Or Kassadin . Or anyone who builds in early Phantom Dancer . edit an <| sep |> backwards movement out of bounds keeps the clock going . <| sep |> Actually it is an amplitude modulated subcarrier inside the fm signal . USFCC rules dictate that 100 % deviation is 75 kHz . There is a rule that allows for . 5 % increase in total deviation for every 1 % subcarrier deviation up to 5 % total so absolute maximum deviation is 105 % in reference to 75 khz . There are also some other tricks to maximize coverage of the rbdsrds subcarrier . Some audio processing can now either generate the rds on board or take the input ahead of the final clipping stage and allow up to 10 % injection effectively without actually increasing total deviation .