RacingTach is a tachometer using the sound or any periodic signal coming from engines. It can measure precisely the RPM of race cars, motorbikes, trucks, motorboats, R/C models but it can also use the sound of plane’s propeller, helicopter’s blades etc… The signal is analyzed in real time using a proprietary FFT algorithm which is one of the fastest implementations.

Settings of the application

– ‘Events per revolution’
It is the number of pulses seen by the software when the crankshaft of your engine performs one revolution.

Examples :
Four-stroke & 4 cylinders engine => 0.5 * 4 = 2 events per revolution (the common value for a car)
Four-stroke & 6 cylinders engine => 0.5 * 6 = 3 events per revolution
Two-stroke & 2 cylinders engine => 1 * 2 = 2 events per revolution

– ‘Min RPM’ and ‘Max RPM’
You can adjust these settings according to your engine capacity in order to improve the reliability of the RPM.

– ‘Filter windows size’
It is the windows size of a high-pass filter on the spectrum data which is effective to reduce influence of low frequency noises (Useful with the embedded microphone or a cigarette lighter RPM pickup)

– ‘Shift light alarm (RPM)’
It is the minimum value of the RPM before the alarm occurs (ie the background screen of the tachometer blinks). For example, in a race car with manual transmission a driver can use it to know when he needs to shift up a gear.

– ‘Shift light sound’
Set to ON only if you have an external microphone far from your iphone / ipod speaker or if you have inductive / cigarette lighter RPM pickup otherwise the alarm sound may disturb the RPM measurement.