Figure out what the callsign is transmitting on 50.105.007 MHz from Australia. keeps repeating. They are on 6m USB using an omni directional. Picked this up while listening on HamSphere

[SSB579B]

Trying to figure out the callsign from Australia. Broadcasting on 50.105 MHz, power of 20watts. Signal fades in/out. strong at times weakens about the time their callsign is given. Sounds like 43m64. I am using an online receiver HamSphere 5.0. I am receiving this USB using a 6m omni with a filter of seven. I have been listening since about 2245 to 2323(Central Time, US).