[Lf] [Fwd: LF: Transatlantic tests]

[Andre' Kesteloot]

Mike Dennison wrote:

> John, VE1J wrote:
> >   I think I agree wth Alan 8 or 10 second dashes  it would be much
> > easier to tell us from the enemy(LORAN in this case).
>
> Beware!
>
> It is true that longer dashes will give you a better S/N ratio and is
> therefore a good thing to do. It will especially improve immunity to
> short term QRM such as static and random noise. It will not improve
> the immunity to Loran - quite the reverse as the averaging will add
> up the Loran pulses and will make good solid lines.
>
> The other problem is that the improvement is =only= realised when
> either the selectivity is increased (use Spectran for this), or the
> averaging is increased (on recent versions of Spectrogram use an
> averaging setting one or two less than the number of seconds per
> dot). This will mean that stations sending 3-4s dots will no longer be
> readable - the dots and dashes will merge into each other.
> Furthermore, the scroll speed will have to be altered. In other words
> the two speeds are incompatible. I suggest that any use of long dot
> lengths is scheduled in advance so that =everyone= can adjust their
> speeds.
>
> It would also help if someone could coordinate frequencies as
> happened with the VA3LK tests. There have already been instances
> of two people selecting the same frequency, and I notice that last
> night I picked what seemed be a clear channel only to find someone
> on exactly the same frequency when I closed down. Perhaps one of
> those who have already made it could take this on. I am happy to do
> it if no-one else wants to, and can post the frequencies on my web
> site.
>
> Lastly, is VE1ZZ doing any transmitting tests? It will be just as useful
> to check the reverse direction. It will also give a chance for those
> without big transmit signals to achieve something. If so, it would be
> preferable to avoid times when the big signals are on the air.
> Perhaps 0400-0500 UTC, or specify a day of radio silence in Eu.
>
> Mike, G3XDV (IO91VT)
> http://www.lf.thersgb.net