dold@mitisft.Convergent.COM (Clarence Dold) (07/07/90)
in article <37442@ucbvax.BERKELEY.EDU>, hegarty@janus.Berkeley.EDU (Christopher Hegarty) says: > > I have a Telebit T2500 on my workstation at Berkeley and another T2500 > at my home six miles away. Both modems are connected to voice-quality > lines via standard jacks. I've been having problems with this setup > and wonder if anyone can help. You might actually have too strong a signal. Check for a dBm level jumper in the modem. Some can drive the line at either -12dBm or -9dBm. Central office equipment is intended to receive -13dBm. If you only have 1 db of loss on your line, the normal -9 setting is too hot, and causing distortion. You can actually measure the loss by dialing in to a special number in your prefix, and measuring RMS volts with a digital meter. I've got the desired readings in a file somewhere, but the name escapes me. All Telco is going to do with their 'adjustments' is to trim your modem output to the proper level. -- --- Clarence A Dold - dold@tsmiti.Convergent.COM (408) 435-5293 ...pyramid!ctnews!tsmiti!dold FAX (408) 435-3105 P.O.Box 6685, San Jose, CA 95150-6685 MS#10-007
njs@scifi.UUCP (Nicholas J. Simicich) (07/12/90)
In article <37442@ucbvax.BERKELEY.EDU> hegarty@janus.Berkeley.EDU.UUCP (Christopher Hegarty) writes: [about a case where he intermittently cannot call one exchange from another, a short distance away.] I have a similar case. I frequently can't call work from home (modems on both end are Telebit Trailblazers, or alternately, T2500's). However, I can call long distance, to another 'blazer in a different area, and there are certain exchanges I never have trouble calling. Furthermore, I have two different phone lines in my home, and I call multiple different lines in that bad exchange, and different lines in that exchange call me, and I also use different modems at each end, if that wasn't already clear. When it fails, all of these combinations fail. When it succeeds, all of these combinations succeed, generally simultaneously. (Other people in my same exchange can't call the remote exchange when I can't call the remote exchange.) (For people in New York, I'm calling from Peekskill, 914-737 or 914-736, and I'm calling to Hawthorne 914-784. Calls to Ossining or Yorktown always work, or fail so intermittently as to not be a problem.) PEP protocol seems to be more likely to succeed than V.32 or slower protocols. When it gets bad, I can't even get through at 300 BPS. It doesn't just turn on or off, but it degrades over as short of a period as five minutes, or as long as a half hour. It stays bad for anywhere between a half hour and a couple of days. I reported this to my phone company. I'm almost 100% sure that it is not my local loop. In California, I had severe problems with a local loop, and it only worked after I ordered dataphone conditioning Type II (which does not seem to be available in New York State). At the time, Dataphone Conditioning Type II was designed to get a Bell 212 modem working, and came with an RJ45S jack. But there, every number I called failed equally well :-). I first reported this before the NYNEX strike. It wasn't fixed in the six weeks before the strike, and it wasn't fixed during the strike. However, about three weeks after the strike, it began working. I was not told what they did to make it work. A number of weeks ago, it quit working again. Last time I called the phone company, all I got was crap, so I decided to let the people in my company who do this sort of thing for a living work on it. Of course, after trying to explain indirectly through them, I decided to call their contact at NYNEX myself. He claimed that there was no notation of my prior problems in my record (although I had escalated as far as phone company management). But he does say that he is going to pursue it and get it fixed, and make a note in my record, so when it recurs again, I will just be able to reference the note. If this does work, I'll let you know the result. I kind of think it might be a clocking problem, with the clocks sliding in and out of sync, but I really don't know. If anyone has any suggestions, I'd like to hear them. But I suspect that whatever problems I'm having sound a lot like Christopher Hegarty's problems. -- Nick Simicich - uunet!bywater!scifi!njs - njs@ibm.com - SSI #OWI 3958