I live in Massachusetts and I get my broadband cable through Comcast .
It seems that my cable falls off only during part of the day ( early to
mid morning ) and is fine at other times . Comcast support says that it
seems like like a modem problem . Are modems tempermental ? Any help
appreciated . BV

"BV" wrote:

I've been with Comcast (S. Calif) for about 3 years using the USR
"shark fin", and I've been using the Motorola 5120 for about 10 months
with not a single problem from either of them. What kind of modem do
you have and does it have clearance on all sides for convective cooling?
Tell us the modem, and someone here might be able to tell you how to
read its web page. In all likelyhood, though, the problem is not the modem.

*TimDaniels*

Timothy Daniels wrote:
Tim ,

The Modem I have is a SurfBoard Sb3100 . I keep in an open space behind
my TV . It has air to breathe . bV

On 12 Sep 2006 10:35:04 -0700, "BV" <bvanasse@hotmail.com> wrote:

What did support say beyond "seems like"? Did they check anything or
was it just "the modem is the problem" without checking, or with
little explanation?

Is this a house, condo, apartment?

I can't speak to Comcast, but you will find an answer. It's taking me
awhile to accept a dumb/passive device could go bad.
--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."

"BV" <bvanasse@hotmail.com> writes:
I can't verify this from my own experience, but a cable tech. once told me
that temperature changes, from the high of the day to the low, can cause
the signals in coax cables to vary by a few dB (but I forget which has the
higher signal loss). If your upstream or downstream signal levels are
marginal even when things are working, then perhaps they go out of range
when it's cooler in the mornings.
-WBE

BV wrote:

What are your RF readings from the modem's status page ?

TVs are plain hot in back esp. up top where they vent. Try moving at
least 3 feet away from the TV, but it's probably not the TV unless
it's plasma.

If you're renting, I'd be looking to upgrade to a DOCSIS 2 modem -
your modem is older than many of the active poster's kids.

since you are using a sb3100 I would guess that a upgrade might help.
That is an old model.
"BV" <bvanasse@hotmail.com> wrote in message
news:1158082504.602550.112910@i42g2000cwa.googlegr oups.com...

BigJim wrote:
I have my modem on the floor while my TV is well up on a stand .There
are five indicator lights on the modem . In the morning , the lights
for ON and RECEIVE come on , then progressively SEND and then Online
and Activity . Then the activity begins slow ( pages on the internet
download slowly) and then great later in the day . It would almost seem
that there is little coming through early in the day or that 100,000
people in the north end of Fall River ( pop 93,000 ) are all on the
line at once but Comcast support said there was no problem in Fall
River . This has been going on for three weeks . They checked my modem
activity and said that there were outages mostly in the AM . I said no
to a house call because I don't believe it's a modem problem .BV

BV wrote:
What are the signal power levels, etc., from the modem web page at
192.168.100.1 ?

Q

Here is the cut and paste of the current reading for 4:37 PM Wednesday
Fall River Time
when all is going well . BV

Downstream Value
Frequency 693000000 Hz Locked
Signal to Noise Ratio 28 dB
Power Level 0 dBmV The Downstream Power Level reading is a snapshot
taken at the time this page was requested. Please Reload/Refresh this
Page for a new reading



Upstream Value
Channel ID 4
Frequency 35600000 Hz Ranged

Power Level 50 dBmV

"BV" <bvanasse@hotmail.com> writes:
That SNR seems a bit low, particularly with such a high downstream power
level. In any case, the important thing is to look again late tonight or
in the morning BEFORE it loses sync/reboots/whatever it does that takes it
offline (since the signal levels are meaningless once it's offline, if the
cable modem's web server will talk to you at all).
-WBE

[I already mentioned possible temperature, and thus time-of-day, effects on
coax in article <ydodtk7mit.fsf@UBEblock.psr.com>.]

BV wrote:

Not the greatest set of numbers. Tx power would be nicer below 50
and SNR should be over 30 and would be nicer in the high 30's.

I still think that old DOCSIS 1 modem would be the first thing to swap
out after verifying the cabling is all good. Maybe swap with a neighbor
and see what your numbers are.

How about a drawing of your cabling ? Are your connections tight ?
Are you using RG6 cable ? How many splitters and type ?

Here's an eg from my house :

/-- Grounding block pass thru connector
|
| RG6 Terayon Netgear PC1 PC2
| /------> TJ715 Modem ----> RP614 Rtr ------|---|---|---|
RG6 V RG6 /
--------->X----->X <-- Signal Vision SV-4G digital 4-way splitter
U/G cable \ (5-1000 Mhz 7 dB/port)
|
| RG59
|-----------------> to Family Room
| RG59
|-----------------> BR1 TV
| RG59
\-----------------> BR2/3 TV (terminated)

My cable comes into the house to my second story suite and in my room
, there is a splitter - one cable goes to the Tv and one to the cable
modem .

I am actually getting very very slow internet this morning and the
Signal to Noise Ratio has gone down to 26 db downstream and the power
level also down to 49 dBmV upstream .

BV wrote:

You only answered one Q - how do you expect to get decent help when you
ignore the rest ?

That's a terrible SNR. The 50 going down to 49 isn't much improvement,
but at least it's below 50. Mine's pretty high at 48 too.

You really do have an old modem--my installation was 6 years ago and it
was a SB4100, eventually upgraded to a 4200 and now to a 5120 to take
advantage of the new higher speed offered by my provider(Cablevision).
I don't know about Comcast's policies but with Cablevision, if there is
a modem (or modem related) problem they let you bring your old one to
the nearest Cablevision center and exchange it for a new one at no
charge. If there is no center nearby they will come and replace it. So
why not try a newer model--what do you have to lose?

Ken

BV wrote:

Just bought a new modem and will install it later today . I will give
progress reports . I'm sorry if I haven't answered all the questions
but I am not very technical and I wasn't sure what I was being asked .
Sorry . BV