30 Years of the Digest ... founded August 21, 1981
The Telecom Digest for October 12, 2011
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Date: Tue, 11 Oct 2011 04:56:36 +0000 (UTC) From: danny burstein <email@example.com> To: firstname.lastname@example.org. Subject: Re: Lightsquared being called to account Message-ID: <email@example.com> In <4E9398FA.firstname.lastname@example.org> Thad Floryan <email@example.com> writes: [ snippeth ] >> This whole thing stinks of inside influence, double-dealing, and >> political sleight-of-hand. I smell a rat, and I think that this is a >> back-room deal in the making. >And you would be 100% correct as we can read here: > > http://nlpc.org/stories/2011/09/16/lightsquared-scandal-explodes > >" Allegations that we first made in February about White House >" political favors for a company called LightSquared are starting >" to get the attention they deserve. >" >" LightSquared is owned by the Harbinger Capital hedge fund, headed >" by billionaire investor Phil Falcone. He visited the White House >" and made large donations to the Democratic Senatorial Campaign >" Committee. Soon after, the Federal Communications >" Commission (FCC) granted LightSquared a highly unusual waiver >" that allows the company to build out a national 4G wireless >" network on the cheap. [mucho snippeth] All nice and good, and probably kind of true, but... I'd betcha that you could make some pretty similar allegations about a hefty number of Big Businesses, and Big Labor, and Big Banks, and lots of not-so-big ones... during this Adminstration, the previous one, and the dozen or three before them. -- _____________________________________________________ Knowledge may be power, but communications is the key firstname.lastname@example.org [to foil spammers, my address has been double rot-13 encoded]
Date: Tue, 11 Oct 2011 07:33:04 -0400 From: John Stahl <email@example.com> To: firstname.lastname@example.org. Subject: Re: Lightsquared being called to account Message-ID: <A8.EF.12608.379249E4@hrndva-omtalb.mail.rr.com> >Date: Tue, 11 Oct 2011 02:08:53 -0400 >From: Bill Horne <bill@horneQRM.net> >To: email@example.com. >Subject: Re: Lightsquared being called to account >Message-ID: <20111011060853.GA16205@telecom.csail.mit.edu> > >OK, please bear with me: I'm going to have to delve into my radio >background, both as a ham operator and a commercial radio technician, >to explain the issues here. ><clip> >The issue in the Lightsquared case is a combination of something >called intermodulation and another problem known as overloading. I >don't claim to be an RF engineer, but I hope I can explain the basic >issue well enough to make my concerns more clear. ><clip> Re: Code of Federal Regulations, Title 47, Part 15 (47 CFR 15) Doesn't nearly every electronics device sold inside the United States which might radiate unintentional emissions [have to] be reviewed to comply with Part 15 before it can be advertised or sold in the US market? If the above is true, won't LightSquared be brought to task to prove all of it terrestrial transmitting equipment [can] pass Part 15 before it can be sold/installed? John ***** Moderator's Note ***** IANALB, as you point out, Part 15 covers UNINTENTIONAL radiators, e.g., my laptop, since it has an internal clock oscillator that might cause interference to nearby receivers, must meet part 15 requirements. If Lightsquared is allowed to repurpose the L Band 1 spectrum for terrestrial use, then they would be operating under an FCC license, and thus not subject to Part 15. There is no way to predict or prevent intermodulation interference to GPS receivers if Lightsquared's plan goes forward. That interference would be caused by the combination of Lightsquared's terrestrial signals with those of other transmitters in other services, such as the Citizens Radio Service (CB), Amateur radio, or the various Public Safety and commercial licensees still operating in the 30 - 50 MHz band. All of the signals that might combine to cause "birdies" in the GPS band would be from licensed services, so the only way to prevent the interference is to stop Lightsquared. HTH. Bill Horne Moderator
Date: Tue, 11 Oct 2011 14:02:50 -0600 From: Ken <firstname.lastname@example.org> To: email@example.com. Subject: Re: Lightsquared being called to account Message-ID: <4E94A0EA.firstname.lastname@example.org> David Clayton <email@example.com> wrote: > This may be bloody obvious - but since most state of the art > military hardware uses GPS for so many things these days (Cruise > missiles, drones etc.) - wouldn't you really not want transmitters > capable of jamming GPS receivers indirectly, or if they were slightly > modified, possibly directly jamming GPS receivers, on the market? > > Wouldn't this give the "Terrorists" an opportunity to negate the > massive technological deficiency some of them currently have? > > It just seems slightly TOTALLY insane to consider allowing these > things to be rolled out given their potential for that sort of use. The military uses a slightly higher power GPS channel (called P/Y/M code) off the GPS satellites and also uses jam resistant antennae, so this less a problem for the military. It's a bigger problem for commercial safety services, like commercial aircraft, if the country was blanketed with Lightsquared transmitters, but less so from single ground based terrorists as the jamming source would need to be above the aircraft for most effectiveness.
Date: Tue, 11 Oct 2011 16:43:42 +1100 From: David Clayton <firstname.lastname@example.org> To: email@example.com. Subject: Re: Lightsquared being called to account Message-ID: <firstname.lastname@example.org> On Mon, 10 Oct 2011 19:29:12 -0400, Bill Horne wrote: > On Mon, Oct 10, 2011 at 08:02:00PM +0000, Thor Lancelot Simon wrote: >> In article >> <CAFY5RQ+enZmZaSrKW=rb5-_gfsGT9CxY6N59dJFk8VJ2C=-kDg@mail.gmail.com>, >> Bill Horne <bill@horneQRM.net> wrote: >> > >> >AFAICT, LightSquared is hoping to create a house of cards that will >> >stand just long enough to get past the current election cycle, and then >> >commence ruining the most accurate source of location and time >> >information available to consumers. I hope they fail. >> >> I disagree. The frequencies in question have been allocated to >> LightSquared for a long time. Why should they suffer because consumer >> GPS manufacturers decided to save a few bucks on proper signal >> filtering? > > As I understand it, Lightsquared was originally assigned those frequencies > for use in a different, satellite-based service, and has now lobbied the > FCC to change the assignments for use with a terrestrial application. .......... This may be bloody obvious - but since most state of the art military hardware uses GPS for so many things these days (Cruise missiles, drones etc.) - wouldn't you really not want transmitters capable of jamming GPS receivers indirectly, or if they were slightly modified, possibly directly jamming GPS receivers, on the market? Wouldn't this give the "Terrorists" an opportunity to negate the massive technological deficiency some of them currently have? It just seems slightly TOTALLY insane to consider allowing these things to be rolled out given their potential for that sort of use. -- 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. ***** Moderator's Note ***** Cruise missiles, by their nature, aren't in a particular area long enough to have their GPS or other guidance systems affected by a cell tower or cellular 4G mobile handset. Either they've vanished over the horizon before the taliban can key their jammer, or the possibility becomes moot in short order. ;-) I don't know what other military devices or aircraft use GPS, but I think it's reasonable to assume that their designers took account of the possibility of jamming. It's a military use, after all. Bill Horne Moderator
Date: Tue, 11 Oct 2011 19:11:33 -0400 From: "Gary" <email@example.com> To: firstname.lastname@example.org. Subject: Re: Lightsquared being called to account Message-ID: <email@example.com> ***** Moderator's Note ***** > > I don't know what other military devices or aircraft use GPS, but I > think it's reasonable to assume that their designers took account of > the possibility of jamming. It's a military use, after all. I'm fairly certain that most of our military uses GPS, from grunts on the ground to ships to probably anything in the air (other than shells, at least for now :-). After all, GPS was developed to server our military's needs. What most people don't know (it's not a secret), is that there is a second GPS band used only by the military. Using two bands allows the receivers to compensate for variations in the ionosphere allowing for a more accurate measurement of propagation delay from the the satellites. The end result is military receivers are much more accurate than civilian receivers (just how much is, of course, a secret). The second channel is encrypted. Because of the second channel as well as minimal concerns about the cost to build a good product, I'm quite certain that it is much harder to jam a military GPS receiver than a $100 civilian receiver. -Gary P.S. For even more, look up "selective availability." GPS used to intentionally put jitter on the civilian channel in order to reduce accuracy. It was turned off after WAAS rendered it pointless. ***** Moderator's Note ***** Per Wikipedia - http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. AFAIK, Selective Availability is still a choice available to the military if circumstances warrant: if it's turned on, civilian GPS receivers are only accurate to within about 1/2 mile, which isn't enough to guide a bomb to it's target. Bill Horne Moderator
Date: Mon, 10 Oct 2011 17:13:20 -0400 From: tlvp <mPiOsUcB.EtLlLvEp@att.net> To: firstname.lastname@example.org. Subject: Re: Incoming Calls: Charged? Message-ID: <email@example.com> On Sun, 9 Oct 2011 21:22:12 -0700 (PDT), Jimmy wrote: > tlvp <mPiOsUcB.EtLlL...@att.net> wrote: >> an unanswered call will just transfer to your voice mail box (unless >> you've succeeded in turning off forward-to-voice-mail on no-answer), >> costing you both the minutes the incoming call is active and >> the minutes for the new outgoing (nominally from your handset) >> call to the voicemail box. > > Are you sure about that? Yep. Protested it numerous times with T-Mobile billing support. No dice. > ... I didn't think minutes got used up when > someone is leaving a voice mail. Used up? Maybe not. But billed? If you're roaming abroad? Yes. At least by T-Mobile (USA). And by at least one Swiss cell phone outfit a decade ago, who advised their customers to turn off forwarding-to-voice-mail if planning to go abroad (so as to curtail just that expense). > It wouldn't make sense, for several reasons. The call isn't actually > being transmitted over a cell tower. And the recipient would have no > control over the length of the call -- a malicious person could use up > someone else's minutes by leaving very long messages over and over > again. All irrelevant. The ring signal for the call is being forwarded to the roaming carrier for transmission to my roaming handset; the no-answer-after-five-rings signal is being forwarded back to T-Mobile from the roaming carrier; T-Mobile is then requesting the roaming carrier to forward the call -- now on the roaming carrier's network -- to my T-Mo voicemail area; lots of lovely international-LD billable events there :-) . As for "leaving very long messages," no, T-Mo cuts messages off at the 1-minute point. And as for victimizing the callee, it'd be enough to switch off the phone, for none of the roaming behavior to get triggered in the first place: if the phone's not registered with any carrier -- neither T-Mo nor any roaming partner -- then only standard domestic-tarriffed voicemail forwarding applies, and (with T-Mo, anyway) that's at zero incremental cost to the subscriber. Cheers, -- tlvp -- Avant de repondre, jeter la poubelle, SVP.
Date: Tue, 11 Oct 2011 16:18:49 +0000 (UTC) From: "Adam H. Kerman" <firstname.lastname@example.org> To: email@example.com. Subject: Re: Incoming Calls: Charged? Message-ID: <firstname.lastname@example.org> tlvp <mPiOsUcB.EtLlLvEp@att.net> wrote: >On Sun, 9 Oct 2011 21:22:12 -0700 (PDT), Jimmy wrote: >>tlvp <mPiOsUcB.EtLlL...@att.net> wrote: >>>an unanswered call will just transfer to your voice mail box (unless >>>you've succeeded in turning off forward-to-voice-mail on no-answer), >>>costing you both the minutes the incoming call is active and >>>the minutes for the new outgoing (nominally from your handset) >>>call to the voicemail box. >>Are you sure about that? >Yep. Protested it numerous times with T-Mobile billing support. No dice. I can turn Call Forwarding off in my handset. T-Mobile ignores it. I will point out that with the plan I'm on, I have 500 minutes of call forwarding (transfers to voice mail or other numbers) available each billing cycle. If I use that up, it's charged to my whenever minutes or overage minutes. It's difficult to use up. It sure would be nice to be able to dump a call with extreme prejudice. ***** Moderator's Note ***** Google Voice. Bill Horne Moderator
Date: Tue, 11 Oct 2011 18:57:17 -0400 From: "Gary" <email@example.com> To: firstname.lastname@example.org. Subject: Re: Lightsquared being called to account Message-ID: <email@example.com> ***** Moderator's Note ***** > > BTW, there's more than one telecom angle to this debacle: Verizon, (and > I assume other LECs) makes extensive use of GPS to provide Stratum II+ > timing information for synchronization of DS3 and other DS-* rate signals > between offices. If the synchronization goes away, so does the digital > data. > > GPS-driven clocks have, of course, "holdover" capability to compensate > for brief outages, but they are NOT, in and of themselves, Stratum II > timing sources, so any prolonged outage will cause them to lose > synchronization and cause failures in digital data and digitized voice > transmission. Years ago I was on a team that developed timing solutions for CDMA base stations for one of the major infrastructure manufacturers. CDMA uses GPS time as a key part of the way it works. This means every base station must have access to GPS time. When I was developing the timing solutions, the accuracy was supposed to be +/- 3uS across a operating area (i.e. a city). The only way to meet this requirement was by putting a GPS timing receiver in each cell site. Of course, we designed redundant systems, so we designed the system to support two GPS receivers. However, the other member of my team was an avid boater and radio geek. As such, he was very familiar with Loran-C. He knew that it was as accurate as GPS since both are traceable back to the USNO's master atomic clock in Fort Collins, CO. So, we designed the system to support a Loran-C receiver as a backup to GPS. If the system lost GPS, it would switch to Loran-C as a timing reference. Since it didn't drift relative to GPS, the site could stay up indefinitely on Loran-C. Of course, the system had to start up with GPS in order to get GPS time, but once a GPS lock was established, it could switch to Loran-C and stay there. It was a really elegant solution, as the Loran-C and GPS are at very different frequencies. So, the likelihood of weather system or an interferer taking out both was very low. Unfortunately, our Government decided that Loran-C wasn't worth the $15 million or so it cost to run each year and shut it down a few years ago. Sure, GPS with WAAS can provide ships and other former Loran-C users with similar navigation data, but it sure was nice to have redundant systems that have very different interference profiles. So, with the loss of Loran-C, the system I worked on now uses a local high accuracy clock for holdover if GPS fails. They are pretty good and can provide days of holdover time with low cost atomic sources, but nothing was ever as good as Loran-C. -Gary ***** Moderator's Note ***** One of my friends, a ham radio operator who was also a Coast Guardsman, was once stationed at a place called French Frigate Shoals. French Frigate Shoals is a coral reef in the middle of the Pacific ocean. When he was there, it had two major features: a high-power radar, and a Loran transmitter. He told me that he and his mates used to go shark fishing for entertainment. For the benefit of those not familiar with Loran, it was a medium-wave technology which operated in the 160 meter band, just above the frequencies used by AM broadcasting in the U.S. to this day, i.e.,, 1.8 to 2 MHz. Propagation delays, atmospheric phenomena, and lightning all affected the performance of Loran, and those factors, in addition to the extraordinary power levels required for the transmitters, were some of the reasons for it being retired in favor of Inmarsat and GPS. Although Loran was still in use during the time I was working on these sorts of issues at Verizon, it was, IIRC, not accurate enough for the timing we required. I don't remember specifics, but (again, IIRC) I think there was too much ambiguity caused by multi-path propagation for us to adopt Loran. Ah, well: sic transit technology. You can still see Loran receivers on E-pay now and then. They usually include a broadcast reception setting, so they're still usable as conversation pieces that can receive baseball games. Bill Horne Moderator
Date: Tue, 11 Oct 2011 18:26:30 -0700 From: Thad Floryan <firstname.lastname@example.org> To: email@example.com. Subject: Tesla Motors Model S sedan takes texting and distracted driving to new level Message-ID: <4E94ECC6.firstname.lastname@example.org> I did a "WTF!?", and fortunately didn't have coffee in hand, when I saw a picture of the new Tesla Model S sedan in today's Almanac (Menlo Park, Atherton, Portola Valley, Woodside [California]) news site today. The equivalent of two iPhone/iPad & 4G communications overwhelms the dashboard as the driver can text with a full-size touch keyboard as can be seen here: http://www.almanacnews.com/news/photos/2011/october/11/7344_full.jpg The Almanac's article is here: http://www.almanacnews.com/news/show_story.php?id=9830 Additional photos showing a driver using a full-size web browser to read the New York Times while driving can be seen here (scroll down to the Photo Gallery): http://www.autoblog.com/2011/10/04/2012-tesla-model-s-beta/ This car is NOT an autonomously-driven vehicle using GPS such as those in the last DARPA competition, it requires the full attention of the driver while on the roads. What are these morons thinking? Will this car earn the nickname "Tesla Deathmobile" when it debuts in 2012? This is clearly a loophole in the no-texting and hands-free laws.
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