Harmonic PWRLink II 4800T Series, Руководство по эксплуатации продукта, Страница: 20 / 43

Transmitter Setup
4–2 Copyright © 2002 Harmonic Inc.
4.1 Factory-Optimized Settings
The Harmonic factory optimizes the performance of each model in the PWL
4800T series (PWL 4802T through PWL 4814T) prior to shipment.
The factory setup is listed in Table 4-1.
The Harmonic factory-optimized setup procedure balances:
• CNR (carrier-to-noise) performance
• CSO (composite second order) distortion performance
• CTB (composite triple beat) distortion performance
Once the Harmonic factory optimizes a PWL 4800T transmitter, the factory
settings are written into the transmitter’s memory. These settings allow the
transmitter to achieve the performance given in Appendix A at factory setup
for any model in the PWL 4800T series of transmitters.
These factory settings include:
• Internal RF pad value (user adjustable)
• Laser bias (not user adjustable)
• Laser current (not user adjustable)
• Laser temperature (not user adjustable)
• Others
4.1.1 Returning to Factory Settings
If at any time the transmitter’s settings are changed, you can always return
the transmitter to the original factory settings through the HLP 4200WD
display interface. In the Transmitter Adjustments Menu, select the Return to
Factory Settings option. Follow the procedure in Section
4.4.3 Resetting the
Transmitter to Factory Defaults .
When the transmitter reverts to the factory-optimized settings:
• If the transmitter is in AGC mode, the internal RF pad level automatically
adjusts to get the adequate drive level to the laser for optimized
performance.
• If the transmitter is in MGC mode, the transmitter reverts to factory
settings based on Table 4-1,
Factory Setup , on page 4-2, regardless of the
actual RF input level. For the best performance, you must adjust the input
level to 16 dBmV per channel. For instructions, see Section
4.4.2 Fine
Tuning the Transmitter on page 4-8.
Table 4-1: Factory Setup
Loading 76 unmodulated System B/G (PAL) channels from 45 to 870 MHz;
100 MHz digital information –10 dBc down from analog channels
RF input level 16 dBmV per video channel
Link loss 100% fiber link (example: PWL 4814T is tested over 14 dB of fiber)
Harmonic
receiver HRM 3811