Harmonic SUPRALink 7110-E Series, Installation Manual, Page: 22 / 38

Chapter 4 Transmitter Setup Factory-Optimized Settings
© 2009 Harmonic Inc. 22 SPL 7110- Exx, Version 1.0, Rev A
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BER (bit error rate) performance
Once the Harmonic factory optimizes a SPL 7110- Exx transmitter, the factory settings are
written into the transmitter’s memory. These settings allow the transmitter to achieve the
optimal performance at factory setup for any model in the SPL 7110- Exx series of
transmitters.
These factory settings include:
■
Internal RF pad value (user adjustable)
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Laser bias (not user adjustable)
■
Laser current (not user adjustable)
■
Laser temperature (not user adjustable)
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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 display interface. In the Transmitter
Adjustments menu, select the Switch to Factory Settings option. Follow the procedure in
Section
4.4.4 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, regardless of the actual RF input level. For the best performance, you must
adjust the input level to 15 dBmV per channel. For instructions, see Section
4.4.3 Fine-Tuning the Transmitter on page 25.
Example
In the case of a transmitter with the following setup:
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Loading: 78 unmodulated NTSC channels from 50 to 550 MHz and 450 MHz digital
loading from 550 MHz to 1000 MHz -6 dBc down
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NTSC carriers RF input level: +18 dBmV per channel
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Factory optimized pad value at 15 dBmV per channel: 0 dB
In this example, the input level at 18 dBmV per channel is higher than the factory setting
of 15 dBmV per channel.
There are two options for resetting the factory settings:
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If you use MGC
⊕
Reset to Factory Settings
⇒
Pad value will be 0 dB.
■
If you use AGC
⊕
Reset to Factory Settings
⇒
Pad value will be 0 +
(18-15) = 3 dB.
If you use MGC
⊕
Reset to Factory Settings, the pad value will be 0 dB.
The laser is overdriven. To optimize the transmitter’s performance, you need to adjust the
RF input level to the factory setting, 15 dBmV per channel.
Using AGC
⊕
Reset to Factory Settings provides the adequate drive level to the laser with
a pad value of 3dB.