>From: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
>Reply-To: g3rzp@g3rzp.wanadoo.co.uk
>To: Tom W8JI <w8ji@w8ji.com>, W7RY <w7ry@centurytel.net>
>CC: amps@contesting.com
>Subject: [Amps] 160m RTTY
>Date: Sun, 30 Jul 2006 13:15:26 +0200 (CEST)
>
>Tom said (in the plexiglas thread, but we're wandering a bit from that)
> >The reason RTTY isn't on 160 is it doesn't work very well on
>160. Multipath kills it.<
>
>
>I don't know how bad the multipath is, and obviously, it's going to depend
>on the path length and so on. However, SS Loran (Skywave Synchronised)
>LORAN was used in WW2 operating in 160m (How many of us are old enough to
>remember LORAN on top band?) SS Loran was used with sync from one end of
>the Mediterranean to the other to provide navigation for bombing raids into
>Romania, and also in the Atlantic for convy escort (see the MIT Radiation
>Lab. series) The Loran pulses were a lower prf than 45.5 baud RTTY signal,
>but were quite short, so multipath would smear them out quite a lot.
>However, it was claimed that they could get to within 400 yards in mid
>Atlantic, which suggests around 1 microsecond of uncertainty, using
>stations in the UK, Canada and I believe, Bermuda.
>Tom, comment, please?
I recall being told that with Loran, the phase comparison was done on one of
the cycles in the early part of the pulse (perhaps the 6th cycle?) so as to
avoid the effects of the multipath which would take longer to get to the
receiver.
I would be grateful if someone could verify this.
David G4FTC
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