Appendix D. Wiring And Noise Reduction Methods; Separating Digital And Analog Scp Signals - HP E1419A User Manual

Wiring and Noise Reduction Methods

Separating Digital and Analog SCP Signals

Appendix D
Signals with very fast rise time can cause interference with nearby signal
paths. This is called cross-talk. Digital signals present this fast rise-time
situation. Digital I/O signal lines that are very close to analog input signal
lines can inject noise into them.
To minimize cross-talk you can maximize the distance between analog input
and digital I/O signal lines. Figure D-1 shows that by installing analog input
SCPs in positions 0 through 3, and analog output and digital I/O SCPs in
positions 4 through 7, you can keep these types of signals separated by the
width of the HP E1419 module. The signals are further isolated because
they remain separated on the connector module as well. Note that in Figure
D-1 , even though only 7 of the eight SCP positions are filled, the SCPs
present are not installed contiguously, but are arranged to provide this
digital/analog separation.
If you have to mix analog input and digital I/O SCPs on the same side, the
following suggestions will help provide quieter analog measurements.
•
Use analog input SCPs that provide filtering on the mixed side.
•
Route only high level analog signals to the mixed side.
Figure D-1 Separating Analog and Digital Siganls
Wiring and Noise Reduction Methods 375
Appendix D