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-   -   30M : My Stats and PM from Virgin (https://www.cableforum.uk/board/showthread.php?t=33677804)

Peter_ 02-06-2011 21:12

Re: My Stats and PM from Virgin
 
Quote:

Originally Posted by pip08456 (Post 35250721)
If the hub prefers to be less than 8dB downstream and we know the VMNG300 doesn't like above 7dB downstream what is the rationale for 11dB being acceptable?

That is overall with regards to all modems, we tend to find hubs above 8 sometimes have issues whereas a standard modem with a single downstream seems to perform fine.

jb66 has already posted to this effect.

Sephiroth 02-06-2011 21:42

Re: My Stats and PM from Virgin
 
Quote:

Originally Posted by pip08456 (Post 35250721)
If the hub prefers to be less than 8dB downstream and we know the VMNG300 doesn't like above 7dB downstream what is the rationale for 11dB being acceptable?

It's all fairly clear now, to me at least.

3 channels x 11 dBmv hits the DOCSIS 3 limit.

4 channels x 8.25 dBmv also hits the limit.

I've noticed that some VMNG 300's don't like > 78 dBmv, others 8 dBmV. El cheapo modem is my take on that.

Masque mauy well be grateful that his team's observations can be rationalised to the DOCSIS 3 spec.

pip08456 02-06-2011 21:51

Re: My Stats and PM from Virgin
 
Quote:

Originally Posted by Sephiroth (Post 35250764)
It's all fairly clear now, to me at least.

3 channels x 11 dBmv hits the DOCSIS 3 limit.

4 channels x 8.25 dBmv also hits the limit.

I've noticed that some VMNG 300's don't like > 78 dBmv, others 8 dBmV. El cheapo modem is my take on that.

Masque mauy well be grateful that his team's observations can be rationalised to the DOCSIS 3 spec.

My take on that would be it leaves no margin for error and we all know ambient temp alters attenuation.

Sephiroth 02-06-2011 22:30

Re: My Stats and PM from Virgin
 
Good point Pip.


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