R&S FSH
Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1309.6275.12 - 14
103
Measuring the Signal Bandwidth
The "n dB Down" marker function places two temporary markers to the left and to the
right of the reference marker and measures the bandwidth between the two temporary
markers. The function therefore is a good way to measure the bandwidth of a signal or
the bandwidth of a filter, for example. The temporary markers are represented as two
vertical lines.
The distance to the reference marker is by default 3 dB below the reference marker.
You can also adjust this value manually. Entering a positive value sets the temporary
markers below the reference marker. If it is, for any reason, not possible to calculate
the frequency spacing, dashes are displayed instead of a value.
Upon entering a negative value, the function turns into a n dB up function. You can use
a n dB up function, for example, for measurements on notch filters.
M
Press the MARKER key.
M
Press the "Marker Function" softkey.
M
Select the "n dB Down" menu item
The R&S FSH displays two temporary markers on the left and on the right of the
reference marker M1. It also shows the bandwidth between the n dB down
markers.
You can then adjust the distance of the temporary markers.
M
Press the "Marker Function"
softkey.
M
Select the "n dB Down" menu item
The R&S FSH opens an input field
M
Enter a different distance (in this
case 6 dB).
The R&S FSH again shows the
temporary markers, this time with
a broader bandwidth.
Demodulating Signals
The R&S FSH features an AM and FM demodulator to demodulate and monitor audio
signals. It demodulates the signal at the marker frequency.
You can listen to the demodulated signal with the internal speaker or headphones that
you can connect to the 3.5 mm headphone jack on the top of the R&S FSH.
When demodulating an AM modulated signal, the R&S FSH turns the video voltage
into an audible sound. You should therefore set the reference level to about the level of
the signal that you are demodulating.
