Just a little more information on the way I am reading ZEVS G3WCD and
me are 'singing from the same hymn sheet'
There appear to be 12 tones.
7 is Idle or Start tone
1 is Repeat or Space tone
A Breakfast or Tea time message is Start - followed by 3 tones with 12
possible tones per unit =1728 posibilities - followed by a Repeat -
followed by the same 3 tones again - followed by Idle.
The repeat gives error detection / correction in the one way messaging
system. I used it this morning when the complete message unit 5 was
corrupted and looked like a tone 3, closer examination confirmed there
was a tone 1 in the correct. expected, place.
Note I could be completely wrong.
73 Eddie G3ZJO
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On 09/05/2011 21:26, wolf_dl4yhf wrote:
Hi Eddie,
You wrote:
Did you ever put numbers to the data units?
080905.jpg is familiar to us as a breakfast or tea time 3 unit code,
reading 6,11,12
0080906jpg is more complex 3,8,6 - 6,8 ---- 9,11,10 - 12,4
This has confirmed some as yet unused (unseen by me) data units which
I had surmised were there and useable.
I didn't try to 'see' anything there, I am not even sure how many
different 'tones' they actually send. But it doesn't seem that much,
only a few bits per symbol.
The filenames use the date in ISO 8601 format, which I often use for
temporary filenames.. YYMMDD . With a full year number, the dates were
2008-09-05 and 2008-09-06. Not sure if the timescale was in UTC or
local time back then (but compare this with Markus' post, the schedule
seems to be the same still). I don't remember what happened on
September 6, 2008, why they sent so many 'data bits' around and after
noon. It's a pity my recording ends before the transmitter switched
back to the 82 Hz idle tone on that day.
73,
Wolf .
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