Symbol 5047 from IEC 60417 - Title/Meaning: Muting; squelch Function/description: To identify the switch position in which the muting (squelch) circuit is switched on.
Additional information: 
Title was editorially improved
Published in: First edition, 1973
Own work using: iso.org/obp/graphics/grs/6db618d1-beed-4b4d-a5e2-9b176dc60a10 200.png
Vectorization:  Mrmw