AppendixB CommonQuestions
SCXI-1190/1191/1192User Manual B-2 ni.com
Whati s VSWR, and howdoes itaffect my system?
VSWR stands for VoltageStanding Wave Ratio; it is am easure of the
reflectionon a transmission line. The percentage of a signal reflected back
tothe source is equal to (VSWR-1)/(VSWR+1). This means that a VSWR
of1 is opt imum, with no reflected signal. On higher powerap plications, a
largeVSWR can damage th e output stage of the source. High VSWR also
means that a large percentage of the power from the source cannot be
deliveredtotheload.
Whati s isolation, and whyi s it important?
Isolation is a measure of the amount of crosstalk between channels in a
bank. Forexample, if a 1 Vp-p signal is isolated by 40 dB to another
channel,then 10 mVp-p will be seen on the adjacent channel (in addition
to the signal already on the channel). Higher channel-to-channel isolation
resultsi n lowercrosstalk.