ATSC 280W TX Quick Start Guide
ACT-280-QSG-DOC-V1.2, 07/12/2018
Page 11 of 13
9.
(
Optional Step
- Rerunning Corrections) If you are operating at reduced power
and wish to rerun corrections to achieve better performance, you may now
perform Linear and Non-Linear corrections. (Please refer to the Exciter User
Manual for detailed instructions on running corrections). 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.
10.
(
Optional Step
) 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 Feedback Sample Signal Input
(FSSI) for both A (after) and B (before) reads somewhere between 45% 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). Add or remove the
appropriate attenuator padding to achieve feedback signal levels in the desired
range. Note the AFTER filter feedback sample is used to compute the SNR and
Shoulder Metrics displayed.
11.
(
Optional Step
) Navigate to the Exciter “SYSTEM” submenu and select
UPDATE under ADPC to run corrections. The exciter will then proceed through
4 stages of correction, computing Linear and Non-Linear corrections, and
automatically 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 LCD.
12.
Check RF Performance metrics (SNR, LIMD, UIMD) on the front panel screen
of the exciter.
Your TX should now be up and running properly into your load or on-air
antenna. Continue to monitor system parameters as you allow the transmitter to
operate and stabilize at full output power for another 30 minutes.
13.
Navigate to the CAL setting under the AD3 Advanced submenu and select CAL
then press OK to calibrate the FWD PWR meter on the Exciter front panel to
100%.
14.
To turn the TX On/Off, please use the RF On/OFF control in the RF submenu
of the exciter LCD or the exciter web interface.
