VHF Trigger for Lighting System

So, I am going to trigger a lighting bus using the Arduino UNO. On the power side of things, I am going to drive an SSR. That part is easy. The thing I haven't quite figured out is the VHF trigger. I have an old VHF radio. The idea is that someone would key their VHF radio 3 times within 3 seconds, to turn on one set of lights, or 5 times in 3 seconds to do a different set of lights, etc...My current idea is to read the stereo out pins for voltage signal on my old VHF radio. Since the sound is created through AC signal, I believe I need to trigger via an AC voltage, or when I pass some threshold (maybe in the neighborhood of 1Vac RMS.

Ideally, I would like to eventually end up using the digital interrupt pins on the Arduino so that I can more accurately count the number of low-high signal transitions. What sort of circuit could I create that would detect this voltage on the stereo out plug and cause a 5V digital interrupt? I was thinking some sort of Capacitor across the signal (to give it a DC like signal) and then feed it into an opamp to deliver my digital signal for the interrupts. Or...I am overthinking all of this, and there is an easier way. Thanks for any help

One person had a similar problem to yours a little while ago and here is what I suggested:

http://ruggedcircuits.com/html/circuit__22.html

I think the voltages and frequencies should be compatible to what you are dealing with.

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons

thank you, I am anxious to give this a shot!

sounds like landing lights. I would probably hookup a pin to the carrier-detect light on the radio. Does the radio have an output that goes high/low on signal RX? If yes, wire it through a resistor to an input pin.

seeeduino has a RELAY shield. If you can detect the transition, turn on/off one of the relays.

It is, too bad that the radio has an LCD display and the RX signal is on the display...all of the ribbons are buried deep in the radio too, so...hesitant to pull the whole thing apart. It is for landing lights though. The problem with the schematic above, is that I believe that is going to cause a low high transition and a low transition for every AC peak. I think I can throw a cap after the diode and more or less maintain the AC+ signal until the person stops keying their mic.