Chapter 3 123
Making EDGE (with GSM) Measurements
Making the EDGE ORFS Measurement
❏ Fast Avg - Fast averaging is a technique developed by HP/Agilent.
The GSM standard specifies 50% to 90% portion of the burst,
excluding the midamble, be measured in 50 averages. Since most
offsets are measured in a 30 kHz filter, there is a lot of variation
from burst to burst, hence the averaging.
The fast average method makes use of the 10% to 90% portion of the
burst, excluding the midamble. The 10% to 50% portion of the burst
has statistically the same average power as the 50% to 90%.
Therefore, measuring both portions from one burst is statistically
the same as measuring 50% to 90% from two bursts. Now, two
averages are completed with one burst. When averaging is turned
on, this will double the speed of the measurement.
This method is only applicable on the modulation portion of the test,
and only when averaging is enabled. The method is not available
when Modulation and Switching are done at the same time.
❏
Advanced - accesses a menu with the following keys:
•
Mod Avg - choose between:
Pwr Avg (RMS)
Log-Pwr Avg (Video)
• Switching Avg - information only. Averaging is fixed at
maximum of peak.
• Modulation Meas BWs - accesses a menu with the following
selections:
Carrier RBW
<1800 kHz Offset RBW
>=1800 kHz Offset RBW
VBW/RBW Ratio - information only. Modulation ratio is
fixed at 1.
•
Switching Meas BWs - accesses a menu with the following
selections:
Carrier RBW
<1800 kHz Offset RBW
>=1800 kHz Offset RBW
VBW/RBW Ratio - information only. Switching ratio is fixed at 3.
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