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[Эксперимент Розенхана] ru.wikipedia.org

Эксперимент Розенхана (англ. Rosenhan experiment) — известный эксперимент, проведённый в 1973 году в США психологом Дэвидом Розенханом и поставивший под сомнение надёжность психиатрической диагностики. Его результаты опубликовал журнал Science в статье «Психически здоровые на месте сумасшедших».

Mystery signal from a helicopter
Last night, YouTube suggested a video for me. It was a raw clip from a news helicopter filming a police chase in Kansas City, Missouri. I quickly noticed a weird interference in the audio, especially the left channel, and thought it must be caused by the chopper's engine. I turned up the volume and realized it's not interference at all, but a mysterious digital signal! And off we went again.
The signal sits alone on the left audio channel, so I can completely isolate it. Judging from the spectrogram, the modulation scheme seems to be BFSK, switching the carrier between 1200 and 2200 Hz. I demodulated it by filtering it with a lowpass and highpass sinc in SoX and comparing outputs. Now I had a bitstream at 1200 bps.
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