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Re: LF: DominoEX and FEC

To: <[email protected]>
Subject: Re: LF: DominoEX and FEC
From: "Graham" <[email protected]>
Date: Sun, 11 Jan 2009 00:48:15 -0000
Importance: Normal
In-reply-to: <19EC4B1A1B35448A802DB3E4DEC497D7@JimPC>
References: <[email protected]> <5ADF9C3861D84576BE1EF01D07F6D67D@AGB> <232F9AD021FE40A98CE6527B4DA482B5@AGB> <19EC4B1A1B35448A802DB3E4DEC497D7@JimPC>
Reply-to: [email protected]
Sender: [email protected]

Fine Jim,

Did you save a copy of the text ?

When you say the fec took longer to recover , was that at the expense of missing text ?

I assume that the system is not quite as robust as olivia if you where not seeing 100%
decodes? But at the data rate , that might be a miss observation ?

I had a couple of qso's with olivia on 7 mhz last night 8x250 it did produce quite a good copy in qsb and recovered very quickly .. may be a little wide for 7 mhz but with the shaped modulation envelope,
very  little spread. the data rate is 'just' qso  speed

Thanks for standing by

Graham ..




--------------------------------------------------
From: "James Moritz" <[email protected]>
Sent: Sunday, January 11, 2009 12:23 AM
To: <[email protected]>
Subject: LF: DominoEX and FEC

Dear Graham, LF Group,

Quite interesting to watch the two modes (BTW, the continuous text gives a
much better comparison, thanks). At present, signal strength has improved a
lot, and both signals are clearly audible between fades, which are 20dB or
more (see attachment). When near maximum, both modes print almost 100%; the FEC version corrects the occasional error due to static cracks and pops, so
has fewer errors, but throughput is only half. When there are bigger
crashes, errors appear in the FEC copy as well, and it seems to take longer
for FEC to "recover", so there are also more gaps in the copy, although
probably less actual printed errors. It also seems to take longer for the
FEC mode to recover after a deep fade. So the FEC does something, but in
this implementation, not really what you want... I suspect it would be more advantageous to go to the narrower-band Domino EX4 sub-mode rather than use
the FEC.

Cheers, Jim Moritz
73 de M0BMU







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