[pskmail] Re: The hardware modem idea (sri, long rant)

On Tue, May 1, 2012 at 5:53 AM, John Douyere <vk2eta@xxxxxxxxx> wrote:

[snip]

>
> But still, I have a genuine question I would really like to have an answer
> for, and believe me absolutely exempt from ulterior motives: for those of us
> who have used/are using Pactor modems and Winlink why would we be interested
> in Pskmail? There must be some reason?
>
> All the best,
>
> 73, John

As I said in the past, PSKmail has the right general idea about an HF
Radio e-mail system. It offers far more features than WINLINK2000
(most important is the ability to send radio e-mail directly, not via
a MAIN server controlled by one body), plus APRS BEACONS in realtime,
TWITTER, KEYBOARD CHAT, MAPS, WEBPAGES etc.

Rein's ingenuity is unlimited here but, and here is the big but, it
lacks decent modem support, not a speedy one necessarily, but it lacks
a ROBUST HF MODEM.

This does not have to be an SCS MODEM necessarily, although since the
P4dragon appeared in the market last June, there are many PTC-II
series modems available on the cheap now.

I hope you John, will be able to improve on this need because your
"andPSKmail" is a great idea. Not sure if the FLDIGI is a good modem
to follow BTW. FLDIGI is FB for what it was designed to do but not for
ARQ. I think you need to make the ARQ mechanism be in the MODEM (or
virtual modem) not in the PSKmail application itself. The modem should
preferably be in a separate small box with it's own CPU that serves
only the ARQ MODEM. You have to use a Soundcard interface even if you
use the soundcard of your PC so a separate small modem box will not
make the system bulkier!

All of today's Operating Systems suffer from one thing! LATENCY! So
you will never be able to build a ROBUST ARQ MODEM if it has to run in
the same Computer (PC or Android or other phone). You will always get
FREEZES and/or DELAYS because the computer has to attend to more
things than serving the MODEM.

The Computer no matter which O/S it uses, has to do interrupt calls
for everything, i.e. keyboard, display, mouse, disk operations,
networking, calculations, decode/encode the MODEM signals just to name
a few!

No matter how fast a CPU is or will become in the future, you will
always have this LATENCY problem, because of the many devices that are
attached to it. That is why it is important to have a smaller CPU that
does only one thing. DECODE/ENCODE the MODEM signals.

You might be able to make a MODE such as PSK31, RTTY, PACKET RADIO,
SSTV and other asynchronous modes work FB in an environment like this
(i.e. using the Soundcard of a WINDOWS or LINUX or Android Computer as
a MODEM) but these modes are not ROBUST and also they will never be
fast enough. The WINMOR guys have done something along these lines,
but even WINMOR is far from being ROBUST. It fails horribly at the
presence of the slightest QRM and our HF Bands are full of QRM!

You just can't expect to find a clear frequency to conduct your radio
e-mail business  today. Even if all the Radio Amateurs listened before
they transmitted, there is always the HIDDEN TRANSMITTER SYNDROME that
will create QRM. This will only get worst in the near future when the
Solar Activity will increase.

I hope something good will emerge from this conversation.

Take care.

-- 
73 de SV1UY
Demetre Ch. Valaris
e-mail: demetre.sv1uy@xxxxxxxxx
Radio e-mail: sv1uy@xxxxxxxxxxx
http://www.qsl.net/sv1uy

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