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FusionOnRGYB

@sonic.net

Did not think that interior wiring made such a big differenc

I relocated the modem and had to run a new phone jack for it. The old jack was Cat3 from the NID spliced into the old style red/green & yellow/black wire which in turn is connected to several jacks. Old house...the phone jack is one of those gray surface mount boxes and the inside was nothing like the surface mount boxes I see nowadays.

New run is Cat5e terminated at both ends with keystones. This new run also allowed me to use a splitter so I removed the 3 line filters. Only reason I used Cat 5e is because I received it free; but I think the price difference compared to Cat 3 is fairly small.

Anyhow, after support changed the settings for my modem, my speed basically doubled from 6 to 12. Pretty slick.



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:9
Reviews:
·SONIC.NET

It is pretty common to think that with 1000s of feet of often ancient copper wire between the CO and the home the last few feet of wire inside the home wouldn't make much of a difference.
That thinking is probably correct when it comes to Attenuation which is one of the factors that determines your maximum speed. Attenuation is the weakening of the signal over distance and without moving home this isn't ever going to change.
However every bit as important for speed is the amount of Noise on the line. Noise can come from external sources (light dimmers are a well known problem for DSL) and get injected into the line if the copper wires aren't twisted (by twisting the pairs external signals tend to affect both wires equally and the noise cancels each other out, so called common mode noise). However noise from external sources tends to only affect some frequencies, leaving much of the wide band used for DSL intact.
The most misunderstood part of Noise on a DSL line and the importance of good inhouse wiring is noise that is generated from the DSL signal itself. One problem that is common whenever you attempt to transmit high frequency signals over copper wires is that at any point where the continuity of the wire is disturbed (plugs, splices) a portion of the signal is being reflected back in the direction where it came from. This happens especially at the very end of the line where the reflections tend to be strongest. In a house where the phone line is split in star topology from the NID to all the outlets you multiply the problem by the number of outlets since you have now multiple ends of the line. Even in a house with daisy chain wiring from outlet to outlet you have some of this problem for each used outlet and the last one in the chain. The special problem with noise generated from the DSL signal itself is that it has exactly the same frequencies as the good signal you want to receive but it is time shifted and corrupts the data. This is why noise from reflections can reduce usable bandwidth in such a significant way.

The Cat3 cable is twisted pair and fine for DSL. The key difference between your old and new setup is the use of a splitter to keep the DSL signal from all the phone outlets on the old style phone wiring.

Good job on doubling your speed!
--
Got some spare cpu cycles ? Join Team Helix or Team Starfire!



FusionOnRGYB

@sonic.net

There are sets of two wires coming off the NID for phone service, one was reg green/yellow black that services the phone in the front of the house and a Cat3 that runs about 3/4 the way to the back where it splices into another 4-color wire that services two bedrooms (one used as an office). I suspect this was added on later as a repair so there is still another 30 or 40 ft of red-green wire from this junction as it follows the base board to where the modem was previously plugged.

You said that any point where the copper is discontinuous causes reflections. Does that mean if wires are soldered rather than connected with the gel-filled Scotchlok connectors there will be less reflections?

As it stands here's how the setup looks:

NID -> UTP cross connect wire -> DSL Splitter -> flat phone cable -> keystone -> Cat5e -> keystone -> flat phone cable -> modem

I've removed the biggest offenders to the DSL signal, but if I replace both pieces of flat phone cable with Cat3 will there be any significant improvement at this point? The section between the modem and jack is about 6 to 7 ft from a dimmer. I have a 25-ish foot section of Cat 3 I was using for phone cord that I made. I have the connectors and tools to attach RJ12 connectors and RJ45.

The DSL splitter has the option of using screw posts or mod-plugs for all three connections, is there advantage to using either side?



DaneJasper
Sonic.Net
Premium,VIP
join:2001-08-20
Santa Rosa, CA
kudos:9

For best performance and reliability, eliminate all flat phone cable - six feet or less of it is "okay", but even that isn't ideal. (Our new modems include a 12 foot twisted-pair line cord.)

-Dane



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:9
Reviews:
·SONIC.NET
reply to FusionOnRGYB

said by FusionOnRGYB :

You said that any point where the copper is discontinuous causes reflections. Does that mean if wires are soldered rather than connected with the gel-filled Scotchlok connectors there will be less reflections?

Any splicing regardless of method will cause some small amount of signal degradation and reflection. The idea is to keep the number of splices low and not necessarily to worry too much about which method of splicing is better. The gel-filled connectors are fine and this is what I used too.
The same applies to the question of screw contacts versus modular plugs. The difference is probably small enough to use whatever is more convenient.

said by FusionOnRGYB :

I've removed the biggest offenders to the DSL signal, but if I replace both pieces of flat phone cable with Cat3 will there be any significant improvement at this point?

It would certainly be better if those two sections were twisted pair cable as well but it is hard to say whether it would improve your speed significantly (or at all). It will mostly make your line more resistant to interference from external noise. However if there isn't any such noise causing interference right now it could mean a lot of effort and no gain in performance to show for it.
--
Got some spare cpu cycles ? Join Team Helix or Team Starfire!


FusionOnRGYB

@sonic.net
reply to DaneJasper

For clarity, you mean to eliminate any flat cable for the modem right?

I'm thinking it should not matter for anything on the voice side of the splitter like my fax.



FusionOnRGYB

@sonic.net

I was digging around and the phone cable that came with my old AT&T modem is round rather than flat. Is this necessarily Cat3?



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:9
Reviews:
·SONIC.NET

There is no guarantee that a round phone cable actually consists of twisted pairs.
Ideally if it came with a DSL modem it should be a twisted pair cable but it would not surprise me if some vendors would cut corners even there.
Quality cable will have certifications and ratings printed along the length of the cable.
--
Got some spare cpu cycles ? Join Team Helix or Team Starfire!



FusionOnRGYB

@sonic.net

Replacing the flat cable from the splitter to the Cat5 with Cat3 with RJ11 on one end and bare wire into screw post terminal on the other made no difference according to the line stats. I don't know what I was expecting to see, but I suppose increased resistance to noise is a good thing since I cannot predict it. All my findings are on quiet Saturday evening and Sunday afternoon when the nearby laundry machines and fluorescent lights were not operating.

As for the round phone cord, the only thing I can make out is "TIA568B2" and "Cat.5 28AWG". I put this between the wall jack and the modem and compared to flat cable, I did not notice any difference.

Here is Cat3 from the splitter to the Cat5e
»i.imgur.com/0SdsZ.png

Flat cable at the same location.
»i.imgur.com/XTY8L.png



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:9
Reviews:
·SONIC.NET

It did have a measurable impact after all, even if it is only a 0.2dB improvement in noise margin (every little bit helps) and a slightly higher attainable rate (theoretical maximum speed).

The TIA568B2 indicates that the cable conforms to EIA/TIA specification 568B with the suffix 2 indicating that the cable only has 2 instead of the normal 4 pairs. Cat.5 means that this is a twisted pair cable meeting the tighter specifications for Cat5 cable. 28AWG is the size of each copper wire. This is definitely a good cable to use for your DSL modem.
--
Got some spare cpu cycles ? Join Team Helix or Team Starfire!



NormanS
I gave her time to steal my mind away
Premium,MVM
join:2001-02-14
San Jose, CA
kudos:11
Reviews:
·SONIC.NET
reply to DaneJasper

said by DaneJasper:

For best performance and reliability, eliminate all flat phone cable - six feet or less of it is "okay", but even that isn't ideal. (Our new modems include a 12 foot twisted-pair line cord.)

That reminds me: GF has a six-conductor flat phone cable to the NID. Strangest thing I ever saw, and terminated with a 6P6C plug (I learned that terminating all six is called, "RJ-25")!

I brought over some remainder CAT-5e cabling from wiring my mother's house. I still need to replace that RJ-25 run with the CAT-5e.
--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum


DaneJasper
Sonic.Net
Premium,VIP
join:2001-08-20
Santa Rosa, CA
kudos:9

We have seen customers use 50 foot Radio Shack "telephone extension cable" to hook up their DSL modem - result is really, really poor performance. Twisted pair is best, and we suggest a maximum of six feet (a typical line cord) of "flat satin".



FusionOnRGYB

@sonic.net
reply to NormanS

I used 6P6C flat phone cables at my last job for digital telephones. The 6P4C cables did not work for those phones.



FusionOnRGYB

@sonic.net
reply to leibold

Thanks for the help leibold! My line is about as good as I care to make it. I did not think that 0.2dB makes any difference because I think that number tends to fluctuate.

I guess another option would be to plug the modem into the splitter and then use the wire run I made for fast Ethernet to the router.

BTW, are the red/green and yellow/black cables twisted pair?



NormanS
I gave her time to steal my mind away
Premium,MVM
join:2001-02-14
San Jose, CA
kudos:11
Reviews:
·SONIC.NET

said by FusionOnRGYB :

BTW, are the red/green and yellow/black cables twisted pair?

Not as far as I know. I think it is also called, "station wire", and has no "twist" standard.
--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum

eugenek

join:2002-06-14
Palo Alto, CA
reply to FusionOnRGYB

said by FusionOnRGYB :

I guess another option would be to plug the modem into the splitter and then use the wire run I made for fast Ethernet to the router.

this sounds like a good option - placing the modem at the NID

bswp

join:2010-11-28
Berkeley, CA
reply to FusionOnRGYB

"I guess another option would be to plug the modem into the splitter and then use the wire run I made for fast Ethernet to the router."

Sure, but if your modem is the ZyXel with wifi that Sonic provides for Fusion service, then you may have issues getting the signal where you want it. OTOH, if you just run fast ethernet to a router w/ wifi, good to go.