Recover Signal From Power Rail

[klr5205]

I have an audio belt pack which receives audio superimposed on the 24VDC rail that powers the pack. In addition to audio, there can be a 20kHz "Call" tone present on the line.  I'd like to detect this 20kHz tone and use it to trigger things. 

My initial thought was to simply capacitively couple the power rail to the input of a high pass filter ---> peak detector ---> comparator ---> OUTPUT

Just wanted to pick the brain of the hive mind to see if there was a better or more obvious way.

[cur8xgo]

I have an audio belt pack which receives audio superimposed on the 24VDC rail that powers the pack. In addition to audio, there can be a 20kHz "Call" tone present on the line.  I'd like to detect this 20kHz tone and use it to trigger things. 

My initial thought was to simply capacitively couple the power rail to the input of a high pass filter ---> peak detector ---> comparator ---> OUTPUT

Just wanted to pick the brain of the hive mind to see if there was a better or more obvious way.

If you are learning, your idea seems like a great way to get involved in many different things of once, with the possibility of success as well.

Might want to consider a resonant circuit that only responds to the frequency of interest. Otherwise any high frequency noise could look like the signal.

This would be a great circuit to simulate as well..could fit everything in there and it would be realistic to the end product.