Wednesday, December 11, 2019

Digital Acoustic Tachometer Android Application Tool



This Android application can measure revolutions per minute (RPM tachometer, RPM tach) by listening to the engine sound, so it can be classified as a non contact tachometer. Can be downloaded on Google Play with the name Acoustic Tachometer (RPM) made by Javier Yáñez. On Samsung smartphones the size is around 11.17 megabytes. Currently the application is free of charge.


As can be seen on YouTube video above, the application is tested with the car door open. It turns out the results are less accurate, especially when engine in stationary.

Also read how to connect the tachometer wiring.

With the door closed, the window closed, the measurement results are more accurate. And of course there is no music in the cabin. Looks like this application detects the sound of engine boom when power stroke. A quiet cabin makes it easy for this application to detect that engine power stroke sound.

When tested on the engine hood (bonnet), the application cannot measure accurately. Possibly because too much mechanical noises. The application cannot detect the thumping sound from the combustion process. Mechanical sounds can come from valves, bearings, fans, V belt, vibrating plates, and others.

More details about the tachometer function on the vehicle.

Inside the cabin the mechanical noise is muted by sound absorbers. While the sound of power stroke is weaker, but it is still clearly heard and roaring.

When it is tested close to exhaust outlet, the application cannot measure accurately. Possibly because the muffler is the silent type.

The menu in the application is quite easy, simple yet functional. Settings that are often adjusted:
  • engine cycle type (2 stroke, 4 stroke)
  • number of cylinders, usually 1 for motorbike and 4 for car
As seen at the end of video. The application is tested on motorbike, smartphone must be brought close to the exhaust outlet so that measurement becomes more accurate. Possibly because the environment is open, and the mechanical sounds are very noisy. So the application becomes confused by too much sounds that are caught by the microphone.

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