Yeah, I was gonna say. In addition to making it hard to detect it also makes the channel robust to some kinds of noise and fading. See Chirp Spread Spectrum for

Yeah, I was gonna say. In addition to making it hard to detect it also makes the channel robust to some kinds of noise and fading. See Chirp Spread Spectrum for example http://nanotron.com/EN/CO_techn-css.php http://nanotron.com/EN/CO_techn-css.php