The point-by-point detection application must analyze the low- and high-frequency components separately. The Array Max & Min PtByPt VI extracts waveform data that reveals the level of energy in the waveform for each wheel, the end of each train, and the end of each wheel.

Three separate Array Max & Min PtByPt VIs perform the following discrete tasks:

• Identify the maximum high-frequency value for each wheel.
• Identify the end of each train.
• Identify the end of each wheel.

Note The name Array Max & Min PtByPt VI contains the word array only to match the name of the array-based form of this VI. You do not need to allocate arrays for the Array Max & Min PtByPt VI.

In the Train Wheel PtByPt VI, the Array Max & Min PtByPt VIs use the following parameters and functions:

• sample length specifies the size of the portion of the waveform that the Train Wheel PtByPt VI analyzes. To calculate the ideal sample length, consider the speed of the train, the minimum distance between wheels, and the number of samples you receive per second. 100 is acceptable for the Train Wheel PtByPt VI. The Train Wheel PtByPt VI uses sample length to calculate values for all three Array Max & Min PtByPt VIs.
• The Multiply function sets a longer portion of the waveform to analyze. When this longer portion fails to display signal activity for train wheels, the Array Max & Min PtByPt VIs identify the end of the train. 4 is acceptable for the Train Wheel PtByPt VI.
• threshold provides a comparison point to identify when no train wheel signals exist in the signal that you are acquiring. threshold is wired to the Greater? function. 3 is an acceptable setting for threshold in the Train Wheel PtByPt VI.