Amateur Operators Use It to Receive Sound Signals
This page is the CodyCross answer for the clue below from Prehistory, Group 1241, Puzzle 5 (Geographic Survey).
Question is: Amateur Operators Use It to Receive Sound Signals
and the answer is: HAMRADIO
Word Meaning:
HAM RADIO — (colloquial) The hobby of amateur radio communication.
Definitions from Wiktionary.