Good morning Andy and all,

Many thanks for the high power transmission.  There is a
picture on my web site.  Some difficulty in decoding, in the
end I converted the jpg to greyscale printed it and drew
(draughted?) a grid thereon.  The vertical line just happened
to pass through the first of each pair conveniently.  There is
a change of speed and back again in the middle of the picture.
Couldn't resist experimenting.

A very happy Christmas to all.  Brian
73 Brian     CT1DRP     IN51QD     41 09 58N  08 39 11W
http://homepage.esoterica.pt/~brian