How to detect speed of encoder

I am using an encoder to tune a radio and want to tune by larger increments when the encoder turns quickly.

The tuning setup now is for each encoder detent the station increments by one, like this:
88.1, 88.3, 88.5, 88.7, 88.9, 89.1 etc. all the way to 107.9 and then it wraps around to 88.1

If the encoder is turning fast, it should increment in steps of 5 stations per detent like this:
88.1, 89.1, 90.1, 91.1, 92.1, etc all the way to 107.9 and then wrap around to 88.1

All I really need help with is setting a boolean variable named fastSwitch. An encoder speed greater than 200ms/detent should set it to the true state and when it slows down below 200ms/detent or stops, it should set it to the false state.

Once the is figured out, I can make the necessary tuning changes. I would prefer to do this without interrupts but if that's not possible or too complicated, it can use them.

You need to record the value of micros() when an encoder pulse is detected and again when the next pulse is detected. Subtract one value from the other to get the interval between pulses.

...R

Wow, so simple. Thank you!