- Folded phone line can mess up DSL. - 3 Updates
| Jeff Liebermann <jeffl@cruzio.com>: May 16 07:46AM -0700 On Fri, 11 May 2018 20:34:49 -0400, micky <NONONOmisc07@bigfoot.com> wrote: >But how come it worked fine for the first 3 or 4 days I was back? And >at least 12 hours, maybe 2 days, before I left? Coiling the cord makes something of an inductor. ADSL2+ goes up to 2MHz. If your coil of wire has enough inductance to act as a choke at 2MHz or less, the speed will slow down, but will not quit as it did in your situation. That's because ADSL has 256 "tones" or channels, while ADSL2+ has 512. <https://www.hardwaresecrets.com/how-the-adsl-connection-works/2/> The added inductance might cause the higher frequency channels to drop, but the lower frequency channels and the uplink channels will continue to work. The ADSL modem also contains an adaptive equalizer that will partially compensate for the loss in high frequency channels. You would need to add quite a bit of inductance for the signal to completely disappear. From my experience with DSL, most of the problems come from rotten wire connections and noise coupled from nearby sources. Bad terminals, mangled connectors, weird adapters, crude microfilters, and such are all too common. Since the ADSL apparently quit completely, I would tend to favor a bad connection as the most likely culprit. It could also be your friendly local telco playing with the DSLAM, router, or provisioning, which would also make the internet disappear. I had this happen to me recently which caused me to go through internet withdrawal for about a week. There's also the possibility of local interference. Running the phone line parallel to power lines or other services that use the same frequency range, such as T1, can cause problems. I had someone in another newsgroup ask why her internet would disappear at night. I turned out that when she turned on the lights at night, the associated noisy light dimmer would couple enough junk into the phone line to kill the DSL signal. Rewiring the DSL to a "home run" configuration solve the problem. If the coil of wire were sitting on top of a length of lamp cord attached to a light dimmer, or switching power supply low voltage light, or LED light bulb, you're likely to see some noise coupled to the coil. Even though the balanced pair offers some noise immunity, the lack of a twisted pair (as in CAT5 cable) in most flat phone cords, can make the common mode rejection less effective. I would look for a bad, loose, intermittent, or corroded connection somewhere in the phone line. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: May 16 07:54AM -0700 On Sun, 13 May 2018 03:27:18 -0400, micky <NONONOmisc07@bigfoot.com> wrote: >>couldn't tell from your post. >No. And it worked fine after I took out the extra cable. That's the >point. You also moved the extra cable and connectors, which makes me suspect that an intermittent connection. It takes a minute or three for the ADSL modem to sync after the carrier returns, which makes cause and effect type of troubleshooting rather difficult. You could wiggle the connetions and NOT see any change in the lights on the modem. If you suspect a bad connection, drag out a roll of CAT5 cable, and plug it directly into the phone line where it enters the house (MPOE). Also, disconnect the rest of the house from that might be loading the line. If that works, your problem is somewhere in your inside wiring. If the speed, SNR, noise power, and channel levels improve drastically when you disconnect the hour phone wiring, then you probably are missing a microfilter, have a microfilter installed backwards, or have a bad microfilter. Or maybe you need a better microfilter: <http://802.11junk.com/jeffl/pics/dsl/slides/DSL-microfilters.html> (4 inductors are better than 2). -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| "NY" <me@privacy.net>: May 17 09:41AM +0100 "amdx" <nojunk@knology.net> wrote in message news:pdh7is$29m$1@dont-email.me... > You may have the clue in your response, "excess was coiled up" > A coil of wire makes an inductor. An inductor is an impedance to high > frequencies. Would that apply so much to a two-core cable, where at any instant, a current is flowing one way in one conductor (eg on the way to the appliance) and the opposite way (on the return) in the other? Would the fact that there are two conductors tend to reinforce or cancel the effect? If you have a cable that is too long and don't want to cut it to shorten it, what is the best way of arranging it so as to avoid/minimise inductance? Is it better to arrange it in a zig-zag rather than loops? |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 3 updates in 1 topic"
Post a Comment