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| Joined: | Sep 22nd, 2008 |
| Location: | Doylestown, Pennsylvania USA |
| Posts: | 130 |
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The original Raudive diode idea was to collect atmospheric radio frequency static (ambient noise) on an antenna and detect the amplitude noise (AM) with a germanium diode. That detected noise is amplified by a recorder to audible levels to be heard on earphones or loud speaker.
Raudive was reported to have recorded his mother's voice while out in the countryside recording bird sounds. He didn't have strong radio stations nearby to overwhelm ambient radio noise. A microphone is not likely to pick up radio stations while recording bird songs.The mothers voice may have been among the background audible sounds of the countryside.
The Raudive diode circuit is a wideband radio detector that doesn't have the selectivity to avoid commercial broadcast stations. It isn't the ideal way to capture pure random atmospheric noise. In populated areas, radio noise signals will contain broadcast radio signals that pollute the radio noise signals.
joe