JDS Uniphase CellAdvisor JD780A Series, User Manual

Page: 62 / 592

JD780A Series Analyzers
62
Using Spectrum Analyzer
steps:
a. Select Attenuation > Manual .
b. Press the Attenuation Value soft key to set the level.
c. Enter a value between 0 and 55 in fives by using the numeric keys.
d. Press the dB soft key or the ENTER hard key.
–
To couple the input attenuator
’s level with your reference level setting, select
Attenuation >
Couple .
As you increase the reference setting, the attenuation level also increases acoordingly.
Optional . To change the scale unit:
1.
Select More (1/2) > Units .
2.
Select the unit of the display scale: dBm , dBV , dBmV , dBµV , V , or W .
The scale unit on the screen changes accordingly.
NOTE
For the Field Strength mode, the units change to dBµV/m , dBmV/m , dBV/m , Volt/m ,
Watt/m^2 , and dBm/m^2 .
Pre-amplifier
You can turn the internal pre-amplifier on to correct and compensate for the gain of the preamplifier so
that amplitude readings show the value at the input connector.
Procedure
1.
Press the AMP/SCALE hard key.
2.
Toggle the Preamp soft key and select On or Off as needed.
NOTE
You can turn the Preamp on when the input attenuation range is from 0 dB to 10 dB. If
the attenuation value is manually set to greater than 10 dB, the instrument will
automatically turn off the pre-amplifier to display low-level signal properly on the chart.
External offset
You can turn the External Offset on and manually set the external offset value. An offset consists of a
cable loss and a user offset and the measurement result shows the value reflecting both offset values.
When the external offset value is set at 40 dB in the Spectrum mode, the measurement result
compensates 40 dB at both the Spectrum Analyzer and Signal Analyzer modes
Procedure
To set the external offset:
1.
Press the AMP/SCALE hard key.
2.
Toggle the External Offset soft key and select On .
3.
Enter a value by using the numeric keys.
4.
Press the dB soft key to complete the entry.
To turn the external offset off:
1.
Press the AMP/SCALE hard key.