0004133373@mcimail.com (Donald E. Kimberlin) (07/15/90)
In article <Digest v10,iss479>, Andrew writes: >In brief, I have heard that at one time AT&T sent out "cleaning >pulses" in the wee hours of morning to "fuse shorts in the line." >Assuming this is drivel, is there any basis for such a thing? Yep, Andrew, it's more of the drivel that gets made out of stories told and retold by telecommunications incompetents. Like all, it has a shred of truth ... but only way down and way back. Hear this: For starters, AT&T _never_ sent out "pulses" down your local line. Your local exchange telephone company does that. AT&T did, of course, own the twenty-plus local "Bell Operating Companies." These were, in no uncertain terms, captive customers of Western Electric, AT&T's manufacturing company, which in turn had only technology of Bell Labs to sell. So, if Bell Labs dreamed up an improvement to running local phone lines, the Bell companies bought it. A well-recognized problem in running local phone lines is: How does one indeed know when a phone line is bad? Wait for the customer to get to another phone and call? With all good intent, AT&T HQ put this on Bell Labs' plate. Bell Labs came up with an adjunct to its Crossbar-era exchanges (we're talking 1950's technology here) called Automatic Line Insulation Test ... ALIT in the trade. The earliest ALITs were totally mechanical, and scanned the office during wee hours, putting a fairly high-voltage (limited current) pulse on the line to measure the leakage resistance of the wire pair, flagging those in which the leakage was lower than the acceptable level; printing a report, in fact, for the local people to "fix your line before you knew about it." Those are the "pulses," but they don't "fuse the shorts in the line." Somewhere down the story trail to you, the incompetents have mushed ALIT together with the old testboardman's trick of "burning" a noisy pair's loose splices or tree branches of long-gone open wire with about 600 Volts for a moment. ALIT doesn't do that. It just measures. ALIT lives today and is now an electronic "test adjunct" to most every telephone exchange switch. It is even a popular manual test method, called up by remote control to get an evaluation of the condition of your wire pair when you do say the line is "noisy" or "weak." There are test criteria and a large backgound of use of the techniques of ALIT, used by every telco. BUT, honest, dirty truth be known, very few ALITs are running all night to check out your line for you. The local plant people dropped the administrative task of keeping ALIT in automatic operation years ago. If you live in GTE areas, you'll find they now run TX spots showing people snoozing away in bed, happily confident that GTE is "testing their lines silently all night." All that happened was GTE started its ALITs back in automatic mode again! So much for "AT&T pulses that clean your line!"
john@bovine.ati.com (John Higdon) (07/16/90)
"Donald E. Kimberlin" <0004133373@mcimail.com> writes: > If you live in GTE areas, you'll find they now run TX spots > showing people snoozing away in bed, happily confident that GTE is > "testing their lines silently all night." All that happened was GTE > started its ALITs back in automatic mode again! One other aspect of living in a GTE area (other than having my most sincere condolences) is that you will probably get your ear blown off eventually if you talk on the phone late at night. While real telcos will skip busy lines during an ALIT cycle, GTE doesn't seem to deem that necessary. While you are on the phone, suddenly you will hear, "CLICK/CLUNK -- BZZZZT/BLAAAAT". Sometimes you remain connected to your party after all that, sometimes you don't. You sort of ride it out -- like an earthquake. I have a tacit agreement with my friends who call me from GTE areas: since it was their brain-dead company that caused the disconnection, they call me back on their nickel. Preventative Maintenance: Work done by GTE to _prevent_ normal use of equipment. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
ritchie@hpdmd48boi.hp.com (David Ritchie) (07/17/90)
>In brief, I have heard that at one time AT&T sent out "cleaning >pulses" in the wee hours of morning to "fuse shorts in the line." >Assuming this is drivel, is there any basis for such a thing? >Andrew Houghton >(ah0i@andrew.cmu.edu) Actually, many switches have an automatic loop quality test that is done on lines in the early morning hours. I had a friend with a cheap phone who complained about this causing his phones to click at 2 A.M. Dave Ritchie [Moderator's Note: *Something* happens here every morning at 1:37 AM. If I am online to Northwestern at that moment, the modem connection is dropped and I have to dial back in. Every day, no exceptions. I do not know if it is Illinois Bell or something at Northwestern. PT]
kam@dlogics.COM (Kevin Mitchell) (07/19/90)
Hi, Pat.
You may not remember me, but I used to frequent one of your BBSes. I
got interested in this telecom stuff mostly due to an insatiable
curiosity. My Uncle works for IBT, and my new boss at work used to run
the phone systems at NU (do you know Phil Atwood?). Anyway, I think
they do automatic line testing but he said it's only done on unused
lines. At least I'm pretty sure; it was a while back.
Kevin A. Mitchell (312) 266-4485
Datalogics, Inc Internet: kam@dlogics.UUCP
441 W. Huron UUCP: ..!uunet!dlogics!kam
Chicago, IL 60610 FAX: (312) 266-4473
[Moderator's Note: You were a regular on {Lakeshore Modem Magazine}
when I was operating it back in 1984-85. Sorry, I don't know Mr.
Atwood. All I know is what happens every morning at 1:37 AM. :) PT]