Pat, the Editor

27 Years of the Digest ... founded August 21, 1981

Classified Ads
TD Extra News

Add this Digest to your personal   or  

 
 
Message Digest 
Volume 28 : Issue 207 : "text" Format

Messages in this Issue:
  Re: Walter's Telephones 
  Walter's Telephones 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: What is this device called 
  Re: Walter's Telephones 
  Re: Walter's Telephones 
  Re: Skype apparently threatens Russian national security           
  Re: Skype apparently threatens Russian national security           
  Re: Cellphone tower coverage Qs 
  Re: Cellphone tower coverage Qs 
  Re: Cellphones and driving 
  Pop song phone number goes up for auction 
  Re: Cellphones and driving 
  Re: Cellphones and driving 


====== 27 years of TELECOM Digest -- Founded August 21, 1981 ====== Telecom and VOIP (Voice over Internet Protocol) Digest for the Internet. All contents here are copyrighted by Patrick Townson and the individual writers/correspondents. Articles may be used in other journals or newsgroups, provided the writer's name and the Digest are included in the fair use quote. By using -any name or email address- included herein for -any- reason other than responding to an article herein, you agree to pay a hundred dollars to the recipients of the email. =========================== Addresses herein are not to be added to any mailing list, nor to be sold or given away without explicit written consent. Chain letters, viruses, porn, spam, and miscellaneous junk are definitely unwelcome. We must fight spam for the same reason we fight crime: not because we are naive enough to believe that we will ever stamp it out, but because we do not want the kind of world that results when no one stands against crime. Geoffrey Welsh =========================== See the bottom of this issue for subscription and archive details and the name of our lawyer, and other stuff of interest. ---------------------------------------------------------------------- Date: Tue, 28 Jul 2009 02:10:23 +0000 (UTC) From: wollman@bimajority.org (Garrett Wollman) To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4lmme$1s1i$1@grapevine.csail.mit.edu> In article comments attached to my article <h4l6hl$1mr9$2@grapevine.csail.mit.edu>, our moderator wrote: >Please tell us about the various combinations of mode and signal >available to digital stations. For example, if a station has two >separate broadcasts going on, as does channel 7 in Boston, are they >both being transmitted as part of the same digital stream, or are they >only logically linked and transmitted on separate physical channels? ATSC digital television is a single MPEG tranport stream. One of the multiplexed data streams is a description of the other data streams, indicating the video format, the particular multiplexed data stream that the video is on, where all the audio and data streams are, and how to combine them all together into a "virtual channel". There is also supposed to be electronic program-guide data, but few stations bother to transmit data for anything other than the program currently airing. Closed captions, V-chip ratings, and all the other stuff that analog television puts on line 21 are all transmitted as separate tables or separate multiplexed data streams. Unlike with "HD Radio", all of the program services transmitted in ATSC are treated identically, although the licensee can of course change the bit budget allocated to each service by adjusting the compressor's controls. >I ask because I regularly get dropouts and pixelation on 7-2 when 7-1 >is coming in OK, and likewise have trouble with 44-3 or 44-4 when >44-1 is fine. If they're all part of the same bit stream, why does the >problem affect only some of them and not all? Just coincidence. The (limited) Forward Error Correction in ATSC takes place before the MPEG demux, so it's entirely chance that the QRM should affect the transmission of bits in one time slice and not another. It's likely that they are assigning a higher bandwidth to the "main" program, which means that it's more likely to be affected by noise, but with higher bandwidth, the display will repair faster, so you don't see it. I'd have to ask my acquaintances over at channel 7 how they're divvying up the bandwidth. -GAWollman -- Garrett A. Wollman | The real tragedy of human existence is not that we are wollman@csail.mit.edu| nasty by nature, but that a cruel structural asymmetry Opinions not those | grants to rare events of meanness such power to shape of MIT or CSAIL. | our history. - S.J. Gould, Ten Thousand Acts of Kindness ------------------------------ Date: Mon, 27 Jul 2009 22:08:37 -0500 From: Neal McLain <nmclain@annsgarden.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Walter's Telephones Message-ID: <4A6E6BB5.80309@annsgarden.com> Our moderator wrote: > Expecting FM broadcast quality audio from a TV audio signal is like > trying to record a song by holding a cassette recorder up to a > radio. Sooner or later, those who attempt it have to admit that it's > not a productive approach. Oh, come on Bill, it's not that bad! Back when I was working in cable TV, we used to offer a cable FM service. We transmitted standard BTSC (or monaural) RF carriers down the FM band, and connected the cable directly to the customer's FM radio. A bit noisy, but certainly not as bad as holding a cassette recorder up to a radio! We even carried TV aural as part of the cable FM service. The headend gear included frequency-tripling circuitry to change the deviation from +/-25 to +/-75. I posted a description of the process back in 2003 at http://massis.lcs.mit.edu/archives/reports/cable-fm-wfmt-mcclain Scroll down to "The Rise of Cable FM". Neal McLain ------------------------------ Date: Tue, 28 Jul 2009 17:35:34 +1000 From: David Clayton <dcstar@myrealbox.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <pan.2009.07.28.07.35.32.755886@myrealbox.com> On Mon, 27 Jul 2009 10:51:53 -0400, Wesrock wrote: > In a message dated 7/27/2009 12:07:39 AM Central Daylight Time, > harold@hallikainen.com writes: > >> None of the stations I worked with put their control on their program >> line. The program lines were generally driven with a WE 111C >> transformer to drop the 600 ohm source resistance (studio equipment) >> down to 150 ohms to drive the line. Another 111C converted it back to >> 600 ohms at the transmitter. > > Just a matter of curiosity--what was the advantage of 150 ohm lines? 600 > ohms was the standard for telco lines, including program grade lines. > > Wes Leatherock > wesrock@aol.com > wleathus@yahoo.com > > ***** Moderator's Note ***** > > I'm always tempted to answer these sorts of questions myself - I worked on > the "Radio" board, after all - but then I realize that a lot of the things > I "know" about program audio lines are just memories of the way we did > things, and I'm not sure of the technical basis. > > Let's see: impedance varies with frequency, so (I'm guessing) I think 150 > ohms is closer to the impedance at the upper frequencies, thus giving a > boost to the "high end" tones, and making equalization easier. Come to > think of it, that would be _part_ of the equalization, wouldn't it? Lower impedance lines/equipment are less susceptible to picking up noise (especially hum) than higher impedance stuff, in audio you would generally go for the lowest impedance possible to reduce the line's noise. As well various types of audio cabling is made with a specific impedance, so 150 ohms may well match those cables along with the interfaces. -- 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: Mon, 27 Jul 2009 19:37:44 -0700 (PDT) From: Neal McLain <nmclain@annsgarden.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <361e509f-f4c1-40ba-9720-edfa2d62be4a@s15g2000yqs.googlegroups.com> On Jul 27, 8:56 pm, woll...@bimajority.org (Garrett Wollman) wrote: > In article <98b8d488-3f82-41bd-bca2-43648ae26...@x25g2000prf.googlegroups.com>, > Neal McLain  <nmcl...@annsgarden.com> wrote: > > >I'm not sure I trust that chart.  I can believe that 12 and 13 could > >be adjacent in Providence, but I doubt that there are three digital > >stations all operating on Channel 7 in Rapid City. > > Actually, that's entirely possible, assuming they are all the same > station, because the FCC now allows something called a "distributed > transmission system": instead of using one big facility to serve their > allocated coverage area, stations may elect to use multiple smaller > transmitters, possibly with directional antennas, to serve their > markets.  A number of stations made the transition using DTS to reduce > the cost, particularly in rural areas where an omnidirectional antenna > would waste a lot of energy over sparsely-populated parts of the > market. > > -GAWollman >  -- > Garrett A. Wollman   | The real tragedy of human existence is not that we are > woll...@csail.mit.edu| nasty by nature, but that a cruel structural asymmetry > Opinions not those   | grants to rare events of meanness such power to shape > of MIT or CSAIL.     | our history. - S.J. Gould, Ten Thousand Acts of Kindness > > ***** Moderator's Note ***** > > Please tell us about the various combinations of mode and signal > available to digital stations. For example, if a station has two > separate broadcasts going on, as does channel 7 in Boston, are they > both being transmitted as part of the same digital stream, or are they > only logically linked and transmitted on separate physical channels? > > What about channel 44 in Boston? It has four separate subchannels: are > they all just slots in one large bit stream coming out of WGBX's > transmitter? > > I ask because I regularly get dropouts and pixelation on 7-2 when 7-1 > is coming in OK, and likewise have trouble with 44-3 or 44-4 when > 44-1 is fine. If they're all part of the same bit stream, why does the > problem affect only some of them and not all? ==================================================== Garrett: After further thought, I agree that it's entirely possible, particularly in a huge DMA like Rapid City. That DMA covers counties in four states, two of which are isolated islands inside other DMAs. Those isolated counties may be served by translators of Rapid City stations, or they may have separate stations. However, your statement "assuming they are all the same station" doesn't fit the situation I just described. The three Channel 7 stations in the Rapid City DMA 7 have separate call signs and they're affiliated with different networks. One of them (KSWY) is in Sheridan County, WY, one of those isolated counties (I should have recognized the Wyoming area code!). http://www.dtv.gov/stationlist.htm Neal McLain ------------------------------ Date: Tue, 28 Jul 2009 16:02:15 +0100 From: Steve Hayes <steve@red.honeylink.blue.co.uk> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4n3to$2c28$1@energise.enta.net> Wesrock@aol.com wrote: > In a message dated 7/27/2009 12:07:39 AM Central Daylight Time, > harold@hallikainen.com writes: > >> None of the stations I worked with put their control on their program >> line. The program lines were generally driven with a WE 111C >> transformer to drop the 600 ohm source resistance (studio equipment) >> down to 150 ohms to drive the line. Another 111C converted it back to >> 600 ohms at the transmitter. > > Just a matter of curiosity--what was the advantage of 150 ohm lines? > 600 ohms was the standard for telco lines, including program grade > lines. > > Wes Leatherock > wesrock@aol.com > wleathus@yahoo.com > > ***** Moderator's Note ***** > > I'm always tempted to answer these sorts of questions myself - I > worked on the "Radio" board, after all - but then I realize that a lot > of the things I "know" about program audio lines are just memories of > the way we did things, and I'm not sure of the technical basis. > > Let's see: impedance varies with frequency, so (I'm guessing) I think > 150 ohms is closer to the impedance at the upper frequencies, thus > giving a boost to the "high end" tones, and making equalization > easier. Come to think of it, that would be _part_ of the equalization, > wouldn't it? My understanding is that the original open-wire telephone lines did have a characteristic impedance of about 600 ohms but, from having worked on analogue carrier systems many years ago, twisted pair lines are about 135 ohms. We designed our carrier equipment to match this impedance. This would give a reasonably flat response up to several hundred kilohertz but losses at all frequencies were very high. That didn't matter much to the carrier system - it could tolerate up to 40 dB of loss. I'd assume the same approach is used for T1/E1 and DSL systems. That sort of loss would be intolerable for ordinary wireline phones (the circuit is duplex and adding much gain makes it oscillate) so they are still designed to match 600 to 900 ohms. The mismatch doesn't matter much at low frequencies or on short lines and the loss is reduced but there is a lot of high-frequency rolloff on longer lines. This can be mitigated by adding loading coils. Along with the line capacitance, they make the circuit into a low-pass LC filter with reasonably flat response to around 3 kHz but little or no transmission above that. I'd guess that it's easier to use 150 ohms for landline feeds to broadcast facilities where perhaps a 15 kHz bandwidth is required and just crank up the gain and tweak the high frequency response a bit than it would be to use 600 ohms with or without loading coils and have to equalise the resulting horrible rolloff. Not that I've ever worked on them... -- Steve Hayes, South Wales, UK ----Remove colours from reply address---- ------------------------------ Date: Mon, 27 Jul 2009 19:53:38 -0700 (PDT) From: "harold@hallikainen.com" <harold@hallikainen.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <a559530f-8533-42ba-9ee7-be9cb6c000d8@q40g2000prh.googlegroups.com> > ***** Moderator's Note ***** > > I'm always tempted to answer these sorts of questions myself - I > worked on the "Radio" board, after all - but then I realize that a lot > of the things I "know" about program audio lines are just memories of > the way we did things, and I'm not sure of the technical basis. > > Let's see: impedance varies with frequency, so (I'm guessing) I think > 150 ohms is closer to the impedance at the upper frequencies, thus > giving a boost to the "high end" tones, and making equalization > easier. Come to think of it, that would be _part_ of the equalization, > wouldn't it? You've got it! Driving and loading the line with a lower impedance makes the capacity of the cable pair have less effect. In many case, no equalization was required at all. Just a transformer at each end. There's a paper on the frequency response of a cable pair (not a telco pair) with various source and load impedances at http://www.richardhess.com/be/aes-80.htm. Harold ------------------------------ Date: Tue, 28 Jul 2009 03:58:58 +0000 (UTC) From: David Lesher <wb8foz@panix.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4lt21$1u2$1@reader1.panix.com> >***** Moderator's Note ***** >Please tell us about the various combinations of mode and signal >available to digital stations. For example, if a station has two >separate broadcasts going on, as does channel 7 in Boston, are they >both being transmitted as part of the same digital stream, or are they >only logically linked and transmitted on separate physical channels? I've not heard of the DTS scheme but it makes sense. Think of LBJ's "It's better to have him inside the tent pissing out..." >What about channel 44 in Boston? It has four separate subchannels: are >they all just slots in one large bit stream coming out of WGBX's >transmitter? One could assume so [and Rabbitears agrees], but magic *is* possible. Look up "Channel 30" in DC and you'll see it is 10 subchannels from two separate transmitter sites; WNVC is 30-1>30-5; on RF 24. WNVT is -6 through -10 on RF 30. >I ask because I regularly get dropouts and pixelation on 7-2 when 7-1 >is coming in OK, and likewise have trouble with 44-3 or 44-4 when >44-1 is fine. If they're all part of the same bit stream, why does the >problem affect only some of them and not all? That's especially interesting since 44-1>-4 are all 480i; so they should be equal in my thinking. On 7-1; it's HD with a video bitrate of 6x 7-2. I'd think that 7-2 should be easier to decode, so there's something else that I don't grok going on. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 ------------------------------ Date: Tue, 28 Jul 2009 03:43:47 +0000 (UTC) From: David Lesher <wb8foz@panix.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4ls5i$c5b$1@reader1.panix.com> wollman@bimajority.org (Garrett Wollman) writes: >WETA uses a Dielectric TUP-O4-12-2 antenna, a high-gain broadband UHF >panel antenna, which was installed a few years ago for the >transitional DTV facilities of WJLA and WUSA, at a different site from >the old channel 26 analog. So, no "retuning" required, or indeed >possible. (The old tower, if I remember correctly, was in Virginia; >the new tower is in far Northwest DC at the Maryland line.) The old tower is next to Arlington Hospital. I wasn't aware they'd abandoned it, at least for TV. They rent out space to others inc. WAVY who was kicked out of their site up at Lee Highway when the ATT building was sold. But it does appear they are now up on RF Hill. Rabbitears IS useful! >The rules have changed over time, and the FCC's approach to the rules >has also changed. The FCC no longer models TV facilities using fuzzy >photocopied charts derived from experiments done in the 1950s; now >everything is done using the Longley-Rice propagation model. ... >>No one has yet to offer a lucid explanation as to why their DTV coverage >>was so much poorer than predicted. >It seems widely agreed that the FCC's modeling did not accurately >reflect real-world coverage of VHF DTV operations. Indeed. Considering the complaining folks all had had viable NTSC reception... Or did they move as well? >It's the Media Bureau these days. And, more importantly, Martin is gone as chair. Insiders tell me that morale was so bad under him that when Copps took over as interum chair; he got a overwheming standing ovation in the packed auditorum, BEFORE he could say word one. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 ------------------------------ Date: Tue, 28 Jul 2009 02:38:34 GMT From: Tom Horne <hornetd@verizon.net> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: What is this device called Message-ID: <Kwtbm.1314$646.872@nwrddc01.gnilink.net> Robert Bonomi wrote: > In article <QUnam.1071$MA3.310@nwrddc02.gnilink.net>, > Tom Horne <hornetd@verizon.net> wrote: >>> ***** Moderator's Note ***** >>> >>> There were a variety of interface devices that were made available >>> after the FCC mandated interconnection. I'm most familiar with the >>> CDH, which was intended to connect POTS lines to customer provided >>> equipment. It did the job, but it was too complicated: not only did it >>> have separate supervision leads that were isolated from the talk path, >>> but it had separate ringing leads as well. There might have been PBX's >>> or other CPE which could access the CDH directly, but ordinary key >>> equipment could not: to use it for CPE key equipment, you needed >>> _another_ interface to match the CDH interface. >>> >>> Ma Bell had too many interfaces and they cost too much to install and >>> rent: it was inevitable that the FCC would dictate type-acceptance and >>> allow direct connections. I don't remember when that happended, but it's >>> been the norm ever since. >> >> Yes Bill, but that doesn't help with stuff that is not type accepted. >> Isn't the new term of art certified? I'm trying to devise a way to >> patch the PSTN incoming calls to manual switchboards that predate >> customer dialing. If you connect the interconnect terminals of some >> of those boards it will look like an off hook condition to the PSTN. > > > If you'd said -that- in the first place, you'd have gotten better first-round > answers. <grin> > > Anything 'off the shelf' in the (even semi-) modern world is going to require > quite a it of custom 'glue' logic to adapt that cordboard to the weirdness of > the CPE side of the adapter box. You may as well just get one of the (many) > registered, type-accepted, 'FCC part 68' qualified, 'phone line interface > integrated circuits (whew!!), and roll your required custom interfacing logic > around -that-. Such chips are only a few dollars (at most), quantity one. > I'm afraid that customizing chip logic is beyond my skill set. I was hoping, vainly it seems, that there existed some box that took in a loop supervised phone line and a supply of some form of power and put out a voice pair, dry closure on ring, and some means to signal the outside lines supervision state. -- Tom Horne "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison ------------------------------ Date: Tue, 28 Jul 2009 03:14:51 +0000 (UTC) From: David Lesher <wb8foz@panix.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4lqfb$gsq$1@reader1.panix.com> Richard <rng@richbonnie.com> writes: >A sampling of channels on low VHF: >Chan City >5 Anchorage, AK >3 Bethel, AK >6 New Haven, CT >3 Key West, FL >6 Pelham, GA >6 Wrens, GA >2 Las Vegas, NV And two DC ones the FCC staff will know well; if they can still receive them at home.... 7 WJLA 9 WUSA -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 ------------------------------ Date: Tue, 28 Jul 2009 17:04:22 +0000 (UTC) From: wollman@bimajority.org (Garrett Wollman) To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Walter's Telephones Message-ID: <h4nb2m$2cjs$1@grapevine.csail.mit.edu> In article <h4lqfb$gsq$1@reader1.panix.com>, David Lesher <wb8foz@panix.com> wrote: >Richard <rng@richbonnie.com> writes: >>A sampling of channels on low VHF: [...] >And two DC ones the FCC staff will know well; if they can still >receive them at home.... > >7 WJLA >9 WUSA No, those are on VHF-high, not VHF-low. (Our European Friends would say "Band III, not Band I".) -GAWollman -- Garrett A. Wollman | The real tragedy of human existence is not that we are wollman@csail.mit.edu| nasty by nature, but that a cruel structural asymmetry Opinions not those | grants to rare events of meanness such power to shape of MIT or CSAIL. | our history. - S.J. Gould, Ten Thousand Acts of Kindness ------------------------------ Date: Tue, 28 Jul 2009 03:53:12 GMT From: "Tony Toews \[MVP\]" <ttoews@telusplanet.net> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Skype apparently threatens Russian national security Message-ID: <l1ss655nopkp660dcq7v205gqgsuc3muv6@4ax.com> Thad Floryan <thad@thadlabs.com> wrote: >Some background for Echelon, SORM, Carnivore, etc. can be read here: A number of years back a client of mine was taken over by another company. As I didn't trust the new IT department I installed OpenVPN on my laptop and my email server so they couldn't snoop on any emails. This has worked quite well for me. However this only ensures no one can snoop on emails between my email server and my laptop. And very few people run their own web and mail servers. We should really be using S/MIME encryption to encrypt the emails for the entire connection from your computer to my computer so the NSA, CSIS (Canada's version of the NSA and CIA), etc, can't snoop.. (Hows that for few acronyms guaranteed to set off a few low level flags.) http://en.wikipedia.org/wiki/S/MIME You can use the Thawte Web of Trust http://www.thawte.com/secure-email/web-of-trust-wot/ to get yourself a free email certificate. Programs such as Outlook Express/Windows Mail and Outlook do support S/MIME quite nicely. (Regretfully the email software I've been using since 1995, Eudora, has *lousy* support for S/MIME. Apparently this is a fundamental architecture problem and Eudora is no longer being upgraded. If I do need/want to start using S/MIME I'll likely be using a dedicated email address just for those emails and use Outlook. .Apparently Thunderbird is somehow being "upgraded"/"sideways changed" to beocme more like Eudora but I haven't checked on that lately.) I'd also like to see a lot more corporations using S/MIME encryption on their emails as it's possible, for example, folks at your upstream provider could be snooping on emails. Now as to how S/MIME would work in a web browser for those who use Hotmail and Gmail? I think Gmail now allows you to choose to always use a https or secured connection if desired. That won't help if you're feeling particularly paranoid about the NSA and the like but will help ensure that the folks at the coffee shop aren't snooping. Tony (one of my job titles is paranoid pessimist) -- Tony Toews, Microsoft Access MVP Tony's Main MS Access pages - http://www.granite.ab.ca/accsmstr.htm Tony's Microsoft Access Blog - http://msmvps.com/blogs/access/ Granite Fleet Manager http://www.granitefleet.com/ ------------------------------ Date: Tue, 28 Jul 2009 19:38:16 -0700 From: Thad Floryan <thad@thadlabs.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Skype apparently threatens Russian national security Message-ID: <4A6FB618.30808@thadlabs.com> On 7/28/2009 9:22 AM, Tony Toews [MVP] wrote: > Thad Floryan <thad@thadlabs.com> wrote: >> [...] >> Some background for Echelon, SORM, Carnivore, etc. can be read here: > [...] > We should really be using S/MIME encryption to encrypt the emails for the entire > connection from your computer to my computer so the NSA, CSIS (Canada's version of > the NSA and CIA), etc, can't snoop.. (Hows that for few acronyms guaranteed to > set off a few low level flags.) http://en.wikipedia.org/wiki/S/MIME You can use the > Thawte Web of Trust http://www.thawte.com/secure-email/web-of-trust-wot/ to get > yourself a free email certificate. > [...] The solution I use is GPG (GNU Privacy Guard), somewhat akin to PGP as was mentioned at several of the URLs I cited in the earlier article. It integrates well with many common email clients (e.g., Thunderbird, et al) and is what I insist people use if they need to send me passwords, and it provides choices as to the depth/style of encryption. >From 1983 to 1995 I designed/manufactured/sold a telephony device for secure data connections over the phone line, with later models incorporating Motorola's MC6859 DES chip. First/earlier models required using an external modem, later/final models incorporated a builtin modem, initially modules from Cermetek (IIRC) and later the Telebit module for higher speeds. There's a funny story about that MC6859 chip. Upon arriving (late) one day at my office, I found a two foot high stack of documentation and several tubes of sample chips, including the MC6859, left earlier by the Motorola rep. Atop the pile of documentation was a black bordered, sternly worded "NOTICE" stating (paraphrased) "Products incorporating this chip may not be exported from the USA without prior approval from the Office of Munitions Control of the US Department of State blah blah blah". When examining the pretty purple-colored ceramic MC6859 chips with gold legs, I turned one over and, WHOA!, emblazoned on its underside was "MALAYSIA". So much for the technology never leaving the country. :-) ***** Moderator's Note ***** This thread reminds me of the debate about the "Clipper Chip", which was a governemnt-backed program that would have mandated that any encryption device include the capability for the government to decode the data which was encrypted. RSA Security and other commercial firms opposed the program, and it was never implemented. However, any widespread use of encryption will revive the debate: the methods aren't important, but the central question is "Should Uncle Sam be entitled to listen in on my calls or read my emails"? ------------------------------ Date: Tue, 28 Jul 2009 11:42:34 +0000 (UTC) From: techie@tantivy.tantivy.net (Bob Vaughan) To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Cellphone tower coverage Qs Message-ID: <h4mo7a$s2d$1@news.stanford.edu> In article <4A6DC5A3.9000104@thadlabs.com>, Thad Floryan <thad@thadlabs.com> wrote: >Today's SF Chronicle COMPUTING column has some Q&As about cellphones >and this URL was mentioned: <http://cellreception.com/> > >Curious, I wanted to see where the local cell towers were located for >my carrier (AT&T Mobility grandfathered all the way back to Cellular One). >I seldom have fewer than 4 (out of 5) bars on my phone's display, so I >figured there would be a hive of towers especially here, Silicon Valley. > >Visiting this URL: > ><http://www.cellreception.com/towers/towers.php?city=los%20altos&state_abr=ca> > >and clicking "[*] AT&T", I wondered where the towers were and had to zoom >out to see a few. > >There's a cluster of 3 flanking Moffett Federal Airfield about 3.5-4 miles >north from my home, another grouping of 5 about 8-9 miles east between Santa >Clara and San Jose, then two NW about 20-25 miles away in Burlingame. That's >it for the places I normally would be concerned about coverage. > >This doesn't make any sense to me for two reasons: >1. I have excellent signal strength at my home, and >2. if I dial 911 (on the cellphone) from home I get the local city's 911 > center, and if I dial 911 while driving along I-280 all the way up to > San Mateo (just south of Burlingame) I get the CHP 911 dispatch. > >My two questions: > >1. is that tower spacing "normal"? The "cellreception" site claims to have > all registered towers in its database of 135,800 towers last updated in > May 2009. See the notes on the site. It mentions that it doesn't have listings for towers that are not registered in the fcc database, nor for towers owned by third parties. It also dosen't have listings for carriers co-located on another carriers tower. I'm guessing that they are basing the database on the FCC Antenna Structure Registration, and not a specific transmitter site license. I'm not sure if individual cell sites are even listed in the FCC DB. I suspect that Nextel sites are more likely to be listed, given that Nextel is/was a SMR licensee with interconnect capabilities, and not a cellular licensee. Different service, different rules. I know of at least one tower (at Foothill College) that is not shown on the map. I forget who is actually on that tower, but there were at least 3 carriers when I last looked. The site is owned/leased by one of the site management companies (Spectrasite?), and not by a specific carrier. It is likely that there are additional cell sites that are not located on a tower at all, but are installed on the roof of a building (there is a office building along El Camino, next next to WalMart and Trader Joe's which I recall as having antennas on it.) Other places where you may find antennas include flagpoles (there are examples at Palo Alto fire stations 3 (Rinconada Park), and 4 (Mitchell Park), lamp posts (the old Elks Lodge parking lot next to Dianah's), and church steeples. There are also some micro sites mounted on utility poles (Junipero Serra @ Stanford Ave). > >2. how/why would I get routed to CHP's 911 while on I-280 headed NW even > just a mile or two from home while I get routed to the local city's 911 > if I call from home? [I'm not complaining because that's exactly what I > want to happen] > >The reason I'm puzzled is that when the service was still Cellular One they >claimed a tower within 1/2 mile of my home and even assisted getting service >to function within the local food supermarket which had a metal roof and >zero reception. Later, as Cingular, again I was informed new towers were >being installed. To date since AT&T acquired the contract, I've received no >indication of new towers, only claims of "service improvements" -- given I >really have no quarrel with AT&T Mobility, I accept that claim. > >Perhaps I should be asking: is there a better resource showing cellphone >coverage and/or tower locations by carrier? I know Jeff Leiberman has/had a list of cell sites in the San Lorenzo Valley area, but I haven't looked at it in quite a while. I don't know if it lists anything down in the Santa Clara Valley. > >I'm still scratching my head wondering how cellphone service works here at >all. :-) > -- -- Welcome My Son, Welcome To The Machine -- Bob Vaughan | techie @ tantivy.net | | P.O. Box 19792, Stanford, Ca 94309 | -- I am Me, I am only Me, And no one else is Me, What could be simpler? -- ------------------------------ Date: Tue, 28 Jul 2009 20:03:12 -0700 From: Thad Floryan <thad@thadlabs.com> To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Cellphone tower coverage Qs Message-ID: <4A6FBBF0.1050606@thadlabs.com> On 7/28/2009 9:23 AM, Bob Vaughan wrote: > In article <4A6DC5A3.9000104@thadlabs.com>, > Thad Floryan <thad@thadlabs.com> wrote: >> [...] >> 1. is that tower spacing "normal"? The "cellreception" site claims to have >> all registered towers in its database of 135,800 towers last updated in >> May 2009. > > See the notes on the site. It mentions that it doesn't have listings for > towers that are not registered in the fcc database, nor for towers owned > by third parties. It also dosen't have listings for carriers co-located on > another carriers tower. Red-faced, thank you! I now see those notes. :-) > [...] > I know of at least one tower (at Foothill College) that is not shown on > [...] > It is likely that there are additional cell sites that are not located on > a tower at all, but are installed on the roof of a building (there is a > office building along El Camino, next next to WalMart and Trader Joe's > which I recall as having antennas on it.) > > Other places where you may find antennas include flagpoles (there are > examples at Palo Alto fire stations 3 (Rinconada Park), and 4 (Mitchell > Park), lamp posts (the old Elks Lodge parking lot next to Dianah's), > and church steeples. There are also some micro sites mounted on utility > poles (Junipero Serra @ Stanford Ave). > >> 2. how/why would I get routed to CHP's 911 while on I-280 headed NW even >> just a mile or two from home while I get routed to the local city's 911 >> if I call from home? [I'm not complaining because that's exactly what I >> want to happen] It's possible those "undocumented" towers at Foothill College and other sites north-westwards is probably why I get the CHP's 911 dispatch while along I-280 instead of the local municipalities' 911 centers. The 20 mile "gap" between Los Altos/Mountain View and Burlingame as depicted on cellreception's site was puzzling, especially so given all the hills and other radio obstructions along I-280. Again, thank you for the info! I'm going to poke around and followup if/when I find sites with better/more information. It's odd (to me) the FCC wouldn't have ALL cellphone (tower) transceivers in their database given how tightly they seem to regulate the spectrum. ------------------------------ Date: Tue, 28 Jul 2009 09:48:07 EDT From: Wesrock@aol.com To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Cellphones and driving Message-ID: <d5a.4c6ca40d.37a05b97@aol.com> In a message dated 7/27/2009 9:07:14 PM Central Daylight Time, Wesrock@aol.com writes: > ***** Moderator's Note ***** > > They could install high-speed readers for cars with transponders, > and promote the service and the time saved in the 'Fly By' > lane. That would cost very little in relative terms, especially > compared to the value of the time wasted by all those motorists. I had not really considered that they did not have transponders since they have been used on all the toll roads I have driven on in Kansas, Oklahoma or Texas. It would be nice if the three states could agree on an interchange, especially since they all use the same system, from a firm with headquarters in Houston, and at least for the Oklahoma turnpikes the bill (statement of usage--you have to prepay in $40 increments) comes out of Houston. There are some transponder lanes in Oklahoma which have "ramp speed 75" signs posted on the entrance to those lanes. -- Wes Leatherock wesrock@aol.com wleathus@yahoo.com ------------------------------ Date: Tue, 28 Jul 2009 10:16:37 -0700 (PDT) From: hancock4@bbs.cpcn.com To: redacted@invalid.telecom.csail.mit.edu Subject: Pop song phone number goes up for auction Message-ID: <bea626a5-32a3-4708-b3dd-00e61567d0fa@g23g2000vbr.googlegroups.com> A telephone number related to the Jenny song is up for auction. For details see: http://www.kyw1060.com/--Jenny-s---Phone-Number-Goes-Up-For-Auction/4888510 ------------------------------ Date: Tue, 28 Jul 2009 13:15:09 -0500 From: bonomi@host122.r-bonomi.com (Robert Bonomi) To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Cellphones and driving Message-ID: <fL-dnQox-qWw3fLXnZ2dnUVZ_jmdnZ2d@posted.nuvoxcommunications> In article <pan.2009.07.27.07.26.42.838735@myrealbox.com>, David Clayton <dcstar@myrealbox.com> wrote: >On Sun, 26 Jul 2009 16:02:26 -0400, John David Galt wrote: > >> David Clayton wrote: >>> Too many people reject attempts to reduce any problem if the proposed >>> solution isn't somehow "perfect" in obtaining a 100% solution to the >>> issue. >>> >>> I rather have 70% (or whatever the compliance rate actually is) less >>> people using phones while driving because that reduces that particular >>> risk to everyone else by that amount, if 30% continue to indulge in that >>> sort of risky behaviour then it is still far better than the original >>> situation. >> >> The vast majority of drivers are still phoning while driving (not a >> scientific survey, just my personal observation). >> >> If we want drivers to obey this law, then let's increase the penalty >> and/or create more enforcement mechanisms (for instance, have the red >> light camera operators look for people phoning). Otherwise, repeal it. > >Hey, I reckon that any driver caught illegally using a phone should have >the phone immediately confiscated and smashed to bits before their eyes. > >Give that sort of enforcement a few months of use and then see the >compliance rate soar...... :-) > >-- >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 ***** > >My first reaction to David's idea was "Get Real!" ... but then I >remembered seeing film of a Connecticut State Trooper confiscating a >radar detector, so now I'm not sure if it's such a far-fetched >idea. Any lawyers want to weigh in? The U.S. Constitution forbids 'takings' without 'just compensation', in general. Things that are present in a place where they are forbidden to be can be confiscated -- *temporarily* -- to remove them from the forbidden locale. But they must be returned to the 'lawful' owner thereof, later, when request/demand is made, *OR* the owner must be reimbursed the fair value thereof. This is precisely _why_ the TSA handles detected 'forbidden' objects the way they do -- you can either _keep_ your object, and make other arrangements for your (or -its-) travel, or you can 'donate' it to the government, and proceed with your scheduled travel. They do _NOT_ "confiscate" anything. <rolls eyes> ------------------------------ Date: Tue, 28 Jul 2009 21:18:39 -0500 From: gordonb.zrsqu@burditt.org (Gordon Burditt) To: redacted@invalid.telecom.csail.mit.edu Subject: Re: Cellphones and driving Message-ID: <fNudnf98kMziLPLXnZ2dnUVZ_ridnZ2d@posted.internetamerica> > The U.S. Constitution forbids 'takings' without 'just compensation', > in general. Things that are present in a place where they are > forbidden to be can be confiscated -- *temporarily* -- to remove > them from the forbidden locale. But they must be returned to the > 'lawful' owner thereof, later, when request/demand is made, *OR* > the owner must be reimbursed the fair value thereof. If that's true, please explain "civil forfeiture" and how, for example, some antique store owner at an airport carrying enough cash to go on an antiques-buying trip to numerous auctions gets his cash confiscated (and he can't get it back) because he can't prove it wasn't drug money. Or, for that matter, explain how a homeowner or landlord can lose his home because his kid (or tenant's kid) has a pot garden in the back yard. Or how some cities confiscate cars of the wives and mothers of men/boys caught soliciting prostitutes. > This is precisely _why_ the TSA handles detected 'forbidden' objects > the way they do -- you can either _keep_ your object, and make other > arrangements for your (or -its-) travel, or you can 'donate' it to > the government, and proceed with your scheduled travel. They do > _NOT_ "confiscate" anything. <rolls eyes> My proposed solution to the penalties for driving under the influence of (hands-free) cell phones: 1. You get a minimum of 24 hours in jail, with the phone. It will ring often, all night. If you answer it, the 24 hours restarts and you get a nasty electric shock. For the severely addicted, this may be a life sentence. 2. You lose your phone number, and it will be forwarded to a recording for the next year (and you have to pay for this) explaining that you're not responsible enough to use a cell phone, with NO forwarding number given. 3. You have to pay the early termination fee on your cell phone contract. ***** Moderator's Note ***** The Fifth Amendment states that "... nor shall private property be taken for public use, without just compensation." I doubt that items confiscated because they were used in the commission of a crime are considered to be "for public use", but I'll defer to the constitutional scholars among us. ------------------------------ 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 Patrick Townson. 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 currently being moderated by Bill Horne while Pat Townson recovers from a stroke. 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. End of The Telecom digest (19 messages) ******************************

Return to Archives**Older Issues