30 Years of the Digest ... founded August 21, 1981
The Telecom Digest for February 1, 2012
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Date: 31 Jan 2012 06:38:48 GMT From: Doug McIntyre <email@example.com> To: firstname.lastname@example.org. Subject: Re: Fiber Optics Connectors Message-ID: <email@example.com> firstname.lastname@example.org writes: > I need to read up on fiber optics connectors. I'm familiar with the > LC, ST, and SC type connectors. Those are the 3 [most widely used] used ones. ST is not used much now. FC was used a lot by Qwest and other ILECs for SONET, but not so much now-a-days, being more SC types in newer installations. > I understand that there are special connectors called APC (Angle > Polished Connectors) and I'd like to read up on when they are used. That isn't a type of connector, but a style of end join. There are APC, UPC and straight. APC actually stands for Angled Physical Contact (not connector). The point of the APC is that the ends are angled instead of flush, so when they mate, if there is any side glancing back reflection from the polished end that it bounces off to the cladding and only straight through signal gets pushed through. Kind of a bear to line up correctly, so they really only get used in FC type connectors that have a notch to line up the ferrule. Unlike what Wikipedia says, I was taught that UPC polish on the end has just a slight curve to it and not just a better "polish", with just the signal path kissing just right in the middle. Same concept as the APC, just done more subtle and circular so it doesn't require mating the angle just right so any connector can be used (ie. SC) Plus if you mate UPC with straight cable, nothing bad happens. APC end to anything else will either break things, or have too large of a loss. It costs just slightly more at the fiber assembly vendor to get UPC polish. Typically in telco/datacenter applications, you'll get single-mode duplex, SC connectors with UPC polish. Ie. my cable vendor doesn't even ask, that is just what I get. Or if it a patch going from one piece of gear to gear without a patch panel in the middle, it'll be an LC to LC cable. I haven't actually seen any installation with APC polished ends, but have heard that there are some out there local to me. > Can someone recommend a book that explains APCs and some of the > newer connectors [those I have not listed here]? Not enough material for a book. And nothing else "new". Wikipedia does a decent enough job. http://en.wikipedia.org/wiki/FC_connector http://en.wikipedia.org/wiki/Optical_fiber_connector Otherwise, talk to a cable vendor (ie. Graybar, Anixter). Their sales critters should be versed enough in it as well. Typically now-a-days, everything is SC and LC. You still see the occasional FC from the ILEC panels. MT-RJ died off along with 100-Base-FL. ST died out earlier, but was installed in a lot more places. SMA and FDDI are long dead. If you end up needing any other style, you just get the proper patch cable and leave it at that. It isn't like everything has to be the same all the way through. ***** Moderator's Note ***** 100BaseFL died? Is multi-mode fiber still in use? I remember a job I did to get a LAN across an isolated ground window: fiber transceivers and ST connectors saved me a lot of grief. Bill Horne Moderator
Date: Tue, 31 Jan 2012 17:40:49 -0800 From: Andrew Carey <email@example.com> To: firstname.lastname@example.org. Subject: Re: Fiber Optics Connectors Message-ID: <F20743B4-3365-4D53-AE7D-6DA5D0803A09@ar-ballbat.org> On Jan 30, 2012, at 2238, Doug McIntyre wrote: > email@example.com writes: >> I need to read up on fiber optics connectors. I'm familiar with the >> LC, ST, and SC type connectors. > > Those are the 3 [most widely used] used ones. ST is not used much now. > FC was used a lot by Qwest and other ILECs for SONET, but not so much > now-a-days, being more SC types in newer installations. All three of those use 2.5mm ferrules (the little pointy part of the connector) and are used for cross connections at fiber panels and some equipment ports. ODC (Outdoor Connector) is another 2.5mm ferrule connector, but not one I've worked with. More and more vendors are using 1.25mm ferrule connectors such as LC or MU (less common) to allow greater port densities. MTP/MPO connectors also show up. Those terminate ribbon fibers composed of several separate fibers in a single connector. And of course there are many older and niche connectors out there. >> I understand that there are special connectors called APC (Angle >> Polished Connectors) and I'd like to read up on when they are used. > > That isn't a type of connector, but a style of end join. There are > APC, UPC and straight. APC actually stands for Angled Physical > Contact (not connector). This is one of those acronyms that depend on who you're talking to. Even fiber vendors use both. Either one works and refers to the same thing. > The point of the APC is that the ends are angled instead of flush, > so when they mate, if there is any side glancing back reflection > from the polished end that it bounces off to the cladding and only > straight through signal gets pushed through. Kind of a bear to line > up correctly, so they really only get used in FC type connectors > that have a notch to line up the ferrule. APC is superior to UPC as far as return loss from the connector. Both types have back reflection due to the transition of material from the core through the connectors but APC minimizes as described above due to the angled surface. I mostly use APC in SC & MTP connectors but according to TE (formerly ADC) it's available in LC connectors too. Neither SC or MTP is difficult to mate because the connectors only come together one way. Inspection probes allow the ferrule to rotate but there's a mark on it to line up the correct angle. It's also not that big of angle, 8 degree slant for APC versus 0 degree for UPC. More on the differences from ADC here: http://www.adc.com/Attachment/1270711936302/105662AE.pdf
Date: Tue, 31 Jan 2012 07:06:24 -0800 (PST) From: HAncock4 <firstname.lastname@example.org> To: email@example.com. Subject: Teen boots banned on account of cell phone smuggling Message-ID: <firstname.lastname@example.org> I thought the following was rather silly at first, but it made the national news and I thought I'd share it. A Pottstown, PA (suburban Philadelphia) school district has banned a very popular style of fashion booth ("Uggs") from school because they believe kids are smuggling cell phones in the boot. Cell phones are forbidden in the school classrooms. The story made the Los Angeles Times: (includes a link to the local paper). http://goo.gl/39uIk -or- http://latimesblogs.latimes.com/nationnow/2012/01/school-bans-uggs-blames-them-for-contraband-gadgets.html In my own humble, this is bureaucracy (paranoia) gone too far. The issue of cell phones and kids is tougher. As discussed, there are problems in getting adults to turn off their cellphones during concerts, religious services, funerals, etc. If adults are unable to "break their connection" for an hour or two, how can we expect kids to do it in class? (I was recently at a business meeting. During the breaks, the participants immediately whipped out their phones to check for emails and send out texts. These days plenty of adults are as focused on their cell phones as much as kids are.) But cell phones are a distraction in class and should not be permitted to be used. Further, they can be used for inproper purposes, such as taking embarassing photos of fellow students, or passing test questions to other students.
Date: Tue, 31 Jan 2012 16:52:50 -0500 From: Pete Cresswell <PeteCress@invalid.telecom-digest.org> To: email@example.com. Subject: Re: Teen boots banned on account of cell phone smuggling Message-ID: <firstname.lastname@example.org> Per HAncock4: >The issue of cell phones and kids is tougher. As discussed, there >are problems in getting adults to turn off their cellphones during >concerts, religious services, funerals, etc. If adults are unable to >"break their connection" for an hour or two, how can we expect kids >to do it in class? Is there some legal problem with technologically-enforced "Cell-Free" zones? As a tMobile user, I can attest that many buildings [in my] area already [have] such zones.... -) -- Pete Cresswell
Date: Tue, 31 Jan 2012 20:03:14 -0500 From: tlvp <mPiOsUcB.EtLlLvEp@att.net> To: email@example.com. Subject: Re: Teen boots banned on account of cell phone smuggling Message-ID: <firstname.lastname@example.org> On Tue, 31 Jan 2012 07:06:24 -0800 (PST), HAncock4 wrote: > ... > A ... school district has banned a very popular style of fashion > booth ("Uggs") from school because they believe kids are smuggling > cell phones in the boot. Heh-heh ... in my day, it wasn't cell phones but shivs or zip guns that kids would smuggle into school, and not in "Uggs" but in their galoshes. I think I'd rather have 'em smuggle cellphones, all things considered :-) . Cheers, -- tlvp -- Avant de repondre, jeter la poubelle, SVP.
Date: Tue, 31 Jan 2012 07:54:17 -0800 (PST) From: HAncock4 <email@example.com> To: firstname.lastname@example.org. Subject: Re: FDA staffers sue agency over surveillance of personal e-mail Message-ID: <email@example.com> On Jan 30, 5:10 pm, Monty Solomon <mo...@roscom.com> wrote: > FDA computers post a warning, visible when users log on, that they > should have "no reasonable expectation of privacy" in any data > passing through or stored on the system, and that the government may > intercept any such data at any time for any lawful government purpose. > > But in the suit, the doctors and scientists say the government > violated their constitutional privacy rights by gazing into personal > e-mail accounts for the purpose of monitoring activity that they say > was lawful. Telecom administrators and labor representatives have often said there is no expectation of privacy for anything a person does on their employer's computer or network. Using a personal email account on the organization's computer does not provide any exemption from that policy. This also applies to conversations made over the employer's telephone. Now, those involved may have a case under "whistle blowing" laws, but that is an entirely separate issue.
Date: 31 Jan 2012 17:10:27 GMT From: Doug McIntyre <firstname.lastname@example.org> To: email@example.com. Subject: Re: Fiber Optics Connectors Message-ID: <firstname.lastname@example.org> Doug McIntyre <email@example.com> writes: >>MT-RJ died off along with 100-Base-FL. >>ST died out earlier, but was installed in a lot more places. >>SMA and FDDI are long dead. >***** Moderator's Note ***** >100BaseFL died? Is multi-mode fiber still in use? I guess in my environment (telco/datacenter), anything new going in is probably going to be 10Gbit. With a smaller percentage of Gigabit ethernet (at whatever standard for fiber related, 1000-Base-SX or 1000-Base-LX or 1000-Base-ZX). Guess I'm not large enough to see any 40G and 100G installations. I haven't seen 100Mbps fiber at 100-Base-FL for maybe 9-10 years now. The switch to gigabit was pretty instant once things there became afordable for almost everybody. The sweet spot for 10Gbps is still in the telco/datacenter realm. Smaller enterprises are probably still on gigabit or LAG'd gigabit. I can buy GigE switches with a few fiber ports for low $200's now-a-days. Yes, multi-mode fiber is still in use. I just installed 100m of OM3 MM (with SC connectors) which is what is needed to run 10Gbase-SX on multi-mode fiber. (50um core, "laser-optimized" fiber). Although I know several places that don't bother figuring out of they want multi-mode or single-mode and just standardize on single-mode fiber, as the gear and material prices aren't that much higher (ie. $200 for a 10Gbase-SX SFP vs $500-$600 for a 10Gbase-LX SFP).
Date: Tue, 31 Jan 2012 17:31:33 -0500 From: "Geoffrey Welsh" <firstname.lastname@example.org> To: email@example.com. Subject: Re: Cloud-based PBX service Message-ID: <c6b88$4f286ba0$adce4491$23211@PRIMUS.CA> Dave Platt wrote: > SIP phone costs have come down a lot in recent years. Alterna- > tively, use an existing analog phone and a separate ATA (analog > telephone adapter)... the latter can be had for around $50. There are also 'soft phones' e.g. Bria* for about that price, assuming that you already have a computer with speaker and microphone. * DISCLAIMER: I have Bria on my laptop and it seems to work, but I don't use it much and this is definitely not to be taken as an endorsement or recommendation of the product. ***** Moderator's Note ***** I'm uncomfortable with the idea that using a laptop for phone calls makes it into a "soft" phone: I think it makes a very expensive telephone instrument with a built-in analog-to-digital adapter. It's not that I don't understand the appeal of saving the cost of a dedicated instrument - far from it. What worries me are the ways in which my PC's power and my investment in internet connectivity can be turned to other uses that aren't possible with a dedicated instrument: some VoIP services demand that users endure pop-up ads and DNS redirections, and they don't allow users to port numbers in or out of the "service" they have subscribed to. I'd rather price a system with dedicated devices, and then consider what, if anything, I can save by using a PC in place of one or more of the dedicated devices. Bill Horne Moderator
Date: Tue, 31 Jan 2012 22:04:36 -0500 From: tlvp <mPiOsUcB.EtLlLvEp@att.net> To: firstname.lastname@example.org. Subject: Proposed legislation triggered by Carrier IQ Message-ID: <email@example.com> Apparently Rep. Edward Markey (D-MA) recently "released draft legislation that would require disclosure of monitoring software when a consumer buys a mobile phone [and] would prevent manufacturers from collecting and transmitting information unless consumer consent is obtained ... ." More at: http://goo.gl/4HrzU -or- http://arstechnica.com/tech-policy/news/2012/01/mobile-device-privacy-act-would-prevent-secret-smartphone-monitoring.ars Cheers, -- tlvp -- Avant de repondre, jeter la poubelle, SVP.
Date: Thu, 26 Jan 2012 20:03:55 +0000 (UTC) From: firstname.lastname@example.org (Garrett Wollman) To: email@example.com. Subject: Re: Justices Say GPS Tracker Violated Privacy Rights Message-ID: <firstname.lastname@example.org> Moderator's Note: I made a mistake and this post was delayed because of it. My apologies to Mr. Wollman. BH In article <email@example.com>, Adam H. Kerman <firstname.lastname@example.org> wrote: >Huh. That's a poor summary of the case. SCOTUSblog's Tom Goldstein posted a long piece criticizing the reporting on the story the other day. >The Supreme Court let the reversal stand. The government tried to bring up >an argument, disallowed as it was not raised in the lower courts, that >there was reasonable suspicion and thus probable cause and therefore the >search wasn't unconstitutional. "Reasonable suspicion" and "probable cause" are two different standards. "Probable cause" is a much stronger standard than "reasonable suspicion". The Court didn't say which standard it favored. >The troubling part of Alito's opinion, with which Sotomayor kinda/sorta >concurred with, making a majority, was that Alito distinguished between >the possibility that a short-term warrantless search might not be >unconstitutional, in case of an investigation into an extraordinary >offense, but that a long-term warrantless search would be. Alito's opinion was concerned with the "reasonable expectation of privacy" standard on the question of long-term continuous monitoring. Scalia did find that a search occurred, when the tracking device was attached to the defendant's car, but didn't say anything about whether a warrant was required or the admissibility of the long-term tracking data as evidence. Sotomayor's opinion says that she would be willing to revisit this whole area of the law in light of how circumstances have changed since the 1960s when the controlling case law was written. (In particular, Sotomayor wants to revisit the so-called "third-party doctrine" that says you have no expectation of privacy in anything you voluntarily disclose to a third party, absent some countervailing law.) >Unlike what the lead of the New York Times suggests, the US Supreme Court >did not uphold the right to privacy against warrantless searches using >modern tracking technology. The Court equivocated on the issue and >await further litigation. Who knows what privacy rights will survive >after the next case is heard? Remember that the case law ex ante said that you have no expectation of privacy when you go about in a public place. You have half of the court suggesting that perhaps you should, at least with respect to the sort of long-term surveillance that would be impractical for a human operative to perform, and another half of the court suggesting that attaching something to your car counts as a search even when the car is not parked in your garage. This is still something of a victory for privacy advocates, even if it leaves open many important questions. Because of some issues with the factual record in this case -- in particular, the fact that the police evidently thought that they needed a warrant, got one, then let it expire, and finally attached the tracking device while the car was parked in a public place in another judicial district -- many of the questions that advocates would like to see answered are really not squarely presented by this case. If the police had attached the tracking device before the warrant had expired, then the court might have addressed the standard for granting such a warrant, or indeed whether one was required at all. -GAWollman  A warrant is supposed to be supervised by a court in the judicial district where it will be executed. -- Garrett A. Wollman | What intellectual phenomenon can be older, or more oft email@example.com| 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
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