Warnings Indicating Impermissible Operating States
R&S FS300
E-1007.9900.15
9-244
Operating manual, 02/2006
9.2
Warnings Indicating Impermissible Operating States
Warnings
Red labels at the upper left corner of the measurement grid tell the user that
the measurement results may be incorrect. This can be caused by exces-
sively high signal levels at the input or by incorrect settings on the instrument.
The warning remains on the screen until the problem has been eliminated.
There are three types of messages that can be displayed on the screen:
OVERLOAD
A level above 13 dBm is detected at the R&S FS300 input and the current
input attenuation setting is less than 20 dB. In this case, the instrument auto-
matically increases the input attenuation by 20 dB to prevent the subsequent
stages from being overdriven. The displayed signal level decreases by 20 dB
as a result of the additional attenuation, without the display being corrected.
1.
To obtain a correct level display, the reference level must be increased
( 6-88) until the message disappears.
2.
If the message does not disappear, it is possible that the input attenua-
tion is set to Manual. Raise the input attenuation above 20 dB ( 6-93),
or switch to automatic setting of the input attenuation ( 6-94).
NOTE:
This display will appear even if the signal is outside the currently se-
lected span. In FULL SPAN mode ( 6-82), check whether a signal exceeds
the permissible value and reduce the level if necessary.
PLL unlock
The control loop, which is used to set the frequency of the internal reference
oscillator with crystal accuracy, does not lock. This causes a frequency error,
and the spectrum analyzer no longer operates according to specifications.
The cause for this may be an internal instrument error or the absence of the
10 MHz reference signal at the external input REF IN. The absence of the
reference signal, however, is not indicated unless the reference has been
switched to “external”.
1.
If the missing external reference signal is the cause of this error mes-
sage, connect a 10 MHz signal to the REF IN [22] input or switch the ref-
erence to “internal” ( 6-168).
2.
If the missing external reference signal is not the cause of this error mes-
sage, an internal instrument error has occurred. In this case, switch the
instrument off and on again. If the error message is still present, the
instrument must be sent to the service shop to be checked.
ADC overload
the level of the input signal is approx. 20 dB above the set reference level. In
this case, the analog/digital converter is being overdriven, causing
intermodulation products and distortions in the spectrum.
•
This can be remedied by increasing the value for the reference level in
the instrument ( 6-88).
Summary of Contents for FS300
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