er ▁equipment ▁to ▁transmit ▁three ▁fe eds ▁in ▁HD ▁simultaneously ▁on ▁one ▁channel ▁was ▁as ▁widely ▁used ▁and ▁it ▁was ▁un common ▁to ▁have ▁any ▁more ▁than ▁two ▁HD ▁fe eds ▁transm itting ▁over ▁a ▁single ▁channel ) ▁but ▁on going ▁up gr ades ▁to ▁the ▁multiple x er ▁equipment ▁being ▁util ized ▁over ▁W TR F ' s ▁full - power ▁signal ▁over ▁the ▁two ▁years ▁following ▁the ▁spectrum ▁sale ▁allowed ▁for ▁the ▁My Network TV ▁and ▁ABC ▁sub ch annels ▁to ▁both ▁begin ▁air ing ▁in ▁ 7 2 0 p ▁HD ▁( al beit ▁in ▁a ▁highly - com pressed ▁variation ▁of ▁that ▁video ▁resolution ) ▁over - the - air ▁via ▁W TR F - TV ' s ▁full - power ▁signal ▁for ▁full - market ▁over - the - air ▁HD ▁distribution ▁of ▁those ▁two ▁sub ch annels ▁( until ▁ 2 0 1 7 , ▁the ▁ABC ▁sub channel ▁was ▁being ▁offered ▁only ▁in ▁ 4 8 0 i ▁ 4 : 3 ▁SD ▁over ▁W TR F ' s ▁full - power ▁signal ▁and ▁until ▁May ▁ 2 0 1 9 , ▁the ▁My Network TV ▁sub channel ▁was ▁being ▁offered ▁only ▁in ▁ 4 8 0 i ▁ 4 : 3 ▁SD ▁over ▁W TR F ' s ▁full - power ▁signal ). ▁CBS , ▁My Network TV , ▁and ▁ABC ▁are ▁now ▁all ▁available ▁in ▁HD ▁over ▁W TR F ' s ▁full - power ▁signal , ▁and ▁due ▁to ▁ag gress ive ▁statistical