Fine John,
Yes, every little helps !
That true, you can communicate over quite a range using 'fec' the navtext on
518 prints well , but as far as I know the published service range is 50
miles for a navtext station , that would fall in with 'our' observations of
reliable, fade free, communication range.
The problem sets in outside that range , I have seen good print from my psk
signals outside the uk and good results from the Olivia system using 250/16
, showing the transmission medium is 'stable' ie not 'phase disorientating'
but notably displaying deep selective fading at carrier shifts over 100 hz ,
leading to recommending shifts of 85 hz and lower. The redundancy in the
250/16 filling the gap's but still a low date rate, with no indication of
actual % reception.
Unless you are experiencing qsb depth and cycle period 'time' considerably
less than 'we' have experienced, your still up against the final test ,
during qsb 'outage times' no signal = no copy,
The time intervals have reduced attempted 'data qso's' to near farce, with
resolution periods of only some 10/20 seconds in a 90 second period. An
increase in power might slightly increase the 'print window' duration , but
is still not proof against the deep fade's
Oddly , I would suspect that 'hf packett' would actually work quite well ,
where it not for the high bandwidth, conversely the short data burst would
actually ensure the bulk of the traffic was transferred in 'one qsb window'
, notably the pk232 tnc will allow the baudrate for 'hf packet' to be
reduced to 50 , 50 is a bit slow , but 75 or 110 may allow the introduction
of the 'missing' arq function , notably it uses a simple two tone fsk
transmission mode as dose rtty and fec and as such my be amplified by
non-linea means.
G ..
----- Original Message -----
From: "John Andrews" <[email protected]>
To: <[email protected]>
Sent: Tuesday, January 01, 2008 10:07 PM
Subject: Re: LF: Re: Keyboard modes for 600 meters
Graham,
Non of the send and forget modes are of any use on 500 as you have no
idea if the other end has even seen your signal ,let alone resolved it,
that's unless the station is in ground range and then any mode works ,
Perhaps with the higher ERP's over here we are getting better results, as
excellent winter-time copy with FEC has been fairly easy over long
distances.
If suitable ARQ software materializes, we'll be happy to put it through
its paces. My T/R setup would certainly need some redesigning, first!
Clunk!
John Andrews, W1TAG
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