[FADCA] Basic Requirement for Demonstration

[Dale Coleman]

At 01:48 PM 4/1/02, you wrote:
>Deltona
>Monday April 1 1340EST

Hi Bud and the group, looks like you made a very impressive demo! Congrats 
on the excellent work.
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I have a few comments of cabling and rig set up that may be worth thinking 
about.

>Getting a data controller to work with the HF radio is not trivial.  Cabling
>between data controller and radio is typical of TNC-to radio cabling.

When you are working on the cables - provided you are making your own 
verses buying a pre made cable it might be worth the time to pull an extra 
audio output from the rig for use with a sound card program. I have been 
running this way for about 1 month now and it is a lot of fun having a 
sound card program with a waterfall to help monitor the band. I have a 
screen shot of how this works at:
http://digitalhamradio.org/amwl2k/index.html#airmaildigipan

I would be happy to provide more info on the simple hookup required to add 
the sound card program.

>For
>the most part, configuring of the data controller for HF is done using
>set-ups in the Airmail program.  The major concern is receiver pass band
>response between about 1900 and 2300hz, and preferably with 500hz IF
>filters.  Most folks use the present US standard:  2100 Hz center frequency
>and 200 Hz shift (Mark 2000 Space 2200).

I think this needs a bit more explaining. If you have a controller that 
only offers Pactor I or Pactor I and G-tor then you may be better off 
running FSK instead of AFSK. Running FSK with the mark and space setting 
above should be the best way to go.

On the other hand if you are running a Pactor II controller then you might 
be better off running the default setting of 1200 and 1400. The reason is 
the Pactor II controller can not use FSK for Pactor II, it uses AFSK and 
APSK instead. Running with the default puts the output in the middle of the 
SSB pass band and may make it easier to get a clean signal. I might be 
wrong about this but this but I think it may be worth debating. Figuring 
out the correct dial frequency to use is simple - if running USB 
just  subtract 1.3 from the listed frequency. Running in wide SSB mode also 
lets me see what's going around on both sides of where I'm about to transmit.

I have some screen cuts showing what the different filters do that I think 
should be very interesting for others to look at.
http://digitalhamradio.org/why_waterfall.html#fskfilters

PS - the page I made on propagation is also definitely worth looking at. It 
has a lot of excellent propagation information that you will not find any 
place else all on one page.

http://digitalhamradio.org/amwl2k/propagation.html


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I hope this helps,

Dale