NX15/NX25 Operations and Maintenance Manual
Operating the transmitter
Page 2-106
Issue 6.0 2019-01-31
AM-AM Correction
The
AM-AM Correction
page (see
) allows you to load or capture a set of AM-AM
correction curves. You can
Load
or
Delete
curves in this list; you can also capture a curve.
When you select
Capture
, the AM-AM Correction 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. Up to three curves can be saved in memory.
AM-AM curves correct for a type of non-linearity where a change in input amplitude does not
cause a linearly proportional change in output amplitude. By applying a test signal and
monitoring the output of the transmitter, the exciter will generate a table of values describing
the required gain versus input signal level in an attempt to find the inverse curve to the AM-
AM non-linearity, and provide a more linear amplifier. Applying the proper AM-AM
correction will result in lower audio distortion and better spectral performance in digital
modes of operation.
Figure 2.78: Precorrection AM-AM
CAUTION:
Making changes to the AM-AM Correction curves automatically places the
transmitter in analog AM mode, with full-scale sine-wave 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.
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