Continuous Tone-Coded Squelch System: Forskelle mellem versioner

Historisk: [[Motorola]] opfandt CTCSS under navnet '''''Private Line''''' i starten af 1950'erne og [[patent]]erede systemet og lavede [[varemærkebeskyttelse]]r. Først senere blev systemet navngivet CTCSS i standarder. Af samme grund kaldes en CTCSS-tone ofte for en '''PL-tone''' eller simpelthen blot ''tone''. Grundet Motorolas patenter og varemærker har andre fabrikanter lavet samme system med lidt variationer, men er blevet nødt til at finde på andre kaldenavne.<ref name="RB">[http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html A Historical and Technical Overview of Tone Squelch Systems. A primer on tone systems, with a little on digital systems. By Mike Morris WA6ILQ] Citat: "...In the early 1950s the geniuses in Moto R&D developed a system that added a low frequency tone to the existing transmitter audio that was present as long as the transmitter was keyed. The receiver was modified by adding a tone detector circuit to the receiver and then the receiver squelch was modified so that it wouldn't open unless the tone was there. They also modified the receiver audio circuits to strip the audio tone out of the speaker audio. The legal folks patented the idea and the technique then trademarked the term "Private Line"...", [https://web.archive.org/web/20200408191637/http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html backup]</ref>