Software Vault: The Diamond Collection/The Diamond Collection (Software Vault)(Digital Impact).ISO/cdr16/tc14_480.zip/TC14-480.TXT

Text File | 1995-01-22 | 12KB | 298 lines

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From: smds![e-mail] (Steve E. Witham)
Subject: Re: Telephone Directory for Entire United States?
Organization: SMDS Inc.
Date: Fri, 30 Dec 1994 16:54:54 GMT


In article <[e-mail]>, Benjamin P. Carter
<bpc@netcom.
com> wrote:

> [100,000,000 phone book entries at 30 bytes each...] we
> obtain the estimate: 3000 Megabytes.  That is a BIG database.  It
> won't fit on a CD-ROM.

No, but it will fit on the five CDs of "Select Phone," which I just
bought.  5 x 600M = 3000M.

> Chances are that such a database, if it exists, is owned by some
> outfit that charges exorbitant dollars per minute to allow you to
> access it.

Well, I guess this is a case of "You get what you pay for," since I
paid $78 for the combination of Select Phone and Street Map USA.

> The CD-ROM directories I have seen cover either business or
residential
> phones (not both) and cover only a subset of states.

This seems to be businesses and residences in all 50 states, but as
Mr.  Carter says, inaccurate, incomplete, obsolete and ...

> mangled in various ways.

Still, it's a taste of omniscience.  Street Map is nice, though the
interface is a little clunky.


Steve

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From: [e-mail] (Brian Roy)
Subject: Re: FM Subcarrier For Data Transmission
Date: 30 Dec 1994 22:57:03 -0500
Organization: The Greater Columbus Freenet


TELECOM Digest Editor noted:

> None the less you can have fun building an SCA receiver out of a
regular
> radio and listening to it now and then, and its a pretty simple
> project, albiet nothing to apply to the FCC for type-acceptance on
> when finished.  PAT]

Pat, could you use one of those full coverage scanners for this, like
the ones that AOR puts out, or am I completely not understanding the
concept?

Of course, it is more fun to build your own.


Brian Roy KB8TEY    [e-mail]
"Type acceptance, we don't need no steenking type acceptance"
             WARNING: NON PC WORD  ^^^^^^^^^ don't bother suing, I'm
broke


[TELECOM Digest Editor's Note: I don't know about scanners. You do
need
a radio with the FM broadcast band. The bigger and fancier it is, I
guess the more bandspread you have and the more room to fit a few
extra components inside it. One of the little pocket radios is not
easy to work with because everything is so crammed up inside it, and
the tuning dial gets all of an inch or so for dozens of FM stations.

Yes, it is fun to build your own. A very pleasant afternoon can be had
building any sort of radio receiver. A couple of the neighborhood kids
ages 11-12 came over here a couple days ago and I spent the afternoon
teaching them how to build a crystal radio using a couple of the Radio
Shack kits.

Another fun gimmick with radio is build a transmitter using an old
tube-style receiver. Yes, there are still a few around ... gotta be
tubes and not transistors. Bearing in mind that all receivers are in
fact also transmitters of sorts -- they all have an IF or intermediate
frequency used internally -- and that some of those old radio tubes
were really potent, you make a little jack into which you plug your
audio source.  That might be a microphone or a tape player or
whatever. Having a little pre-amp helps. Now inside the old radio, you
find that IF, and snip the wire which sends it out the usual way. Send
it instead through the tube and up a makeshift antenna. A thin piece
of wire will work, but more about antennas in a minute.  Use the
tuning
dial on the front of the radio to diddle the frequency up to somewhere
where you won't interfere with other (legit) stations, nor they with
you. For both potential long range and convenience later in cutting an
antenna, I tuned to 1620 kilocycles. 1600 has a station, 1610 is the
expressway traffic service, and 1630 is some navigational beacons out
in Lake Michigan.

When the kids were here the other day, we used an old Philco table
radio I had found in a garbage bin a month or so ago.  It works fine,
but some fool had tossed it out because the electrical plug was mostly
broken off.

Now start the music, and get your little portable radio in hand and
ready to go. Modulation is the name of the game -- you sure won't get
far otherwise with *maybe* half a watt -- so let's play an old 1949
recording of E. Power Biggs made at Columbia University entitled
{French Organ Music}. When it finishes, it will start over again, and
again.  We were able to walk about a block down the street with the
little portable transistor radio tuned to 1620 and hear the music.
After that, for about two blocks more if we listened closely, we could
hear the music in the background buried under a lot of hash.

But as I explained to the kids, antennas are 85-90 percent of what
radio is all about. A very cheap radio will talk loud and clear and
sound great with a good antenna; conversely the best radio in the
world
will -- as the CB'ers phrase it -- sound like pooh when you go to get
those radio checks if your antenna is not cut correctly, to say
nothing
of potentially harming the radio -- blowing out the final, or worse if
the power is sufficiently high. Now we know that the antenna length
has
a direct relationship to the frequency (or cycles, or number of times
the wave travels at the speed of light from one end of the antenna to
the other). Full wave antennas in the US broadcast band would be
obscenely
long, and quarter-waves will do okay for our project. A quarter-wave
at
1620 kilocycles is still a few hundred feet in length, so let's find
something we can use ... hmmm ....

In my phone box in the basement there are pairs going back to the
telephone exchange ... a distance of some three thousand feet. So
let's
attach the antenna from our old Philco receiver turned transmitter to
one of the pairs <wink> ... no one will ever know the difference,
seriously.
RF can travel on the phone pair; it gets along fine with telco's
thing.
So we found an idle pair and hooked it up.

Start the music and let's go again. Since its the holiday season and
all,
this time a recording of Gustalf Holst's {Choral Fantasy on Christmas
Day}
provided the modulation. Interesting music as several traditional
carols
are heard in vertical juxtaposition; that is, men's voices singing The
First Nowell while women's voices are singing God Rest Ye Merry,
Gentlemen.
We got three blocks before we were unable to easily hear the signal
and
then we moved into the alley and started following the telephone
poles.
Even when we were getting only static and hash about a half-mile from
my
house, whenever we stopped at a telephone pole and held the radio
right
next to the pole with the antenna upward to the wires we'd hear that
music in the background. Since the kids live only a few doors from me
we went to their house and they turned on *their* radio to insure I
was
not playing some tricks on them -- and when they could hear the very
same
thing from their loudspeakers they were just thrilled.

That's radio!  A fun, very mysterious thing. I've used CB radios with
only two watts -- but great modulation -- to 'work skip' and talk all
over
the world, to the consternation of people who have seen me do it. They
cannot understand how it is possible .. and frankly at times, neither
can I. *Why* radio waves go where they go as far as they go at times
is
anyone's guess.  Have fun with a radio soon!       PAT]

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From: [e-mail] (Dave Van Allen)
Subject: Re: FM Subcarrier For Data Transmission
Date: 31 Dec 1994 05:15:04 GMT
Organization: You Tools Corporation/FASTNET


Dave Van Allen ([e-mail]) wrote:

>> Bill McMullin ([e-mail]) wrote:

>>> I am trying to learn more about using FM subcarrier technology to
>>> deliver data.

>> The equipment involved from the radio station point of view is a
SCA
>> generator, possible some additional monitoring equipment and
perhaps
>> some antenna/RF chain tuning or filtering.

>> [TELECOM Digest Editor's Note: Here in Chicago, we have several
SCA's
>> operating on the sub-carriers of FM stations.

[incomplete brew-your-own-SCA receiver plans delteted]

>> None the less you can have fun building an SCA receiver out of a
regular
>> radio and listening to it now and then, and its a pretty simple
>> project, albiet nothing to apply to the FCC for type-acceptance on
>> when finished.  PAT]

Well, it's a pretty simple project for one skilled in the art, but I
wouldn't say it's as easy as a stop at Radio Shack.

Todays SCA at mostly digital, due to the fact that frequency response
and a high S/N ratio makes "quality" analog audio hard to come by.
I've installed a number of both analog and digital SCA's in my time,
and with a little work, you can keep the main channel and both SCA's
clear of each other. Because of the fact that most installs are
digital, your plans for a quick n' dirty SCA receiver won't invoke
much pleasure to the eaves-dropper :-)


*Dave Van Allen - You Tools/FASTNET - [e-mail] - (610) 954-
5910
       -=-=-=- FASTNET(tm) PA/NJ/DE Internet 800-967-2233 -=-=-=-


[TELECOM Digest Editor's Note: Well, I can't really imagine anyone
even *wanting* to spend much time listening to stuff via SCA. It is
all rather specialized and dreary. Even the Muzak is not very good.
For about ten years I produced thrice-weekly programs on Chicago
history
called 'Traces of Chicago' for the Chicago Public Library which were
aired on the CRIS channel. In those days I listened to the station
a lot, but not any longer.   PAT]

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From: [e-mail] (Hendrik Rood)
Subject: Re: Metropolitan Area Networks in USA
Date: 31 Dec 1994 04:59:25 GMT
Organization: Hendrik's Humble Home Hero


In article <[e-mail]>, [e-mail]
says:

> I need urgently as much as possible informations about Metropolitan
Area
> Networks in USA. The more important questions are:

> 1. What is the architecture of MAN (physical layer - FDDI, B-ISDN;
protocols)

A MAN is a ring network in a city/region which deploys the
QPSX-protocol (IEEE 802.6). The physical layer is a standard
Telecom-trunk, most used is T3 (45 Mbit/s) in USA and E3 (34 Mbit/s)
or E4 (140 Mbit/s) in Europe.

A MAN uses cells (cell-relay) of 53 octets, the same size as ATM.  Due
to heritage to an earlier version of the ATM cell-format the header of
the MAN cell slightly differs. But that can be managed by your
operator. So you can connect with future ATM-networks over a MAN.

> 2. Do banks participate and use MAN? In which way?

I don't know for the US but in Germany, Frankfurt yes!

> 3. What type of network services are most popular?

As far as I know, SMDS.

> 4. Who is the main investor?

Question is not clear, clarify please?  Suppliers? Siemens, Alcatel
and protocol-founder QPSX from Australia (also in the USA).

> 5. What level of data security is provided?

About the same as in Virtual Private Networks over X.25 and Frame
Relay.  Except for equipment malfunctioning cells are only routed to
the correct destination and not broadcasted of the MAN-ring outside
the required group.


Hendrik Rood

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End of TELECOM Digest V14 #480
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