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PA2AGA > HDDIG 09.10.99 16:13l 182 Lines 6616 Bytes #-9725 (0) @ EU
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Subject: HamDigitalDigest 99/253A
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Ham-Digital Digest Thu, 7 Oct 99 Volume 99 : Issue 253
Today's Topics:
56k UHF-100W / 19.2K VHF -50W
Download Ia.n.i.!!! It's free!
HOW TO BECOME A MILLIONAIRE IN WEEKS!!
Japanese packet radio hinted at on TAPR site.
Let's look at real numbers for TNC software sales (2 msgs)
Packet with an HT
Personal Mail Box Software
Send Replies or notes for publication to: <Ham-Digital@UCSD.Edu>
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We trust that readers are intelligent enough to realize that all text
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Loop-Detect: Ham-Digital:99/253
----------------------------------------------------------------------
Date: Wed, 6 Oct 1999 19:58:41 -0700
From: "Hank Oredson" <horedson@att.net>
Subject: 56k UHF-100W / 19.2K VHF -50W
Paul Keinanen <keinanen@sci.fi> wrote in message
news:so35Nw7kgSA1El+KeLuoUluLsnMy@4ax.com...
> On Mon, 4 Oct 1999 10:18:08 -0700, "Hank Oredson" <horedson@att.net>
> wrote:
>
> >
> >Paul Keinanen <keinanen@sci.fi> wrote in message
> >news:eTf4N75Xk2kSxK5rE7r41oDXWehP@4ax.com...
> >
> >Just a couple amusing observations ...
> >
> >> Why do you need a fade margin for a true line-of-sight path ? If you
> >> need a fade margin, it is not a true line-of-sight path anymore :-).
> >
> >It is line of sight in the sense that we can see each other's antennae,
> >using high power binoculars or small telescopes, if it is not foggy
> >or raining as is usual most of the time here.
>
> Let me clarify my use of _true_ line-of-sight. On optical wavelengths,
> if there is a visual contact, the Fresnel zone(s) are usually
> unobstructed, since the zones are very close to the geometric line
> between the end points. On a 10 km path the first Fresnel zone radius
> for green light (550 nm) at midpoint is only about 37 mm. However, at
> longer wavelengths, the zone radius is much larger and it is hard to
> have sufficient clearance to keep the Fresnel zone above ground. On 70
> cm, the required clearance at midpoint below direct line-of-sight line
> would be nearly 42 m, thus if you now have just barely visual contact,
> the antennas would have to be 42 m higher to have sufficient clearance
> and that the simple path loss formula would apply. With insufficient
> clearance, the path loss would be usually larger.
>
> >However there are
> >the expected tropo refraction effects, particularly at 70 cm., which
> >may make the radio path very different from the optical path.
> >This is another "feature" of this area, a lot of inversions and strong
> >changes in air moisture from one place to another and one time
> >to another. We often have "capping inversions" that tend to trap
> >signals inside of valleys.
>
> I have seen measurements taken at a place in which there is a clear
> visual contact between antennas, but the lower part of the Fresnel
> zone is hitting deeply into the ground near the receiving station,
> with large signal variations at extreme weather conditions, so this is
> not a _true_ line-of-sight path and thus you have to have a fade
> margin.
I don't think I have any "true line of sight" paths available, other than
my one "good" 9600 baud link. 30 km and roughly 100 meters above
ground at the worst case.
For most cases, there is no visual path between the two antennae.
i.e. the paths are obstructed.
I'm "lucky" in some directions: 250 meters above the valley, with a
strong slope downhill right in front of the tower. So I have very good
paths out to perhaps 30-40 km. to similar stations. But there is nobody
running digital modes there, so I have no choice but to work on longer
links that are at best "somewhat" obstructed.
--
... Hank
http://horedson.home.att.net
>.
------------------------------
Date: 3 Oct 1999 10:47:38 GMT
From: madQ <madq968@djeksta.comNOSPAM>
Subject: Download Ia.n.i.!!! It's free!
Download Ia.n.i. RemoteControlSystem 1.2 beta. It's free!!!
New site: http://jump.to/IaniProject
>.
------------------------------
Date: 7 Oct 1999 00:38:08 GMT
From: phiberop@hotmail.com
Subject: HOW TO BECOME A MILLIONAIRE IN WEEKS!!
just read the document...trust me....
>.
------------------------------
Date: 6 Oct 1999 11:41:04 GMT
From: "Eric S. Johansson" <esj@harvee.billerica.ma.us>
Subject: Japanese packet radio hinted at on TAPR site.
marsgal42@hotmail.com wrote:
> The Slovenian stuff (http://www.hamradio.si) is well-documented,
> simple, and looks eminently reproduceable. They are on my Things
> To Do Someday list.
thanks for the pointer! I'll look into the radios and see how
reproducible they are. I have a bad habit of collecting a bag of
parts and letting them sit underneath my bench until they compost. if
I can't get all of the component easily, I don't even start the
project anymore.
> The catch phrase seems to be "reproducible by amateurs". Too many
> amateurs nowadays seem incapable of anything more technical than
> plunking down a credit card.
I must admit I'm guilty as charged. Between rocketry, astronomy,
speech driven programming design work, and running my business, I
don't have a lot of energy for chasing down small collections of
parts. I'll make the time to build if I have a complete set of parts
and boards but I can't do much more than that right now.
--- eric
--
Eric S. Johansson ka1eec esj@harvee.billerica.ma.us
This message was composed almost entirely using NaturallySpeaking
>.
------------------------------
Date: Wed, 6 Oct 1999 19:48:26 -0700
From: "Hank Oredson" <horedson@att.net>
Subject: Let's look at real numbers for TNC software sales
Hamish Moffatt <hamish@rising.com.au> wrote in message
news:7tcqie$2nlj$2@arachne.labyrinth.net.au...
> > "Power Spread" - The difference between the ERP and noise floor at a
To be continued in digest: hd_99_253B
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