[Lf] Transatlantic LF...

[Steve Olney]

G'day All,

Viewing, as it were, from the sidelines down-under, may I make a suggestion
towards efforts to bridge the Atlantic on LF.

As some of you may be aware I have been playing around with ultra-narrowband
techniques for the past year or so (0.001Hz) and I venture to put forward
few things which may be of help.

Ultra-narrowband techniques have the best chance of bridging the gap I
believe.   I know most stations will be concentrating on sending a signal
which has callsign etc impressed on it, but this is not the best condition
for detecting the weakest signal.  Tests I have done here using even the
relatively wide bandwidth of 0.3Hz (Spectrogram) show that while a steady
carrier is easily seen, when any keying is done the signal completely
disappears into the noise.

I note that Spectran has a minimum bandwidth of 0.032Hz so using that
program on a signal that has a constant carrier with fast short CW ident
every minute only would be suitable.

The other thing that needs to be taken into account is frequency
accuracy/stability.   In order to take full advantage of the narrow
bandwidth of 0.032Hz, the transmitter and receiver should be at least that
stable over say 10 minutes.  In the order of 0.1ppm should be used.   This
is not too hard as TCXO modules are available which have +/- 2ppm over a
wide temperature range.