Operating instructions

OPERATING MANUAL 2945A
46882-311D 3-55
(6-2) to be displayed. Repeated presses of the [10 dB/2 dB] key will toggle the options, with the
current choice being shown in the display.
The LEVEL [
] and [ ] keys adjust the reference level in either 2 dB or 10 dB steps, depending
on the setting of the reference level vertical range.
Video filter
A video bandwidth filter can be switched into the display path to reduce the visible noise. To set
the state of this, first press the [Vert Scale] key. Alternate presses of the [Video Filter] key will
set the Video filter
ON or OFF.
The filter frequency is selected automatically to provide optimum performance for the selected
resolution bandwidth.
Peak hold
The spectrum analyzer mode has a peak hold facility. When set ON, this facility displays the
highest received signal level at each frequency point of the display. Signals of a lower level will
not over-write the display, signals of a higher level will over-write previously recorded signals.
To set the state of the peak hold facility, first press the [Vert Scale] key. Alternate presses of the
[Peak Hold] key will set the facility
ON or OFF.
Markers
Marker and
δ
Marker
The Marker and δ Marker facility allows frequency and level measurements to be made to the signal
displayed on the spectrum analyzer screen. The Marker or δ Marker readout is shown at the lower left
of the display. The RF level is given in dBm and the RF frequency in MHz, kHz or Hz.
Pressing the [Mkr/
δ mkr} key toggles through the following actions:-
• Displays marker line and marker readout.
• Selects Marker function and allows adjustment using the variable control.
• Selects δ Marker function and allows adjustment using the variable control.
• Removes marker line and marker readout from the display.
With Marker selected and the
legend highlighted, adjusting the variable control will move
the marker line across the display. The RF level and frequency of the signal at the intersection of
the marker line and the displayed signal is shown by the marker readout.
With δ Marker selected and the
legend highlighted, adjusting the variable control will move
the marker line across the display. The marker readout shows
the difference in RF level and
frequency between the intersection of the
marker line and the displayed signal and the
intersection of the
display centre line and the displayed signal. A negative frequency value
indicates that the marker line is at a frequency lower than the frequency of the display centre line.
Marker to reference
Pressing the [Marker to Ref} key moves the marker line to the display centre line.
• With the Marker function active, the marker readout will display the RF level and frequency
of the signal at the intersection of the display centre line and the displayed signal
• With the δ Marker function active, the marker readout will display 0 dBm and 0 Hz until the
marker line is repositioned.
Tracking generator facility
The tracking generator facility uses the RF generator of the Service Monitor to provide a tracking
signal source.
This allows the spectrum analyzer to show the frequency response of frequency dependent circuits
such as filters.