8-6 Time and Distance Information Time Domain, Option 2
8-18 PN: 10580-00289 Rev. K Vector Network Analyzer MG
Figure 8-14. Distance Info Window
Note
As you can see in Figure 8-14, the user has entered a Dstop value of 35 m,
whereas the calculated maximum usable range (Distance max) is 12.6 m for a
reflection measurement and is 25.2 m for a transmission measurement. As the
user, you need to make some adjustments either to the frequency range or to the
number of data points in order to increase Dmax to 35 m. Suggestion 1 (of the
Distance Info) tells you that you need to reduce your frequency span to 7.199 GHz
(14.399 GHz for transmission). You can do that by changing just the stop
frequency, or you can change both the start and stop frequencies such that the
difference between them equals the calculated Max Span. By making that
adjustment, you can achieve a Dmax of 35 m. What you give up is distance
resolution. In the example in Figure 8-14, the resolution will degrade to 17.5 mm.
To avoid changing the frequency span (and thereby degrading the resolution), you
can increase the number of points (at the expense of slower sweep speed). In the
example in Figure 8-14, however, even if you increase the number of points to the
maximum allowable number of 4001 (for reflection), you can achieve only a Dmax
of 25.2 m. For a transmission measurement, 2779 points will let you achieve 35 m.
In this case, you should either use a transmission measurement or adjust the
frequency span to meet your goal.
The Time Info window does not contain any cable or waveguide information
because those parameters affect only the distance setup. Also, in the Time Info
window, the two columns for round trip and one way are identical because the time
domain has no round trip compensation.
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