RacingTach is a tachometer using the sound or any periodic signal coming from engines. It can measure precisely the RPM up to 100 000 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.

- 'Fund. vs Harmonic ratio (%)'
Use this parameter to adjust the threshold of the tracking of the RPM frequency peak. Try to keep the value as high as possible but decrease it if one of the harmonic peak of the RPM signal is often higher than his fundamental frequency.

- '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.

See my video on Youtube :
http://www.youtube.com/user/racingtach