Predicta?! -> philco computers - test-drb@ccmp.vtda.org

20 Oct 2007

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Subject: Re: Predicta?! -> philco computers
   From: "Ethan Dicks" <ethan.dicks at gmail.com>
   Date: Sun, 21 Oct 2007 12:37:06 +1300
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

On 10/21/07, William Donzelli <wdonzelli at gmail.com> wrote:
   I did not
look, because I did not think any were left. 
 Talk to hams. RTTY was very popular many years back. Hams never throw
 anything away. 
Until we moved Comms out of the Dome to the new Station, we still had
an RTTY rig set up for emergency communications.  It was used in 2004,
for certain, when we were between satellite passes and we couldn't get
a call through on our Iridium phones.

To keep this nominally on-topic, it was one of two 386s in production
when the dome was still in use - the other was a Dell 386SX-16 working
as a front-end to our PBX.  There was a sign on it warning people not
to throw it away.

RTTY always sounded like fun, but, despite my Ham ticket, I have yet
to set up so much as a packet station, let alone something I know less
about.

-ethan 
RTTY is one of the oldest digital modes, Amtor and Clover are newer. 
Some of the newest weak signal modes require 500mhz systems
with decent soundcards.  Examples are PSK31 and JST65, they work to 
the noise level and below.

One of my pet projects is to get somthing like PSK31 working on a 
Qbus PDP11 I have fast A/D and D/A needed to do the 22K or better 
samples/sec. but the DSP software is a new thing to me.  PSK31 
translates user text IO  at 31.5 baud to a variable length code 
and then to something a transmitter can digest (Narrow audio 
bandwidth, less than 31hz!).  The software to do it on curent 
laptops and PCs exist but that's no fun. 

Allison