random hacks & assorted infodumps. by windytan [oona räisänen] home list of posts what? My Nerd Story corrects IE6 width calculation google_ad_section_start(name=default) Feb 1, 2014 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. (Here, a HTML5 audio element used to be) The signal sits alone on the left audio channel, so I ca...