Nautel NX25, Operation And Maintenance Manual

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NX300 Operations and Maintenance Manual Operating the transmitter
Page 2-102 Issue 3.0 2012-11-01
Envelope Equalization
The
Envelope Equalization
page (see Figure 2.78 ) allows you to load or capture a set of envelope
equalization curves. You can
Load
or
Delete
curves in the list; you can also capture a curve. When
you select
Capture
, the EQ Frequency Response window is displayed. Press
Done
to capture the
curve, type a name for the curve, then press
Save
(or
Cancel
).
Value changes are not typically required.
Envelope equalization curves correct for the frequency response of the magnitude path, dominated
by the response of the modulator filter. By applying a test signal and monitoring the output of the
transmitter, the exciter will use an LMS (Least Mean Squares) algorithm to generate a filter in an
attempt to find a complementary response to the frequency response of the magnitude path (out to
approximately 70 kHz). Applying the proper equalization curve will result in a flatter frequency
response, and improved spectral performance in digital modes of operation, where the frequency
content of the magnitude signal can be significant, as far out as 100 kHz..
Figure 2.78: Precorrection Envelope Equalization
CAUTION:
Selecting the Wide Band Noise training signal (see
Figure 2.78 ) applies full-scale
white noise modulation. To avoid undesirable output or possible antenna
damage, it is highly recommended that you perform these calibrations while
operating the transmitter into a test load.
Wide Band Noise
Current Input