# Coax internet splitting question



## cnsf (Jun 6, 2002)

If I want to split an incoming internet coax connection used by my cable-modem, what is the best type of splitter to get? Will one of the standard splitters work or will I lose significant speed? Are there amplified splitters that might be better?

Topology:

Cable juncture at street goes underground to house and is split outside via a 1-3 way "old" cable splitter (Internet seems to work). One cable goes to cable modem and passes by my TV. 

I'd like to split the cable at the TV and feed one to the TV for lifeline cable and one to the cable modem.

Any issues that should concern me? Should I replace the outside splitter first?

Thanks in advance.


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## Bogy (Mar 23, 2002)

Someone else here will have more specific information, but the simple answer is, yes. You can add a splitter to the cable. Just be sure it is a high quality splitter, with as wide a frequency range as possible. I can't remember what range I used, and I'm in no shape to check it right now. You do want to keep the number of splits to a minimum. I have noticed no decrease in speed after adding a splitter to my cable. 

There may be an amplified splitter that will work, but I tried one and it didn't, and from what I have read, you probably won't find one that will. If I am wrong, I am sure someone will point that out.


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## waydwolf (Feb 2, 2003)

Okay, and now a response from a tech who does cable as well as DBS.

You *might* be able to split.

Does your modem have an internal status web page that can be accessed with an address such as http://192.168.100.1 or similar?

If so, check it out and see what the signal characteristics are. You need the signal strength of the downstream, the signal strength of the upstream, and the downstream frequency.

The splitter needs to pass the low side between 5-42Mhz without question. It needs to pass above the downstream frequency as well. In general a 5-1000Mhz splitter is what you will go with.

The signal strength of the upstream at the modem should be between -2 and +3dB. It *might* lock as low as -6dB or high as +10dB. Some systems won't. If your upstream signal strength is +40 to +45dB then your modem isn't screaming too loud. If it is +52dB, then you've got issues.

One other thing, if you have DBS, and do not have cable video, they may have installed an HSD Only trap at the tap to block all but cable modem. If they didn't or you remove one, know that it is theft of service to use the cable video service without paying for it and it is a felony, a federal one at that. Not making an accusation, but one of my jobs is cable security audits and I find people removing their filters all the time and thinking nothing of it.

BTW, if you want it done right, let the cable company do the additional outlet instead.


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## cnsf (Jun 6, 2002)

wolf, thanks for that. I did try the internal page a while back. I'm getting +42dB up. Anything I should check on the downstream side?

I realized they split the cable outside 1-3 with an old splitter. I went out and got a 5-900Mhz gold 1-2 splitter (don't need that third cable). I'm going to replace it tonight. The question is once it's split there, can I split it again inside the house before it hits the modem without losing Internet altogether?

Also, not stealing a thing here. I only work on the up and up as being honest is part of my job.

Thanks.


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## Bogy (Mar 23, 2002)

I *told* you someone else would show up if I gave an answer. :lol:
I just did it by trial and error. I tried it and it worked. That was the answer I was looking for. Actually, the cable techs had already split the cable once where the computer was originally located, and I wanted to shift it to the other side of the house, on a different cable run. I figured since they had originally split the signal once, I could as well.


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## cnsf (Jun 6, 2002)

So, the gold 5-900 splitter didn't work. Couldn't get a signal on the cablemodem. Put back the old 1-3 5-900 mhz splitter that's been there for years and it was working again. Very strange.

And, YES, I did check to make sure the cables were tight and went into the right connections.


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## Bogy (Mar 23, 2002)

Personally, I don't change what the cable company puts on the outside of the house. For all the nasty cracks you will find around here about cable installers, in many cases the splitters they use are better than what you will normally buy, even if they do have gold plating. Whats inside the splitter makes a bigger difference than the plating.


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## Chris Blount (Jun 22, 2001)

I tried splitting the cable modem line coming into the house so I could feed the cable modem and a TV at the same time. It worked for a while but I had intermittent problems with the signal dropping below the the point where the modem could lock. Over time, it got annoying and I took the splitter out.

My advice would be the same as Waydwolf. Have the cable company do it or don't do it at all.


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## Rick_EE (Apr 5, 2002)

I split mine fine. I found the digital cable wouldn't work right with less than a 1Ghz splitter. I got a 2.3Ghz splitter, which I am sure is overkill, but was only $2 more. But everything works great.


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## waydwolf (Feb 2, 2003)

cnsf said:


> wolf, thanks for that. I did try the internal page a while back. I'm getting +42dB up. Anything I should check on the downstream side?


+52dB would be a marginal system barely complying with the DOCSIS standard. +42dB sounds pretty low in noise which is a good thing.

On the downstream side, you want to check the level and it should be again between -2 and +3. 0 is ideal. If it is quite a bit negative, it means you've got a multitude of things that could be causing it including long drop, bad fittings, bad tap, bad splitter, bad diplexor(cable system), bad line amp, bad line(cable system), or long distance to previous active.

The only thing you can do is make sure that all is fine from the ground block in and unless you have the tools and supplies, you'll want the cable company to do it. An "AO"(additional outlet) shouldn't be too expensive, under $20 usually.

If the signal at the tap is already marginal, reading taken by the cable installer, then splitting more than once, with a 3.5dB nominal drop, is not likely to work.

You should go to Start | Run | winipcfg.exe and check the IP for your Ethernet adapter in Win95/98. Start | Run | command in Windows XP and then ipconfig at the prompt. Note your default gateway and issue the command: ping (your default gateway address) -l 1500 -t. Let it ping about a hundred hits or so and note the time and if any packets are lost. When you break with Ctrl-C, note the stats. Higher than 5% packet loss indicates a problem, and since upstream is only +42dB I'd suspect a problem with the downstream.

I've worked some systems where HSD was pushed early to compete in the market for residential broadband and the system topped at 550Mhz while downstream was at 556Mhz. The system was so tightly tuned, a trace showed the signal drop like a rock past 553Mhz or so. As a result, there was massive packet loss across the whole town until they upgraded to a 750Mhz system. The downstream frequency on the modem status page can give a clue here as well.



> I realized they split the cable outside 1-3 with an old splitter. I went out and got a 5-900Mhz gold 1-2 splitter (don't need that third cable). I'm going to replace it tonight. The question is once it's split there, can I split it again inside the house before it hits the modem without losing Internet altogether?


Many splitters claim to pass a given band and don't. What the cable company issues to field service will work. I recommend they do the AO. The rule for cable in order of precedence from most important to least is telephony, HSD, digital video, analog video. Telephony having voltage on the drop will of course come first, then the first split would be modem and all others would go to video.

They would most likely put the drop to a two-way with the modem line on the first leg, then the other leg to the three-way splitter and those ports to video. The only other option short of line work to correct that side, is to put a return path compatible drop amp at the service entrance which would kick up the signal considerably. Just remember, that amplifiers amplify everything. That means any noise already on the line.



> Also, not stealing a thing here. I only work on the up and up as being honest is part of my job.
> 
> Thanks.


I have to check. I've in the past couple months disconnected over five hundred people stealing cable outright and about another three hundred who'd removed their filters to take a more expensive service they also were not paying for.

Like I said, let the cable company do the AO. They will make sure you get TV where you want it. Just don't ask a DBS guy to do it as they don't know return path from a garden path and work from 950Mhz to 1450Mhz and few of them carry high-end 5-2300Mhz splitters or use good fittings.


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