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TomBeckman
join:2009-01-10
Boulder Creek, CA

TomBeckman

Member

[Signals] Power level question

I have two SMCD3G modems connected to the incoming Comcast cable via a splitter. I read the signal level FAQ and have a couple of questions. Two of the downstream channels have a -23 dB power level and SNR of 18 dB on one modem, and -21 dB power level and SNR of 6 dB on the other modem. One of the upstream channels hasn't been locked for several days. I've attached the statistics pages for the two modems. Anything to be concerned about?
medbuyer
join:2003-11-20
Memphis, TN

medbuyer

Member

»Comcast High Speed Internet FAQ »What should my Signal Levels be?

uuhhmm...why do you have 2 SMCD3G's? is this in a residential setting or business?
TomBeckman
join:2009-01-10
Boulder Creek, CA

TomBeckman

Member

They're on a business account. I have some high-traffic users on one of the modems, and the other is on a load balancer for the rest of the company.

tshirt
Premium Member
join:2004-07-11
Snohomish, WA

tshirt

Premium Member

Channels 9-11 the last 2 downstream channels are WAY out of spec on both modem (or the syncing is not completeing.
You need a tech to troubleshoot in person.
BTW was that setup designed/configured by comcast?

andyross
MVM
join:2003-05-04
Aurora, IL

andyross to TomBeckman

MVM

to TomBeckman
Something is weird. They both show those last 2 downstram channels on the same frequency??? And, it's a very different frequency than the first two. Typically, Comcast puts the channels sequential, so they should be relatively close to each other (some modems use wideband tuners that cannot tune too wide a range at the same time.)
TomBeckman
join:2009-01-10
Boulder Creek, CA

TomBeckman to tshirt

Member

to tshirt
I told Comcast what I was doing when I ordered the second circuit.

The reason I posted the question is that I asked multiple Comcast techs about the power numbers and they all said that they didn't know what they meant.

EG
The wings of love
Premium Member
join:2006-11-18
Union, NJ

EG to tshirt

Premium Member

to tshirt
said by tshirt:

(or the syncing is not completeing.

FWIW, the status does appear as the channels being in a "locked" state. Hmmm.....

NetFixer
From My Cold Dead Hands
Premium Member
join:2004-06-24
The Boro
Netgear CM500
Pace 5268AC
TRENDnet TEW-829DRU

NetFixer to TomBeckman

Premium Member

to TomBeckman
said by TomBeckman:

The reason I posted the question is that I asked multiple Comcast techs about the power numbers and they all said that they didn't know what they meant.

Were they techs field techs or tier 1 phone support techs? The business class tier 1 phone support techs generally are familiar with the SMC gateway setup options to which they have access, but I suspect that some of them have never touched an RG6 coax cable or an F connector.

The "two" high frequency channels are definitely wonky, especially the fact that they both show as being the same frequency. It is hard to believe that the SMC's modem actually shows them as "locked". I would say, that in effect, you only have two downstream channels that are actually bonded. Since it is happening on two modems, it is likely a Comcast infrastructure problem (but if it is not causing you to have connection or throughput problems, it may be difficult to convince Comcast to even investigate it).

As for only seeing three upstream bonded channels, that is all that I have ever seen on my connection, and for the couple of days I was on the borked 3.1.4.51.1 firmware last week, I only had two upstream bonded channels.

tshirt
Premium Member
join:2004-07-11
Snohomish, WA

tshirt to EG

Premium Member

to EG
I saw that EG See Profile, but it doesn't make sense with the power levels and the freq's are weird.
I think they need some from the local plant to look it over.

EG
The wings of love
Premium Member
join:2006-11-18
Union, NJ

EG

Premium Member

Agreed. It's "weird"..