Tachometer Frequency Manipulation

Hi All! First post here. Take it easy on me!

I'd like to read a 2 pulse per rev signal and output a rather odd signal. The input and output signals would be, with an 'I' representing a single pulse:

Input Signal (per revolution), 0 - 5V I _ _ _ _ _ _ I _ _ _ _ _ _ _ _

Output Signal (four pulses, then skip two pulses--or 18 pulses with a total of 6 missing) 0 - 5V I_I_I_I _ I_I_I_I _ I_I_I_I _ _

Input frequency would range from 0 to 12,000 pulses per min = 0 to 200 hz

I've been reading on interrupts, etc., but what I wonder is can the Arduino continually send the output signal while running an interrupt routine to measure the changing period of the input signal?

Thanks for any ideas!

Not sure if this thread will help you, but I needed some help just a few days ago building a tach for my scooter:

http://forum.arduino.cc/index.php?topic=167040.0

BackWoodsBrewer: Not sure if this thread will help you, but I needed some help just a few days ago building a tach for my scooter:

http://forum.arduino.cc/index.php?topic=167040.0

Thanks! I'll look through your code as a starting point.