Hi Alan
Yes interesting.
I had a Creed 7B? Rattler as well as my Z80 microprocessor set up,
so I kept compatible with the mechanical methods. The Creed was in
the garage and I sent to it via co-ax for any hard copy and also
printing tickets for local do's on card, a man with a printer was a
rarity.
I wonder if you ever came across a problem I had one winter, the
Creed stopped printing and I found that the magnet had permanently
lost its magnetism due to extreme cold.
73 Eddie
On 06/03/2013 19:03, Alan Melia wrote:
Hi Eddie, we were using line
machines for a purpose other than that for which they were
designed :-)) The way round this was to have some "special"
operating methods which got lost when the ZX80 came along.
On HF I remember sending RlsRlsR
at the begining of an over to ensure that the receiving
machine had not slipped into figure shift due to noise. On
weak signals it was common to insert lots of extra ls. The
standard end of line was CRLFCR to ensure the carriage had
time to get back to the stop, before the text started. Many of
the "ZX" ops didnt send any CR or LF at all because their
display wrapped......the Creed didn't!!
The QSO finished as a square
black block at the end of the line.
All good fun.
My mate G3YKB used to be on the
LF reflector he was editor of the BARTG newsletter around
1970.
Alan
G3NYK
----- Original Message -----
Sent: Wednesday, March 06,
2013 1:38 PM
Subject: Re: LF: Re: RTTY
Protocol
On 06/03/2013 13:14, Minto Witteveen wrote:
That settles it. The info I got (from an untrusworthy
source it seems) told me mark is 2125 and space is 2295.
See my original message below.
But it is the other way around.
But it is only independent of the sideband used if
both sender and receiver use the same sideband.... You
still have to agree.
And it seems that the current consensus is mark =
highest tone = highest frequency. So USB if AFSK is
used.
Yes yes.
BTW regarding missing the first character 's. In the mechanical
days did we not send CR/LF first to get things going? I have
seen the software have problems during the recent tests,
printing Numbers instead of Letters. This can be alleviated by
sending 46RY first, 46 I think being RY with LetFig set wrong.
Eddie
73’s Minto pa3bca
--------------------------------------------------------------------------
Ceterum censeo Carthaginem delendam esse
Sent: Wednesday, March 06, 2013 13:57
Subject: Re: LF: RTTY Protocol
From my days on HF RTTY
(~1970) with mechanical 'printers, the highest RF
frequency was Mark (or idle tone) It was
independent of which sideband was used. I think this
was also the mode used by the commercial stations
Remember only European
lines used bi-polar signalling. The US used a 20mA
mark and no current for space. A mechanical machine
of either type would chatter if the mechanism was
not held in Mark. Timing was mechanical and
stop-start was necessary to maintain character
timing sync. with simple mechanical governors.
Alan G3NYK
----- Original Message
-----
Sent: Wednesday,
March 06, 2013 11:09 AM
Subject: Re: LF:
RTTY Protocol
Hmm might this be because
‘in the old days’ (amateur)
RTTY was done with the rig in LSB mode
using AFSK?
With mark at 2125 Hz and space at 2295 hz
and mark being the idling position, when
using LSB the actual transmitted
frequencies would be ‘swapped’ (reversed)
So MTTY seems to assume rig at USB, while
all (all?) others assume LSB…
Still, Stefan and I seem to
do RTTY wrong (i.e. amateur reversed, as
in AFSK on USB). I just checked my PIC
code and I have mark at high (DDS_BASE +
85 Hz) and space at low (DDS_BASE). This
then gets swapped around by fldigi because
I listen (via websdr) in USB… This
explains why fldigi decodes me (and
Stefan) just right.
This is of course based on
the assumption that ‘right’ means AFSK on
LSB, that the space must be the high tone
AND the low(est) frequency.
What _is_ the consensus (if any)?
73’s Minto pa3bca
--------------------------------------------------------------------------
Ceterum censeo Carthaginem delendam esse
Sent: Wednesday, March 06, 2013
11:44
Subject: LF: RTTY Protocol
Graham
Just confirmed by test, MMTTY is backwards
compared to all other Software. Others idle
on the high tone MMTTY idles on the low,
unless the REV is pressed.
From Wiki
the upper tone used for idle condition
(MARK).
Another site says
You also have to switch the correct phase
position (whether the lower or higher frequency
carrier in frequency modulation corresponds to
"Mark" or "space").
Mind you a Ham education site on the subject
says.
Remember that bfo’s help filter out the
carrier waves to allow for the original
signals to come through
Eddie
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