Surfboard SB5120
I have a problem, so hopefully having some geek friends (being a sub geek myself ya know) and network administrators will pay off.
Last year when I moved into this townhouse I had to buy a new cable modem (Motorola SB5120) to deal with all of the noise on my badly wired apartment cable lines. It was a painful but effective solution, until now. Through process of elimination I’ve eliminated my wifi card, desktop NIC, and router as problem hardware when I finally got down on my knees today and bypassed everything with a straight CAT5 to my desktop. In 3 minutes I had my answer.
I used a seemingly surfboard specific (but other modems probably have this too) utility that gives me signal information and came up with the following:
Here’s my current setup, one I really don’t want to change if I can help it.
- New wall plate connector
- 3ft high gauge line running to a splitter
- 3ft high gauge line running from splitter to modem
- 20 ft low guage line running from splitter to tv across room
- 6ft CAT5 modem to router
- 6ft CAT5 router to desktop
- Modem powered thru power strip (wont reach APC)
- Desktop/Router powered thru APC
There have been a few heavy storms that have passed through recently which I know can reek havoc on a line system, but these problems began before those occured. I can’t translate those signal readings, but to anyone who can, are those nominal, is there something I can do in my home to help this or am I gonna have to have Cox come back out and tell me again “it’s not them”. Mind you I cancelled my line insurance a month or two ago so that Murphy’s Law could screw me.Help! 
**Edit*
I guess I left out what the problem was in all this. For the past week or so my modem keeps dropping the connection. It’s very random, and when I reset everything (unplug modem, unscrew cable from modem, unscrew cable from wall, put it all back together) it all works fine for about 5-15 minutes before it drops it again. It’s usually around that point that I’m tired of resetting everything, so I’ll leave it alone and it will eventually connect again without my resetting everything.
And to answer your question directly Brandon, it drops the connection when it’s connected directly to the NIC, and when it’s connected through the router. Which naturally lead me to the modem…
May 21st, 2006 at 8:21 am
The important figure is the SNR figure, which needs to be above 30 db. You didn’t actually state what your problem was (or maybe you did, either way I’m too lazy to go back and read it). Does it go away when the modem is plugged directly into your computer?
My mom had slow transfer rate on her cable modem, so they ran a brand new cable line from the box to her house; although, her SNR was very low. That might be why they are saying it’s not their fault.
May 21st, 2006 at 3:47 pm
I found this: Cox Signal FAQs and it looks like all your readings are within reasonable limits, and actually quite GOOD compared to those suggestions. I’d suggest sitting on your PC and taking new readings every 2 or 3 minutes and chart them out in a spreadsheet and see how much they change.
The splitter is definitely the weakest link in any coax system. Was it provided by Cox or one you put in? The data portion of your coax operates in a much higher frequency range than the video portion and is not as forgiving as video either to signal quality. If it was purchased at Wal-Mart or Best Buy even, theres a good chance it doesn’t carry those higher frequencies reliably. I’d suggest trying it without the splitter and see what happens too.
Of course, none of this really matters if the coax in the wall can’t carry the signal reliably.
May 22nd, 2006 at 7:52 am
Does it drop the connection “hard” (connection lights go out) or does it drop the connection “soft” (lights are still on but your computer won’t go anywhere on the Internet)? If your lights go out every 15 minutes (then it won’t matter if it’s connected to a router or your NIC), I don’t see how your cable company would say it’s not their fault. Their servers should be showing that it’s losing a connection every 15 minutes, which is why it makes no sense to me that they would say it’s not their fault.
Justin is right about the splitter — I use a powered one for this reason — but you’re still getting those nominal results through the splitter. (I would still take his suggestion and try 3 or 4 tests at different times to see how much your stats change if at all.) I’d raise hell and tell them to come “fix it” as long as I’m having hard connection problems. Also, if it won’t work until you reboot the modem, I’d leave it offline on the day they are supposed to come — just make sure you’re not connected to a router at the time so they have nothing to complain about.
May 22nd, 2006 at 1:20 pm
Thanks fella - after I typed all that out and responded to Brandon the first time I broke everything down to discharge any built up static. The splitter I’m using was provided by Cox (PDI Mega Splitter, 3.5 db on each output). Before I did all that though I was getting both hard and soft drops on the modem. Since resetting everything I’ve only had one soft drop and no hard drops.
If it starts acting up again I’ll run it straight into the wall and see how that works out. I’ve tried so many different things and just realized today that the last time I tried that I was still using the old modem.
May 23rd, 2006 at 7:38 am
The next time you have “soft” problems, try issuing this command (I assume you’re on Windows):
ping -t -w 10000 www.yahoo.com
If you get returns from Yahoo, but the time is in the seconds (not milliseconds), then you most likely have poor wiring. Don’t bother with this command if the lights on the modem are off.
May 23rd, 2006 at 8:56 am
If all else fails, for about $1,000 I can afford to take a few days off and come down there and run you some new RG-6.
May 23rd, 2006 at 6:16 pm
I’m going to bet it’s poor wiring. This place blows lightbulbs all the time, so if it’s not the RG-6 it could be all sorts of electrical noise surging every once in a while and bumping me off temporarily.
I’ll try that command though
May 24th, 2006 at 8:05 am
Well, now you’re getting rediculous in pricing, but I guess you could get an APC UPS that would regulate power spikes. You could always find one to borrow for a day or two.
May 24th, 2006 at 9:05 pm
Last night I discovered that certain electrical devices in this apartment are causing hard and soft drops for the modem. I presume its because of shitty wiring in this apartment. Those two devices are an old fan I have in the room with the modem (which I can move downstairs) and the central air unit (which I can’t do anything about).
After much frustration last night I stretched my modems power cord around the world to my APC and ran the cable directly from the wall to the modem, bypassing the splitter all together. It seems to have helped and the modem doesn’t drop as often now in general, nor does it drop when I use the fan or the AC kicks on.
So with that said, I’ll continue using the APC to protect from some of the surges, but is there anything I can use on the wall plate between the plate and the cable..a filter of some sort? I do have one filter, but don’t know if it’s high or low band, when I use it between the cable & wall plate the modem won’t connect at all. I’m guessing it’s a high band, but I can’t be sure so I won’t act like I am.
May 25th, 2006 at 7:53 am
If It is power spikes and drops, there’s nothing that I know of. You’ll need a UPS that provides adequate protection. The same thing happens in my office. I have so much electronics crap in there, it’s pulling right at 15 amps. That’s the full load of the breaker for that room, and every time the fax machine comes on to receive a fax, the lights flicker.
On the other hand, if it’s certain devices, see if you can put them on a different breaker (different room).
May 25th, 2006 at 9:22 am
Every time you add a new connection into a piece of coax (splitter, filter, etc.) theres a signal loss. So, unless you are adding a booster of some sort as well, a filter won’t help much. Lot’s of surge protectors offer coax protection as well - might be worth a try though since your signal levels were more than acceptable.
Why exactly are the three of us having a converstaion in the comments here instead of via email or our * system?
May 25th, 2006 at 1:21 pm
Alrite..I’ll be switching things around and seeing what it does to help. Thanks
And as for why we are talking here…I’m trying to beat my S&W Post comment record ;).
As for *….I hate talking on the phone when I don’t have to
June 4th, 2006 at 12:07 am
Gentlemen, I am plagued with this problem exactly. I have random had dropouts, a powered splitter provided by charter. My sb5120 had never dropped off before I moved to this apartment. It’s an older apartment, but it’s also much hotter (long beach). Out of curiosity, is your surfboard located in a hot environment? Did you get this resolved?
June 6th, 2006 at 5:25 pm
I’ve basically resolved mine. I ended up running power for the modem thru an APC and moved an older fan downstairs because it made the modem drop soft everytime I turned it on. I still have to reset everything every once in a while, but for the most part it is stable. The modem wasn’t really in a hot location per se..I kept the room it was in fairly cool.
Good luck!