The Telecom Digest for November 01, 2010
Volume 29 : Issue 294 : "text" Format
Messages in this Issue:
====== 28 years of TELECOM Digest -- Founded August 21, 1981 ======
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Date: Sat, 30 Oct 2010 18:38:21 -0400
From: Monty Solomon <monty@roscom.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Three Unknown Features of the iPhone 4
Message-ID: <p06240841c8f24e975797@[10.0.1.3]>
Three Unknown Features of the iPhone 4
By DAVID POGUE
August 12, 2010
It seems as though Apple dodged a bullet. Ever since the Steve Jobs
press conference a couple of weeks ago, in which Apple offered free
carrying casesbumpers (or full refunds) to anyone whose iPhone 4
exhibits the signal-drops-when-you-hold-the-phone-a-certain-way
problem, the jeering and mockery online seems to have gone into
hibernation.
Meanwhile, enough time has passed, and enough millions of people have
been playing with their iPhones, that a critical mass of tricks and
tips have started to pile up. Here's a look at three cool iOS 4
features that nobody, including Apple, seems to be talking about.
...
http://www.nytimes.com/2010/08/12/technology/personaltech/12pogue-email.html
Date: Sat, 30 Oct 2010 19:03:13 -0400
From: Monty Solomon <monty@roscom.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Get ready for Verizon's 'Dream Phone'
Message-ID: <p06240845c8f253fb9b00@[10.0.1.3]>
October 29, 2010 3:00 AM
The soon-to-be-unveiled Verizon iPhone is the answer to many
consumers' prayers. But a deal with Apple will test the company that
Ivan Seidenberg has spent his career building.
By Sarah Ellison, contributor
The most talked-about cellphone in America is one that doesn't
officially exist: the Verizon iPhone. Ever since the 2007 launch of
Apple's iPhone -- which crippled swaths of AT&T's network --
consumers have yearned for a Verizon iPhone as if it were the Second
Coming. When Verizon Wireless, the nation's largest mobile-phone
operator, recently agreed to sell Apple's iPad tablet bundled with a
MiFi card that works on Verizon's network, tech analysts and media
were abuzz with speculation that the real news -- the announcement of
the much-anticipated Verizon iPhone -- was in the offing. "Apple and
Verizon Wireless finally are getting it on. But are there bigger
plans in the works?" tech site Appolicious asked after the companies
announced their iPad pact. (The answer: yes. Fortune has confirmed
that a Verizon iPhone will be released in early 2011.)
That so many Americans covet Verizon (VZ) iPhones --analysts estimate
that Apple (AAPL) could sell 8 million to 9 million of them next
year, compared with an estimated 22 million iPhones sold to date in
the U.S. -- is partly a testament to the efforts of Ivan Seidenberg,
who has presided over one or another of Verizon Communications'
predecessor companies since 1995, when he became CEO of Nynex. From
that perch Seidenberg has transformed a boring, lumbering,
$13-billion-a-year in sales phone company into a technology giant
with $108 billion in sales last year. He did it through a series of
acquisitions and a particularly shrewd wireless joint venture with
U.K.-based carrier Vodafone, which today serves an industry-leading
93 million U.S. customers, many of whom have disconnected their
Verizon landline phones in favor of an all-mobile existence. "One of
Ivan's great strengths is he is not afraid to cannibalize his own
business," says Blair Levin, a former chief of staff at the Federal
Communications Commission and now a fellow at the Aspen Institute.
"What Ivan did is as if GM 15 years ago decided to be the world
leader in electric cars and today was that leader." (In late October,
Verizon Wireless agreed to pay a $25 million fine -- and reimburse
customers -- for fees improperly charged to approximately 15 million
customers.)
...
http://tech.fortune.cnn.com/2010/10/29/verizon_iphone_seidenberg/
Date: Sat, 30 Oct 2010 21:14:15 -0400
From: "Bob Goudreau" <BobGoudreau@nc.rr.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: paypass, was A Simple Swipe on a Phone
Message-ID: <264F207C46B24135B1B90D24AA620079@meng.lab.emc.com>
tlvp <tPlOvUpBErLeLsEs@hotmail.com> wrote:
> Perhaps just urban legend, but I've heard of a Speedpass user who, prior
> to relocating across the country, sought to have his Speedpass device
> taken out of service. "UPS it to its issuer," was the advice he got ...
>
> ... and followed. Then, at the usual time of the month, a Speedpass bill
> got forwarded to his new address, with some 38 toll collections, 19 in
> each direction, at a NJTPke toll booth near his former home, all for
> transits after he sent his Speedpass in for deactivation.
>
> TMALSS, it turns out the UPS flat his Speedpass got itself sent in
> slipped behind the dash of a UPS delivery van, and was dinging up a
> toll every time it passed through a NJTPke Speedpass lane toll both,
> day in, day out :-) .
>
> Or so I've seen it recounted :-) .
Surely you mean E-ZPass (the multi-state remote toll transponder), not
Speedpass.
This is actually plausible (though still perhaps no more than a good story).
When one of the state agencies that issues E-ZPass transponders sends one to
a new customer, they enclose it in a radio-reflective envelope (looks like
Mylar) precisely for that reason. The customer is instructed to retain the
envelope for when the transponder needs to be returned to the issuing
agency, because it is quite possible for mail trucks to travel over toll
highways.
Bob Goudreau
Cary, NC
Date: Sat, 30 Oct 2010 21:32:55 -0400
From: Monty Solomon <monty@roscom.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Funeral for a Friend
Message-ID: <p06240855c8f27770ea9e@[10.0.1.3]>
Funeral for a Friend
By VIRGINIA HEFFERNAN
The New York Times
October 29, 2010
I started to distrust telephones the instant they stopped working. I
can't pinpoint when that was - the first time I "dropped" a call, or
someone said, "I'm losing you" - and I don't know why the telephone,
the analog landline telephone, was never formally mourned. I do
remember clearly what life was like when telephones worked.
What a many-splendored experience it once was to talk on the phone.
You'd dial a number, rarely more than seven digits, typically known
by heart and fingers. You'd refrain from calling after 9 p.m. or
"during dinner"; there were many ideas of politeness around phones,
and those ideas helped people pretend that the emotional chaos
telephones fostered by all that ungoverned, nonpresentational,
mouth-to-ear speech - like whispering across great distances - didn't
exist.
...
https://www.nytimes.com/2010/10/31/magazine/31fob-medium-t.html
Date: Sat, 30 Oct 2010 19:52:07 -0700
From: Thad Floryan <thad@thadlabs.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Communications infrastructure reliability, uptime, and information availability
Message-ID: <4CCCD9D7.5030501@thadlabs.com>
On 10/30/2010 5:31 PM, Jeff Liebermann wrote:
> On Sat, 30 Oct 2010 14:25:39 -0700, AES <siegman@stanford.edu> wrote:
>
>> I recall being told by a Bell Labs old-timer that in the pre-divestiture
>> days the Bell System had a published standard for its local operating
>> companies which said that no individual premises should be without dial
>> tone for more than an accumulated total of 18 minutes/year.
>
> That sounds about right, assuming my memory from 40 years ago is still
> functional.
>
>> And, he added, their performance against these and other standards was
>> regularly measured, at least on a statistical sampling basis -- and the
>> results of these measurements became a part of the periodic performance
>> reports for the managers and executives of the local Bell telcos.
>
> Not only for internal consumption, but outage reports go to the FCC.
> See:
>
> http://www.fcc.gov/pshs/services/cip/nors/nors.html
>
> and industry groups:
>
> http://www.atis.org/nrsc/index.asp
>
> More:
>
> http://www.fcc.gov/pshs/techtopics/techtopics15.html
>
> It was previously possible to view the reports and sometimes the raw
> faxed outage reports online. However, in the "interest of national
> security", the FCC has decided that you don't need to know. This
> includes network outages, tower light outages, cell site outages, and
> most every form of communications the FCC regulates. For example:
>
> http://redtape.msnbc.com/2006/12/why_cell_phone_.html
> http://www.wired.com/politics/law/news/2004/07/64168
A local newsgroup, ba.internet (San Francisco Bay Area), occasionally
has interesting telecom tidbits. Today I found this exchange between
a regular poster here in comp.dcom.telecom and another in ba.internet.
Some really interesting URLs were posted by Jeff.
Date: Sat, 30 Oct 2010 21:10:39 -0700
From: Steven <diespammers@killspammers.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Welcome to India, Mr. Obama
Message-ID: <iaiq82$b91$1@news.eternal-september.org>
Oct 31, 12:03 AM EDT
Welcome to India, Mr. Obama, land of many cell phones and not enough toilets
By RAVI NESSMAN
The Associated Press
MUMBAI, India (AP) -- The Mumbai slum of Rafiq Nagar has no clean water
for its shacks made of ripped tarp and bamboo. No garbage pickup along
the rocky, pocked earth that serves as a road. No power except from
haphazard cables strung overhead illegally.
And not a single toilet or latrine for its 10,000 people.
Yet nearly every destitute family in the slum has a cell phone. Some
have three.
http://hosted.ap.org/dynamic/stories/A/AS_FEA_INDIA_TOILETS_AND_CELL_PHONES?SITE=ILROR&SECTION=HOME&TEMPLATE=DEFAULT
--
The only good spammer is a dead one!! Have you hunted one down today?
(c) 2010 I Kill Spammers, Inc. A Rot in Hell Co.
Date: Sun, 31 Oct 2010 11:04:04 -0500
From: John Mayson <john@mayson.us>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Speaking of mobile phones on planes
Message-ID: <AANLkTinLW0=Rohv8LCL3B6C+5FkfPwTjWemb3O+ApFE6@mail.gmail.com>
I was flying home on Singapore Airlines this weekend. They had a
short article about a service they plan to launch early next year.
Every aircraft will be GSM capable. Any passenger with a GSM phone
with global roaming will be able to place calls, SMS, and have 3G
data. The billing will be handled through the passenger's carrier.
The article did not give prices. It did qualify the statement about
phone calls saying it was dependent on further market research. I
suppose that's their phrase for "will our passengers bolt if we allow
phone calls on planes". I have to think the costs will be exorbitant
which might prevent overuse.
--
John Mayson <john@mayson.us>
Austin, Texas, USA
Date: 31 Oct 2010 02:27:03 -0000
From: John Levine <johnl@iecc.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Happy anniversary cellphone!
Message-ID: <20101031022703.53568.qmail@joyce.lan>
>> ... As to old phone numbers, I wonder how many landline numbers are
>> over 50 years old. Given how often people move these days, I
>> suspect very few. ...
My mother in law died a few weeks ago, and had the same number she had
in 1950. Originally her number was just four digits, sometime in the
fifties they added a WAlnut-4 prefix to make it the standard seven
digits, and sometime around 1970 they went to all figures, making the
prefix 924. The family moved across town in the early 1960s, but kept
the same number.
R's,
John
Date: Sun, 31 Oct 2010 12:21:34 -0700 (PDT)
From: Lisa or Jeff <hancock4@bbs.cpcn.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Happy anniversary cellphone!
Message-ID: <ba50f430-4718-4bb8-b605-cd20cd5699b7@e14g2000yqe.googlegroups.com>
On Oct 30, 10:27 pm, John Levine <jo...@iecc.com> wrote:
> My mother in law died a few weeks ago, and had the same number she had
> in 1950.
A friend of mine is living in his parents house and it has the same
number since 1950. His parents passed on recently and he called the
phoneco to change the service to his name. They wanted a deposit.
Apparently being a customer for 60 years didn't count. He's leaving
the listing alone.
(He also wants to get DSL but most phones in the house are hard wired--
old 2500 sets when they went to Touch Tone in the early 1970s. So
there's the problem of installing the DSL filter in front of all the
phone sets.)
***** Moderator's Note *****
He doesn't need to put a filter in front of every phone: he can do as
I did, and put a single filter in the line at the demarc.
Bill Horne
Moderator
Date: 31 Oct 2010 02:29:19 -0000
From: John Levine <johnl@iecc.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Disconnected: Attention Passengers it's perfectly safe to use your cellphones
Message-ID: <20101031022919.54130.qmail@joyce.lan>
>Ok, the reasoning does make sense of how a handset in flight can get a
>RF path to multiple towers on the ground, but don't all the cell phone
>protocols specifically pick out the strongest/most available signal
>and then connect to that?
Yes, but the key improvement of cellular phones over the earlier IMTS
is that they can switch towers during the call without dropping the
call. It rescans periodically to see if another tower has a better
signal.
>Wouldn't that prevent the "connecting to multiple towers" issue that
>has been mentioned?
Nope.
R's,
John
Date: Sat, 30 Oct 2010 19:35:08 -0700 (PDT)
From: Lisa or Jeff <hancock4@bbs.cpcn.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Happy anniversary cellphone!
Message-ID: <a240eb73-407e-47ac-90ea-14e9ad4c529b@x42g2000yqx.googlegroups.com>
On Oct 30, 5:20 pm, bon...@host122.r-bonomi.com (Robert Bonomi) wrote:
> Those early phones sent the individual digits 'in real time',
> _as_you_dialed_, to the head end for processing. Just like with
> POTS, you were 'off hook' (and "on the air", tying up the scarce
> channel) from the time you picked up the handset, until you hung up.
AFAIK, originally and through to today, cell phone billing is based on
"send to end" timing, as opposed to a land line's "from answer to hang
up". That adds a little bit to each call, and could push the call an
extra minute if the called party is slow to answer.
I recall seeing early cell phone contracts in which the user paid for
calls even if the line was busy or no answer. So if a caller waited
the suggested ten rings before hanging up, he would get charge all
that wait time. By the time I got my cell phone unanswered/busy calls
were not charged.
> One of the driving forces behind the implementation of cellular was
> that there were getting to be 'too many' users out there. vs the
> fixed number of base stations. In 'congested' areas, it could take
> a long time (tens of minutes, to an hour _or_more_) to luck into
> an open channel to place a call on.
There was a huge demand for service that they couldn't meet until
cellular came out despite the high service charges--there was a long
waiting list to get a mobile unit. I suspect the aforementioned state
senator got his mobile phone because of his being a politician as
opposed to a real legitimate need for it (say, as opposed to a
physician).
As an aside, the Bell Labs history suggest Bell was ready to test
cellular mobile service several years before they actually did--they
were held up by the FCC 'thinking' about it.
The PRR/Penn Central Metroliner trains, which had direct dial mobile
pay phones on board, used a basic cellular technology. There's a Bell
Labs article on line describing it. Calls were automatically handed
off from one 'cell' to another, though back then the cells were
usually much bigger. The Baltimore tunnel complex was wired to
provide service (not an easy job), though the Hudson River tunnels
were not.
Regarding operator assistance, when I got my cell phone I presumed
hitting 0 would connect me to a mobile operator, specialized in
handling mobile issues. Nope. Not only did 0 bring in a plain
operator who couldn't help at all with mobile problems, it was
chargeable time. To get help with mobile issues, one had to call
'customer service', who might have a backlog to answer and not be open
all the time.
Also, when I got the phone I assumed the Bell store would be staffed
by skilled and trained Bell personnel. Ha ha.
***** Moderator's Note *****
Prior to cellular phones, mobile service was allocated on a priority
basis, with elected officials having precedence over others. I don't
recall the exact order, but politicians were high on the list.
Bill Horne
Moderator
Date: Sun, 31 Oct 2010 11:02:14 -0700
From: Richard <rng@richbonnie.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Happy anniversary cellphone!
Message-ID: <1tarc6p5ucgr7539fifodo05uqhksgh1kj@4ax.com>
On Sat, 30 Oct 2010 19:35:08 -0700 (PDT), Lisa or Jeff
<hancock4@bbs.cpcn.com> wrote:
>I recall seeing early cell phone contracts in which the user paid for
>calls even if the line was busy or no answer. So if a caller waited
>the suggested ten rings before hanging up, he would get charge all
>that wait time. By the time I got my cell phone unanswered/busy calls
>were not charged.
With my Tracfone pay-as-you-go service, I get charged for air time on
busy/no-answer calls. At least they don't charge if my phone rings
and I don't answer. (Ooh, I hope Tracfone doesn't read this. :-)
>As an aside, the Bell Labs history suggest Bell was ready to test
>cellular mobile service several years before they actually did--they
>were held up by the FCC 'thinking' about it.
The FCC does seem to take a lot of time to act. They claim that it's
because the law requires them to propose changes, then gather and
process comments and counter-comments.
When the international Amateur Radio rules dropped the requirement for
Morse code and made it optional, many countries dropped the code
requirement immediately. The FCC took a couple of years to drop their
code requirement, because of the above process.
And sometimes the FCC will not decide. A few decades ago, there were
three proposed systems for stereo AM radio, neither of which was
compatible with the others. The FCC decided not to pick one, but to
le them fight it out in the marketplace. As a result, none of the
systems became popular.
Date: Sat, 30 Oct 2010 22:27:28 -0700
From: Richard <rng@richbonnie.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Happy anniversary cellphone!
Message-ID: <k2vpc6pevupdba1v3rm3kntj66p8ggq98h@4ax.com>
On Wed, 27 Oct 2010 20:30:25 EDT, Wes Leatherock <wesrock@aol.com>
wrote:
>
>
>In a message dated 10/27/2010 5:23:15 PM Central Daylight Time,
>johnl@iecc.com writes:
>
>>> 339-DOG-TITS. Beat that for being easy to remember!
>>
>> My 800 number spells my wife's name. I think that's why she
>> finally agreed to marry me.
>
>A reporter on our company (SWBell Oklahoma) employee newspaper went to
>Stillwater to do a story on the fall enrollment rush at the business
>office. (I believe the business office had a set up on the camous
>where students arrived.) They had a list of numbers they would not
>assign because of what they spelled. One of them spelled TITS. I
>don't remember some of the others.
>
>
>Wes Leatherock
>wesrock@aol.com
>wleathus@yahoo.com
The Department of Motor Vehicles maintains similar lists of forbidden
vanity license plates. In Nevada, the application for vanity plates
has a line for a word description of what the plate means.
When I lived in New Hampshire 20 years ago, I saw one which slipped
through:
3M-TA3
(Look at it in a mirror.)
I first saw it in my rear-view mirror on the car behind me.
***** Moderator's Note *****
When I lived in New Hampshire $% years ago, the pastor at the church
had his initials on his plate: "LSD". They finally made him give them
back.
Bill Horne
Moderator
Date: Sat, 30 Oct 2010 21:52:14 -0500
From: bonomi@host122.r-bonomi.com (Robert Bonomi)
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Disconnected: Attention Passengers it's perfectly safe to use your cellphones
Message-ID: <uKWdncfdgc1DRFHRnZ2dnUVZ_uqdnZ2d@posted.nuvoxcommunications>
In article <pan.2010.10.30.22.33.01.100590@myrealbox.com>,
David Clayton <dcstar@myrealbox.com> wrote:
>On Fri, 29 Oct 2010 17:45:24 -0700, Thad Floryan wrote:
>
>> On 10/27/2010 9:59 PM, Robert Bonomi wrote:
>>> In article <pan.2010.10.27.21.53.31.460692@myrealbox.com>, David Clayton
>>> <dcstar@myrealbox.com> wrote:
>>>> On Tue, 26 Oct 2010 22:04:08 -0500, Gordon Burditt wrote:
>>>>
>>>>>> Experts I've read claim the problem is a cell phone at such an
>>>>>> altitude would light up too many cell towers and the towers couldn't
>>>>>> handle the hand offs of such a fast moving phone.
>>>>> That would tie up one frequency in each of however many cells you lit
>>>>> up (maybe hundreds).
>>>> Can someone explain to me how cell towers - which must have antenna
>>>> arrays deliberately designed with focussed radiation patterns to
>>>> maximise the signal going to handsets either on the horizontal plane to
>>>> the tower, or below that plane - are able to somehow connect with all
>>>> these handsets above them (way, way above them)?
>>>
>>> The answers are to be found in spherical trig, and _absolutely_
>>> _unobstructed_ signal paths.
>>> [...]
>>
>> I agree. Anyone wanting a refresher and a note about haversines might get
>> a kick out of this article I posted to sci.math back in 1988, some 22
>> years ago:
>>
>> http://groups.google.com/group/sci.math/msg/d6c891302914fd84 or
>> http://groups.google.co.jp/group/sci.math/msg/d6c891302914fd84
>
>Ok, the reasoning does make sense of how a handset in flight can get a
>RF path to multiple towers on the ground, but don't all the cell phone
>protocols specifically pick out the strongest/most available signal
>and then connect to that?
Think about what is involved to do make that 'pick'.
Every station receiving the signal has to report 'who', and 'how well'
to a central clearing-house. which then directs the 'best performing'
station to pick up the call.
Those 'clearinghouse' operations use overlapping "local area" coordination
zones. that are, in general, only "a few" cell footprints wide.
Hit towers at locations 'far enough' apart _from_each_other_, and those
towers =DO=NOT= directly co-ordinate with each other. And all heck breaks
loose.
Not to mention, there are only a very =limited= number of cell voice
"channels" (a combination of frequency and TDM time-slot). the same
channels are not used in adjacent cells, to minimize the risk of a
'far away' phone (talking to a distant tower) "covering up" communications
between a nearby phone and the local tower. Put that 'far away' phone
up where it has an _absolutely_ obstacle-free 'line of sight' shot to
the a tower, and give the 'nearby phone' some "obstacles" to deal with
(inside a building, multi-path reflections, on the wrong side of a hill,
etc.,etc.) and that remote phone may make the 'local' channel "unusable",
_even_though_ it is not talking to 'that' tower.
The airborne phone locks up to one tower to 'talk to', and renders maybe
40, 50, 100, or more occurrences of that frequency/time-slot combination
(in the other cells it is 'in sight of"is 'in sight of")) 'unusable'.
NOT good.
>Wouldn't that prevent the "connecting to multiple towers" issue that
>has been mentioned?
short answer: No.
'Control' communications go on on a single common channel. and -after-
the matter of which tower to talk to (based on who the mobile hears best,
and who hears the mobile best), a 'not in use _locally_' channel (frequency
and TDM Mux slot) is assigned. It there is 'somebody else', "somewhere
else" putting out an overwhelming signal on that channel, the 'local' user
can't communicate on that channel.
Even worse if the local phone and tower are already using the channel
when the 'far away' phone gets assigned the same channel by the tower it
is talking to. And the in-progress local conversation gets clobbered.
I'm -not- sure, but I think that the current cellular system does -not-
have the capability to recover from that particular scenario, without
dropping the in-progress call completely.
The other thing one has to be aware of is that the cellular phone system
is extremely limited in the number of calls it can handle without
'reusing' channel assignments in geographically separated areas. I'm not
going to run through the math, but as I recall, "cellular" can only handle
around 2,000 simultaneous calls. That is -not- 'per cell' but among the
whole set of adjacent cells (usually 7) that use non-overlapping frequencies.
A mere 50 'high in the sky' phones has the potential to 'take out' 2.5%
of the total capacity of the cell phone system for many hundreds
of mile around their location. (A mere 2,000 feet above ground gives
a 'horizon' of 100 miles or so.)
Date: Sat, 30 Oct 2010 22:48:29 -0700
From: Richard <rng@richbonnie.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Disconnected: Attention Passengers it's perfectly safe to use your cellphones
Message-ID: <utvpc6tb879ppt2cggga8ea5b5irn8nm5n@4ax.com>
On Wed, 27 Oct 2010 20:57:38 -0500, bonomi@host122.r-bonomi.com
(Robert Bonomi) wrote:
>In article <e5717175-91d8-441c-9e27-71c0a9a42d14@g13g2000yqj.googlegroups.com>,
>Lisa or Jeff <hancock4@bbs.cpcn.com> wrote:
>
>>I'm surprised they still use AM. IIRC, back in WW II radios in tanks
>>originally used AM but then switched to FM (from the Bell System
>>History "War & Peace").
>
>AM is _intentionally_ used for aircraft radio. Specifically to avoid the
>'capture' effect of FM receivers. You want to be able to hear the
>weaker/more distant station that is calling "mayday" under the routine
>traffic of the nearby station.
Single-sideband, suppressed carrier (SSB-SC) would be even better for
hearing that weak mayday message. The AM broadcast band channel uses
double-sideband, full carrier. At night, when I hear two stations on
the same channel, often the weaker signal is garbled becaue of phasing
errors between the sidebands of the weaker signal and the carrier of
the stronger. And if the carriers aren't zero-beat, there is a
heterodyne tone. With SSB-SC, there is no distortion or tone. In my
ham radio experience using SSB-SC, during a net check-in when many
stations are calling at once, I can hear a several signals on top of
each other, and make them out clearly.
Of course, making aircraft switch to SSB-SC would be difficult, as all
aircraft and towers would have to switch at the same time.
***** Moderator's Note *****
There's the rub: all aircraft, all towers, all emergency operations
centers, all portable equipment, and all at the same time. It would be
a salesman's dream, and Narco isn't giving away the AM radios anyway,
but the aviation community is extremely conservative, and (as a
group), also very wealthy and therefore very influential. It won't
happen.
Bill Horne
Moderator
Date: Sun, 31 Oct 2010 14:44:02 -0500
From: bonomi@host122.r-bonomi.com (Robert Bonomi)
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Disconnected: Attention Passengers it's perfectly safe to use your cellphones
Message-ID: <BZ6dnWYk9PufWlDRnZ2dnUVZ_hOdnZ2d@posted.nuvoxcommunications>
In article <utvpc6tb879ppt2cggga8ea5b5irn8nm5n@4ax.com>,
Richard <rng@richbonnie.com> wrote:
>On Wed, 27 Oct 2010 20:57:38 -0500, bonomi@host122.r-bonomi.com
>(Robert Bonomi) wrote:
>
>>In article <e5717175-91d8-441c-9e27-71c0a9a42d14@g13g2000yqj.googlegroups.com>,
>>Lisa or Jeff <hancock4@bbs.cpcn.com> wrote:
>>
>>>I'm surprised they still use AM. IIRC, back in WW II radios in tanks
>>>originally used AM but then switched to FM (from the Bell System
>>>History "War & Peace").
>>
>>AM is _intentionally_ used for aircraft radio. Specifically to avoid the
>>'capture' effect of FM receivers. You want to be able to hear the
>>weaker/more distant station that is calling "mayday" under the routine
>>traffic of the nearby station.
>
>Single-sideband, suppressed carrier (SSB-SC) would be even better for
>hearing that weak mayday message. The AM broadcast band channel uses
>double-sideband, full carrier. At night, when I hear two stations on
>the same channel, often the weaker signal is garbled becaue of phasing
>errors between the sidebands of the weaker signal and the carrier of
>the stronger. And if the carriers aren't zero-beat, there is a
>heterodyne tone. With SSB-SC, there is no distortion or tone. In my
>ham radio experience using SSB-SC, during a net check-in when many
>stations are calling at once, I can hear a several signals on top of
>each other, and make them out clearly.
If that were the only consideration, SSB would be a superior alternative.
SSB, because of the need to tune both the carrier frequency and the BFO,
is "somewhat problematic" for the 'push button' 'channel' tuning that
air operations requires..
Also, one of the 'historical' requirements for aircraft radio was a
direction-finding capability. Trying to RDF on a SSB signal, using
anything like the traditional 'loop antenna' is the next best thing
to an exercise in futility. Yeah, it's doable with a billboard-style
phased-array, but that technology has a -really- 'non-trivial' price-
tag, not to mention the physical space requirements of such a system,
at roughly 3 meter wavelengths.
>Of course, making aircraft switch to SSB-SC would be difficult, as all
>aircraft and towers would have to switch at the same time.
"That happens not to be the case". if the decision was made, you start
by deploying SSB-capable receivers 'everywhere". A SSB rig will happily
tune an AM signal, as well as SSB. Once you have receive _capability_
universally deployed, then you can start deploying the transmitters.
A mandate that all air-band radios manufactured after a given date must
have SSB receive capability, that transmitters manufactured after a
second date must have SSB xmit _in_addition_to_ AM, and that after a
-third- date, all installed gear must be 'multi-mode' capable.
For 'fairness' to all involved, you have to do this across an extended
time frame. SSB-receive required on all new radios, a minimum of 3-5 years
out, Probably 5-8 for the xmit capability. and a minimum of 10-15
years _after_that_ for the requirement that all installed equipment be
SSB TX/RX capable. At that point, anybody/everybody can switch to using
SSB 'whenever they like'. Then, another 5-10 years down the road, you can
forbid the use of AM.
Realistically, you're looking at 20 years to get to the 'all installed gear
is SSB capable' point, and being able to -start- weaning the off of AM use.
Of course, you still have deal with replacing the direction-finding
capabilities. <grin>
Date: Sun, 31 Oct 2010 05:58:09 -0500
From: rpw3@rpw3.org (Rob Warnock)
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Disconnected: Attention Passengers it's perfectly safe to use your cellphones
Message-ID: <cr6dnYXrgqxc1lDRnZ2dnUVZ_oudnZ2d@speakeasy.net>
tlvp <tPlOvUpBErLeLsEs@hotmail.com> wrote:
+---------------
| Rob Warnock <rpw3@rpw3.org> wrote:
| > There's a perfectly good reason for aviation sticking with AM: ...
| > ... you need to be able to hear when two airplanes are
| > transmitting at the same time ("stepping on" each other), so that
| > you know information has been lost and/or you can send a
| > warning/request to re-transmit after a collision.
|
| Or, better yet, before one, as "after" is a mite too late :-) .
+---------------
Yes, well, I was speaking of *transmission* collisions [as with AlohaNet
or Ethernet], of course, but you are correct that undetected transmission
collisions can lead to physical airframe collisions. :-{
-Rob
Rob Warnock <rpw3@rpw3.org>
627 26th Avenue <URL:http://rpw3.org/>
San Mateo, CA 94403 (650)572-2607
Date: Sat, 30 Oct 2010 17:55:41 -0600
From: Neal McLain <nmclain@annsgarden.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Kerry outlines bill to resolve TV disputes
Message-ID: <4CCCB07D.30700@annsgarden.com>
The latest:
Cablevision, Fox End Retrans Stalemate
Deal Reached In Time For First Pitch Of Game 3 Of World Series
bY Mike Farrell, Multichannel News, 10/30/2010
| After two weeks of increasingly nasty
| accusations and calls for binding arbitration
| and government intervention, Cablevision
| Systems and Fox Networks begrudgingly reached
| a retransmission-consent agreement Saturday,
| ending their stalemate just in time for Game 3
| of Major League Baseball's World Series.
http://tinyurl.com/2fasafl
Date: Sun, 31 Oct 2010 18:21:26 +0000 (UTC)
From: "Adam H. Kerman" <ahk@chinet.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Does ADSL interfere with cordless phone?
Message-ID: <iakc36$246$1@news.albasani.net>
Adam H. Kerman <ahk@chinet.com> wrote:
>Adam H. Kerman <ahk@chinet.com> wrote:
>>My question was, Does a specialized filter exist for cordless phones
>>that use 43-60 MHz range. It must not be old enough to use 1.7 MHz, as
>>it has 10 channels.
>Finally found the manual:
>The cordless phone in question is Sony SPP-2000, manufactured in 1994.
>It uses 10 channels at 46MHz and another 10 channels at 49MHz. With the
>ADSL2 modem plugged in, sound quality on the cordless phone is dreadful.
>Sorry about my earlier confusion. No, it's not old enough to have been a
>1.7 Mhz cordless phone.
Yay! Months later, I have the solution, and yes, a filter does exist!
I had an AT&T repair tech out to deal with a long-standing echo on
the line. He found that the installer had pinched the the inside wire where
it was connected at the network interface inside the new grey box he installed.
We then discussed the problem with ADSL interfering with the cordless phone.
He knew what filter to install and said he'd look on his truck to see if
he'd brought any.
He had one available and installed it at the network interface. The first
pair of inside wire is now used for telephone (including the cordless phone)
and my fax machine and is filtered. The second pair is used for ADSL,
unfiltered. He replaced the jack where I have the DSL device with a dual
jack, each tapping one of the pair of inside wire, so I can still plug a
telephone in there plus the DSL device.
My cordless phone is usable once again.
He said it's long been known that ADSL interferes with this style of
cordless phone as there are frequencies in common. Newer cordless phones
that use frequencies in the gigahertz range aren't affected.
No one at repair service knew about these filters. No one at the DSL help
desk knew about these filters.
Also, he spotted an uncovered junction box in the alley. He said he'd climb
the pole and secure and seal the cover to avoid problems with water
infiltratrion. Conscientious guy.
Unfortunately, AT&T ruined one of my few excellent customer service
experiences by choosing to bombard me with recorded phone calls informing
me that the problem had been corrected. These calls started the day before
the repair tech visited.
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