[GreenKeys] WRU, SELCAL, and other features in TTY-CONNECT

Wed, 28 Apr 2004 13:47:05 -0600

Hi Gil,

On HF, and particularly on 80 and 40 meters we are dealing with very
noisy channels and varying propagation. I ran a 24/7 autostart operation
for about ten years and the biggest problems were with weak stations
that were not strong enough for copy but would intermittently trigger
the autostart on signal peaks.  Secondly, stations tuning up on
frequency with an intermittent carrier, slightly off frequency stations
that would trigger the autostart but were not printable, CW stations
operating on or near the autostart frequency, and static crashes which
are very prevalent on 40 and 80 meters during the summer months, were
all major problems.

For these reasons I would favor a system which triggered on reception of
a space character which would work nicely as long as we all followed the
suggested start up convention of diddles,(CR)(CR)(LF) 5 SPACES
(CR)(CR)(LF)(LTRS) or something similar.  Others' thoughts ??

Best regards --Roy Norris

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of gil smith
Sent: Wednesday, April 28, 2004 12:56 PM
To: Roy Norris
Cc: [email protected]
Subject: RE: [GreenKeys] WRU, SELCAL, and other features in TTY-CONNECT

Hi Roy:

TU Autostart (if enabled) will activate on the first char from the TU 
port.  Since the TU (and loop) ports are bit-banged, it simply means
that I 
have found valid start and stop bits half-way through the respective bit

times.  If the TU is on a noisy channel, this may give false autostart 
triggers if there is a mark-to-space transition and then a space is
found 
in the middle of the start bit period  (an apparent start bit), and a
mark 
is also found in the middle of the stop bit period (an apparent stop 
bit).  This is the only framing check I am doing.  I could, perhaps, 
qualify multiple samples in the start/stop bits.

Autostart on the PC port will be no problem, since the chars will always
be 
good.  Is there a better way to qualify autostart on the TU port?
Someone 
mentioned looking for a SPACE char.

Suggestions?

gil

At 11:36 AM 4/28/2004, you wrote:
>Hi Gill,
>
>Please,please make sure there is a provision for copying every valid
>RTTY signal that appears on channel for those who want to copy
>everything, coupled with an autostart that turns on the TTY motor ONLY
>when a valid digital signal is being received.  AUTOSTART operation on
>the HF bands using the TU's mark carrier sensing work very poorly in
>practice.  They trigger every time a carrier crosses the freq and on
>stations that are too weak to copy.
>
>Roy --K4EEG