohm

Noise (re max signal level) n/s

THD n/s

Input/output characteristics

No. sample rates > 1000

Maximum signal level ± 10 Volts

Maximum signal length Limited by physical disk size

Digitizing resolution 12-bit = 72 dB

Converter type Linear

Anti-alias filter Not included

Triggering Software / external TTL

Trigger latency < 1 microsec

Synchronization TTL

Synchronization accuracy < 1 microsec [w/ special I/O panel]

n/a = not applicable, n/s = not specified

Bandwidth Limitations of PCI-6251

This section discusses the acquisition bandwidth (BW) of the PCI-6251 and the conditions

under which that BW can be extended in practice. The NI-specified BW of the 6251 is 1.25

MHz single channel and 1.0 MHz multi-channel.

Acquisition Settling Time

The acquisition BW of a digitizing board is limited by the settling time of its input amplifier,

which is the time required for the amplifier to register the voltage change between successive

input samples to a certain accuracy. Because there is only one input amplifier, successive

samples may come from a single channel or consecutive channels in multi-channel mode. If

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Engineering Design NIDisk Guide de l'utilisateur Page 31