kinstrey@wsqtba.crd.ge.com (M. A. Kinstrey) (12/13/89)
I have a telephone which had been dropped a few times, and the bell-ringer arm had bent somewhat. I bent it back as best I could, and the phone works just fine. I have noticed, however, that every night between 11:35pm and 11:45pm (Usually 11:35pm) the bell weakly rings twice. "Tink... Tink". Every night like clockwork. The weak ring suggests to me that the pulse is lower than phones should ring at, but since my ringer is so close to the bell, a lower pulse sets it off. Anybody have any ideas? Does the phone company pulse their lines to check connectivity or something? ------------------------------------------------------------------------------ kinstrey@wsqtba.crd.ge.com | "Balls." said the queen, "Balls." kinstrey@wsqtba.UUCP | "If I had them I'd be King." ___________________________|__________________________________________________
wiml@blake.acs.washington.edu (William Lewis) (12/14/89)
In article <4208@crdgw1.crd.ge.com> kinstrey@wsqtba.crd.ge.com (M. A. Kinstrey) writes: >I have noticed, however, that every night between >11:35pm and 11:45pm (Usually 11:35pm) the bell >weakly rings twice. "Tink... Tink". Every night > >The weak ring suggests to me that the pulse is lower than >phones should ring at, but since my ringer is so close >to the bell, a lower pulse sets it off. The same thing happens here (Seattle, Wa., for those who can't see the header =8) ) at about 12:00-1:00 at night, every night. (I have one of those hyper-cheap phones hanging off of my modem line, and if I'm awake and offline at that time, the over-sensitive ringer will make a few sickly beeps ... this is a very sensitive ringer: it rings from pulse dialing, even ... ) I don't have any idea what it's caused by, though... --- phelliax -- wiml@blake.acs.washington.edu (206)526-5885 Seattle, Washington
dplatt@coherent.com (Dave Platt) (12/15/89)
In article <4910@blake.acs.washington.edu> wiml@blake.acs.washington.edu (William Lewis) writes: > The same thing happens here (Seattle, Wa., for those who can't see > the header =8) ) at about 12:00-1:00 at night, every night. (I have > one of those hyper-cheap phones hanging off of my modem line, and > if I'm awake and offline at that time, the over-sensitive ringer > will make a few sickly beeps ... this is a very sensitive ringer: > it rings from pulse dialing, even ... ) This was discussed in comp.dcom.telecom some time ago. As I recall, the explanation is that the telco sends a measured voltage pulse down the phone lines periodically. By measuring the current flow and certain other things, they can check the quality of the phone line and detect some physical problems as they develop (e.g. insulation failure, etc.). The phone-switch in your central office does this automatically, at a time when the line is idle (usually late at night), and enters a trouble-report in the database if anything unusual is detected. The voltage-pulse used for this purpose is small enough that it won't cause phones to ring, _if_ their ringers comply with Bell standards. Many don't. In particular, cheap phones often use piezoelectric beepers hooked up in series with a capacitor; these will often "chirp" whenever there's a small voltage-change on the phone line. -- Dave Platt VOICE: (415) 493-8805 UUCP: ...!{ames,apple,uunet}!coherent!dplatt DOMAIN: dplatt@coherent.com INTERNET: coherent!dplatt@ames.arpa, ...@uunet.uu.net USNAIL: Coherent Thought Inc. 3350 West Bayshore #205 Palo Alto CA 94303
dleblanc@joplin.mpr.ca (David LeBlanc) (12/15/89)
In article <42002@improper.coherent.com> dplatt@coherent.com (Dave Platt) writes: >This was discussed in comp.dcom.telecom some time ago. As I recall, >the explanation is that the telco sends a measured voltage pulse down >the phone lines periodically. By measuring the current flow and >certain other things, they can check the quality of the phone line >and detect some physical problems as they develop (e.g. insulation >failure, etc.). The phone-switch in your central office does this >automatically, at a time when the line is idle (usually late at night), >and enters a trouble-report in the database if anything unusual >is detected. Yup, its technically called "Time Domain Reflectometry". Any transmission line has two important properties : a finite propagation velocity and a characteristic impedance. When energy impinges upon an interface between two transmission lines of differing impedance a portion of the energy is reflected and a portion is transmitted (the exact proportions determined by the impedance mismatch - a dead short or open results in 100% reflection - a perfect match results in 100% transmission). The telephone cable is a transmission line. By launching a pulse which propagates down the line at a known velocity and by measuring the reflections sent back and the time at which they arrive back at the central office (eg. microseconds later) locations and severities of faults can be determined amazingly accurately. There are optical TDR systems for fiber which can resolve position down to millimeters and losses (reflections) down to < 1dB !! Have fun with your chirps. Dave LeBlanc dleblanc@joplin.mpr.ca
witters@tc.fluke.COM (John Witters) (12/16/89)
In article <42002@improper.coherent.com> dplatt@coherent.com (Dave Platt) writes: >This was discussed in comp.dcom.telecom some time ago. As I recall, >the explanation is that the telco sends a measured voltage pulse down >the phone lines periodically. By measuring the current flow and >certain other things, they can check the quality of the phone line >and detect some physical problems as they develop (e.g. insulation >failure, etc.). The phone-switch in your central office does this >automatically, at a time when the line is idle (usually late at night), >and enters a trouble-report in the database if anything unusual >is detected. Of course, one of the physical "problems" that can be detected is whether there is more than one bell connected to your phone line. The Phone Company (tm) probably used this technique to find out about "illegal" extension phones in the bad old days when TPC had a monopoly on all phone equipment. Now days, since you don't have to lease your phones from TPC, they probably don't care how many phones you have attached to your line. The only thing TPC cares about is whether your equipment will damage TPC's equipment. -John -- * * * John Witters voice: (206) 356-5274 * \ * John Fluke Mfg. Co. Inc. * \ * P.O.B. C9090 M/S 245F fax: (206) 356-5116 * P A G\I N G * Everett, Washington 98206 or (206) 356-5174 * \ * * \ * domain: witters@fluke.COM * * * uucp: {sun,microsoft,uw-beaver}!fluke!witters
Nagle@cup.portal.com (John - Nagle) (12/22/89)
The basic measurements made from the CO are usually the
DC resistance and AC impedance between tip, ring, and ground.
From this you can usually tell how things stand on the line.
A standard ringer, as in a WE 600 phone (the "Traditional"),
draws "one Ringer Equivalence Unit". The usual phone line
provides six Ringer Equivalence Units. As long as you have
less than 6 REU on-line, the telco will be happy. Most modern
phones draw less than one REU. If you really have more than six
telephones, the central office will be undamaged but your phones
may not ring. Some central offices may notice the problem, after which
they will probably try to sell you a small PBX and multiple lines.
John Naglelarry@kitty.UUCP (Larry Lippman) (12/23/89)
In article <1967@eric.mpr.ca>, dleblanc@joplin.mpr.ca (David LeBlanc) writes: > >This was discussed in comp.dcom.telecom some time ago. As I recall, > >the explanation is that the telco sends a measured voltage pulse down > >the phone lines periodically. By measuring the current flow and > >certain other things, they can check the quality of the phone line > >and detect some physical problems as they develop (e.g. insulation > >failure, etc.). The phone-switch in your central office does this > >automatically, at a time when the line is idle (usually late at night), > >and enters a trouble-report in the database if anything unusual > >is detected. > > Yup, its technically called "Time Domain Reflectometry". Both of the above posters have described the operation of a TDR (Time Domain Reflectometer). HOWEVER, the CO apparatus responsible for line insulation testing (ALIT), does NOT operate on the principle of a TDR. ALIT apparatus measures the leakage of Tip and Ring to ground, generally using a measuring circuit which applies DC excitation. An optional ALIT function is the measurement of foreign potential (FEMF) - which is indicative of leakage resistance to adjacent cable pairs. The "chirp" in the el cheapo telephone ringers is caused by the momemntary interruption of line relay (or ESS supervision) voltage, followed by application of ALIT test voltage, following by reapplication of line relay voltage. While a TDR will detect various types of cable faults, it is generally impracticable for for routine ALIT testing. Furthermore, the automatic analysis of a TDR signature is complex, and there are no off-the-shelf systems for automated telephone pair testing which employ a TDR, anyhow. In addition, while a TDR is useful, it has distinct limitations when applied to testing of cable pairs, with such limitations including but not limited to: distance, inability to pass through more than one loading coil, susceptibility to crosstalk interference from adjacent working, and inability to function in the presence of FEMF leakage. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {boulder|decvax|rutgers|watmath}!acsu.buffalo.edu!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
jim@mmsac.UUCP (Jim Lips Earl) (12/24/89)
Is that why my chirp-ring phone chirps ONE time around 1:10am each night?
How often do they do this?
--
Jim "Lips" Earl UUCP: ucbvax!ucdavis!csusac!mmsac!jim
KB6KCP INTERNET: mmsac!jim@csusac.csus.edu
=======================================================================
The opinions stated herein are all mine.larry@kitty.UUCP (Larry Lippman) (12/26/89)
In article <2922@mmsac.UUCP>, jim@mmsac.UUCP (Jim Lips Earl) writes: > Is that why my chirp-ring phone chirps ONE time around 1:10am each night? That's why there is one chirp. Most ALIT apparatus uses a DC excitation voltage between 24 and 50 volts (not necessarily the same as CO battery, however). Since minimizing test time per line is of importance in the design of ALIT apparatus, the excitation voltage is often applied of *opposite* polarity in order to rapidly counter the telephone line capacitance. Therefore, the chirp is usually caused by the reversal of polarity on the telephone line - which acts, in effect, like one cycle of ringing voltage. Mechanical ringers will not respond this fast, and neither will *well-designed* electronic tone ringers. > How often do they do this? Generally, once per night. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {boulder|decvax|rutgers|watmath}!acsu.buffalo.edu!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"