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PA2AGA > HDDIG 25.09.99 03:21l 198 Lines 7381 Bytes #-9766 (0) @ EU
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> of HF bands. There are a few little issues. Doing this at 100 watts
> is pretty easy, but running power with this kind of scanning setup is a
> little
> involved -- I would guess. That is without buying one of the top of the
> line amps.
> Which way do you point the beams? Do the beams turn to fixed positions
> for each part of the day -- or what. I dont know.
>
> Also, sometimes, with HF, no matter what band you are on, with a
> country as big as the US, you just plain can't get there from here. That is
> with a modest HF station like mine. Maybe there is some way to predict
> HF paths reliably, but I'm not aware of it. You know, the CB-ers call it
> skip for a reason -- that is the signals tend to skip lots of places in
> between
> here and there. So, sometimes you'll hear stations far away, but not up
> close.
> Or you'll hear them very far away, but slightly closer won't come in.
> There's
> a lot of strange unpredictability here. This deserves a whole book in
> itself.
>
> Maybe if you'd want to systemize this in some way, perhaps then each
> HF gateway, would collect statistics on which links were available to it
> at what times -- since I think with all the antenna variables and such,
> this information, practically can only be measured and not calculated. And,
> then transmit this information back to a central hub for the region where
> maybe a clever piece of code somewhere could stew all the numbers
> together including how much throughput each HF link was capable of and
> parcel out the messages in an optimum manner. That means, perhaps,
> taking data from past connections, and mixing that with some sunspot
> numbers and the time and date or whatever, and coming up with a sensible
> forcast that a connection would be good. I don't know, this is all just
> speculation.
Thanks, again:
I'm remembering my days of yore on third shift RTTY watch for Uncle
Sam. That's why I was wondering about bands and fixed distances. We
would determine our frequencies by the distance between stations and
peak traffic periods. We always had "A", "B", & "C" systems online with
the "B" & "C" systems on hot standby tuned to different frequencies. We
rarely had stations much more than 500 kilometers apart and usually kept
our frequencies below 10 Mhz. We would relay (manually, back then)
between networks
and could often get traffic sent thousands of kilometers in a very short
time. Basing on these distances it would take 10 - 12 hops to work from
coast to coast, but I don't
know if there are that many hf digital nodes online.
Thanks for the information on this. It's really great.
Tony -- KF3BX
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>.
------------------------------
Date: Thu, 23 Sep 1999 03:18:11 -0500
From: "Charles Brabham" <n5pvl@texoma.net>
Subject: Those Wide, Open Spaces
Tony Giroux <agiroux@cvn.net> wrote in message
>
> More questions:
>
> As far as deciding on HF Forwarding or Satellite forwarding -- should
> the HF Sysop have to work that hard? Can the software transmit packets
> via a "shortest known path" -- then if there are no acknowledgements
> resend via other routes?
That's basically what the software is doing when it scans the bands for a
contact first at 10m, then 15, then 20, etc.
Sometimes in HF forwarding, the shortest path is not always the best. For
example: I used to live at the southern tip of Texas, and worked a fwd
network on 20m with stations in Ohio and Novia Scotia. The Ohio and Novia
Scotia stations could not hear each other, but they could both hear my
station in south Texas just fine. - So messages the Nova Scotia station
picked up from Europe often went through my south Texas station on the way
to Ohio!
With HF radio, distance is not nearly the issue that the everyday quirks of
radio propagation are. I've seen lots of situations where it is easier to
communicate with hams 1,500 miles away than it is with other hams only 750
miles away. It all depends on a goodly number of variables such as how clean
and powerful the output from your XMITter is, to what kind of antenna you
are using, the weather, and how precisely you are tuned in to the other
station. If all of that is just perfect, then you still need to deal with
daily changes in how the signals behave as they bounce around the planet.
There are ways to predict these propagation changes, but there is no way to
control them. They generally go in an 11 year cycle associated with the way
our sun behaves.
--
73 DE Charles Brabham, N5PVL
N5PVL @ N5PVL.#NTX.TX.USA.NOAM
http://www.texoma.net/~n5pvl
>.
------------------------------
Date: Thu, 23 Sep 1999 08:18:16 GMT
From: nomail@pe1chl.demon.nl (Rob Janssen)
Subject: Those Wide, Open Spaces
Hank Oredson <horedson@att.net> wrote:
>> Can software determine, through the
>> TNC, what are the best frequencies to use? Does the
>> average Clover or Pactor controller have the capability of relaying that
>> kind of data to the software?
>The software running on the computer controls the TNC and the radio.
>That software simply tries a connect, and if the connect fails, it tries on
>a different frequency or band. Very simple actually.
Of course that approach is much too simple... it is just like the firmware
in the old TNC's: when the CONNECT succeeds, it starts retrying the data
transmission until hell freezes over.
What you need is some link quality data on each of the available
frequencies, and a decision algorithm to decide which is the best frequency
to use. That will be a bit harder to implement, so it is probably left
for version 2.0
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: Wed, 22 Sep 1999 20:56:56 -0500
From: kriss@spec.com (Dick Kriss)
Subject: What happened to tcpip gateways?
Our gateway has been QRT for a few months (long story) and it is now alive
and well. I have been trying to find some of the old gateways and many
seem to be QRT.
If you know of an active gateway, please send me its name and ip number.
73 de Dick, KD5VU
kd5vu@ausgw.n5smn.ampr.org
>.
------------------------------
End of Ham-Digital Digest V99 #239
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