May thanks for the files Paul!

Paul Nicholson wrote:
> Well that 24dB is a 5 hour integration in 55uHz.  It
> makes a big sharp line on the spectrum though.  At
> VLF that counts as 'armchair'.

Yes. It will never become a popular "realtime chat mode" of course...


> No problem.  5 hours compressed into 22.5 seconds
> and frequency shifted so that 29499 Hz is moved
> to 400 Hz.  wav format 32k samples/sec mono 1.4 Mbyte
> 
>  http://67.207.143.181/wh2xba1_140303a.wav
> 
> How good is your 'CW ear' I wonder?

Not exactly armchair copy but by looping the file a couple of times for
"mental integration" I got XBA XBA XBA without any doubt. Yes, the
second file wh2xba1_140303b.wav was slightly easier to read due to the
higher CW speed. Thank you for the music Bob!

An MFSK system with integrate-and-dump detectors synchronized to the TX
should be capable of conveying quite a number of bits per hour. The low
speed would allow many tones in a small BW. Some tones could even be
reserved for commonly used words or sentences like "It is not raining in
Tokyo also" :-)

73
Johan