TELECOM Digest Tue, 18 Jan 94 01:43:00 CST Volume 14 : Issue 38 Inside This Issue: Editor: Patrick A. Townson CA State Report on LA Quake (Mike King) Los Angeles Earthquake, January 17 (Nigel Allen) More on the LA Earthquake (Robert L. McMillin) FYI AT&T Reduces LA Quake Services to 203, 310, 805 and 818 (Dan Arthur) Still Alive (Lauren Weinstein) Book Review: "Basics Book of Frame Relay" by Motorola (Rob Slade) DBS Satellite Services in Europe (Alfredo E. Cotroneo) Case History of a Phone Rip-Off (Part 1) (David L. Kindred) Cost of GTE Dialup Lines (Charles M. Hatcher) Shannon and Echo Canceller Protocols (Arnim Littek) More on Communication Over Power Lines (Michael Duane) V.32vis -> Bell_102 Due to CO Data Compression (Ross Porter) TELECOM Digest is an electronic journal devoted mostly but not exclusively to telecommunications topics. It is circulated anywhere there is email, in addition to various telecom forums on a variety of public service systems and networks including Compuserve and GEnie. Subscriptions are available at no charge to qualified organizations and individual readers. Write and tell us how you qualify: * telecom-request@eecs.nwu.edu * The Digest is compilation-copyrighted by Patrick Townson Associates of Skokie, Illinois USA. We provide telecom consultation services and long distance resale services including calling cards and 800 numbers. To reach us: Post Office Box 1570, Chicago, IL 60690 or by phone at 708-329-0571 and fax at 708-329-0572. Email: ptownson@townson.com. ** Article submission address only: telecom@eecs.nwu.edu ** Our archives are located at lcs.mit.edu and are available by using anonymous ftp. The archives can also be accessed using our email information service. For a copy of a helpful file explaining how to use the information service, just ask. TELECOM Digest is gatewayed to Usenet where it appears as the moderated newsgroup comp.dcom.telecom. It has no connection with the unmoderated Usenet newsgroup comp.dcom.telecom.tech whose mailing list "Telecom-Tech Digest" shares archives resources at lcs.mit.edu for the convenience of users. Please *DO NOT* cross post articles between the groups. All opinions expressed herein are deemed to be those of the author. Any organizations listed are for identification purposes only and messages should not be considered any official expression by the organization. ---------------------------------------------------------------------- From: mk@TFS.COM (Mike King) Subject: CA State Report on LA Quake Date: Mon, 17 Jan 1994 16:06:01 PST Passed along FYI: FROM: Governor's Office of Emergency Services, Sacramento STATE OFFICE OF EMERGENCY SERVICES STATUS REPORT AS OF JANUARY 17, 1994, 1130 HOURS SAN FERNANDO VALLEY EARTHQUAKE 1. Proclamations/Declarations 1. Local Declarations - County & City of Los Angeles, City of Hawthorne, County of Ventura 2. Governor's Proclamation of a State of Emergency - County of Los Angeles 2. Disaster Assistance Programs/Facilities 3. Dead/Injured 3 - 19 fatalities reported--not confirmed. 4. Evacuations (See medical) 5. Damages/Incidents OES Fire reports 70+ structures involved or down from fire. All fires under control. LA City - 100 incidents reported. Numerous building collapses; mainly in north area. Ranging from single family homes to larger structures including an apartment building and Northridge shopping mall. People trapped. Partial collapse to pancaking. LA County - City of El Monte--unreinforced masonry moderate damage. Cities of Sierra Madre and Alhambra--broken glass in business districts. Ventura County - Fillmore hardest hit; partial collapse of Fillmore Hotel. Petro chemical plant at SR 126 and Santa Clarita; potential chlorine release. Fire at El Dorado Mobile Home Park, Fillmore. Saugus - 1,000 hydrocloric acid and 500 gallon of sodium hyperchloride spill. Lake Castaic - Ruptured tank - crude oil spill with one-mile plume (unconfirmed). Valencia - pipeline rupture, crude oil. Oil flowing into Santa Clara River. Three more pipeline leaks in Newhall, Pyramid Lake, and Quail Lake (I-5 & SR 138). Train derailment 5,000 gallon acid sulfuric acid - Northridge. State Facilities--Have inspected three major state buildings. Los Angeles State Building and Ronald Reagan Building - no power; Long Beach State Building - no reports of damage. Three sites damaged (Santa Monica, Culver City, and Inglewood). California Aqueduct overpassing cracked at Silverwood Lake to Bakersfield. Counties of Orange, San Bernardino, San Diego, Riverside, Santa Barbara, Imperial, Mono, Inyo, San Luis Obispo- Report no major damage. 6. Care & Shelter American Red Cross identifying shelter sites; have experienced power problems at their Headquarters in Los Angeles. 4 shelters open--Sylmar High School; Canoga High School; Simi Valley High School; Oxnard Armory. 7. Medical Inspectors are in the field. Problems appear to be power outages and broken glass. L.A. County reports three hospitals with major damage (Holy Cross, Panorama City, VA Sepulveda); patients evacuated. State Fire Marshal reports Holy Cross appears most impacted. Major problems for hospitals are no water; on emergency power with approximately 4 hours of emergency fuel left. Injury reports from these hospitals are minor. EMSA reports emergency radio net to hospitals has broken down twice. Have received reports of 6 or 7 severely impacted hospitals. 8. Utilities Reported oil pipeline rupture in Valencia; spill only, no ignition. Southern California Gas - Numerous interruptions at their facilities; assembling crews and moving them into critical areas; Southern California Edison - Numerous power outages; detailed report to follow. Telecommunications - AT&T and GTE report major switch problems; will be coordinating movement of equipment into critical areas. Local communication service out in Pacoima due to structural damage to Pac Bell switching center. Water - LA Dept. of Water and Power reports aqueduct broken in San Fernando Valley. Trunk line breaks in the area. Large water tank has collapsed and another has sustained minor damage. 9. Road Net See Caltrans report 10. Air Space/Facilities Los Angeles International (LAX) and Long Beach Airports closed for inspection. Orange County - All airfields open. 11. Other critical information 12. EOCs and other facilities activated State Operations Center; Southern Region EOC CHP Emergency Response Center - Headquarters and Southern Division. State Police EOC - Headquarters CDF EOC - Headquarters Caltrans EOC - Headquarters Office of Statewide Health Planning & Development (OSHPD) EOC - Headquarters DHS Emergency Coordination Center - Headquarters Dept. of Fish & Game EOC - Headquarters FEMA Region IX EOC, Disaster Field Office (Pasadena) Major utilities' EOC's including GTE, Pacific Bell, Southern California Edison City/County EOC's - Los Angeles City; Los Angeles County; Orange County; San Bernardino County; San Diego County; Santa Barbara County Operational Area American Red Cross National Operations Center, State EOC, 3 zone EOC's 13. Response actions taken and resources committed by function Medical - California National Guard dispatching 10 air ambulances; expected to arrive at 1/17/94, 1700 hours. Urban search and rescue teams and equipment being transported to Los Alamitos. Fire & Rescue - Orange County reports sending strike teams to L.A. County. L.A. City reports major fire at San Fernando Road Trailer Park. Natural gas fires in Balboa region. OES Fire & Rescue reports 30 strike teams ordered from Region VI and 8 strike teams from the north state. 7 of 8 of the state USAR teams have been activated. The eighth is the City of LA which is committed to its own operations. LA, Orange, and Riverside county teams have been committed to assist LA City. The others will be stationed at Los Al; three northern CA teams on way from Travis AFB 1/17/94, afternoon. LA City being assisted by local USAR resources. 10 person federal USAR team enroute. Law Enforcement - LAPD and LASO are on tactical alert. No requests for out of area mutual aid. Anticipate security problems with businesses. Transportation - Caltrans conducting damage assessment. Receiving calls from vendors offering equipment; so far Caltrans does not need extra equipment. Caltrans is coordinating resources from their unimpacted districts; staff and equipment on standby. CHP reports 108 officers deployed in LA area; more call-ups occurring. They are on tactical alert. Water - DWR inspecting dams in area; dispatching two teams. Dam owners report no problems. Owner of Santa Felicia Dam reports no damage. CCC - Assembling resources list Federal - Air Force will fly U-2 mission; photos will be ready by 2400 hours, 1/17/94; will have staff to interpret. EDIS-01-17-94 1309 PST ------------------------------ Date: Mon, 17 Jan 1994 11:03:22 -0500 From: ae446@freenet.carleton.ca (Nigel Allen) Subject: Los Angeles Earthquake, January 17 Organization: The National Capital FreeNet, Ottawa Reply-To: ae446@freenet.carleton.ca Information on the Los Angeles earthquake is available in the ca.earthquakes newsgroup. Nigel Allen ae446@freenet.carleton.ca ------------------------------ Date: Mon, 17 Jan 94 06:37 PST From: rlm@helen.surfcty.com (Robert L. McMillin) Subject: More on the LA Earthquake At about 4:35 AM, Los Angeles suffered an earthquake of magnitude 6.6 on the Richter scale, centered in the San Fernando Valley. Phones and electricity were reported out throughout the entire Valley. Major fires started by gas main ruptures have been reported, and at least four large apartment complexes have burned completely to the ground. Valley residents will probably report this with more harrowing detail that I can. Los Angeles Mayor Richard Riordan announced one death on the freeways caused by today's earthquake, but failed to say where or which freeway. Interstate 405, the main coastal artery, has suffered extensive damage in the Valley, and is completely closed. In fact, except for one, all freeways in the San Fernando Valley are closed. Los Angeles International Airport is closed. Details as they come in. Robert L. McMillin | rlm@helen.surfcty.com | Netcom: rlm@netcom.com ------------------------------ From: siproj@i-link.com (Dan Arthur) Subject: FYI AT&T Reduces LA Quake Services to 203, 310, 805 and 818 Date: 17 Jan 1994 14:35:07 -0600 Organization: I-Link, Ltd., Des Moines, Iowa, US - 515/255-2754 FYI - from siproj@ilink1.i-link.com The following area codes are considered in an emergency condition according to a national newscaster: 213 - California, Los Angeles 310 - California, Beverly Hills 805 - California, Bakersfield 818 - California, Glendale AT&T has apparently reprogrammed the long distance switching network to free up lines for disaster personnel. Any business with one of the above area codes as an origin will likely have problems getting in touch with you or vice versa. Please e-mail any other specifics. ------------------------------ Date: Mon, 17 Jan 94 18:44 PST From: lauren@vortex.com (Lauren Weinstein) Subject: Still Alive Still alive. A total mess, but still here. Power just came back and I just managed to bring up the main systems. Miraculously, the routes back to the net are up. More details later. Basically, much of the region is still w/o power and water. I have water in theory, but the main broke so I can't get at it. The valley is still largely black -- I'm amazed this area came back online as soon as it did. Phones stayed up pretty much throughout, with only the usual overloading problems. Definitely the worst I've been through in my lifetime here. Much worse damage than '71. --Lauren-- [TELECOM Digest Editor's Note: Please keep us posted whenever you can with more details. PAT] ------------------------------ Date: Mon, 17 Jan 1994 21:18:33 MDT From: Rob Slade Subject: Book Review: "Basics Book of Frame Relay" by Motorola BKBSFRRL.RVW 931125 Addison-Wesley Publishing Co. Kelly Ford, Promotion/Publicity Coordinator P.O. Box 520 26 Prince Andrew Place Don Mills, Ontario M3C 2T8 416-447-5101 fax: 416-443-0948 or Tiffany Moore, Publicity tiffanym@aw.com John Wait, Editor, Corporate and Professional Publishing johnw@aw.com 1 Jacob Way Reading, MA 01867-9984 800-822-6339 617-944-3700 Fax: (617) 944-7273 5851 Guion Road Indianapolis, IN 46254 800-447-2226 "The Basics Book of Frame Relay", 0-201-56377-0 The preface states that this is an easy-to-read introduction to frame relay for busy communications professionals who presumably want to know something about the new technology besides the fact that it is generating a lot of interest. Fine. I fit the bill perfectly. I'm a communications (specifically *data* communications) professional. I'm busy. Let's get to the frame relay. Not so fast. First, we have an introduction that wants to tell me I should be interested in frame relay. Look, I got the book, didn't I? Then, we have a chapter one which wants to tell me what a "protocol" is, and about packet switching. Pack it in, guys: I'm a professional, remember? Then, we get another *two* chapters of sales pitches! Buried in the verbiage, there is a *bit* of information about frame relay: - it has higher throughput than X.25 (how? less error correction and recovery); - you can connect anything to it (how? probably the same way you do now-- with difficulty); - you can connect voice to it (maybe. or maybe that's *cell* relay, or ATM); - it has faster response time (how? don't know); - it has higher throughput, again (how? by letting you use more bandwidth, if it is available. Huh.) On the other hand, it takes less than an hour to read. copyright Robert M. Slade, 1993 BKBSFRRL.RVW 931125 Permission granted to distribute with unedited copies of the TELECOM Digest and associated mailing lists/newsgroups. ====================== DECUS Canada Communications, Desktop, Education and Security group newsletters Editor and/or reviewer ROBERTS@decus.ca, RSlade@sfu.ca, Rob Slade at 1:153/733 DECUS Symposium '94, Vancouver, BC, Mar 1-3, 1994, contact: rulag@decus.ca ------------------------------ From: alfredo@quickt2.it12.bull.it (Alfredo E. Cotroneo) Subject: DBS Satellite Services in Europe Date: 17 Jan 1994 04:53:32 -0600 Organization: UTexas Mail-to-News Gateway I am looking for information on companies which offers audio subcarriers on European DBS (Direct Broadcasts Satellite) such as the Astra(s), the Eutelsat(s), Intelsat(s) or others. As I have heard, tipically, unused audio subcarriers may be rented directly also from companies which have rented a transponder, and use it for their DBS TV transmission (e.g. MTV, Sky, TNT, etc.). Phone and fax numbers of TV stations on European satellites, as well as those of the original satellite service providers (AStra, Eutelsat, etc. ) will be greatly appreciated. Thanks, Alfredo Cotroneo, Milano, Italy 100020.1013@compuserve.com fax: +39-2-706 38151 ------------------------------ Date: Mon, 17 Jan 94 14:51 EST From: kindred@telesciences.com (David L Kindred ) Subject: Case History of a Phone Rip-Off (Part 1) As "Dragnet" used to say, "The following is a true story. Only the names were changed to protect the innocent". My mother is Manager of a credit union in one of the small cities adjacent to Newark, NJ. The office is on the ground floor in a mixed use area (street level business, upper floor residences). In addition to herself, there are two part time employees. They have two or three phone lines coming in. The local phone company is NJ Bell, and AT&T is their long distance carrier. One day, a NJ Bell service guy showed up. After checking with her employees, my mother informed him that no one had called for service, and that everything thing was ok. In a later conversation with her computer service company, it turns out that they had called NJ Bell, as they had had difficulty reaching my mother's office one day after hours. The computer service claims to have gotten some sort of circuit failure intercept. A day or two later, my mother was working late (there's a lot of extra work this month generating 1099 forms and such). At one point, my mother picks up the phone to make a call, and finds a conversation in progress. Her first reaction was to hang up. After thinking about it for a minute, she realized that she was the only person in the office, and that the lines couldn't be in use. At this point she picks up the line, and "This is the Credit Union, may I help you?". One of the people on the line mumbles something like "isn't so-and-so there?" and hangs up. My mother then hung-up and was able to use the line to make her call. The next day, she reported this event to NJ Bell. A day or two after that, one of the phone lines went dead, and again NJ Bell was involved. As you might expect, the next phone bill was quadruple the normal. Most of the "mystery" calls were to Manilla (sp?), and a few to Panama. This is where things stand for the moment. I'll report further on whether NJ Bell/AT&T give her a hassle about the bogus charges, and how long it takes to clear the "unexpected" connections. This is the second time the credit union has been targeted for phone rip-off. The earlier incident involved improper third-party billing. (Even though NJ Bell claims to only allow third-party billing after voice confirmation, the bogus calls still occurred). In that incident, NJ Bell added third-party blocking to the Credit Union's lines, and both NJ Bell and AT&T removed the bogus charges without question. Retribution may harsh if the parties involved are identified, as the name of the credit union is "The xxxxxx Police and Firemen's Federal Credit Union". I think if I lived in a city, that would be the group of people I'd pick on ... There have been numerous reports here about unscrupulous persons making their own connections to other people's phone lines. The person (or persons) involved here seem to have known that the lines they "borrowed" were from a business, and what the normal working hours for the business were. Only a few late nights led to the discovery of the problem before the first bill showed up. Is there a way a small business can protect themselves from this, or do we all have to rely on the phone company straightening things out afterwards? Dave ------------------------------ From: chatcher@world.std.com (Charles M Hatcher) Subject: Cost of GTE Dialup Lines Organization: The World Public Access UNIX, Brookline, MA Date: Mon, 17 Jan 1994 19:56:00 GMT I'm installing some dialup lines for a modem pool in an area served by GTE South and I'm trying to figure out the most cost effective way to order the lines. A normal business line in this area costs about $52 per month flat rate. GTE doesn't offer measured use lines here. In addition, to set the lines up on a rotary will be $21 per month per line extra. As far as I have been to determine, in talking to GTE and looking through their tariffs (which I admittedly don't have a complete grasp of) there doesn't seem to be a cheaper way to go. If I install 96 lines, the cost will be about $7000 per month plus tax. My question is this: Am I missing something here? Is there a way to get lines at a lower rate? The lines need only be inward-dialing (no calls will be made from them) and I don't need any PBX-type features. All I need is a group of lines that can answer a single dialed number. I'm willing to take individual lines or T1 multiplexed lines. Anyone have any experience with GTE's tariffs? Thanks in advance! Chuck Hatcher, Infomedia Corp. chatcher@world.std.com ------------------------------ Date: Tue, 18 Jan 1994 08:52:28 NZS From: Arnim Littek Organization: Digi-Tech Ltd, Wellington, New Zealand Subject: Shannon and Echo Canceller Protocols >> But now I remember Shannon's Law (you have placed wrong the brackets): >> BPS(max) = Bw * log(2)(1+(S/N)) > I'm the one who originally posted this question, for those who don't > know. It's nice to know what Shannon's law says -- if you assume a 30 > dB SNR and 3100 Hz bandwidth, the law above works out to about 31 > kilobits per second. If you happened to get a quiet channel, say, 40 > dB SNR, the equation returns about 41.2 kilobits per second. However, > this is still quite a ways off from a full-duplex, 28.8 kbps link, or > 57.6 kbps total transfer rate. So my question still stands: How do > they do it? Are they assuming a particularly quiet channel? Are they > assuming more than the standard 3100 Hz of bandwidth is available? You've got most of it, now it just remains to understand how the concept of echo cancellation fits into the picture. While the actual telephone line sees both signals at the same time, at each end, the receiver does not. The echo canceller makes an effort to remove most of the signal that had been transmitted (by prior knowledge of the transmitted signal and the reflection characteristics of the line it sees). Hence the receiver at either end sees the S/N from the other end plus the remaining noise from the incomplete cancellation of the transmitted signal. There is also a related effect from any hybrid circuitry in the box, but not to the same degree. I'm not trying to mathematically rigorous, but intuitively it has to be close to this ... Arnim arnim@digitech.co.nz ------------------------------ From: duanem@apollo4.eng.sematech.org (Michael Duane) Subject: More on Communication Over Power Lines Date: 18 Jan 1994 02:01:27 GMT Organization: SEMATECH, Austin Reply-To: michael_duane@sematech.org Thanks for the responses so far. There are still some coming in, and I need time to compile them. When I can I will send you the summarized results--they are interesting. In the meantime, some food for thought: Keep in mind that I was asking about long distance. That is, it's interesting to know that you can use the power lines to connect your speakers (and how do they *do* that?), but how far can you go outside of the house? The transformers seem to pose a problem because of the high inductance. Agree or disagree? Or is it because the signal would have to be kilovolts on the line to make any detectable signal in the home? Or another reason? Are the power lines tuned to 60 Hz to eliminate high frequency noise and low frequency drift? I've seen massive capacitors in the substations, but I don't know what they do. If the lines are tuned, that would exclude telecom. Still looking for that bandwidth vs. distance curve. Can you use the same curve as twisted pair? I think not, because of skin resistance in the power line, single wire approximations, etc. However, some of these considerations may not apply to the high frequency signal. Related to the above, we know that the high frequency signal is superposed on the larger amplitude 60 Hz. However, in the transmission line, maybe they follow different paths -- can this be? Is the current path frequency dependent? Thanks for the help!! ------------------------------ From: ross@turock.psych.upenn.edu (Ross Porter) Subject: V.32vis -> Bell_102 Due to CO Data Compression Date: 17 Jan 1994 22:14:53 GMT Organization: University of Pennsylvania, Department of Psychology A few days ago my father-in-law reported that he could no longer get a V.32bis connection between his Gainesville home and the University of Florida's modem pool. 1200bps (Bell 102) was the best he could do. He of course initially suspected his own equipment, but he later learned from the data center staff that a number of other people suddenly developed this problem. The local telephone people reported that they had recently installed some data compression equipment that could well cause this problem. Since voice traffic is relatively unaffected, the phone company politely abdicated any further responsibility. Could someone speculate and enlighten me as to what kind of data compression is being used -- is it lossy (given the large drop in maximum transmission rate)? I am not unsympathetic to the telephone company's position, but does anyone have suggestions for lobbying the telephone company? Thanks, Ross Porter ross@psych ------------------------------ End of TELECOM Digest V14 #38 *****************************