Chapter 4 Transmitter Setup
Fine-Tuning Each Transmitter
© 2009 Harmonic Inc.
23
SPL 7110- Exx, Version 1.0, Rev A
4.2
Fine-Tuning Each Transmitter
Harmonic recommends fine-tuning each transmitter to fit your specific requirements and
preferences precisely. You can modify the transmitter configuration to trade off CNR
performance for improved CSO and CTB distortion performance.
If you increase the RF pad by 1 dB, the following results occur:
■
Transmitter CNR decreases by 1 dB
■
CSO decreases by approximately 1 dB
■
CTB decreases by approximately 2 dB
You can adjust the RF level by using any of the two interface options.
For the RF adjustment procedure using each of the interface options, see:
■
4.4.3 Fine-Tuning the Transmitter
■
4.5 Setup via NETWatch Site Controller
4.3
Autosetup, Automatic Gain Control, and Manual Gain Control
The
Autosetup
feature enables you to quickly set the internal drive level to the laser as close
as possible to the optimal value determined at the Harmonic factory. The transmitter operates
in either the Automatic Gain Control (AGC) mode or the Manual Gain Control (MGC) mode.
Figure 4-1: Autosetup via the HLP 4200 and HLP 4800 front panel
4.3.1
Autosetup
What does Autosetup achieve?
The Autosetup feature calibrates and automatically adjusts the internal
RF pad for very close-to-optimum modulation performance.
How does Autosetup operate?
Autosetup
AGC or MGC
ENTER
ENTER
Microprocessor sets
RF pad level
Return to
Main Menu
From Main
Menu
Yes
No
The Autosetup procedure works in two steps: