On Monday, June 16, 2014 04:19:04 you wrote:
> Hi,
>
> The attached file contains the results of an experiment in recording
> signals of short duration.
>
> Comments welcomed.
>
> Regards, Edgar
> Moonah, Tasmania.
Interesting experiment. Two sudden ideas...
1- Usually NDB are AM modulated, so you can find a continuous carrier with two
keyed sidebands +- about 1000 Hz. Carrier and sidebands are phase correlated.
2- The keyed pattern is periodic at defined timestamps (but some NDB are keyed
by a mechanical keyer and the period may have some jitter).
Using multichannel averaging software on the recorded .wav file you can add
many correlated sound pattern with uncorrelated noise.
http://123.physics.ucdavis.edu/week_4_files/narrow-band.pdf
May be Paul Nicholson vlfrx-tools can do something.
Regards
Claudio IK2PII
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