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Chapter 7 Tutorial
System Cabling and Connections
Shielding Techniques
Shielding against noise must address both capacitive (electrical) and
inductive (magnetic) coupling. The addition of a grounded shield around
the conductor is highly effective against capacitive coupling. In switching
networks, this shielding often takes the form of coaxial cables and
connectors. For frequencies above 100 MHz, double-shielded coaxial
cable is recommended to maximize shielding effectiveness.
Reducing loop area is the most effective method to shield against
magnetic coupling. Below a few hundred kilohertz, twisted pairs may be
used against magnetic coupling. Use shielded twisted pair for immunity
from magnetic and capacitive pickup. For maximum protection below 1
MHz, make sure that the shield
is not one
of the signal conductors.
Separation of High-Level and Low-Level Signals
Signals whose levels exceed a 20-to-1 ratio should be physically
separated as much as possible. The entire signal path should be
examined including cabling and adjacent connections. All unused lines
should be grounded (or tied to LO) and placed between sensitive signal
paths. When making your wiring connections to the screw terminals on
the module, be sure to wire
like
functions on adjacent channels.
Recommended Low-Frequency Cable:
Shielded twisted pair
Recommended High-Frequency Cable
:
Double-shielded coaxial cable
LO
HI
LO
HI
Twisted Pair Shield
Center Conductor
Shield Foil
Shield Braid PVC Jacket
34970A Refresh UG.book Page 260 Wednesday, February 17, 2010 12:34 PM
Summary of Contents for 34970A
Page 16: ...16 34970A Refresh UG book Page 16 Wednesday February 17 2010 12 34 PM ...
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Page 21: ...1 1 Quick Start 34970A Refresh UG book Page 21 Wednesday February 17 2010 12 34 PM ...
Page 39: ...2 2 Front Panel Overview 34970A Refresh UG book Page 39 Wednesday February 17 2010 12 34 PM ...
Page 59: ...3 3 System Overview 34970A Refresh UG book Page 59 Wednesday February 17 2010 12 34 PM ...
Page 87: ...4 4 Features and Functions 34970A Refresh UG book Page 87 Wednesday February 17 2010 12 34 PM ...
Page 217: ...5 5 Error Messages 34970A Refresh UG book Page 217 Wednesday February 17 2010 12 34 PM ...
Page 241: ...6 6 Application Programs 34970A Refresh UG book Page 241 Wednesday February 17 2010 12 34 PM ...
Page 254: ...254 34970A Refresh UG book Page 254 Wednesday February 17 2010 12 34 PM ...
Page 255: ...7 7 Tutorial 34970A Refresh UG book Page 255 Wednesday February 17 2010 12 34 PM ...
Page 324: ...324 34970A Refresh UG book Page 324 Wednesday February 17 2010 12 34 PM ...