User's Manual
PINEAPPLE TECHNOLOGY, INC V.6 - ADAPTIVE PRE-CORRECTOR WEB SERVICE OPERATION
DXDPRO-10VH MODULATOR MANUAL
THE INFORMATION PROVIDED HEREIN IS PINEAPPLE TECHNOLOGY INCORPORATED PROPRIETARY INFORMATION AND
CANNOT BE COPIED OR DISTRIBUTED WITHOUT PRIOR AUTHORIZATION
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V.6 ADAPTIVE PRE-CORRECTOR WEB SERVICE OPERATION (Continued)
E. APPENDIX-A CLIPPER OPERATION
2. OPERATION OF THE CLIPPER FUNCTION
Identification of Optimal Clipper Setting
The optimal clipper setting can be identified by monitoring the output of the power amplifier using a
spectrum analyzer. The steps are as follows:
a) Ensure that the clipper initially is set to 12dB.
b) Ensure that the clip filter is initially set to 0%.
c) Configure the spectrum analyzer for zero-span operation with the view focused on either the upper
or lower shoulder of the signal. A resolution of 0.1dB to 0.5dB per division is recommended.
Maintaining the original level in the form of a second trace on the analyzer (clear-write View) is
recommended for easy identification of change in the shoulder level.
d) Now, gradually increase the level of clipping applied by the PT2000 Terrestrail Gateway unit
(1211,51110,510……..etc). When an increase of the shoulder level observed on the
spectrum analyzer is just noticed it shows that the clipping applied by the Terrestrial Gateway is
now limiting the peaks to a point fractionally below the clip point of the amplifier itself. Although the
point will be individual from amplifier to amplifier and dependent on the actual average power level
and peak power rating of the amplifier the point is typically found around of a clipper setting
between 8 to 6 dB.
Selection of Clipper Softness (Clip Filter)
The clip filter setting may be varied according to preferences between 0% and 100%. The 100% setting
provides for maximum suppression of the clipper noise from the sidebands (lower and upper adjacent
channel) while the trade-off is a reduction of the in-band MER performance.
PT2XXX
Power
Amplifier
Channel
Filter
RF out
Spectrum Analyzer
(Zero-span view of
shoulder for establishment
of clipping point for PA)