R&S FSH Setting the Amplitude Parameters
1309.6275.12 4.7 E-2
The reference level is in dBm for the default setting. However, the units dBmV, dBKV, Watt and Volt can
a
lso be selected. Unit selection is of most relevance to the marker level display as the marker level is
displayed in the unit of the reference level.
A reference offset (REF OFFSET) can be defined for the reference level. The reference offset is a way
o
f increasing the reference level by a certain amount. This is useful if, for example, an attenuator or
amplifier has been inserted before the RF input. The R&S FSH automatically takes the loss or gain into
account when the level is displayed and no manual calculations are necessary. A loss introduced at the
RF input must be entered as a positive number and a gain as a negative number.
The measurement range (RANGE) determines the resolution along the level axis in the measurement
diagram. When the PRESET or default setting has been selected, the level axis is scaled in dB. The
measurement range is 100 dB or 10 dB per division (10 dB/DIV). The R&S FSH also provides the level
ranges 50 dB (5 dB/DIV), 20 dB (2 dB/DIV), 10 dB (1 dB/DIV) and 1 dB (0.1 dB/DIV), which enhance
the resolution along the level axis. However, increasing resolution does not increase the accuracy of,
for example, the marker level readout, but only makes it easier to read values off the trace. You can
also select a linear level scale with LIN 0-100 %. The level is expressed as a percentage (0 % to
100 %) of the reference level. This mode is useful if you want to display, for example, a carrier being
amplitude modulated in the time domain (SPAN = 0 Hz).
The R&S FSH can also handle measurements on 75 systems. The R&S FSH does not select a
75 RF input per se, but instead only 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. Other
matching pads such as the R&S RAM or R&S FSH-Z38 can be taken into account by using a
transducer factor (included with the R&S FSH4View control software).
Setting the reference level
Press the AMPT key.
The reference level entry is activated immediately. The
REF LEVEL softkey label is highlighted in red.
Enter a reference level with the number keys and
either terminate the entry with one of the unit keys
(-dBm or dBm for relative measurements or (), m,
K, n for absolute measurements) or press the
ENTER key, or
Adjust the reference level with the rotary knob or
the cursor keys.
Any changes you make to the reference level with the
rotary knob or the cursor keys are immediate. The
trace moves as changes to the reference level are
made.
When the reference level you want has been set,
you can remove the value entry box from the
screen by pressing the CANCEL key.
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