Rohde & Schwarz FSH4, Руководство по эксплуатации

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R&S FSH Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1309.6275.12 - 14 84
2.2.2.7 Setting the Input Impedance
In the default state, the input impedance is 50 [ .
The R&S FSH can also handle 75 [ systems. The R&S FSH does not select a 75 [
\ RF input per se. Instead it selects a 75 [ \ matching pad connected at the RF input. The
50/75 [ matching pad R&S RAZ is recommended for 75 [ matching (see
recommended accessories). The R&S FSH automatically considers the conversion
factor when a value of 75
[ is set.
Press the AMPT key.
M Press the "RF Att / Amp / Imp" softkey.
M Select the impedance you need.
You can also use other matching pads (e.g. R&S RAM or R&S FSH-Z38) by
activating transducer factors.
2.2.2.8 Using Transducer Factors
For more information see " Using Transducer Factors ".
2.2.3 Setting Bandwidths
The bandwidth menu contains all settings to set up filter bandwidths available in the
R&S FSH. You can access it with the BW key.
2.2.3.1 Setting the Resolution Bandwidth
The resolution bandwidth in a spectrum analyzer determines the frequency resolution
for frequency domain measurements and therefore determines how well it can
separate adjacent frequencies. The results as you see them on the display depend on
the passband of a resolution filter.
The resolution bandwidth (RBW) has several effects on measurements.
C To be able to display two or more signals whose frequencies are close together
separately, you need a (resolution) filter whose bandwidth is small enough. The
frequency difference between two sinusoidal carriers can not be less than the
selected resolution bandwidth if the carriers are to be resolved, for example.
C The bandwidth of the resolution filter also affects the noise that is displayed by the
R&S FSH. The smaller the bandwidth, the less noisy the results are. The rule is,
that if you increase or decrease the bandwidth by a factor of 3, the noise goes
down or up by 5 dB. If you change the bandwidth by a factor of 10, the displayed
noise changes by 10 dB.