olemus
vastuvõtja väljundsignaali automaatne summutus
piisavalt tugeva sisendsignaali puudumisel

Wiktionary:
2. (transitive, radio technology) to suppress the unwanted hiss or static between received transmissions by adjusting a threshold level for signal strength

ülevaateid
https://en.wikipedia.org/wiki/Squelch

https://pdfserv.maximintegrated.com/en/an/TUT5428.pdf

demo
https://www.youtube.com/watch?v=lUsgD-QHZIY