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General discussion

dsl distance

May 19, 2005 6:10AM PDT

Hi I just got on dsl in the country and I am about 3 miles from the telephone office. I signed up for 1.5 and am geting anywhere from 1.1-1.3 i know this is good but am wondering how it works so far from the office??? rocky

Discussion is locked

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(NT) (NT) 3 miles I understand. What are the other numbers of?
May 19, 2005 6:32AM PDT
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Most phone companys
May 19, 2005 12:24PM PDT

use RT's (Remote Terminal)to boost the signal. If you're more then 12,000' or so from the phone co. and have a RT near by, then DSL is avalable to you. I've seen some people that are 18,000' from the CO. and not on a RT, that still get good speeds, because their lines (from CO. to their NID) are in real good shape. 1.1 to 1.3 speeds are about correct for a 1.5 line.

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Uh, sorry, but nope. . .
May 20, 2005 9:11AM PDT

RTs are not compatible with ADSL.

RTs such as SLC-96, Series-5 and DISC*S multiplex the voice frequencies into a T-1 type of signal. Voice frequencies in the 200-3400 Hz range work perfectly and have since 1957 when T-1 was invented.

ADSL is an analog signal in the 80 KHz to 1.1 MHz bandwidth. RTs don't even hear the signal.

ADSL will work out to about 17,500 feet from an central office.

Now.

The newer technology using fiber will handle the voice and the ADSL signal, and T-1, and anything you want to push through the fiber. But it's not deployed in a large area. The latest offering is called FTTP, Fiber to the Premises. It's on the fast track for obvious reasons. But don't expect it to replace the gazillion miles of copper already in the ground.

Go to my site below and scroll down to the "A Short Course in DSL" link.

Wayne

Give a person a fish and you feed them for a day; teach that person to
use the Internet and they won't bother you for weeks.

Click here to see the CNet faces, learn a little about telephones, internet
connections and data, and download free software.

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You're telling me that
May 20, 2005 12:22PM PDT

DSL is not run through or compatible with a RT?
DSL here and all over SBC land is run through RT's.

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Yep, I am. . .
May 20, 2005 7:11PM PDT

Hey Ed,

RTs listed there are not compatable with DSL. As mentioned above, these RTs deal in voice band frequencies only. As I said, an RT converts the analog voice frequencies to a T-1 signal. The analog bandwidth has to be in the voice band of 200-3400 Hz. ADSL is waaaaaaay outside the voice band.

Some of the newer systems, I believe the latest is called LightWave-2000 (doing this off the top of my head) will handle any type of signal. But it's not generally used for residential services, only high capacity business applications.

The link in the broadbandreports is in error when it mentioned extending the DSL signal. It just ain't going to happen.

Wayne

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I asked the SBC/SNET techs
May 21, 2005 6:40AM PDT

[quote]He is mixing up terms there, between what we in this state refer to as an RT is as you describe, for DSL. The gear he's referring to we refer to as a SLC (slick) or subscriber line concentrator which is similar though for dialtone and have been around for decades.. Apples and oranges....[/quote]

[quote]Not to mention we currenty fit SLC with new cards in areas w/o a DSL RT & they then can serve DSL & pots. Also, a Lightspan RT can be fed by T1 or fiber.[/quote]

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Ohhhhhhh, those guys. . .
May 21, 2005 11:22PM PDT

Since I taught courses for SBC in most states, you may have talked to someone I had in my class.

Let's get back to the original question.

Pair gain devices were designed for analog signals; voice. They took 24 to 48 voice lines, multiplexed them into a digital signal, and sent them over 4 wires, two for transmit, two for receive. The terms were as I mentioned above.

Now.

The newer technology can and does incorporate the higher level signals including DSL. I remembered a newer one from ATT/Lucent called AnyMedia. It uses an OC-3 and OC-12 (this is the last thing I taught for Fujitsu) or higher fiber ring and can carry just about anything. Including an RT for DSL.

Apples and oranges? Definately. But the original Pair Gain devices are still in use and will not carry a DSL signal.

Wink

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Well then. That explains it
May 22, 2005 10:47AM PDT

A few years back I used dial-up and had a second line installed for business voice and internet use. My USR modem was happily negotiating V.90 and speeds in the high 40s. Suddenly, I dropped back to V.34 and low 20s speeds. I called SBC to complain but they said they could do nothing because spec called for 14.4 only. They suggested I check to see if DSL was available. I suspected an SBC plot was in action.Happy I called and was told DSL was available to me as I was near enough the CO and they sent me out a kit with a zillion filters, a modem, and software. Not wanting to hang filters off all my 2 line phones, I rewired line 2 using 1 filter for all the voice connections and ran a dedicated unfiltered line to the DSL modem...in other words, I prepped the place as some cost. When the "go live" date arrived, nothing happened. I called SBC and they said they had made a mistake....that I could not have DSL. When I finally got to a person that seemed to be knowledgable, he said it was because I was on a "pair gain" connection and there were load coils and something about litespan. They had been working in a hole down the road and I knew they had been agressively pushing DSL service to compete with Time Warner's service. So, I thought the activity was to install new technology to bring DSL to more potential customers. Wrong! It turns out that the old copper had run out of available pairs as more folks wanted extra land lines plus there was no more business expansion capabilites. So, I guess they just MUXed what they had as a stopgap. They would not admit it but I suspect that this new equipment also is what killed my V.90. dial up negotiation. Anyway, I have cable now getting 4500kpbs down. Take that, SBC!Wink

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Pair Gain & DSL
May 24, 2005 7:12AM PDT

As a DSL Tech in the Atlanta area I must tell you we have been placeing the DSL signal at the RT since the first days of DSL. SLC 96 was the first system to carry DSL. A special heat coil is placed on the frame at the RT site which replaces the original heat coil with a jumper from the DSL cabinet direcly on to the cable pair and SLC card with the dial tone. It works with SLC 96, series 5, light spain, fujitsu, all remote terminal cards work the same. Im not talking apples or oranges, dialtone is dialtone and it doesnt matter where you add the DSL circuit be it in the CO or at the RT, the band width allowes it to ride the dial tone. By the way I am a 32 year veteran of BellSouth.

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Well, hmmmmm. . .
May 25, 2005 4:36PM PDT

SLC-96 is a T-1 device. 96 voice circuits in one cabnet fed by 8 wires. Series-5 is the same, but the cards are physically half the size. DISC*S handles 672 circuits and can be fed by fiber, and is software controlled.

Pray tell me how you can get a T-1 (D-4) card to handle the 80 KHz to 1.1 MHz signal of ADSL.

Lightspan is getting close because of the bandwidth of the OC-3 signal, and the Fujitsu FLM-150 (OC-3) and 600 (OC-12) could handle the traffic, but only if there was a DSLAM involved in the field.

Back to square one. ADSL will not pass through a SLC-96 or Series-5 without more bandwidth and more magic.

This is from my site:

Analog signals can be multiplexed too. The combining of several frequency bandwidths into one larger bandwidth is called Frequency Division Multiplexing. This is how DSL works. A frequency range (bandwidth) of 80,000 Hz to 1,100,000 Hz is the carrier frequency. This larger bandwidth is broken down into 256 specific bandwidths, and each one can carry up to 15 bits of data. In the event that noise affects a specific frequency, bit robbing occurs (bits are removed from the noisy frequencies and placed into quieter frequencies). Because the carrier frequency is so high, up to 1.1 MHz, the data speed is correspondingly high. This function is called DMT, or Discrete MultiTone. This is also why you do not share a connection like cable modems. You have full use of your connection and the entire bandwidth.

When you purchase DSL from your phone company or any other provider, dial tone is also placed on the telephone cable pair (if you have chosen this option). Voice frequencies, 200 to 4000 Hz and the DSL signal are multiplexed into one composite signal. This is done at the telephone office by a device called a DSLAM, Digital Subscriber Line Access Multiplexer. This device is also connected to the high speed ATM (Asynchronous Transfer Mode) switch (see VDSL above) and is then connected to the Internet. The DSLAM splits the signal sending dial tone to the telephone switch and the DSL signal to the Internet.


For the complete text, visit my site below.

Give a person a fish and you feed them for a day; teach that person to
use the Internet and they won't bother you for weeks.

Click here to see the CNet faces, learn a little about telephones, internet
connections and data, and download free software.

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Pray tell, are we at odds, or just a misunderstanding?
May 26, 2005 8:30AM PDT

I think we are misunderstanding each other on this. Your description of T-1's and SCL 96/series 5 is right on...I have installed many T-1 to turn up an RT site for both. I also know the dial tone coming out of any DLC can carry DSL from the DSLAM to the outgoing cable pair. Every RT in Atlanta Metro has a DSLAM that the pair gain system can access, be it SLC 96, series 5, Fujitsu, Lightspan. It makes no differance. They all work.

I could not have explained what an RT is any better than the link which Ed Mead gave us. Thanks Ed!
also here is an article I found which adds insight to your link.

From Telacommunications Magazine:

As the broadband marketplace evolves, carriers are turning their attention toward boosting market penetration and revenue streams from suburban and rural markets. Incumbent telco providers see the chance to move ahead of cable MSOs because of the ubiquitous reach provided by existing POTS copper loops. However, for a significant percentage of subscribers, the older legacy equipment serving their areas and/or the length of the copper loops can make it difficult to maximize coverage economically in many suburban and rural areas.

Although overall DSL penetration has been increasing during the past five years, most of the activity has focused on CO-based deployments. COs typically address large, high-density areas consisting of many thousands of subscribers over which to amortize capital and facility investment. Whenever telco providers have addressed RT (remote terminal) deployments, they have focused on RTs with widely deployed DLCs (digital loop carriers) such as first generation SLC 96, Lucent?s SLC

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Hey there, back to you. . .
May 26, 2005 11:58AM PDT

New tech is so hard to keep up with. Very interesting excerpt.

Thanks for the reply and the visit to my site, it was fun to build. Have a good one yourself, I plan to smoke a brisket on Pecan and down a few cold ones.

Wayne

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Thinking alike!
May 26, 2005 12:29PM PDT

Sounds like "old phone men" think alike! Im gona smoke some ribs and throw on some Brats! And have a couple a cold ones myself!

Have a good one...

Tom

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This is the RT's I'm talking about.
May 20, 2005 1:14PM PDT