Cable & Phone companies

[Swerd]

This may be a familiar rant, but I have to get it off my chest just the same. I just got a new home computer and now have cable internet service at home. This is not such a new thing any more, and I'd have thought that the cable companies have had plenty of practice to get it right. They guy came yesterday to install some cable and cable modem. No problem there, he came on time and got the job done OK.

Then the trouble began. I was trying to figure out how to set up my email account when the internet connection froze up. After sitting on hold for 45 minutes with customer service, some guy (the 3rd guy I talked to) said "Oh it is easy, unplug everthing from the back of your modem, wait about 1 or 2 minutes, reattach the plugs, and reboot your computer." Well that worked. In fact it has worked so well, that I've lost count how many time I've had to repeat this. It seems the slightest wrinkle or hiccup in the internet-ether causes my modem to freeze up. I strongly suspect it was a rebuilt modem. And why did I have to learn that rather simple solution of pulling all the plugs to reset the balky modem the hard way over the phone. You'd have thought that some one could have printed up some simple instructions to include with the modem. Has any one else had similar problems with Motorola cable modems?

It eventually took me another day and another hour and a half on the phone before I got my email working, but that is another story.... Again the repeating theme was that absolutely no information or help was available until I screamed for it.

It seems like the cable companies business plan is to ignore customer service and collect the monthly fees from their customers - assuming they are so stupid that they won't ever figure out how they've been cheated. I wonder how many customers give up and say "Oh well" without staying on the phone as long as I did this weekend. I had to take names and get really whiny with some so-called Customer Service Supervisors before I got any satisfaction at all.

I suppose it could be worse. Did you hear the story about the woman sueing Best Buy because they resold her laptop computer that she brought in for repair? They denied reselling it, claiming it got "lost". She is sueing for $54 million because her computer had all the usual information that is supposed to be personal and confidential!!! That ought to bring some great publicity for BB.

 

[MDS]

The reboot process is about the only thing the level 1 customer support will tell you. It's the same with the cable box.

The modem should not lose sync so easily but it may not be the modem itself that is the problem but rather the cable company's servers. Mine has been running 24/7 for years. It occasionally goes out for a few minutes very early in the morning but comes back up in a few minutes. If the modem is working fine it will automatically re-range and re-sync with the cable server and you won't need to unplug it.

If it continues to be unreliable I'd ask for another modem.

 

[yettitheman]

Typically Moto cable modems aren't bad... but maybe your's is having a sync issue or there is something in your demarc box that isn't quite right.

I know with DSL modems, they say it needs to run for a while to get the highest speed possible.

 

[10010011]

It sounds like you might have signal strength or S/N issues.

Type http://192.168.100.1 in your browser.

You should see a cable modem info page. Navigate to the diagnostics page you should see information like this:

What should my Signal Levels be?

Downstream (Rx) Receive Power Level:
This is the amount of signal received by the modem from the transmitter in the cable company head-end.

For all modems:
-10 dBmV to +10 dBmV "Recommended".
-11 dBmV to -14 dBmv / +11 dBmV to +14 dBmV "Acceptable".
-15 dBmV & +15 dBmV "Maximum".

SNR (signal to noise ratio) levels:
This is how clear the signal is at either the modem receiver (downstream SNR) or the receiver in the cable company head-end (upstream SNR).

DOCSIS specifications list minimum CNR (carrier to noise ratio) levels not SNR levels. The SNR levels listed here are based on commonly recommended MER levels for digital cable signals. Not all QAM demodulator chipsets accurately calculate SNR levels that approximate actual MER levels, so these levels may vary depending on which chipset and/or firmware is used in the equipment.

QPSK: 12 dB minimum. 15 dB or higher recommended. (often used in upstream channels)
16 QAM: 18 dB minimum. 21 dB or higher recommended. (often used in upstream channels)
64 QAM: 24 dB minimum. 27 dB or higher recommended. (often used in downstream channels)
256 QAM: 30 dB minimum. 33 dB or higher recommended. (often used in downstream channels)

There is no upper SNR limit; however, 40 dB is the highest most people see. Going above 40 db is possible though.

Downstream SNR levels are read at the modem on the downstream data channel and can be viewed using the modem diagnostic screens.

Upstream SNR levels are read at the CMTS on the upstream data channel, not the modem or the modem diagnostic screens. The end-user cannot get the upstream SNR directly. Only the provider can read the upstream SNR level, directly from the CMTS. Also, the upstream SNR level provided by most CMTSs is not specific to any single modem, but is an averaged, aggregate level from all modems on that upstream channel on the upstream port.

Upstream (Tx) Transmit Power (a.k.a. Return Signal) level:
This is the amount of signal transmitted by the modem to reach the receiver in the cable company head-end.

+8 dBmV to +58 dBmV maximum for QPSK. (DOCSIS 1.0, 1.1)
+8 dBmV to +55 dBmV maximum for 8 QAM and 16 QAM. (DOCSIS 1.0, 1.1)
+8 dBmV to +54 dBmV maximum for 32 QAM and 64 QAM. (A-TDMA DOCSIS 2.0)
+8 dBmV to +53 dBmV maximum for S-CDMA DOCSIS 2.0 (All Modulations)

Recommended upstream signal levels are +35 dBmV to +52 dBmV.

A cable modem running a higher upstream modulation rate may downgrade itself to a lower modulation rate (i.e. 64 QAM to 16 QAM or 16 QAM to QPSK) if the upstream transmit level is higher than the maximum signal level allowed for the higher modulation rate and the CMTS is configured to allow such a change. This downgrade can cause slow speed, packet loss, and connection loss issues depending on the condition of the upstream channel.

A house or drop amplifier will NOT fix an upstream signal problem because most house amplifiers don't amplify the upstream signals; they only pass the upstream signal through with some loss.

Important notes concerning signal levels:
1. Signal levels not within the specifications listed above can cause slow speeds, connection problems, and connection loss due to packet errors, packet loss, and/or constant packet retransmission.

2. It's recommended to have the modem's signal levels at least 3dB away from the maximum/minimum levels listed above due to normal temperature related signal variation. If the modem's signal levels are at the maximum or minimum limits, they may be out of spec. if the temperature changes significantly. Signal levels that vary more then 3 dB in a 24-hour period usually indicate a problem that should be looked into.

3. Excess splits, bad connectors, and/or poor quality cabling will certainly effect cable signal levels and will cause problems. Make the cable run to the modem as clean as possible; the less junk in the way, the better.

BTW: you do not need to remove all the cables to reboot your modem, just pull the power for about a minute then plug is back in.

Also what cable company?

 

[MDS]

All I get is basic modem information like MAC address and software and hardware version numbers. No signal strength information at all.

 

[Swerd]

Thanks for all that info. I'll get busy looking into all that today.

The cable company is RCN. I told them the modem or its service is unsatisfactory. A tech is scheduled to visit Wednesday afternoon with a replacement modem.

 

[10010011]

All I get is basic modem information like MAC address and software and hardware version numbers. No signal strength information at all.

What brand modem?

Click around, the first page you reach is often just an info or status page, but there should be links to other pages.

I use to have a Motorola SB5100, (probably the most popular modem) and there were a few pages under the main status page one of them gave very similar information.

 

[MDS]

The status page says Ambit. I've had this particular modem for at least 5 years (from Time Warner).

There are only two links: login and modem information. Maybe detailed status would be available after logging in but I have no idea what the username and default password would be.

 

[10010011]

The status page says Ambit. I've had this particular modem for at least 5 years (from Time Warner).

There are only two links: login and modem information. Maybe detailed status would be available after logging in but I have no idea what the username and default password would be.

The username is root and the password is also root.

 

[MDS]

You were right, logging in with root/root then enables more links under an Advanced menu and does show more diagnostic info such as upstream and downstream frequencies and data rate.