ings ▁help ▁prevent ▁co - channel ▁inter ference , ▁and ▁these ▁take ▁advantage ▁of ▁FM ' s ▁capture ▁effect ▁and ▁receiver ▁select ivity . ▁ ▁IT U ▁Region ▁ 2 ▁band plan ▁and ▁channel ▁number ing ▁The ▁original ▁frequency ▁allocation ▁in ▁North ▁America ▁used ▁by ▁Ed win ▁Arm strong ▁used ▁the ▁frequency ▁band ▁from ▁ 4 2 ▁through ▁ 5 0   M Hz , ▁but ▁this ▁allocation ▁was ▁changed ▁to ▁a ▁higher ▁band ▁beginning ▁in ▁ 1 9 4 5 . ▁In ▁Canada , ▁the ▁United ▁States , ▁Mexico , ▁the ▁Bah am as , ▁etc ., ▁there ▁are ▁ 1 0 1 ▁FM ▁channels ▁number ed ▁from ▁ 2 0 0 ▁( center ▁frequency ▁ 8 7 . 9   M Hz ) ▁to ▁ 3 0 0 ▁( center ▁frequency ▁ 1 0 7 . 9   M Hz ), ▁though ▁these ▁numbers ▁are ▁rarely ▁used ▁outside ▁the ▁fields ▁of ▁radio ▁engineering ▁and ▁government . ▁▁ ▁The ▁center ▁frequencies ▁of ▁the ▁FM ▁channels ▁are ▁spac ed ▁in ▁incre ments ▁of ▁ 2 0 0   k Hz . ▁The ▁frequency ▁of ▁ 8 7 . 9   M Hz , ▁while ▁techn ically ▁part ▁of ▁TV ▁channel ▁ 6 ▁( 8 2 ▁to ▁ 8 8   M Hz ), ▁is ▁used ▁by ▁just ▁two ▁FM ▁class - D ▁stations ▁in ▁the ▁United ▁States . ▁Port able ▁radio ▁tun ers ▁often ▁t une ▁down ▁to ▁ 8 7 . 5   M Hz , ▁so ▁that ▁the ▁same ▁rad ios