How are PL tones (CTSS, et.al.) typically removed from the audio of received VHF FM repeater signals?

Is it done with a fixed high-pass filter? Or a notch, when using a transceiver with the PL tone configured correctly? Or dynamically, by assuming any constant low tone detected is hum to be removed by an auto-adaptive notch?

Or is it sometimes not removed by filtering because the tiny speakers on handheld receivers don't have sufficient low frequency response?


I would expect some low-frequency roll-off in the amp and the speaker. You could check by putting headphones on the speaker output.

Wikipedia says that a 300 Hz cutoff high-pass filter is common.


Also, the CTSS tone is injected at a lower level than the voice content, usually 15% of full deviation. That is about 8 dB below full modulation.


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