User's Manual

MHPTV TX User Manual
MHPTV-USR-DOC-V3.0, 10/18/2019 Page 87 of 148
3. Before running corrections, it is important to verify proper feedback signal
levels. There are two feedback signal samples used to compute corrections.
“RF IN A” (After BPF) is used to calculate Linear correction coefficients
while “RF IN B” (Before BPF) is used to compute the Non-Linear correction
coefficients.
4. Navigate to the Exciter “DPD” submenu in the Advanced User menu
(simultaneously press Left and Right buttons, then simultaneously press Up
and Down buttons). Be sure the value of the Feedback Sample Signal Input
(FSSI) for both A (after) and B (before) reads somewhere between 35% and
75% - which roughly corresponds to a value of -15 to -5 dBm as measured on
a power meter (note: the FSSI indicator toggles between A and B and will
“flash” when the signal level is out of range, too high or too low). Optimal
FSSI level is typical ~ 50%. Add or remove the appropriate attenuator
padding to achieve feedback signal levels in the desired range.
5. Check and set the value of PDT (correct time) (set to 5) and CFR (Crest
Factor Reduction) (set to F) in the DPD Advanced Menu (above) (Note:
CFR=F means NO CFR, CFR=0, means maximum CFR)
6. Navigate to the Exciter “SYSTEM” submenu and select UPDATE under
ADPC then press the OK button to run corrections. The exciter will then
proceed through 4 stages of correction, automatically computing Linear and
Non-Linear corrections, and saving the coefficients into non-volatile memory
upon completion. The correction process typically takes from 8-10 minutes to
complete while real-time performance metrics of SNR and Shoulder
performance are displayed on the Exciter LCD.