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P-Theta measurement using Angle Domain Acquisition


I am facing issue in triggering and cycle alignment while measuring cylinder signature acquisition.

(Tracked-free run (angle) is used for measuring P-theta, Engine is 4 cylinder, 4 stroke)

I am using incremental encoder for measuring rpm and zero reference is defined using reference tacho.

TDC is defined with Engine off condition and it comes at 180 while engine is cranking (No ignition)

Though I have followed all the steps as mentioned GTAC support website for Angle domain Processing, Cylinder peak is coming sometimes at 191 deg (Which is correct) and sometime at 551 (191+360).

What is correct way of defining TDC or triggering event so that Peak cylinder Pressure comes exactly at 191 independent of triggering event/crankshaft rotaion. 



Re: P-Theta measurement using Angle Domain Acquisition

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello,  can you use a second channel to set the correct TDC?


For example under the Advanced... button next to the zero reference, reference angle, you can select to conditionally accept the reference pulse based on some level on another channel.  That channel could be an accelerometer or pressure sensor on one of the cylinders for example.  Or it could be a cam and crank sensor.  See #2 in the slide below.


If that's not clear, please reach out to your local GTAC support team and they can either help over the phone or via a desktop share.


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