National Instruments 1192 User Manual
Page 43
Appendix B
Common Questions
SCXI-1190/1191/1192 User Manual
B-2
ni.com
What is VSWR, and how does it affect my system?
VSWR stands for Voltage Standing Wave Ratio; it is a measure of the
reflection on a transmission line. The percentage of a signal reflected back
to the source is equal to (VSWR-1)/(VSWR+1). This means that a VSWR
of 1 is optimum, with no reflected signal. On higher power applications, a
large VSWR can damage the output stage of the source. High VSWR also
means that a large percentage of the power from the source cannot be
delivered to the load.
What is isolation, and why is it important?
is a measure of the amount of crosstalk between channels in a
bank. For example, 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
results in lower crosstalk.