Nautel NX15, Operation And Maintenance Manual

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NX15/NX25 Operations and Maintenance Manual Operating the transmitter
Page 2-108 Issue 6.0 2019-01-31
Envelope Equalization
The
Envelope Equalization
page (see Figure 2.80 ) 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 2.80: Precorrection Envelope Equalization
CAUTION:
Selecting the Wide Band Noise training signal (see
Figure 2.80 ) 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