National messaging system

[Curt, WE7U]

On Tue, 18 Jan 2005 dubose at texas.net wrote:

> Ok...Here's what I got from Jim Haynie ARRL President talking to him at HamCom
> 2004 and talking with David Woolweaver, K5RAV, West Gulf vice-Director...
>
> The ARRL would like to see a high speed, robust, data messaging systen that is
> not dependent on the Internet...use it if you got it but if you don't have its
> availability, then the system must still work.

Seems easy enough.


> It ought to be as fast as possible and stay with the current 3 KHz bandwidth.

Dennis or other RF-type people:  What's the theoretical maximum
symbol rate (data-rate/whatever) that we can get with a 3kHz
bandwidth signal using whatever way-cool multiplexing techniques
they're using these days for getting lots of symbols through with
less bandwidth, like qpsk16 and such.


> I should be robust enough to copy signals that can hardly be seen on a
> "waterfall" display or even not seen on a display for modes such as MFSK16 and
> MT63.  It needs to be more robust than where Pactor III quits transferring data.

At what level does Pactor-III fail?  At what levels do MFSK16 and
MT63 fail to display?  I understand that the way the text is worded
he wasn't trying to give exact specs, but we can at least get
ballpark figures out of it to strive for.


> The robustness is hard to pull out because most hams haven't a clue about what
> is being talked about "specwise" when we talk about robustness.  That's not
> the ham's fault, just generally where we are.  So maybe we say it has to work
> when even the S Meter isn't moving and you cna't tell the signal from noise.

That still gives quite a wide range I'd think, so perhaps throw this
one out.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"