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PA2AGA > HDDIG 29.09.99 05:01l 187 Lines 7436 Bytes #-9754 (0) @ EU
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From: pa2aga
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Subject: HamDigitalDigest 99/244D
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those bands if when and if it's as easy and inexpensive to use them as it is
to use 2m. - Not anytime soon, in other words.
One way to look at it is that there will not be a big problem with
"maverick" types trying to directly access the backbone links if they are
microwave at 1MB or better. Networkers can rest assured that their "backbone
freqs" will not be congested with other activity. - Seems like a good deal
to me.
That's what the average networker wants anyway... Why not take advantage of
that, and plan accordingly?
Sometimes it's better to take the situations we face and look for the
advantages inherent in them, instead of spending all of our energy trying to
fight the inherent liabilities. I think they call it "going with the flow",
or "bending with the wind"... Something like that.
73 DE Charles Brabham, N5PVL
N5PVL @ N5PVL.#NTX.TX.USA.NOAM
http://www.texoma.net/~n5pvl
>.
------------------------------
Date: Tue, 28 Sep 1999 10:22:11 +0300
From: Paul Keinanen <keinanen@sci.fi>
Subject: Kinda spooky - Bandwidth to burn . . .
On Mon, 27 Sep 1999 08:09:05 GMT, nomail@pe1chl.demon.nl (Rob Janssen)
wrote:
>Well, over here (Netherlands) the 3cm band is quite densely filled with FM
>ATV relays located at high sites. They have different output frequencies
>and many are equipped with receivers that are tuned to other relays.
You have the luxury of a ham density that makes it possible to build
such dense infrastructure. At less dense populated areas, it is hard
to find other enthusiasts with similar interest within a comfortable
RF-path distance, 10 GHz FM-ATV is more or less line of sight anyway.
While in addition to line of sight paths, microwaves also propagates
through other modes, however, any short to medium distance non-line of
sight paths (such as scattering from buildings in urban area), have
much higher path losses compared to line of sight losses. With
available transmitter powers (a few watts) the baseband bandwidths
must be much less than the 5 MHz required by analogue video. While
highly directional antennas are useful in increasing the ERP on
transmit and the capture are an reception, due to the narrow beam
widths, these are usable only for line of sight, troposcatter and
single reflection paths, but not for mobile communication or
scattering from buildings.
>They usually have picture-in-picture systems (4 or 16 pictures) that
>display an overview of activity on several relays.
This is a nice idea to keep the spectrum occupied :-).
>One or more active
>contributors to the relay often have a private link to it.
It is nice to hear that you have active contributors, but is it
realistic to expect that they would contribute more than 1-2 hours
each day on a daily basis ?
What about the rest 22 hours of the day ? Do you show the test card or
an aquarium the rest of the time (remembering that some fish require a
few hours of darkness each day :-).
Paul OH3LWR
>.
------------------------------
Date: Tue, 28 Sep 1999 10:27:51 GMT
From: nomail@pe1chl.demon.nl (Rob Janssen)
Subject: Kinda spooky - Bandwidth to burn . . .
Paul Keinanen <keinanen@sci.fi> wrote:
>>Well, over here (Netherlands) the 3cm band is quite densely filled with FM
>>ATV relays located at high sites. They have different output frequencies
>>and many are equipped with receivers that are tuned to other relays.
>You have the luxury of a ham density that makes it possible to build
>such dense infrastructure. At less dense populated areas, it is hard
>to find other enthusiasts with similar interest within a comfortable
>RF-path distance, 10 GHz FM-ATV is more or less line of sight anyway.
That is true. The nearby FM-ATV relay that I have permanently wired
to my TV set (using a sat-tv rx and a modified LNB, no dish necessary,
just the LNB pointing at the relay. just press EXT-2 to see ATV!) is at
220M AGL in an otherwise flat area (it is on a 380M tv broadcast tower).
The range is 80km or so. Within that range there are 3 other relays
that it receives permanently, and more when propagation is good.
>While in addition to line of sight paths, microwaves also propagates
>through other modes, however, any short to medium distance non-line of
>sight paths (such as scattering from buildings in urban area), have
>much higher path losses compared to line of sight losses. With
>available transmitter powers (a few watts) the baseband bandwidths
>must be much less than the 5 MHz required by analogue video.
Right, it (mostly) only works with line-of-sight. But then we have
nearly broadcast-quality pictures.
>>They usually have picture-in-picture systems (4 or 16 pictures) that
>>display an overview of activity on several relays.
>This is a nice idea to keep the spectrum occupied :-).
Yes, usually there are 4 pictures showing some other 16-picture
transmissions. Some of these pictures are in fact re-incarnations of
these 4 pictures as received at the remote relay, etc etc etc :-)
>>One or more active
>>contributors to the relay often have a private link to it.
>It is nice to hear that you have active contributors, but is it
>realistic to expect that they would contribute more than 1-2 hours
>each day on a daily basis ?
Contributors to the hardware, of course. The programme material they
contribute is normally not more than beer-drinking ugly guys in a very
messy room :-)
>What about the rest 22 hours of the day ? Do you show the test card or
>an aquarium the rest of the time (remembering that some fish require a
>few hours of darkness each day :-).
You are getting the idea. If you like, I could mail a captured image as
a .jpg.
It shows testcards, static shots of the operator, webcam-like "shots
of the shack with nobody but the cat", etc. There is even a picture
showing a computer receiving SSTV signals :-)
Of course, to have audio with all this, the repeater has lots of FM audio
subcarriers ranging up to 8.1 MHz, plus NICAM. Poor IARU guy that wants
to mandate sound-in-sync because he is worried that a 6 MHz FM subcarrier
would cause unnecessarily-wide ATV signals :-)
The local relay also has a camera showing the surrounding area as viewed
from 220M AGL. The camera slowly rotates.
These ATV guys are reasonably active these days, kind of like the packet
guys 10-15 years ago. They come up with news ideas and actually implement
them, instead of only discussing them on the usenet...
Rob
--
+----------------------------------+--------------------------------------+
| Rob Janssen pe1chl@amsat.org | WWWhome: http://www.pe1chl.demon.nl/ |
| AMPRnet: rob@pe1chl.ampr.org | AX.25 BBS: PE1CHL@PI8WNO.#UTR.NLD.EU |
+----------------------------------+--------------------------------------+
>.
------------------------------
Date: Sun, 26 Sep 1999 20:15:20 -0700
From: "Hank Oredson" <horedson@att.net>
Subject: Let's look at real numbers for TNC software sales
Peter O. Brackett <ab4bc@ix.netcom.com> wrote in message
news:7sjv7v$s1v@dfw-ixnews19.ix.netcom.com...
To be continued in digest: hd_99_244E
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