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The Telecom Digest for February 7, 2013
Volume 32 : Issue 34 : "text" Format
====== 31 years of TELECOM Digest -- Founded August 21, 1981 ======
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Date: Wed, 06 Feb 2013 10:43:16 -0500
From: Barry Margolin <barmar@alum.mit.edu>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: A new encryption app
Message-ID: <barmar-1B0722.10431606022013@news.eternal-september.org>
In article <p0624087fcd3786abd85e@[10.0.1.10]>,
Telecom Digets Moderator writes -
> Mike Janke can say "This has never been done before", but that is
> incorrect. In the "PC" space, I watched Phil Zimmerman demonstrate a
> VoIP phone call, which was secured via PGP, back in the 90's: the
> equipment wasn't as small, but it was being done.
What he's claiming is groundbreaking is the ease of use, not the basic
encryption technology. He's providing the infrastructure that makes it
easy; PGP users have to do much of this themselves.
And if you read the rest of the article, you'll see that Phil Zimmerman
is part of the team that created this.
---
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
***** Moderator's Note *****
So, Mr. Janke claims it's "Groundbreaking" to push one button instead
of two or three. I'm sorry, but PGP was "groundbreaking". This is
an app to implement encryption.
Bill Horne
Moderator
Date: Wed, 6 Feb 2013 18:21:44 +0000 (UTC)
From: David Lesher <wb8foz@panix.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: A new encryption app
Message-ID: <keu6vn$32c$1@reader1.panix.com>
>***** Moderator's Note *****
>So, Mr. Janke claims it's "Groundbreaking" to push one button instead
>of two or three. I'm sorry, but PGP was "groundbreaking". This is
>an app to implement encryption.
But that IS a vital part. I've met PRZ and we talked about a
then-new paper "Why Johnny can't encrypt" & what it meant.
Core crypto technology has not been an issue for a long time,
it's getting it into a usable but secure form. It was foremost
in his thinking at the time.`
After all, Enigma was broken mostly on operational errors, not
core weakness.
I have no doubt various TLA's are quite PO'ed.
--
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: Wed, 06 Feb 2013 10:35:57 -0500
From: Barry Margolin <barmar@alum.mit.edu>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <barmar-E94E77.10355706022013@news.eternal-september.org>
In article <20130206002424.GA15126@telecom.csail.mit.edu>,
Bill Horne <bill@horneQRM.net> wrote:
> Academically, the United States ranks near the bottom on the list of
> math and science test scores when compared to other nations. I think
> careless and casual "reports" such as this one contribute to that
> dismal record.
What's the problem with this report? GPS satellites are in
geosynchronous orbits, about 22,000 miles above sea level.
Here's part of a report about the asteroid at investorplace.com:
Specifically, it will hit perigee - closest approach - at 11:24 a.m.
pacific standard time on the 15th. At that point it will be 17,200 miles
from the surface and 5,000 miles inside the orbits for our Global
Positioning System satellites. It will still be thousands of miles above
the atmosphere and the International Space Station, which orbits at
about 240 miles above the surface.
http://investorplace.com/2013/02/nasa-asteroid-to-pass-close-to-earth-feb
-15-wont-hit-us/
Is your complaint that they have to use GPS as a reference point in
order to "dumb it down" for US audiences? Or maybe that he referred to
17,200 as "about 18,000"?
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
Date: Wed, 6 Feb 2013 13:29:09 -0500
From: Bill Horne <bill@horneQRM.net>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <20130206182909.GA13492@telecom.csail.mit.edu>
On Wed, Feb 06, 2013 at 10:35:57AM -0500, Barry Margolin wrote:
> In article <20130206002424.GA15126@telecom.csail.mit.edu>,
> Bill Horne <bill@horneQRM.net> wrote:
>
> > Academically, the United States ranks near the bottom on the list of
> > math and science test scores when compared to other nations. I think
> > careless and casual "reports" such as this one contribute to that
> > dismal record.
>
> What's the problem with this report? GPS satellites are in
> geosynchronous orbits, about 22,000 miles above sea level.
>
> Here's part of a report about the asteroid at investorplace.com:
>
> Specifically, it will hit perigee - closest approach - at 11:24 a.m.
> pacific standard time on the 15th. At that point it will be 17,200 miles
> from the surface and 5,000 miles inside the orbits for our Global
> Positioning System satellites. It will still be thousands of miles above
> the atmosphere and the International Space Station, which orbits at
> about 240 miles above the surface.
>
>
> http://investorplace.com/2013/02/nasa-asteroid-to-pass-close-to-earth-feb
>
> -15-wont-hit-us/
>
> Is your complaint that they have to use GPS as a reference point in
> order to "dumb it down" for US audiences? Or maybe that he referred to
> 17,200 as "about 18,000"?
My complaint is that CBS didn't check the facts, and therefore is
guilty of sloppy reportage. Although I am often amazed at the impact
television has on the public's knowledge base, I'll concede that TV
does have power to affect public perception, and therefore, an
obligation to get the story straight.
Let me say, right up front, that I'm not a rocket scientist. What
little knowledge I have of orbital mechanics comes from my experience
using OSCAR (Orbiting Satellite Carrying Amateur Radio) Satellites as
a ham radio operator. When I was working on SS7 at Verizon, another
engineer in our group was buying GPS timing sources to replace
"Stratum I" clocks, so I assume that I gained some background on GPS
from him, but I don't hold myself out as any sort of expert.
GPS satellites are not in geosynchronous orbit. They do not share
the Clarke Belt with communications relay satellites: in fact, the
satellites that make up the GPS "Constallation" orbit at a much lower
altitude.
This is from Wikipedia:
The space segment (SS) is composed of the orbiting GPS satellites,
or Space Vehicles (SV) in GPS parlance. The GPS design originally
called for 24 SVs, eight each in three approximately circular
orbits,[44] but this was modified to six orbital planes with four
satellites each.[45] The orbits are centered on the Earth, not
rotating with the Earth, but instead fixed with respect to the
distant stars.[46] The six orbit planes have approximately 55°
inclination (tilt relative to Earth's equator) and are separated by
60° right ascension of the ascending node (angle along the equator
from a reference point to the orbit's intersection).[47] The
orbital period is one-half a sidereal day, i.e., 11 hours and 58
minutes.[48] The orbits are arranged so that at least six
satellites are always within line of sight from almost everywhere
on Earth's surface.[49] The result of this objective is that the
four satellites are not evenly spaced (90 degrees) apart within
each orbit. In general terms, the angular difference between
satellites in each orbit is 30, 105, 120, and 105 degrees apart
which, of course, sum to 360 degrees.
Orbiting at an altitude of approximately 20,200 km (12,600 mi);
orbital radius of approximately 26,600 km (16,500 mi), each SV
makes two complete orbits each sidereal day, repeating the same
ground track each day.[50] This was very helpful during development
because even with only four satellites, correct alignment means all
four are visible from one spot for a few hours each day. For
military operations, the ground track repeat can be used to ensure
good coverage in combat zones.
http://en.wikipedia.org/wiki/Global_Positioning_System
And, from a Powerpoint slide file I found at NOAA:
* GPS Nominal Constellation
* 28 Satellites in 6 Orbital Planes
* 4 Satellites in each plane
* 20,200 km Altitudes, 55 Degree Inclination
www.ngs.noaa.gov/PUBS_LIB/ppt/GPS_Orbit_Determination.ppt
Frankly, when I heard the CBS report, I was surprised to find that the
GPS Constellation isn't in LOW Earth orbit - I had assumed it was,
just like the OSCAR birds - but rather in MID Earth orbit. In other
words, I had my own preconceived notion of how high the GPS satellites
are, but I knew they weren't in the Clarke Belt, so I looked it
up. I think CBS' viewers are entitled to a higher standard of research
than what little I did.
The fact that investorplace.com echoed CBS' error only bolsters my
argument: I don't know which cart got in front of which horse, but a
national news organization is responsible for paying attention to the
basics.
Bill
--
Bill Horne
(Remove QRM from my address to write to me directly)
Date: Wed, 6 Feb 2013 18:33:10 +0000 (UTC)
From: Lee Choquette <leec@xmission.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <keu7l6$f7s$1@news.xmission.com>
In article <barmar-E94E77.10355706022013@news.eternal-september.org>,
Barry Margolin <barmar@alum.mit.edu> wrote:
>What's the problem with this report? GPS satellites are in
>geosynchronous orbits, about 22,000 miles above sea level.
According to Wikipedia, that font of infallible knowledge, GPS
satellites orbit at about 12,600 miles. After all, they have no need to
remain at a fixed point in the sky. A better comparison would have been
to the satellites that retransmit TV signals, or that take weather
photographs.
>Here's part of a report about the asteroid at investorplace.com:
I see that report also assumes that GPS satellites are in geosynchronous
orbit, but I see no reason why a website called investorplace should
have special expertise here. NASA, on the other hand, doesn't mention
GPS satellites in its FAQ on the asteroid, but does distinguish between
two groups of satellites:
[Asteroid DA14] will pass between the outer constellation of
satellites located in geosynchronous orbit (22,245 miles/35,800
kilometers) and the large concentration of satellites orbiting much
closer to Earth.
http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html
Lee
Date: Wed, 06 Feb 2013 12:46:49 -0500
From: Retired <retired@home.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <xe-dnbn16bKUCo_MnZ2dnUVZ_vydnZ2d@giganews.com>
On 2/6/13 10:35 AM, Barry Margolin wrote:
> In article <20130206002424.GA15126@telecom.csail.mit.edu>,
> Bill Horne <bill@horneQRM.net> wrote:
>
>> Academically, the United States ranks near the bottom on the list of
>> math and science test scores when compared to other nations. I think
>> careless and casual "reports" such as this one contribute to that
>> dismal record.
>
> What's the problem with this report? GPS satellites are in
> geosynchronous orbits, about 22,000 miles above sea level.
>
> Here's part of a report about the asteroid at investorplace.com:
>
> Specifically, it will hit perigee - closest approach - at 11:24 a.m.
> pacific standard time on the 15th. At that point it will be 17,200 miles
> from the surface and 5,000 miles inside the orbits for our Global
> Positioning System satellites. It will still be thousands of miles above
> the atmosphere and the International Space Station, which orbits at
> about 240 miles above the surface.
>
>
> http://investorplace.com/2013/02/nasa-asteroid-to-pass-close-to-earth-feb
>
> -15-wont-hit-us/
>
> Is your complaint that they have to use GPS as a reference point in
> order to "dumb it down" for US audiences? Or maybe that he referred to
> 17,200 as "about 18,000"?
>
It appears that someone has "kilometers" confused with "miles".
According to the government's own GPS website at
http://www.gps.gov/systems/gps/space/
The sats are at 20,200 KILOMETERS, which would be approx. 12,550
miles, ie; less than 17,200 miles of the asteroid.
Date: Wed, 06 Feb 2013 14:55:18 -0500
From: Barry Margolin <barmar@alum.mit.edu>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <barmar-763E2E.14551806022013@news.eternal-september.org>
In article <xe-dnbn16bKUCo_MnZ2dnUVZ_vydnZ2d@giganews.com>,
Retired <retired@home.com> wrote:
> On 2/6/13 10:35 AM, Barry Margolin wrote:
> > In article <20130206002424.GA15126@telecom.csail.mit.edu>,
> > Bill Horne <bill@horneQRM.net> wrote:
> >
> >> Academically, the United States ranks near the bottom on the list of
> >> math and science test scores when compared to other nations. I think
> >> careless and casual "reports" such as this one contribute to that
> >> dismal record.
> >
> > What's the problem with this report? GPS satellites are in
> > geosynchronous orbits, about 22,000 miles above sea level.
> >
> > Here's part of a report about the asteroid at investorplace.com:
> >
> > Specifically, it will hit perigee - closest approach - at 11:24 a.m.
> > pacific standard time on the 15th. At that point it will be 17,200 miles
> > from the surface and 5,000 miles inside the orbits for our Global
> > Positioning System satellites. It will still be thousands of miles above
> > the atmosphere and the International Space Station, which orbits at
> > about 240 miles above the surface.
> >
> >
> > http://investorplace.com/2013/02/nasa-asteroid-to-pass-close-to-earth-feb
> >
> > -15-wont-hit-us/
> >
> > Is your complaint that they have to use GPS as a reference point in
> > order to "dumb it down" for US audiences? Or maybe that he referred to
> > 17,200 as "about 18,000"?
> >
>
> It appears that someone has "kilometers" confused with "miles".
More likely, they assumed GPS satellites were in geosynchronous orbits
(22,000 miles), like most communication satellites. I was actually
surprised to see that they aren't.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
Date: 6 Feb 2013 22:57:11 -0000
From: "John Levine" <johnl@iecc.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <20130206225711.23930.qmail@joyce.lan>
>More likely, they assumed GPS satellites were in geosynchronous orbits
>(22,000 miles), like most communication satellites. I was actually
>surprised to see that they aren't.
Then they wouldn't be usable at high latitudes, which would be a
problem. (Remember where the DEW line was.)
There's enough GPS satellites that no matter where you are, there are
always several visible overhead so your receiver can triangulate among
them.
Date: Wed, 06 Feb 2013 11:34:25 -0600
From: pv+usenet@pobox.com (PV)
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: closer than the satellites that guide your GPS
Message-ID: <n8GdnSLXg8q8CY_MnZ2dnUVZ_uudnZ2d@supernews.com>
Bill Horne <bill@horneQRM.net> writes:
>Scott Pelle, on the CBS Evening News tv show, just stated that an
>asteroid will pass about 18,000 miles from earth next week, which he
>said is "Closer than the satellites that ... guide your GPS".
Meh. Possibly they confused miles for kilometers - GPS satellites orbit at
about 20,000km. Asteroid 2012DA14 will come within about 21,000mi of th
earth. Easy mistake for anyone; even rocket scientists do it sometimes ...
Alternatively, the confused GPS for "geosyncronous". There is some concern
that the asteroid's path will take it right through the geostationary
belt and a satellite will get nailed.
In any event, it's the closest encounter with an earth-crossing asteroid
in many years. A little excitement is warranted!
>Academically, the United States ranks near the bottom on the list of
>math and science test scores when compared to other nations. I think
>careless and casual "reports" such as this one contribute to that
>dismal record.
https://www.scientificamerican.com/article.cfm?id=does-the-us-produce-too-m
Interesting read for a contrary opinion on the state of science education
in the US. *
--
* PV Something like badgers, something like lizards, and something
like corkscrews.
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