Installation Guide
AD1200 Reference
Wiring Guidelines.
_________________
The AD1200 system is designed to accurately measure low
voltage signals thus noisy input signals will tend to render the
advanced design features useless. In particular, the performance
of the Programmable Gain Amplifier feature, available on the
boards, can be greatly effected by noise if signals are incorrectly
connected. It is imperative that good wiring practice be used to
obtain optimum results from the AD1200 card.
Twisted Pair Cables.
__________________
Twisted pair cables may reduce the noise on Differential
Inputs noticeably. The high and low inputs of each channel
are twisted together so that any noise identical effects each
of these inputs. Since the converter measures the
DIFFERENCE between these two inputs the noise, being
identical is subtracted out. This is called Common Mode
Noise Rejection and it also greatly reduces the effects of
ground potential differences in taking signals from various
parts in a system.
Obviously this scheme does not work and should not
be attempted on Single Ended Inputs.
The output from the D to A converters, DAC0 out
with DAC0 ground and DAC1 out with DAC1 ground, can
similarly benefit from twisted pair cables.
Shielded Cables.
_______________
All leads, Single Ended Analogue input, Differential
Analogue Input, Analogue output, Digital input and Digital
output, should be shielded. This is the guard shield.
Each differential input twisted pair should be separately
shielded with the shield tied to analogue ground, AGND,
only at the SOURCE end of the connection, and that the
shield be continuous, ie through screw terminal boards,
panels, connectors etc.
The shield of each signal, or pair of differential signals,
should also be insulated from each other since each is
carrying its own current!
Chapter 2
Page 49
Содержание AD-593
Страница 1: ...2 1 EDITION Feb 1995 d a 1200 Series...