Morse code, SOS signal transmission:
-
Radio Setup
-
Electronic signal
-
Transfer, Morse code, reception
-
Police radio
-
Low-frequency rumble, high-frequency squeak
-
Geiger counter
-
Morse code transmission
-
SOS signal reception, Morse code
-
Low frequency electronic signal
-
High frequency pulsating electronic signal
-
Low frequency pulsing and humming signal
-
Radio noise
★★★★★