Charles A Taylor wrote: > I have three jacks (plus a phone on one) paralleling my PC's access jack. > Some 75 feet of excess pair. But, on the other hand, I'm only 1/3 mile from > 919-524-XXXX switchstation. That connects to Kinston (NC) via fiber. > (Embarq/Carolina Telephone & Telegraph).
If it works I wouldn't worry about it :) You have a short run there. Telco lines are really balanced transmission lines, and as such need the same sorts of care that RF transmission lines do to get the most out of them. You want to maintain balance. Standing waves can occur on audio transmission lines, too. If they do at a high enough level and with a sufficient phase shift, this will degrade modem performance. This can occur because of unterminated runs of wire, telephone devices with poor or non-standard values of termination, etc. Any telco wiring run that runs in close proximity to noise producing devices in the home and has environmental effects that cause it to be unbalanced even slightly can fail to use the inherent common-mode noise rejection ability of the telco balanced line. If this happens you'll have a noisy line and this will affect your modem. I've seen poorly designed telephone devices cause line issues, and some so-called telco surge suppressors too. (get a good gas-discharge suppressor and install it at the demarc.) Most of the time if folks have a second phone line for data most of this is moot as that line will run directly to the modem. Keeping some of this in mind might help when looking to maximize connect speeds. And as I mentioned the speed reported on connect is not the speed the line may be running at at the current time. The modem will train upward and downward as line conditions change. Not all cheap modems will re-train up if conditions improve. So there really can be advantages to getting yourself a really good modems on some lines (the argument could be made this to some extent is true for all lines). These issues (noise, loading, unbalance, messed up baseband) can also occur out on the telco plant, but at least if your own home is in order, you know where the problem is. The best way to test the telco part of the line is using a TIMS (transmission impairment measurement set) and see how the line looks. Any telco tech will have one (I'm lucky enough to need one so I have my own an HP4934A). There are standards a line needs to meet and if it doesn't, then having the measurements can be a way to force the telco to do the repairs. I have a lot of issues like this on leased lines for public safety remote base connections back to a central Motorola CEB (Central electronics bank). Unfortunately most homes aren't wired so that disconnecting unused lines is easy, most being daisy chained. This in itself isn't too bad if the end of the daisy chain is terminated into a telephone device of decent quality. On the dial-up setups I've had I either had a dedicated second line for the dial-up or one way or another disconnected the internal telco devices from the premises wiring at the demarc and had only the modem connected during the times I was using the dial-up. As was mentioned, some ISPs will allow line-bonding to allow you to dynamically bring up a second dial-up line up and bond the lines together during times of higher demand to balance the load, but finding one that allows this is getting harder and harder to do. With some ISPs both connections must come into the same modem rack at the POP, and special arrangements usually have to be made. Almost always at additional cost. Pretty soon, you are at the cost of cable access or ISDN. Really, if higher speed access is available it is a genuine bargain. Cable Internet access costs may seem high, but a commercial line at 25% the capacity of the typical burstable cable or DSL connection is many magnitudes of expense higher. Broadband, if you can get it, really does open up new worlds of possible uses for your computer or home network. I've generally had a home network going at all of my homes, whether using dial-up or higher speed access methods. I've found this to be invaluable for so many reasons. Most folks don't think that you can have a top-quality 100 Mbps or faster home network running behind a real top-quality hardware firewall offering enterprise level services (transparent proxy caching, DNS caching, intrusion detection, real IPtables, etc.) and protection almost for free and dead simple to maintain and setup, and still use dial-up for accessing the Internet at large. The home network alone is worth the trouble of setting up an installation like this. Not to mention the speed up that the caching offers. Moving files, remote controlling devices, radios, wireless, etc, all can be accomplished even on a dial-up based mixed OS network. Anyway... back to radio... don't want to risk getting too off-topic :) Rick Kunath > > 73, > > Charles > > At 08:31 PM 2/14/2007 -0500, you wrote: > > > >>"If you are stuck with dial-up or ISDN, and want to maximize what you have, >>email me off list and we can discuss some of the options that are easily >>implemented dirt cheap to make things lots better than your current setup. >> >>Rick Kunath" > > > ----- > Charles A Taylor, WD4INP > Greenville, North Carolina > > > _______________________________________________ > IRCA mailing list > [email protected] > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the original > contributors and do not necessarily reflect the opinion of the IRCA, its > editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: [email protected] > > _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
