I have two signals, and each has a square wave, 0-5v, digital pulse that can vary from as slow as 10Hz to as fast as 3kHz. I need to compare the frequencies of these two signals and calculate their ratio. Think of it as the tachometers on two motors, where the goal is to say Motor A is spinning X% as fast as Motor B. Is there a chip out there designed to do this -- i.e., accept two digital pulses, compare their ratio, and output that ratio (via a serial output or otherwise)?