|
|
Message Digest
Volume 28 : Issue 125 : "text" Format
Messages in this Issue:
Re: Waveguide (was "size a major consideration...")
Re: Waveguide (was "size a major consideration...")
Re: Waveguide (was "size a major consideration...")
Re: Waveguide (was "size a major consideration...")
Hackers Break Into Virginia Health Professions Database, Demand Ransom
Telecom Digest archives questions [TELECOM]
Re: Telecom Digest archives questions [TELECOM]
Re: Telecom Digest archives questions [TELECOM]
Re: FiOS in MDU Buildings
====== 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: Wed, 06 May 2009 03:28:45 GMT
From: "Tony Toews \[MVP\]" <ttoews@telusplanet.net>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <pr0205hp4jr0lrtp0npbgi9rnbi28i41fe@4ax.com>
Dan Lanciani <ddl@danlan.com> wrote:
>What problem are you trying to solve? If it is feed line loss in amateur
>applications then (IMHO of course) the best bang for the buck would be
>achieved by moving the front end (receive) and final output stage(s)
>(transmit) to the antenna. I've often thought about a little solar/battery
>powered tower-mount broad-band receiver with a few selectable IF sections
>coupled to an A/D driving a fiber downlink. Single-band tower-mount
>amplifiers would be much easier, though...
However if something goes wrong in Canada's winters it's a lot easier to deal with
the electronics if they are at ground level. Commercial quality antennas and
feedline don't fail too terribly often compared to the electronics.
Tony
--
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, 05 May 2009 23:22:20 -0500
From: Neal McLain <nmclain@annsgarden.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <4A01107C.5030603@annsgarden.com>
David Lesher <wb8foz@panix.com> wrote:
> I was amazed to hear of the cable co. stringing miles of
> waveguide. At the cost, I'd assumed they used microwave
> links or coax.
Huh? Where did you hear that?
If you "heard" it in my post in this thread in Volume 28 Issue 121, I
guess I'd better clarify things.
CATV companies used microwave relays to transmit signals up to 25 miles
in the "CARS" band (11.7-12.2 GHz). This band was open to franchised
CATV operators and non-profit co-ops comprised of two or more franchised
CATV operators. It was shared on a co-equal basis with other fixed
microwave services assigned to other industries.
Back in the early days of the cable industry, "CATV" stood for
"Community Antenna Television" because that's all it was: an antenna
(often on a nearby hill) that picked up broadcast signals and
distributed them to customers. So the FCC called the microwave relay
service "CARS" for "Community Antenna Relay Service."
As the industry grew and started carrying non-broadcast signals, the
term "CATV" evolved to mean "cable television." The FCC renamed the
CARS service "cable television relay service" ("CTRS"), but cable guys
liked "CARS" better, so the term persists to this day.
What makes the CARS band unique is the allocation of frequencies within
the band: it precisely matches the CATV RF band (54 MHz and up) shifted
up to the 11.7-21.2 band.
The modulation scheme is single-sideband suppressed-carrier amplitude
modulation operating at a carrier frequency of 12.6465 GHz. Thus, for
example, the channel 2 visual carrier is upconverted as follows:
54.25 MHz + 12646.5 MHz = 12700.75 MHz.
Nothing unique about that, of course: it's the same modulation scheme
that AT&T Long Lines had been using for years for their intercity relays.
As I noted in the previous post, these systems used radio equipment
(transmitters and receivers) manufactured by Hughes Aircraft Company.
Hughes called the equipment "Amplitude Modulated Link," or "AML."
Waveguide was used only at the transmit and receive ends to connect the
antennas to the radio equipment. For short runs, we used elliptical
heliax; for long runs (for example, a vertical run on a tower) we used
round rigid waveguide with short pieces of elliptical for the last few
feet at each end.
Transmit antennas were mounted on towers or building roofs. Some
transmit sites had as many as a dozen antennas transmitting in different
directions.
Receive antennas were mounted on whatever structures were available:
buildings, water towers, radio towers, or even wood poles. Receivers
were usually installed outdoors, at the base of a tower or on a building
roof near the antenna. Hughes designed the receivers for outdoor
installation in locations without environmental protection or AC power.
The receiver had only two ports:
- INPUT: RF at CARS band from the antenna.
- OUTPUT: RF at CATV distribution frequencies, for direct connection to
the distribution trunk. The output port also served as the power input
port, designed to accept a 60-volt square wave, the standard industry
voltage used to power line amplifiers.
My "Utility Poles" website has an example of a receive antenna and a
receiver mounted on a wood pole. Accompanying drawings show a block
diagram of the receiver and the frequency allocation for cable channels
2-24.
http://www.annsgarden.com/poles/poles.htm#odd
(Scroll down to "A Pole Supporting a Microwave Antenna.")
Neal McLain
------------------------------
Date: Wed, 6 May 2009 15:14:33 +0000 (UTC)
From: David Lesher <wb8foz@panix.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <gts9gp$qkr$1@reader1.panix.com>
Neal McLain <nmclain@annsgarden.com> writes:
> > I was amazed to hear of the cable co. stringing miles of
> > waveguide. At the cost, I'd assumed they used microwave links or
> > coax.
>Huh? Where did you hear that? If you "heard" it in my post in this
>thread in Volume 28 Issue 121, I guess I'd better clarify things.
...
>Waveguide was used only at the transmit and receive ends to connect the
>antennas to the radio equipment. For short runs, we used elliptical
>heliax; for long runs (for example, a vertical run on a tower) we used
>round rigid waveguide with short pieces of elliptical for the last few
>feet at each end.
That makes far more sense. But it is true that at one point, AT&T
Long Lines was experimenting with buried waveguide for long haul
transmission. One such station was in Ballard MO.
I've known of CATV companies that did use some coax backhauls to the head
end; now fiber rules the nest.
--
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 May 2009 11:54:59 -0700
From: Richard <rng@richbonnie.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <n5k305pu74j1bbs2vc29hn4jn8iuboo36o@4ax.com>
On Wed, 6 May 2009 07:32:55 -0400 (EDT), Neal McLain
<nmclain@annsgarden.com> wrote:
>What makes the CARS band unique is the allocation of frequencies within
>the band: it precisely matches the CATV RF band (54 MHz and up) shifted
>up to the 11.7-21.2 band.
>
>The modulation scheme is single-sideband suppressed-carrier amplitude
>modulation operating at a carrier frequency of 12.6465 GHz. Thus, for
>example, the channel 2 visual carrier is upconverted as follows:
>
>54.25 MHz + 12646.5 MHz = 12700.75 MHz.
>
>Nothing unique about that, of course: it's the same modulation scheme
>that AT&T Long Lines had been using for years for their intercity relays.
No. To transmit the video of one TV signal, AT&T Long Lines used FM
modulation of one 20 MHz channel at 4 GHz or 11 GHz or one 29.xx MHz
channel at 6 GHz. The audio was transmitted separately on other
facilities using wide-band audio channels which were intermixed with
regular 4 KHz-wide analog voice circuits. The microwave systems had
names like TD, TH, TJ, and TL; the "T" meant televison because they
originaly were designed to capture the television transmission market.
The wider-band systems at 6 GHz were developed in the late 1950's in
case high-def TV for theaters was developed.
When not carrying television, these systems carried 1200 multiplexed
SSB voice channels (1860 channels for the 6 GHz system).
------------------------------
Date: Tue, 5 May 2009 23:34:18 -0400
From: Monty Solomon <monty@roscom.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Hackers Break Into Virginia Health Professions Database, Demand Ransom
Message-ID: <p06240807c626b4e57a6f@[10.0.1.6]>
Hackers Break Into Virginia Health Professions Database, Demand Ransom
By Brian Krebs
Washington Post
May 4, 2009
Hackers last week broke into a Virginia state Web site used by
pharmacists to track prescription drug abuse. They deleted records on
more than 8 million patients and replaced the site's homepage with a
ransom note demanding $10 million for the return of the records,
according to a posting on Wikileaks.org, an online clearinghouse for
leaked documents.
Wikileaks reports that the Web site for the Virginia Prescription
Monitoring Program was defaced last week with a message claiming that
the database of prescriptions had been bundled into an encrypted,
password-protected file.
...
http://voices.washingtonpost.com/securityfix/2009/05/hackers_break_into_virginia_he.html
http://wikileaks.org/wiki/Over_8M_Virginian_patient_records_held_to_ransom,_30_Apr_2009
------------------------------
Date: Tue, 5 May 2009 23:45:23 -0500
From: John Mayson <john@mayson.us>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Telecom Digest archives questions [TELECOM]
Message-ID: <6645152a0905052145l380bcd39g3d8d3dcbf5e23380@mail.gmail.com>
All,
I had a discussion tonight with Bill about our archives. As most of
you are aware we have long maintained our own set of archives here:
http://massis.lcs.mit.edu/telecom-archives/. This forum started in
1981 when Sergey and Larry were doing whatever 8 year-olds did in 1981
and Google Groups did not exist. If we wanted an archive we had to do
it ourselves. I can't speak for everyone, but going back and reading
the old archives has been like a trip down memory lane. I remember
when we had The Phone Company and would wait until 11 PM to call our
grandparents to save on toll charges. Comparing 1981 to 2009 is
really stunning.
A couple of years ago I made the archives available in mbox
(http://en.wikipedia.org/wiki/Mbox because I wanted them in that
format to facilitate my walk down memory lane. Since I had already
done the work, sharing it was the obvious next step.
Since that time Pat fell ill and since the exercise to put the digest
in mbox was more of a rearview mirror and I didn't do it going
forward. Here are our two questions:
1. Should we continue to maintain our own archives or should we point
people to http://groups.google.com/group/comp.dcom.telecom ?
2. Is there any interest in making the current and future archives
available in mbox?
I am going to defer question #1 to Bill. I have no strong opinions
either way. On #2, as I told Bill, if even one person wants the
archives available in the highly portable mbox format, I'm glad to do
it.
John
--
John Mayson <john@mayson.us>
Austin, Texas, USA
------------------------------
Date: Wed, 06 May 2009 10:20:17 -0500
From: Dave Garland <dave.garland@wizinfo.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Telecom Digest archives questions [TELECOM]
Message-ID: <ZZmdnZ4jp8P5N5zXnZ2dnUVZ_qidnZ2d@posted.visi>
John Mayson wrote:
> I am going to defer question #1 to Bill. I have no strong opinions
> either way. On #2, as I told Bill, if even one person wants the
> archives available in the highly portable mbox format, I'm glad to do
> it.
I must admit, I don't think I have ever used the group archives.
However, I would point out that single-sourcing is a dangerous thing,
even (or perhaps especially) when the source is as big and powerful as
google. IMO, the quality of the dejanews archives deteriorated after
they moved to google, especially due to the post-munged addresses.
Their search facility (or perhaps the completeness of the archive) is
a bit of a mystery to me, I have had searches fail even though I knew
with certainty that there should be hits.
Ultimately it comes down to how much work is involved, since we're
trading in the services of you fine folks who have volunteered to
carry the load. I would suggest that if it can be done without undue
burden, we should continue to maintain archives in a standard (e.g.
mbox) format.
And thank you all, Pat, Bill, John, John, et al. for the great work.
Dave
------------------------------
Date: Wed, 6 May 2009 17:45:45 +0000 (UTC)
From: techie@tantivy.tantivy.net (Bob Vaughan)
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Telecom Digest archives questions [TELECOM]
Message-ID: <gtsic9$nor$1@news.stanford.edu>
In article <6645152a0905052145l380bcd39g3d8d3dcbf5e23380@mail.gmail.com>,
John Mayson <john@mayson.us> wrote:
>All,
>
>I had a discussion tonight with Bill about our archives. As most of
>you are aware we have long maintained our own set of archives here:
>http://massis.lcs.mit.edu/telecom-archives/. This forum started in
>1981 when Sergey and Larry were doing whatever 8 year-olds did in 1981
>and Google Groups did not exist. If we wanted an archive we had to do
>it ourselves. I can't speak for everyone, but going back and reading
>the old archives has been like a trip down memory lane. I remember
>when we had The Phone Company and would wait until 11 PM to call our
>grandparents to save on toll charges. Comparing 1981 to 2009 is
>really stunning.
>
>A couple of years ago I made the archives available in mbox
>(http://en.wikipedia.org/wiki/Mbox) because I wanted them in that
>format to facilitate my walk down memory lane. Since I had already
>done the work, sharing it was the obvious next step.
>
>Since that time Pat fell ill and since the exercise to put the digest
>in mbox was more of a rearview mirror and I didn't do it going
>forward. Here are our two questions:
>
>1. Should we continue to maintain our own archives or should we point
>people to http://groups.google.com/group/comp.dcom.telecom ?
I would strongly argue in favor of continuing to maintain the existing
archives.
Google groups is nice to have, but it dosen't have the ability to
intelligently group a set of articles, based on some loose criteria,
without picking up some extra cruft along the way.
>
>2. Is there any interest in making the current and future archives
>available in mbox?
I find mbox to be a very useful format.
One of my major frustrations with Yahoo groups is the lack of any bulk
download capability, or any way of importing group archives into a
offline reader, other than saving individual posts.
>
>I am going to defer question #1 to Bill. I have no strong opinions
>either way. On #2, as I told Bill, if even one person wants the
>archives available in the highly portable mbox format, I'm glad to do
>it.
>
>John
>
>--
>John Mayson <john@mayson.us>
>Austin, Texas, USA
>
--
-- 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: Wed, 6 May 2009 10:37:51 EDT
From: Wesrock@aol.com
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: FiOS in MDU Buildings
Message-ID: <d17.46a419f4.3732fabf@aol.com>
In a message dated 5/5/2009 11:10:40 AM Central Daylight Time,
hancock4@bbs.cpcn.com writes:
On May 4, 9:23 am, "Tony Toews \[MVP\]" <tto...@telusplanet.net>
wrote:
> 8 Hours is a Long Time
As stated, it's rare but it has happened. When a major storm hits,
power is out for _days_; a really major storm, for _weeks_.. I
watched them restring power wires after a bad storm, it is not trivial
work.
In such circumstances the telephone is needed more than ever.
The traditional Central Office had a diesel generator in addition to
its batteries, so a few days is not a problem.
Eight hours is simply not enough.
-----------------------------------------Reply------------------------------
----
Some offices never had a generator. In case of an extended
outage a portable generator was brought in.
Wes Leatherock
wesrock@aol.com
wleathus@yahoo.com
------------------------------
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) 2008 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 (9 messages)
******************************
|
or 