I have just calculated the FFT of the time series recorded by my accelerometer installed in an electric motor (I previously integrated the signal to obtain the data velocity's units). I want to get the graph in "Order" to visualize faults in the components, with the motor RPM. The calculation command to do this process is ORD (Cx, Rx), where I know that Rx is the value registered in the RPM channel (I know that value). My question is: What is that channel? I need to create it? I'm working offline and I did not use a tachometer.
In order to use ORD(Cx, Rx) the RPM channel must be in the same dataset as the analog channel; which mean during data acquistion if you were measuring acceleration, you must acquiring a tacho/rpm channel as well. Here I have a screen shot of the dataset which has a rpm channel:
Without a tacho you cannot use ORD(Cx, Rx) formula.