[TriLUG] roadrunner woes

[Steve Williams]

25+ is acceptable for SNR, 30+ is preferred.

Upstream between 28 and 55, 35-40 is optimal.

Downstream -15 through +15 is acceptable, 0 is optimal.

Remember this is dBmv - the amount of power added to the signal so that it
can traverse the cable plant to its endpoint.  The fact that your downstream
is 0, means the signal is perfectly calculated to get to your modem, with
the right amount of loss figured through the cable plant.  Your 38dBmv means
your CM is adding that much power to the signal, so that it can traverse the
cable plant to get to the headend with a power of 0, figuring all the loss
along the way through the return path.  The CMTS (what your CM talks to)
will communicate with each CM,  adjusting the transmit level of the CM
accordingly.

When the cable lights flash - that means the CM has lost communication with
the head-end.  When that happens, do you also lose TV signal (or does it
degrade?).  You'll need to note the times it happens - are there any
patterns (rain, cold weather, when your dishwasher is on, etc)?  Ask
neighbors if they see the same things, at the same times.  There are any
number of things that can cause ingress, noise, common path distortion,
etc - from a unterminated jack on a 2-way splitter, to a squirrel chewing
through cable on a pole.  It's rarely easy to find...

-Steve

----- Original Message ----- 
From: "H Brett Bolen" <brettb at nc.rr.com>
To: "Triangle Linux Users Group discussion list" <trilug at trilug.org>
Sent: Friday, October 17, 2003 11:15 AM
Subject: Re: [TriLUG] roadrunner woes


> Steve Williams wrote:
>
> > Those numbers are spot-on, very good.  What kind of troubles are you
having?
> >
>
> cable modem lights start to blink, and I get no connection.
>
>
> today i get downstream  33db  s/n and 0 dBmv, upstream  38dBmv.
>
> Whats good and what's bad?
>
> How come the downstream power level is 0?
>
>
>
>
>
>
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