I heard these irregular dits zerobeat on 6822.0 kHz USB and zerobeat on 7001.0 kHz simultaneously for over 30 minutes - - for the duration of my monitoring, the characteristics of the signal were consistent with the attached audio.
Attached is a 30 second audio clip recorded on 6822 kHz. There was a very faint MARS voice net up 1 kHz unconnected to the beeps.
Dag