, ▁only ▁government - run ▁public ▁radio ▁stations ▁are ▁still ▁active ▁on ▁O IR T . ▁All ▁stations ▁on ▁O IR T ▁in ▁Bel arus ▁are ▁a ▁mirror ▁of ▁normal ▁FM ▁broadcast s . ▁The ▁main ▁purpose ▁of ▁those ▁stations ▁is ▁compatibility ▁with ▁older ▁equipment . ▁ ▁In ▁ 2 0 1 4 , ▁Russia ▁began ▁replacing ▁O IR T - band ed ▁transmit ter ▁with ▁CC IR - band ed ▁( the ▁" western ") ▁FM ▁transmit ters . ▁The ▁main ▁reason ▁for ▁the ▁change ▁to ▁CC IR ▁FM ▁is ▁to ▁reach ▁more ▁listen ers . ▁ ▁Un like ▁Western ▁practice , ▁O IR T ▁FM ▁frequencies ▁are ▁based ▁on ▁ 3 0   k Hz ▁rather ▁than ▁ 5 0 , ▁ 1 0 0 ▁or ▁ 2 0 0   k Hz ▁multi ples . ▁This ▁may ▁have ▁been ▁to ▁reduce ▁co - channel ▁inter ference ▁caused ▁by ▁Sp or adic ▁E ▁propag ation ▁and ▁other ▁atmos pher ic ▁effects , ▁which ▁occur ▁more ▁often ▁at ▁these ▁frequencies . ▁However , ▁multip ath ▁dist ort ion ▁effects ▁are ▁less ▁anno ying ▁than ▁on ▁the ▁CC IR ▁band . ▁ ▁S tere o ▁is ▁generally ▁achieved ▁by ▁sending ▁the ▁s tere o ▁difference ▁signal , ▁using ▁a ▁process ▁called ▁polar ▁mod ulation . ▁Pol ar ▁mod ulation ▁uses ▁a ▁reduced ▁sub car rier ▁on ▁ 3 1 . 2 5   k Hz ▁with ▁the ▁audio ▁on ▁both ▁side - b ands . ▁This ▁gives ▁the ▁following ▁signal ▁structure : ▁L