Operating instructions

LOCAL OPERATION
3-57
Start frequency
Pressing the [Start Freq] key allows the required start point to be entered using the data entry
keys.
The variable control is active when the
Start legend is highlighted.
Note that when using the variable control the span of the display remains constant. Therefore the
stop frequency will follow any change to the start frequency. This is not the case when entering a
start frequency by using the data keys.
Stop frequency
The [Stop Freq] key highlights the Stop legend under the graticule and allows a frequency value to
be entered from the data keys.
The variable control is active when the
Stop legend is highlighted.
Note that when using the variable control, the span of the display remains constant. Therefore the
start frequency will follow any change to the stop frequency. This is not the case when entering a
stop frequency from the data keys.
Peak find
Press the [Peak Find] key to set the marker to the highest level on the trace.
Resolution bandwidth
The bandwidth of the spectrum analyzer acceptance circuits is selectable by the user.
The spectrum analyzer detector circuits will give an output corresponding to the mean level of
signal within the acceptance passband. Therefore the choice of pass band, or resolution
bandwidth, will depend upon the characteristics of the signal being examined.
The sweep speed is dependent on the resolution bandwidth. A high resolution analysis will take
longer to process than a low resolution analysis.
The resolution bandwidth can be selected manually or set automatically.
To set the resolution bandwidth, first press the [Res BW] key. The menu shown in fold out
diagram (6-12) will be displayed. The options then available are:-
• Press the [Auto Res BW] key to set the resolution bandwidth to the optimum setting as
determined by the Service Monitor software. The setting is then shown on the display. Use
the return key as appropriate to resume setting up or testing.
• Press the [Manual Res BW] key to set the required resolution bandwidth by manual selection.
The passbands available for selection are:-
300 Hz 3 kHz 30 kHz 300 kHz 3 MHz
The setting is then shown on the display. Use the return key as appropriate to resume
setting up or testing.
• Press the [Return] key to exit the resolution bandwidth selection menu.
Reference level
The top of the graticule represents the reference level which can be set between -50 dBm and
+52 dBm
Pressing the [REF LEVEL] key will highlight the
Ref Level legend and allow a level within the
above range to be entered using the data entry keys. The entry must be terminated with the [dBm]
terminator key.