Cablemodem dBm Levels

[Far-N-Wide]

I have a LinkSys cable modem, model CM-100-4A (http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1175238345652&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=4565222279B04).

What should I get for good dBm levels for up and down stream?
The link I posted did not list anthing helpful as far as what I should have for a good output level on the upstream. or a good input level on the downstream from the provider, cough... Comcast.

I have...

Down Stream

Lock Status Operational
Modulation 256QAM
Channel ID 74
Provisioned Rate 6600 kbps
Symbol Rate 41879.195 Ksym/sec
Downstream Power -7.0 dBmV
SNR 38.0 dB

Up Stream

Lock Status Operational
Modulation 16QAM
Channel ID 10 Provisioned Rate 384 kbps
Symbol Rate 2560 Ksym/sec
Upstream Power 52.0 dBmV


The Up Stream seems awful cold of a signal. Bad spliter? or maybe cable rott on a connector or two?

The cable is some older RG-6 that was put in around summer 1977 when the house was build. I have basic calbe, the TV comes in fine. It's not a HDTV, but it looks ok.

[Sava700]

I bolded my suggestions within quote... the levels can be adjusted at the pole...give them a call if your having issues with it going out since the upstream is pretty darn close to spiking at times and knocking your connection out.

I have a LinkSys cable modem, model CM-100-4A (http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1175238345652&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=4565222279B04).

What should I get for good dBm levels for up and down stream?
The link I posted did not list anthing helpful as far as what I should have for a good output level on the upstream. or a good input level on the downstream from the provider, cough... Comcast.

I have...

Down Stream

Lock Status Operational
Modulation 256QAM
Channel ID 74
Provisioned Rate 6600 kbps
Symbol Rate 41879.195 Ksym/sec
Downstream Power -7.0 dBmV - low...bring up to 0
SNR 38.0 dB - good

Up Stream

Lock Status Operational
Modulation 16QAM
Channel ID 10 Provisioned Rate 384 kbps
Symbol Rate 2560 Ksym/sec
Upstream Power 52.0 dBmV - too high..bring down to low 40's


The Up Stream seems awful cold of a signal. Bad spliter? or maybe cable rott on a connector or two?

The cable is some older RG-6 that was put in around summer 1977 when the house was build. I have basic calbe, the TV comes in fine. It's not a HDTV, but it looks ok.

[Far-N-Wide]

I bolded my suggestions within quote... the levels can be adjusted at the pole...give them a call if your having issues with it going out since the upstream is pretty darn close to spiking at times and knocking your connection out.

My previous modem gave up it's ghost last night. It ran in the 50's and 70s, almost all the time. In the past Comcast tech support said this is a bit high but within their limits. Not getting a good answer to my question of "what do you consider a normal level to be?". I checked LinkSys website for an answer and found nothing.

I do thank you for the reply. I really asked becasue I tend to look to hard at the simple things and miss the the stuff right in front of me. Plus I got a bad vibe for the tech guy, like he was shoveling manure...

Anyway, since one is low and the other is high. Adjusting at the pole may not be a good option for both coming and going signals. The signal coming in from the Pole is low. If they up that... It will improve my RX signal coming in from them.

The outgoing signal from my modem is most likely "hot", as you suggest. I really don't know the specs for any cable modems, nothing was listed on LinkSys site about the levels for that modem.

In any case I can't set the output on the modem, I can only monitor it. The signal going out Is automaticlly adjusted by the signaling coming in from the provider. "Hey I can't hear you speak up. My modems shouting... ".

Plus I sometimes miss the obvious... It's why I asked maybe bad cable connector or rott ect... I have some time to work this out, fishing for input never hurts.

Thanks.

Anyone else?

[Indy]

Couple of things you can do. First of all, if you've got an extra run of cable that'll reach, try going from the ground block straight to your modem to see what kind of levels you have there. Secondly, since you said that the cable's been there for over 30 years, I'd seriously consider having the wire re-ran. That, and check to make sure that any splitters that you may have are rated 900 MHz or better. Older splitters tend to be 500 MHz splitters, and usually will clip the signal on the upper end where the downstream signal is sent to your modem.

[YARDofSTUF]

Your Downstream isnt that bad, 0 is the middle ground within the tollerences so the closer to that the better.

Your SNR is great.

Upstream power level is fine, towards the high side though. My upstream is 50, my friend a town or so over is 54 and we both get the max speed, we're both comcast as well.

If you're having issues and think signal is the issue I'd work on adjusting the upstream lower, while keeping the downstream between -10 and +10, the tolerance is suppose to be -15 to +15 for downstream.

[Far-N-Wide]

Indy - I'll look into the 900 Mhz splitters. I replaced the only one on the line outside my home. It was at the hook up point on the back side of my house. I noticed it was a 5 way plitter with 2 un-used and uncapped connections. they looked pretty gro-dee... The replacemnet was a three way stainless steel splitter I picked up at home depot. Not sure about 900 or 500 though. It was with the cable and TV connector section of the store.

Yard - I'm planning on re-cabling the house with the HDTV grade cable when it warms up a little more and stops raining a bit.


Thanks for the replys ghents. I'm largely happy with what I've read. It's not bad service. just could be better. Thanks agin.

Cheers
FNW

[Sava700]

I would go back to suggest as others have said to replace some wires.. remove the cause from your home and put it back into the ISP's hands.

The Power levels on the upstream are high and can spike without you even seeing it but cause a drop in your connection..saw this many times with Comcast and some odd ball problems going on in the area. The power level would spike above 60 out of the blue and I believe from the discussion I had with the tech..that they would prefer you be down in the 40's but your area might be different with different equipment.

I would again switch out cables...then call them and have them adjust your levels and check for noise from your home to the nod and beyond since noise will cause speed drops and issues.