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The Telecom Digest for December 09, 2010
Volume 29 : Issue 332 : "text" Format

Messages in this Issue:

Factors affecting social networking site use(Monty Solomon)
Sharing music files: Tactics of a challenge to the industry (Monty Solomon)
Twitter content classification(Monty Solomon)
Mobile Health 2010(Monty Solomon)
586A/586B/586C (was: Re: Another odd question)(Thad Floryan)
Pre-natal mobile phone use leads to naughty kids(David Clayton)
Re: Another odd question(Garrett Wollman)
Re: Another odd question(Robert Bonomi)
Re: A question about CO wiring(Eric Tappert)
Re: A question about CO wiring(David Clayton)
Re: A question about CO wiring(Robert Bonomi)
Re: Question about an old scrambler phone(Robert Bonomi)


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Date: Tue, 7 Dec 2010 23:34:22 -0500 From: Monty Solomon <monty@roscom.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Factors affecting social networking site use Message-ID: <p0624081cc924baf13473@[10.0.1.2]> First Monday, Volume 15, Number 12 - 6 December 2010 Factors affecting the frequency and amount of social networking site use: Motivations, perceptions, and privacy concerns Jiyoung Cha Abstract The purpose of this study is to explore the factors that affect the use of social networking Web sites. In doing so, this investigation focuses on two dimensions of social networking site use frequency (i.e., how often people use social networking sites) and amount (i.e., how much time people spend on social networks). Integrating the technology acceptance model with uses and gratification and other consumer characteristics, this study found that interpersonal utility, perceived ease of use, privacy concerns, and age predict the frequency of social networking site use. Interpersonal utility motive, escape motive, and Internet experience explain the time spent on social networking sites. ... http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/2889/2685
Date: Tue, 7 Dec 2010 23:36:24 -0500 From: Monty Solomon <monty@roscom.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Sharing music files: Tactics of a challenge to the industry Message-ID: <p0624081dc924bb7352e8@[10.0.1.2]> First Monday, Volume 15, Number 12 - 6 December 2010 Sharing music files: Tactics of a challenge to the industry Brian Martin, Chris Moore, Colin Salter Abstract The sharing of music files has been the focus of a massive struggle between representatives of major record companies and artists in the music industry, on one side, and peer-to-peer (p2p) file-sharing services and their users, on the other. This struggle can be analysed in terms of tactics used by the two sides, which can be classified into five categories: cover-up versus exposure, devaluation versus validation, interpretation versus alternative interpretation, official channels versus mobilisation, and intimidation versus resistance. It is valuable to understand these tactics because similar ones are likely to be used in ongoing struggles between users of p2p services and representatives of the content industries. ... http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/2986/2680
Date: Tue, 7 Dec 2010 23:37:47 -0500 From: Monty Solomon <monty@roscom.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Twitter content classification Message-ID: <p0624081fc924bbdb6b68@[10.0.1.2]> First Monday, Volume 15, Number 12 - 6 December 2010 Twitter content classification Stephen Dann Abstract This paper delivers a new Twitter content classification framework based sixteen existing Twitter studies and a grounded theory analysis of a personal Twitter history. It expands the existing understanding of Twitter as a multifunction tool for personal, profession, commercial and phatic communications with a split level classification scheme that offers broad categorization and specific sub categories for deeper insight into the real world application of the service. ... http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/2745/2681
Date: Tue, 7 Dec 2010 23:42:57 -0500 From: Monty Solomon <monty@roscom.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Mobile Health 2010 Message-ID: <p06240821c924bd3fbe9b@[10.0.1.2]> Mobile Health 2010 by Susannah Fox Oct 19, 2010 Pew Research Center's Internet & American Life Project OVERVIEW The online health-information environment is going mobile. 17% of cell phone users have used their phone to look up health or medical information and 9% have software applications or "apps" on their phones that help them track or manage their health. ABOUT THE SURVEY The results in this report are based on data from telephone interviews conducted by Princeton Survey Research Associates International between August 9 and September 13, 2010, among a sample of 3,001 adults, age 18 and older. Interviews were conducted in English and Spanish and included 1,000 cell phone interviews. For results based on the total sample, one can say with 95% confidence that the error attributable to sampling is plus or minus 2.5 percentage points. For results based on Internet users (n=2,065) and cell phone users (n=2,485), the margin of sampling error is plus or minus 3 percentage points. ... http://www.pewinternet.org/Reports/2010/Mobile-Health-2010.aspx http://www.pewinternet.org/Reports/2010/Mobile-Health-2010/Overview.aspx
Date: Tue, 07 Dec 2010 22:00:31 -0800 From: Thad Floryan <thad@thadlabs.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: 586A/586B/586C (was: Re: Another odd question) Message-ID: <4CFF1EFF.8040508@thadlabs.com> On 12/7/2010 5:08 PM, Bill Horne wrote: > This seems to be a day for odd questions, and I just thought of one. > > The Ethernet plugs we use at work are wired for the "568B" standard, > with the orange wires on pins 1 and 2, and the green wires on pins 3 > and 6. > > Here's the question: _why_? I've been told that the whole idea with > Ethernet is to avoid "Near end crosstalk", so it seems to me that the > best way to do that would be to put one pair on pins one and two, and > the other on pairs seven and eight. How did we wind up with 568B? 568B supersedes 568A. 568B is also known as "AT&T Configuration" and is common in wired installations. 568A, when still found, is typically in jumper cables. 568B is essentially mandatory for 100 Mbps and faster. Both 568A and 568B are now superseded by 568C as of February 2009. :-) Brief details of that can be found in this document: http://www.tiaonline.org/standards/about/documents/StarReport_09-10.pdf Search for 568 in the above PDF for some background. Here's a brief clip copy'n'pasted from page 21 of that PDF: " " In February 2009, TR-42 published a new " standard: ANSI/TIA-568C.0, Generic Telecommunications " Cabling for Customer Premises. " This publication created a foundation for three " types of documents (common standards, " premises standards and component standards) " and now becomes the TR-42 standard covering " cabling topologies, design, distances and " outlet configurations, as well as specifics for " cabling infrastructure in all locations. Later In " 2009, TR-42 published the ANSI/TIA-568-C.2, " Balanced Twisted-Pair Telecommunications " Cabling and Components Standard, covering " the component and performance requirements " for balanced twisted-pair cabling. " [...] " TIA-568-C.1 was published with " TIA-568-C.0. The publication of ANSI/TIA-568-C.2, " Balanced Twisted-Pair Telecommunications " Cabling and Components Standard, completed " the third revision of the 568 standard, since " ANSI/TIA-568-C.3, Optical Fiber Cabling Components " Standard, was published in 2008. A simple diagram comparing 568A and 568B is here: http://www.pera.net/Images/Category_5_Diagram.gif Unfortunately, copies of ANSI standards cost big bucks; the (expletive deleted) standard for tripod camera attachments cost me US$35 IIRC and that was only ~15 pages.
Date: Wed, 08 Dec 2010 17:18:49 +1100 From: David Clayton <dcstar@myrealbox.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Pre-natal mobile phone use leads to naughty kids Message-ID: <pan.2010.12.08.06.18.48.907179@myrealbox.com> http://www.itwire.com/your-it-news/mobility/43753-pre-natal-mobile-phone-use-leads-to-naughty-kids Pre-natal mobile phone use leads to naughty kids By Anthony Caruana Tuesday, 07 December 2010 16:40 Your IT - Mobility Danish research has identified a potential link between mobile phone use by pregnant mums and their children, linking this to the development of behavioural problems. According to the study, children exposed to mobile phones before birth and who used phones before the age of 7 were 50% more likely to have behavioural problems, while those who were exposed to mobile phones only before birth had a 40% increased likelihood of behavioural problems. The study, published in the Journal of Epidemiology and Community Health, ran from March 1996 to November 2002. It followed nearly 100,000 pregnant mothers who completed a detailed questionnaire on lifestyle factors, dietary habits and environmental exposures. When their children were seven years old, they were questioned again on information pertaining to the health of her child, cell phone use among children as well as among the mothers during pregnancy. The study found that "There is an association between prenatal as well as postnatal use and behavioural problems by age 7 years among a general population of mothers who are cell phone users. These results replicate the findings of an association observed among only early technology adopters. These new results also reduce the likelihood that these are chance findings or findings that did not adequately consider the influence of other important factors for behavioural problems. These results should not be interpreted as demonstrating a causal link between cell phone use and adverse health effects for children, but if real - and given the nearly universal use of cell phones - the impact on the public's health could be of concern." In other words, there is a correlation but not necessarily a causal effect. Professor Rodney Croft, Executive Director of the Australian Centre for Radio Frequency Bioeffects Research and a Professor of Health Psychology at the University of Wollongong, said that "Although this new study is interesting in that it reports greater behavioural problems in 7-year-olds whose mothers reported more mobile phone use during pregnancy (than in those who reported less mobile phone use), the data is not strong enough to indicate that prenatal mobile phone exposure causes behavioural problems in children". Professor Croft's main concern is that the nature of the study relied on parental "parental recall of mobile phone use" and that this may not have been particularly accurate or measurable. >From the other side of the world, Professor Patricia McKinney, Emeritus Professor of Paediatric Epidemiology at the University of Leeds, said that "The conclusions from this large study, associating behavioural problems in very young children with mobile phone use, over-interpret the results. There is no scientific basis for investigating exposure of the growing baby when pregnant mothers use a mobile phone, as exposure to radio-frequency radiation from mobile phones is highly localised to the part of the head closest to the phone; there is no evidence to suggest that other parts of the body, such as the abdomen where the baby is growing, are affected by mobile phone use". Similarly Professor David Spiegelhalter, Professor of Biostatistics at the University of Cambridge, said he was "skeptical of these results".
Date: Wed, 8 Dec 2010 02:34:44 +0000 (UTC) From: wollman@bimajority.org (Garrett Wollman) To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: Another odd question Message-ID: <idmqs4$2cji$1@grapevine.csail.mit.edu> In article <20101208010810.GB3356@telecom.csail.mit.edu>, Bill Horne <bill@horneQRM.net> wrote: >Here's the question: _why_? I've been told that the whole idea with >Ethernet is to avoid "Near end crosstalk", so it seems to me that the >best way to do that would be to put one pair on pins one and two, and >the other on pairs seven and eight. How did we wind up with 568B? Early on, there was an idea that you might want to put a voice pair on 4/5. Then an eight-position modular plug wired for single-line voice would work if plugged in to a data line. I suppose if you were running the original AT&T StarLAN over category-3 wiring, this might have worked. AIUI, MIT's internal phone wiring is still done very much like that: all the home runs end up at a distribution frame in the closet, and then are cross-connected to analog voice, ISDN, or an Ethernet switch. (We run our own network in my building, and we use VoIP, so all of that wiring lies fallow in the nearly-empty phone closets.) Gigabit Ethernet (and higher speeds) require all four pairs, and in fact use them bidirectionally. (That's why "crossover" cables are no longer useful.) -GAWollman Disclaimer reinformcement: I may work for MIT, but they don't pay me enough to speak for them. -- Garrett A. Wollman | What intellectual phenomenon can be older, or more oft wollman@bimajority.org| repeated, than the story of a large research program Opinions not shared by| that impaled itself upon a false central assumption my employers. | accepted by all practitioners? - S.J. Gould, 1993
Date: Wed, 08 Dec 2010 07:14:17 -0600 From: bonomi@host122.r-bonomi.com (Robert Bonomi) To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: Another odd question Message-ID: <9OWdnSwXYMQ0GWLRnZ2dnUVZ_rqdnZ2d@posted.nuvoxcommunications> In article <20101208010810.GB3356@telecom.csail.mit.edu>, Bill Horne <bill@horneQRM.net> wrote: >This seems to be a day for odd questions, and I just thought of one. > >The Ethernet plugs we use at work are wired for the "568B" standard, >with the orange wires on pins 1 and 2, and the green wires on pins 3 >and 6. > >Here's the question: _why_? I've been told that the whole idea with >Ethernet is to avoid "Near end crosstalk", so it seems to me that the >best way to do that would be to put one pair on pins one and two, and >the other on pairs seven and eight. How did we wind up with 568B? We 'wound up' with 568B because people didn't like 568A. <grin> The 8P8C pin-out is 'upward compatible' with the RJ-11/-14, so 'pair 1' is on the center pins (4 & 5), 'pair 2' is the 'surrounding' pair (3 & 6), and the remaining 2 'pairs' were put on sets of adjacent pins (1&2 , 7&8). 10-Base-T Ethernet was designed to share a 4-pair cable with a phone line. the phone is on pair 1, for compatibility, and 'data' went on pairs 2 and 3. Now, -if- the two Ethernet pairs were on 1&2, 7&8, the separation between 'tip' in the two pairs would have been the same as the separation between 'ring' in the two pairs. Meaning the inductive coupling would have been roughly _equal_, effectively _maximizing_ the induced signal in the differential circuit. By placing the conductors ad -different- distances, one gets different amounts of induced signal in each wire -- this leads to the 'excess' amount on one wire being 'ignored' by the differential receiver, so that, effectively, only the lesser of the two induced signals is 'seen' by the attached equipment.
Date: Tue, 07 Dec 2010 23:32:12 -0500 From: Eric Tappert <e.tappert.spamnot@worldnet.att.net> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: A question about CO wiring Message-ID: <ik1uf6d0rck9j6igasufgi4enev68bpf54@4ax.com> On Tue, 07 Dec 2010 20:25:28 -0500, Bill Horne <bill@horneQRM.net> wrote: >I've been working for a company that sells a line-switching device for >use by the utility industry. We routinely get boxes returned to us >that have been fried by voltage spikes, and it occurs to me that a >central office must take a lot of surges, spikes, etc. That's a >paradox, because I never heard of a CO being damaged by anything but a >direct lightning hit the whole time I was a tech. > >We had, of course, "carbons" and "heat coils" at the frame that were >intended to take care of spikes coming in on the cable, but to gauge >by the way today's electronic boxes get burned up so easily, I'm >really surprised we didn't have a lot more trouble with lightning. >Ergo, I'm wondering what other equipment was used to keep the CO's >from suffering at Zeus' hands. > >Bill Bill, The old electomechanical switches (including the analog ESS) were pretty much immume from anything that got through the carbon blocks. The heat coils were for overcurrent protection due to a short in the cable plant. Modern digital line cards have "secondary protection" circuits which are specifically design to deal with anything that can get past the gas tubes that replaced the carbon blocks. Don't forget the gas tubes short the pair to ground when activated (as did the carbon blocks). Gas tube protectors are more closely controlled as to breakover voltage than the old carbon blocks. That and maintenance issues are the reason they replaced the carbon blocks. This secondary protection often uses high voltage tolerant technology and can be designed to be very effective. The heat coils are still in place to protect from shorts in the cable plant, but modern digital line cards also current limit the loop current to something in the 20-40 mA range. CO bonding and grounding is also very good compared to most subscriber locations. Of course the cable plant is shielded (except, perhaps, the drop) and twisted to minimize capacitive and inductive coupled surges. Where poles are shared, then the power company conductors are above the telco wiring, acting as one of old Ben Franklin's lightning rods... Underground cable sees large surges only in the area of a strike being grounded, so they see less of the effect of lightning. In short, if things are properly designed for the environment, then things short of a direct strike are usually pretty harmless. BTW, subscriber telephones seem to do pretty well behind the telco protection blocks (at least the good ones).... Perhaps the boxes you see are being fried by power line surges (which can be large due to either switching actions at substations or power line faults). COs run on batteries and have some decent isolation from power line surges. ET --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Date: Wed, 08 Dec 2010 17:16:32 +1100 From: David Clayton <dcstar@myrealbox.com> To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: A question about CO wiring Message-ID: <pan.2010.12.08.06.16.29.335749@myrealbox.com> On Tue, 07 Dec 2010 20:25:28 -0500, Bill Horne wrote: .......... > We had, of course, "carbons" and "heat coils" at the frame that were > intended to take care of spikes coming in on the cable, but to gauge by > the way today's electronic boxes get burned up so easily, I'm really > surprised we didn't have a lot more trouble with lightning. Ergo, I'm > wondering what other equipment was used to keep the CO's from suffering at > Zeus' hands. > I know for a fact that all incoming connections in Australian COs are protected by heavy duty surge protection devices (and have been since the exchange equipment went digital decades ago). These devices clipped directly onto the Krone termination blocks along with a good ground connection. These will protect the electronic exchange ports from anything bar a direct hit, but at the other end of the cables things like ADSL modems will just get progressively degraded by induced spikes if they do not have some protection. One just has to frequent various forums and see the posts of people complaining about their ADSL services immediately after storm activity in their local area, but it takes a while for them to stop blaming their ISP and realise that their equipment "...but it's been working perfectly for years..." is the problem. -- Regards, David. David Clayton Melbourne, Victoria, Australia. Knowledge is a measure of how many answers you have, intelligence is a measure of how many questions you have.
Date: Wed, 08 Dec 2010 08:38:19 -0600 From: bonomi@host122.r-bonomi.com (Robert Bonomi) To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: A question about CO wiring Message-ID: <7tqdnQyxXd3GBWLRnZ2dnUVZ_hydnZ2d@posted.nuvoxcommunications> In article <E1PQ8me-0001Il-CM@telecom.csail.mit.edu>, Bill Horne <bill@horneQRM.net> wrote: >I've been working for a company that sells a line-switching device for >use by the utility industry. We routinely get boxes returned to us >that have been fried by voltage spikes, and it occurs to me that a >central office must take a lot of surges, spikes, etc. That's a >paradox, because I never heard of a CO being damaged by anything but a >direct lightning hit the whole time I was a tech. > >We had, of course, "carbons" and "heat coils" at the frame that were >intended to take care of spikes coming in on the cable, but to gauge >by the way today's electronic boxes get burned up so easily, I'm >really surprised we didn't have a lot more trouble with lightning. >Ergo, I'm wondering what other equipment was used to keep the CO's >from suffering at Zeus' hands. There are only about two things one can do to 'protect' equipment from spikes/surges/etc.: 1) give the 'excess' voltage/current a 'more attractive' path to 'ground'. 2) deny it a path 'in'. (1) typically involves a 'gap' between the cabling and ground. sufficient to be an effective insulator at 'normal' voltage, but, at moderate over-voltage, it will 'arc over', and provide a near 'zero-ohm' path to ground. In the simplest form it is just a calibrated "air gap", fancier forms use gas discharge conductivity similar to a NE-2 indicator bulb, or something else that 'avalanches' into conduction when a threshold is crossed. (2) is the equivalent of a fuse, albeit in a variety of forms. Upon detection of the overload condition, it -open- the circuit, preventing the spike from going further. Then there are combinations of the above. 'crowbar' circuits are a 'selective' short to ground, installed 'downstream' of a fuse type device. The crowbar detects a 'slight' over-voltage, and provides a massive short to ground, causing an immediate reaction from the circuit interruptor. The radical increase in the overload brought about by the crowbar causes the interruptor to react much faster than it would have to just the 'natural' overload itself.
Date: Wed, 08 Dec 2010 06:38:59 -0600 From: bonomi@host122.r-bonomi.com (Robert Bonomi) To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org. Subject: Re: Question about an old scrambler phone Message-ID: <tNOdnQFjner-4WLRnZ2dnUVZ_j6dnZ2d@posted.nuvoxcommunications> In article <AANLkTikNo4yk3iRENuKp_f4QRTgnedkZuknL1PEFju-E@mail.gmail.com>, Ernest Donlin <ernest.donlin.remove-this@and-this-too.gmail.com> wrote: >(moderator please change my email address so spammers can't use it.) > >I've got an odd sort of a question for your group. > >When I was a kid, my friend's dad had a phone in his house that he told me >was a "scrambler". It was a regular telephone, mounted on a metal >base, with an AC cord for the base. The base had just two vacuum tubes in >it, and a couple of transformers. It didn't look like much, but my friend >said his dad used it to make scrambled phone calls to his reserve unit. > >Has anyone ever seen anything like that? I never knew if he was yanking my >chain or not. One of the simplest forms of a 'scrambler' simply frequency-inverted the audio input. basically, use the audio to AM modulate a circa 4kHz 'carrier', and send only the the lower sideband over the wires.. Conveniently, you can 'unscramble' the signal by doing exactly the same thing to the 'scrambled' signal. Necessary components are: 1) an oscillator, 2) a modulator, 3) a low-pass filter. That's two tubes, and an inductor with a couple of capacitors, plus a multi-tap (filament and B+) power transformer to run it all. Sounds real close to what your friend's dad had. <grin>> Now, to answer the actual question you asked: "No, I've never actually seen one of them myself." I only know "of" such devices, having read about, seen schematics in books, etc.
TELECOM Digest is an electronic journal devoted mostly to telecom- munications topics. It is circulated anywhere there is email, in addition to Usenet, where it appears as the moderated newsgroup 'comp.dcom.telecom'. TELECOM Digest is a not-for-profit, mostly non-commercial educational service offered to the Internet by Bill Horne. All the contents of the Digest are compilation-copyrighted. You may reprint articles in some other media on an occasional basis, but please attribute my work and that of the original author. The Telecom Digest is moderated by Bill Horne. Contact information: Bill Horne Telecom Digest 43 Deerfield Road Sharon MA 02067-2301 781-784-7287 bill at horne dot net Subscribe: telecom-request@telecom-digest.org?body=subscribe telecom Unsubscribe: telecom-request@telecom-digest.org?body=unsubscribe telecom This Digest is the oldest continuing e-journal about telecomm- unications on the Internet, having been founded in August, 1981 and published continuously since then. Our archives are available for your review/research. We believe we are the oldest e-zine/mailing list on the internet in any category! URL information: http://telecom-digest.org Copyright (C) 2009 TELECOM Digest. All rights reserved. Our attorney is Bill Levant, of Blue Bell, PA. --------------------------------------------------------------- Finally, the Digest is funded by gifts from generous readers such as yourself who provide funding in amounts deemed appropriate. Your help is important and appreciated. A suggested donation of fifty dollars per year per reader is considered appropriate. See our address above. Please make at least a single donation to cover the cost of processing your name to the mailing list. 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.
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