![Rohde & Schwarz FSH13 Скачать руководство пользователя страница 233](http://html.mh-extra.com/html/rohde-and-schwarz/fsh13/fsh13_operating-manual_1477832233.webp)
R&S FSH
Distance-to-Fault Mode (R&S FSH-K41)
Performing Cable and Antenna Measurements
Operating Manual 1173.6275.12 - 30
218
7.1.4 Selecting the Measurement Format
You can select several measurement formats for each measurement. The
measurement format selects the way the results are displayed.
● Magnitude (dB Mag)
This is the default format. It shows the magnitude of the results in dB.
● VSWR
The VSWR shows the standing wave ratio in a cartesian diagram. The VSWR is
the ratio of the maximum voltage and the minimum voltage that occur in an
electrical transmission line. The VSWR format is available for DTF and reflection
measurements.
● Reflection Coeffcient
Shows the reflection coefficient of the DUT.
The reflection coefficient is the ratio of the amplitude of a reflected wave and that
of the incidental wave that occur in an electrical transmission line.
● Cable Loss
The cable loss measurement is a
reflection measurement on an
open cable. It evaluates the
amount of energy that a signal
loses while traveling through a
cable. .The amount of lost energy
depends on the frequency and the
length of the cable
The R&S FSH shows the result
(graphically) over the specified
frequency range (span) in dB.
The numerical result is the average cable loss over the specified span. The image
above shows a typical cable loss result, with a steadily declining loss over the
selected frequency range and several maximums and minimums.
By default, the R&S FSH evaluates the cable loss over its entire frequency range
(full span of the R&S FSH). When you reduce the span, make sure to define a
span that is appropriate for the measurement, especially for high center
frequencies, and consider the cable length and the wavelength of the selected
center frequency. For a typical cable loss trace, you should select a span that is
large enough to evaluate at least one peak and one minimum. Otherwise, the
result might not be valid.
If the cable loss is constant over a large span (for example in case of low center
frequencies), you can select any span.
Note that if the cable loss is greater than 20 dB, you are better off using the S21
measurement, because the cable loss measurement might yield invalid results.
The cable loss format is available for reflection measurements.