Complex sentence: Only one station, VOCM-FM, has been allowed to adopt a "VO" callsign after 1949; it was granted the VOCM calls because of its corporate association with the AM station.
Split into simpler sentences: Only one station, VOCM-FM, has been allowed to adopt a "VO" call sign after 1949. It was granted the VOCM calls because of its corporate association with the AM station.