Chapter 14 651
Analyzer Messages
Interpreting Analyzer Messages
RES-BW NOISE FAIL (H)
During the confidence test routine, CONF TEST, the noise floor level was
too high for the indicated resolution bandwidth.
Starting with the widest resolution bandwidth, the test compares the
noise floor amplitude of each bandwidth to the noise floor amplitude of
the next, narrower resolution bandwidth. If a decrease in noise-floor
amplitude does not occur, the test displays the narrower bandwidth as a
test failure.
Related Assemblies A11 bandwidth filter, A13 bandwidth filter.
Troubleshooting Hints Refer to the CONF TEST description in
Chapter 13 for more information about the confidence test routine.
• A high noise floor can be caused by a defective bandwidth control
line.
Look for a change in noise floor level and bandwidth when manually
switching between bandwidths. If no change occurs, check the
bandwidth control lines from the A7 analog interface assembly.
Refer to Foldout 11-1, IF/Control Overall Block Diagram, and
bandwidth control line information in Chapter 5 for further
information.
• A high noise floor can also be caused by loose screws in the IF
assembly section. Make sure the IF assembly cover screws are
properly tightened.
RES-BW SHAPE FAIL (H)
During the confidence test routine, CONF TEST, the 3 dB bandwidth of a
resolution bandwidth was not within 20% of its nominal value. The
10 kHz, 30 kHz, 100 kHz, 300 kHz, 1 MHz, and 3 MHz bandwidths are
checked and the bandwidths that fail are displayed.
Related Assemblies A7 analog interface, A11 bandwidth filter,
A13 bandwidth filter.
Troubleshooting Hints •The bandwidth of the failed resolution
bandwidths may have drifted since the last time the self-calibration
routines were run. The
CAL AMPTD self-calibration routine corrects
for bandwidth error.
If a bandwidth drifts out of tolerance soon after performing CAL
AMPTD, a bandwidth-filter assembly or bandwidth control line may
be unstable.
1. Check the 3 dB bandwidth of the failed resolution bandwidths
using the
3 dB POINTS softkey.
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