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Message Digest
Volume 28 : Issue 124 : "text" Format
Messages in this Issue:
Re: Waveguide (was "size a major consideration...")
Re: Nebraska commission loses appeal on Internet call fees
Re: Nebraska commission loses appeal on Internet call fees
Re: Waveguide (was "size a major consideration...")
Re: Waveguide (was "size a major consideration...")
Re: Waveguide (was "size a major consideration...")
Re: FiOS in MDU Buildings
Re: AT&T doubling 3G capacity
Re: Waveguide (was "size a major consideration...")
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Date: Mon, 4 May 2009 17:43:12 -0400 (EDT)
From: Dan Lanciani <ddl@danlan.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <200905042143.RAA00174@ss10.danlan.com>
|***** Moderator's Note *****
|
|Given the cost of Heliax, and the losses of generic coax at 70cm, is
|it possible/advisable to homebrew waveguide? A previous post mentioned
|circular waveguide, and I wonder if I could feed 70cm or 23cm antennas
|with waveguide made from copper pipe.
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...
Dan Lanciani
ddl@danlan.*com
***** Moderator's Note *****
Not an option for me: I wear a brace on my leg and I can't be climbing
towers anymore. Anything that I put up has to be passive, since I
can't get up there to maintain electronics.
Bill Horne
Temporary Moderator
------------------------------
Date: Mon, 04 May 2009 17:51:05 -0600
From: Robert Neville <dont@bother.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Nebraska commission loses appeal on Internet call fees
Message-ID: <rnvuv4hbms6q6g3l6kjdavfg60au6ds63g@4ax.com>
"harold@hallikainen.com" <harold@hallikainen.com> wrote:
>This "telecommunications service" versus "information service" is very
>strange.
Yep. It's an artifical constraint designed to preseve the revenue being
generated by the various mandated fees/taxes on POTS service.
The reality is that bits are bits, being voice/date/video, and that if there are
socially necessary functions that need to be funded, they should be funded out
of general tax revenues.
***** Moderator's Note *****
Ah, but where's the fun in that? If you're going to rob a man, at
least have the brains to do it a penny at a time!
By the way, bits are no longer bits: bits that traverse a path in 3
milliseconds are different than those which take 3000.
Bill Horne
Temporary Moderator
------------------------------
Date: Mon, 4 May 2009 18:53:40 -0700 (PDT)
From: hancock4@bbs.cpcn.com
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Nebraska commission loses appeal on Internet call fees
Message-ID: <9554e368-981b-457c-8f72-b2fa0c18fbe2@o30g2000vbc.googlegroups.com>
On May 3, 5:47 pm, Robert Neville <d...@bother.com> wrote:
> A point of clarification here: this ruling pertains to a state that
> was attempting to force Vonage to fund a state USF. This is on top
> of, but separate from the Federal USF. Vonage is still required to
> fund the Federal USF, as well as Federal Relay and local 911
> centers.
What's really ironic is that under the old system none of this was an
issue or necessary. Rates were intentionally set so that (1) the bare
bottom users could get very cheap phone service and (2) emergency
calls were partially paid for by the phone company through its dial
zero operators. In an emergency, a dial zero operator would stay on
the line as needed. In very small towns, the operator was the 911
call center.
Today we have a bureacracy to qualify low-income people for specially
priced phone service (which is still bare bones), when in the past
there was nothing to do. You wanted bare bones a la carte service,
you got it. You wanted flat rate service or premium equipment, you'd
paid more for it.
None of this "FCC Line Charge" or "PIC charges", etc.
One problem today is that established land line carriers are required
to eat a lot of bad debts by their states, something that newcomer
carriers don't have to worry about.
For a TRUE competitive environment, eliminate all the special burdens
on traditional carriers, OR, require newcomer carriers to offer
bargain service, take on bad debt, etc.
------------------------------
Date: Mon, 04 May 2009 23:57:23 GMT
From: Howard Eisenhauer <howarde@REMOVECAPShfx.eastlink.ca>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <lkvuv4dacm1n721evjsl2n2qijrbb46223@4ax.com>
On Sun, 3 May 2009 20:34:03 -0400 (EDT), T
<kd1s.nospam@cox.nospam.net> wrote:
>In article <jdepv45644ebu932478ko767gs1f376mue@4ax.com>,
>howarde@REMOVECAPShfx.eastlink.ca says...
>>
>> On Sat, 2 May 2009 09:49:39 -0400 (EDT), Neal McLain
>> <nmclain@annsgarden.com> wrote:
>>
>> >Temporary moderator wrote:
>> >
>> >> I'm surprised at the difference in loss of waveguide vs. coax:
>> >> all the cell sites I've ever seen appear to use coax, so either
>> >> they're using the flexible type [of waveguide] or the cellular
>> >> engineers are employing the coax loss to contribute a large part
>> >> of their loss budget for the antenna arrays being used.
>> >
>>
>> It does indeed contribute a lot of loss, typically 3db. Wave guide
>> would be alot more efficient but for the frequencies used for cellular
>> (850-900 Mhz), or even the PCS bands (~2000 MHz) it would be
>> impractical due to size.
>
>[Moderator snip]
>
> I've dealt with hardline for amateur radio repeaters. Tough to work
> with but fairly low loss on 70cm.
Everything is relative, compared to Radio Shack RG58 it certainly is
low loss :).
Not all hardline is created equal, the 3dB I spec'ed is a typical "aim
point' for the cellular industry, when you get to the point feedline
losses exceed 3dB then you up to the next larger size line, with a
correspondingly lower loss. If you can get by with a smaller line
(less $$$) & not exceed the 3 db loss figure then you go with the
smaller line. If you've maxed out on size then you move up to an
air-dielectric cable which is even lower loss than the typical foam
core cable.
H.
***** Moderator's Note *****
Compared to Radio Shack RG-58, Dixie cups and string are low loss!
Bill Horne
Temporary Moderator
------------------------------
Date: Tue, 5 May 2009 12:47:37 -0400
From: T <kd1s.nospam@cox.nospam.net>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <MPG.246a37b2b4848a79899fe@reader.motzarella.org>
In article <lkvuv4dacm1n721evjsl2n2qijrbb46223@4ax.com>,
howarde@REMOVECAPShfx.eastlink.ca says...
>
> On Sun, 3 May 2009 20:34:03 -0400 (EDT), T
> <kd1s.nospam@cox.nospam.net> wrote:
>
> >In article <jdepv45644ebu932478ko767gs1f376mue@4ax.com>,
> >howarde@REMOVECAPShfx.eastlink.ca says...
> >>
> >> On Sat, 2 May 2009 09:49:39 -0400 (EDT), Neal McLain
> >> <nmclain@annsgarden.com> wrote:
> >>
> >> >Temporary moderator wrote:
> >> >
> >> >> I'm surprised at the difference in loss of waveguide vs. coax:
> >> >> all the cell sites I've ever seen appear to use coax, so either
> >> >> they're using the flexible type [of waveguide] or the cellular
> >> >> engineers are employing the coax loss to contribute a large part
> >> >> of their loss budget for the antenna arrays being used.
> >> >
> >>
> >> It does indeed contribute a lot of loss, typically 3db. Wave guide
> >> would be alot more efficient but for the frequencies used for cellular
> >> (850-900 Mhz), or even the PCS bands (~2000 MHz) it would be
> >> impractical due to size.
> >
> >[Moderator snip]
> >
> > I've dealt with hardline for amateur radio repeaters. Tough to work
> > with but fairly low loss on 70cm.
>
> Everything is relative, compared to Radio Shack RG58 it certainly is
> low loss :).
>
> Not all hardline is created equal, the 3dB I spec'ed is a typical "aim
> point' for the cellular industry, when you get to the point feedline
> losses exceed 3dB then you up to the next larger size line, with a
> correspondingly lower loss. If you can get by with a smaller line
> (less $$$) & not exceed the 3 db loss figure then you go with the
> smaller line. If you've maxed out on size then you move up to an
> air-dielectric cable which is even lower loss than the typical foam
> core cable.
>
> H.
>
> ***** Moderator's Note *****
>
> Compared to Radio Shack RG-58, Dixie cups and string are low loss!
>
> Bill Horne
> Temporary Moderator
>
LOL on the RG-58 comment. We used Belden 9913 for most coaxial
applications. But even that has a nominal loss of 2.6db per 100 feet at
400MHz.
------------------------------
Date: Tue, 05 May 2009 00:01:58 GMT
From: Howard Eisenhauer <howarde@REMOVECAPShfx.eastlink.ca>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <n40vv4tuh4b6ad92oa9g7uc5ehkj2r7e8k@4ax.com>
On Mon, 4 May 2009 09:24:28 -0400 (EDT), Neal McLain
<nmclain@annsgarden.com> wrote:
>I wrote:
>
> > I think what you're seeing on cell towers is flexible waveguide
> > ("Heliax"): http://tinyurl.com/cudezg
>
>Howard Eisenhauer <howarde@REMOVECAPShfx.eastlink.ca> wrote:
>
> > Wave guide would be a lot more efficient but for the frequencies
> > used for cellular (850-900 Mhz), or even the PCS bands (~2000 MHz)
> > it would be impractical due to size.
>
> > "Heliax" (Andrews trade name) as used on cell towers is actually a
> > hard line coax, not wave guide. There is a w/g product thats very
> > hard to tell from the hardline from more than a few feet away but
> > the w/g generally has an oval cross section where the hardline is
> > round. The lowest frequency I've seen the w/g used for is 6 GHz.
>
>I stand corrected.
*Snip*
Understandable, "heliax" has attained about the same status as
"asperin' or "kleenex". I had to stop & think for a moment on my
original post to remember whether or not the "Heliax" trade name also
applies to the w/g product. :/
H.
***** Moderator's Note *****
While "asperin" is safely in the public domain AFAIK, it seems that
some other "generic" trademarks are coming back to life, like undead
corpses in old movies: "Kerosene", which is "generic" in the United
States, can't be used to refer to kerosene, because the word still
enjoys trademark status in some countries. This caused a lot of
confusion when the media started to cover conditions in African
refugee camps: reporters would talk about a "Lack of cooking oil", but
U.S. audiences were puzzled, because "cooking oil" means "vegetable
oil" in the U.S., and most viewers thought the lack of vegetable oil
wasn't anything that serious.
It took several years, but now reporters covering refugee camps have
learned to refer to kerosene as "cooking fuel", so that it's more
clear what is being discussed.
Bill "Your treasurehouse of trivia" Horne
Temporary Moderator
------------------------------
Date: Mon, 4 May 2009 19:00:50 -0700 (PDT)
From: hancock4@bbs.cpcn.com
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: FiOS in MDU Buildings
Message-ID: <20b44e0d-3816-49ee-b0e5-196df721df8a@e20g2000vbc.googlegroups.com>
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.
***** Moderator's Note *****
I remember an occasion, when I was new to engineering, on which I
remarked that the fuel tanks which fed a generator at a major SS7
office seemed to be unusually high off the ground. I was told it was
because it's not possible to make them watertight.
It took me about a week to figure out what had been said.
Bill Horne
Temporary Moderator
------------------------------
Date: Tue, 05 May 2009 03:03:32 GMT
From: tlvp <PmUiRsGcE.TtHlEvSpE@att.net>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: AT&T doubling 3G capacity
Message-ID: <op.utfr4eexwqrt3j@acer250.gateway.2wire.net>
On Mon, 04 May 2009 14:01:56 -0400, Scott Dorsey <kludge@panix.com> wrote:
> "C'est un Nagra. C'est suisse, et tres, tres precis."
And it was developed by a disenchanted Polish emigre to Switzerland,
named Kudelski, previously employed by the record company Polskie Nagranie.
Donc c'est a la fois Suisse et Polonais :-) .
Et ca te coute les yeux de la tete
(French for "an arm and a leg", colloquially).
The German outfit Uher produced a cheaper competitor (Uher 4000)
that was so precise that if anything went even a tenth of a mm
out of whack, the whole tape-transport mechanism was immobilized.
No leeway or margins of error in their tolerances whatsoever.
Cheers, -- tlvp
------------------------------
Date: Tue, 05 May 2009 09:42:40 -0700
From: Richard <rng@richbonnie.com>
To: redacted@invalid.telecom.csail.mit.edu
Subject: Re: Waveguide (was "size a major consideration...")
Message-ID: <bfq0055se6j3d8qs9r0f8gd2rhtqhcub72@4ax.com>
On Mon, 4 May 2009 15:26:43 -0400 (EDT), kludge@panix.com (Scott
Dorsey) wrote:
>I have seen 450MHz waveguide used for early satellite antenna systems.
>It wasn't big enough to walk inside, but you could climb through it.
>--scott
For a really big waveguide, consider a highway tunnel. AM radio, at
frequencies around 1 MHz, cannot penetrate the tunnel. But FM radio,
at about 100 MHz, can penetrate. A 100 MHz signal has a wavelength of
3 meters, which is 10 feet. The cut-off frequency of a waveguide is
that at which the longest dimension of the opening is 1/2 wavelength.
For a 100 MHz signal, 1/2 wavelength is 5 feet, and any highway
vehicle tunnel is larger that that. I have even picked up FM radio in
the parking garage under Boston Common in Boston, MA.
***** Moderator's Note *****
... which would mean waveguide for 450MHz would be about 13 inches
wide, so that's not likely to be economical. The 23 cm band could be
done with ~4.5 inches, but the price of copper is too high for that
unless someone knows a way to do it with less expensive material.
Bill Horne
Temporary Moderator
------------------------------
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