Because you use light to communicate in sign language, and light is just an electromagnetic wave like radio but on another frequency. You just need to be in line of sight

  • astrsk@kbin.social
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    1 year ago

    RADAR: RA(dio) D(etection) A(nd) R(anging)

    It doesn’t rely on self transmission. It can but you can detect and range other sources without generating it yourself.