Operating instructions

LOCAL OPERATION
3-58 46882-311D
The Span setting controls the sweep range covered by the spectrum analyzer. When in the Look
and Listen mode the sweep span is selected from the Span menu accessible by pressing the
[Span] key. Four span widths are available as listed below.
1 MHz 500 kHz 200 kHz 100 kHz
Demod settings
The ‘listen’ demodulator and its associated circuits are set to extract the information from the
signal tuned to the centre frequency of the display. The following options are available through
the [Demod] key.
Modulation type AM FM
De-emphasis ON OFF
AF filter
300 Hz to
3.4 kHz
15 kHz LP
’Listen’ IF bandwidth
Instruments with the 'Demod Filters' option fitted, have additional IF filters included in the
'Listen' IF amplifier. This allows an appropriate filter, matched to the channel spacing and
modulation characteristics of the signal of interest, to be selected. This is independent of the
spectrum analyzer resolution bandwidth selected.
Pressing the [Listen IF BW] key will display the following filter options:-
5 kHz 12.5 kHz 25 kHz 50 kHz 300 kHz
The selected filter is shown on the display, above the 'Demod' type legend.
Instruments not fitted with the 'Demod Filters' option can be set to 15 kHz or 300 kHz. This also
is irrespective of the spectrum analyzer resolution bandwidth selected. The current setting is
shown to the left of the display. To change the setting, first press the [Listen IF BW] key, which
will display [15 kHz] and [300 kHz] keys. Press the appropriate key to select the required
setting.
Switching to the Tx TEST mode after a signal has been located will allow the signal to be
monitored with the IF bandwidth set to 300 Hz, 3.0 kHz, 30 kHz or 300 kHz.
Resolution bandwidth selection
The resolution bandwidth for the display can be selected from the following through the [Res
BW] key:-
Auto
Res BW
3 kHz 30 kHz 300 kHz
With automatic resolution bandwidth selected, the resolution bandwidth is dependent on the
sweep span, as shown below:-
Span Setting Resolution Bandwidth
1 MHz 30 kHz
500 kHz 30 kHz
200 kHz 3 kHz.
100 kHz 3 kHz.