“In radio or wireless telephony, Private Line is a term trademarked by Motorola to describe their implementation of Continuous Tone-Coded Squelch System (CTCSS), a method of using low-frequency subaudible tones to share a single radio channel among multiple users.”
Learn about the technical background of this squelch tone system in the CTCSS, DTMF and More episode of the ARRL The Doctor is in podcast.
These short podcasts are an approachable way of learning about technical topics related to Amateur Radio. Recent podcast topics include:
About the ARRL The Doctor Is In Podcast
The Doctor is In was a biweekly podcast which presented lively discussions of many technical aspects of Amateur Radio from April 7, 2016, to December 19, 2019.
The podcast was hosted by QST Editor in Chief Steve Ford, WB8IMY, and the Doctor himself, Joel Hallas, W1ZR.
Sponsorship for this podcast was provided by DX Engineering.
A complete podcast archive is available on the ARRL's The Doctor is In page.