Outside Wiring for Cable Modem [cable modem service] [uhf antenna]
Q: Hi,
Not sure if anyone here has done externally coaxial cabling in their homes, but if you have, you could help me.
We just bought a house and moved in. I try to reconfigure the wiring, so I can my three inputs have been implemented in harmony: cable modem service, DirecTV and VHF / UHF antenna (to get local HD signals) 0.
At present, the cable modem wired as such:
Direct line from the cable box to the community local box on the back of the hits house.
Line a standard grounding block, and then a 2-way divider splitter.
One (we call this out-A) goes directly to the cable modem in our “office.”
One boundary (we call this Out-B) goes down to the basement where it is split again three times, each running for a room in the house.
So here what I want to do:
Run the cable modem line directly to the ground block, which splitter.
Run the over-the-air antenna line directly to the interior splitter in the basement (with half block on the ground) 0.
And heres the problem: when I unplug the
The Out-B line (see above), the cable modem (on the Out-A) * * working.
stops or
The minutes I remove the splitter and connect the cable modem line, cable modem stops working.
As soon as I have the splitter back, with both Out A-and B-out-connected, the modem picks up right up again and Im back on.
Does anyone know why this would occur? Or suggestions on what I need on the line to get the modem working again, * without * using the splitter?
Thanks!
Best Answer: What you are looking for doesn't exist. There are many ways to get your information, however, without wiring in some sort of hardware. If you have a keylogger, it is hidden behind a rootkit.
In the meantime, change all of your passwords to all of your sites to something with a capitol letter, a number, a small letter, and a symbol or a space, if allowed. It should be no less than 8 characters.
Further, find, download, install and use a rootkit reveler. Backlight is one, but I can't remember who makes it. F-Prot maybe?
Good luck to you.
Re:No, they're just resistors on a connector ….. inherently bidirectional.
I'm not clear on what you did. Was the signal -13 with the splitter in?
Worse case, if you were at -13 with the splitter, the straight line signal should have gone to ~-9 (recovering some losses from the splitter) and gone to -15/16 ish with the 6db attenuator in.
If it was -13 with the splitter out, then adding the splitter should have taken it to ~-16 ish, then with the attenuator ~ -22db.
It might end up being less trouble to cable it the way you wantit, then call the cable company out to balance the line / adjust the drive to you cable to match your cabling. It isn't rocket science, but having the right tools ($$) and the access to the boxes makes a big difference. It'll cost you a service call but, in theory, it'll be done "right."
They fed my BB cable in a little hot (+12), to cover the setup I told them I was going to use (I, um, kinda tricked 'em). I have access to a Field Strength meter, so I do the balance job in my closet.
Good Luck
Scott
Re:I noted that some of the fancier adjustable attenuators like the one I mentioned above noted that they were bidirectional. Is it possible that the little 6 dB inline one is not?
I will take a look at Home Depot today to see what I can find.
Re:I've noticed that some splitters thoughtfully include terminators for any unused outputs; using them reduces signal noise that is produced when the signal running down your 75 ohm coaxial cable crashes into the infinite impedance of the unterminated output. You might find cable terminators in the video section of someplace like Home Depot. If you can't find one, then find a resistor of roughly 75 ohms and connect that from the central hole of the output across to its outer threaded body (that's really what a terminator is). I'm a little surprised that the 6 dB attentuator didn't work…
Re:I checked at Radio Shack and all they had were 6 dB attenuators, which I tried, and it didn't do the trick. The cable modem's signal level dropped to -19 dB, where it was previously in the -13 (or so) range when it was working. The modem also gives data on a signal-to-noise ratio, but I'm not certain on how to interpret that accurately.
I didn't think of the terminator, I might try that next if I can find one. I can't think of any other places offhand to by an attenuator, other than ordering one. Radio Shack also has a bidirectional adjustable attenuator, but it says on the package that the minimum return loss at 1000 MHz is 8dB, so I think that's out of the question.
Any ideas on other local stores that might have something like that? A hardware store like Home Depot, perhaps?
Re:I'm thinking along the same lines as guy. A passive splitter essentially splits the incoming signal's energy into two signals that each have half that energy (which is equivalent to 3dB attenuation). If you don't intent to use that splitter somewhere else, you should also be able use a cable terminator on Out-B. The terminator is essentially a resistor that matches the impedance of the coax. It helps eliminate the signal noise generated by open outputs and should give you back that 3 dB. If that doesn't work, then it may be a shield grounding problem…
Re:Thanks for the information. I know a little bit about this stuff but this is really the first time I've dabbled in any of it hands on.
The current splitter was marked as 3.5 dB at each output, so I'm guessing that means it is stepping down the signal by that much as it passes through. I'll try a 3 dB attentuator and see if it makes a difference before calling up the cable techs.
Re:It sounds like the line in is a little hot (too much signal). When you remove the splitter, the signal (at least) doubles…. overloading the cable modem.
It might also be ground loop or other noise related. The only way to tell for sure is to call the cable company and let them come meter it out and re-balance the line.
You can buy attenuators, usually at 3, 6, 9, 12 db increments to bring the signal level down. From what you've posted so far, a 3db attenuator should work Ok, 6db might be better is the signal is so hot.
If it's a grounding or noise issue, there's a number of corrective actions possible. These tend to be fairly specific remedies, depending on the actual causes.
Good Luck
Scott
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Tags: cable modem service, uhf antenna