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User can also save the data first and then get the group delay by getting the der-
ivation of the phase on PC to get the electric length. In this case, user should choose
the smaller SPAN or many sweeping points to avoid phase aliasing.
Take the SPAN which is as small as possible to make the curve in the display area
can go through one or two periods so that it can get the higher range resolution.
If connect the under-the-test transmission line through the patch cord, user
needs to do the user calibration on the end of the patch cord. In this time, the cable
length compensation needs to be set as zero in FUNC menu.
What chart4-5 shows is the typical curve when test the electric length. This cable
electric length is 1.432m. The actual length which is already known is 1.005m. The
velocity coefficient can be calculated as 0.7018.
Chart 4-5: Measuring the Cable Electric Length in Phase Frequency Characteristic
When the cable’s end is open circuit or short circuit, the cable loss is about half
of the return loss. When there is an antenna in cable connection, the echo loss in an-
tenna’s non-working frequency can be used for evaluating the cable loss preliminarily.
4.4 Spectrum Analysis
We have enhanced the performance of KC901V’s input circuit. Therefore, it can
provide simple spectrum analysis display.
Warning:
KC901V’s input port’s allowed level is +20dBm. Limiting direct voltage is 15V.
Once beyond them, the instrument will be broken immediately. When testing the
transmitter, there must be enough attenuators concatenated. In this way, the input
won’t beyond the limitation in any accidence.
Attention:
The limiting power input level is the maximum level which won’t break the in-
strument. But it doesn’t mean that it can test this level’s signal accurately. In order to
do the accurate test, the input level should less than +10 dBm.
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