102 Chapter3
Making EDGE (with GSM) Measurements
Making the Tx Band Spur Measurement
Make sure the Tx Band Spur measurement is selected under the
Measure menu. The Meas Setup key will access a menu which allows you
to modify the averaging for this measurement. The following Tx Band
Spur measurement parameters can be modified:
•
Meas Type - select the measurement type from the following
selections:
Full - In Continuous Measure, it repeatedly does full search of all
segments.
Examine- In Continuous Measure, after doing one full search
across all segments, it parks on the worst segment and
continuously updates that segment.
•
Limit - set the absolute or relative limit. The limit range is from
-200 dBm to 100 dBm.
dBm - Absolute limit
dBc - Relative to Mean Transmit Power.
Changing the View
The View/Trace key will allow you to further examine the desired
spectrum segment. Each of these choices selects a different part of the
frequency spectrum for viewing:
Troubleshooting Hints
Almost any fault in the transmitter circuits can manifest itself as
spurious of one kind or another. Make sure the transmit band is
correctly selected and the frequency is either the Bottom, Middle, or
Top channel. The “Unexpected carrier frequency (BMT only)”
message usually indicates the transmit band and/or carrier frequency
is not correct. The “ADC overload -- unexpected carrier
frequency” message usually indicates the channel frequency of the
VSA does not match the carrier frequency of the signal.
Lower
Segment
lower Tx band edge to -6 MHz offset
from the channel frequency
Lower Adj
Segment
-6 MHz to -1.8 MHz offset
from the channel frequency
Upper Adj
Segment
+1.8 MHz to +6 MHz offset
from the channel frequency
Upper
Segment
+6 MHz offset from the channel frequency to
the upper Tx band edge
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