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Re: Channel loading


With a standard DFB optical transmitter you would need to find out the manufacturer's reccomended input level at full (100%) channel loading.

Then,

input level = 10log(# actual channel's) - mfg. rec. level

I hope that this helps. Also remember that whenever you use half (50%) of the maximum channel loading (100%), you have a 3dB difference in overall input. This means you could increase the input by 3dB.

EXAMPLE: You have a DFB laser with a maximum input 15dBmV with 80 NTSC channels per the manufacturer spec's.

In reality, you only have 40 active NTSC channels. Since you have half channel loading (50%), you should increase input by 3dB to 18dBmV for better c/n performance.

If you have 20 channels, ditto. Another 3dB difference to 21dBmV input.

Just like a 2-way splitter. You split the input in half, you lose 3.01dB in theory. Reality you lose 3.4 - 4.0dB depending on the quality and frequency of the splitter. In optical input power, you are much closer to that 3.01dB theory number than with coaxial splitters.

Good luck!


> Help! What is the formula for figuring a power level based on channel loading,e.g. I am allowed a maximum RF input level of +60dBmV on a device based on 1 NTSC channel loading and have 118 analog channels, what is my maximum allowable input level? THIS IS JUST AN EXAMPLE, I AM LOOKING FOR FORMULA.
> Thanks for your help.(spin)
This is CABL.com posting #69370. Tiny Link: cabl.co/msc2
Posted in reply to: Channel loading by Big O
There are 2 replies to this message
Re: Channel loading Joe50 4/27/2002 11:01:00 AM
Re: Channel loading * CORRECTION * Buffalo Chips 4/24/2002 10:35:00 PM