1825 S9+30 and earlier there was a control of audibility
the signal strength points to the Kaliningrad region
I hear them for the first time - there are spark interferences from a running car engine / generator in the background
intensive communication of messages is taking place, as during exercise
the syntax indicates the management of military flights
1900 the change of operator, is lower work intensity, in the breaks the sounds of the receiver or the other operator