JDS Uniphase JD7105B Manual page 40

JD7105B Base Station Analyzer
2. Set the attenuation level
[Attenuation]
<Auto> or <Manual>
Enter an attenuation value
AMP/SCALE
 AUTO SCALE: The instrument can automatically set the scale to the minimum and maximum
values on the Y-axis of the graph for optimum display of the traces measured. Each time the Auto
Scale is selected, the top and bottom scales are set to the minimum and maximum values with
margin on the Y-axis of the display screen.
 REFERENCE LEVEL: Sets the maximum Y-axis range when using the Spectrum Analyzer or
Signal Analyzer function.

ATTENUATION

AUTO: Input attenuator's value is automatically set depending on the reference level. This is
the default operation mode, so it is recommended to use this mode unless a special
measurement condition is needed.

MANUAL: Sets the attenuator's value for the Spectrum Analyzer RF In 50Ω port. The
reference level changes according to the change of the attenuator's value, but the
attenuator's value does not change when the reference level is changed.
If the input signal level is higher than +30 dBm or higher than the allowable mixer
!
input limit per input attenuator's value set by the user, a "IF Overload" message will
be displayed on the screen indicating that the input attenuation value must be
increased. When the instrument is exposed to an over power condition for a long
time, its performance may be degraded.

PREAMP: Turns on or off the internal pre-amplifier. The pre-amplifier is to amplify a low-level
input signal. This soft key toggles between the On and Off. When it is turned on, the allowable
attenuation input range is 0 dB to 10 dB with 5 dB step. If user sets attenuation value beyond 10
dB, then the instrument will automatically turn off pre-amplifier to display low level signal properly
on the screen.

EXTERNAL OFFSET: Sets an 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.
GSM/GPRS/EDGE SIGNAL ANALYZER
Press the Attenuation soft key. The Auto mode is set by
default. This key toggles between the Auto and Manual.
Press the Attenuation soft key to highlight the Manual mode
and change the attenuation value to optimize S/N.
Use the numeric keys or the rotary knob that changes in a 5
dB step. The attenuation setting range is 0 to 55 dB.
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