A Performance Analysis System for the Sport of Bowling

Figure 3-1: MASTER "Raw Data" Screen Capture
The non-homogenous nature of the overhead lighting can be seen in Figure 3-2, which
zooms in on the first 800 msecs of Figure 3-1. Multiple local peaks are evident during
each revolution, with each of these "side lobes" occurring as a row of ceiling lights comes
into view of the light sensor. Looking closer, it is also evident that the side lobes grow
and recede as the ball travels further down the lane. Eventually they disappear
completely, as is evident in Figure 3-3, which zooms in on the last 800 msecs of the shot
in Figure 3-1.
The directionality of the module can be seen in the shape of Figure 3-3. The light level
rapidly approaches a peak value when the light sensor is pointing almost directly at the
light source, and just as rapidly retreats as the light sensor rotates away from the light.
Notice that the valleys of the waveform do not display this directional characteristic.
Drawing from Fourier analysis techniques, the cyclic waveform shown in Figure 3-1
must have a fundamental frequency close to that of its major peaks, which resulted from
each rotation of the ball. For a cyclic waveform to exhibit such sharp peaks, there must
also be a significant amount of high-frequency harmonic content. The multiple local
peaks present in each revolution, as shown in Figure 3-2, will be responsible for some
significant intermediate harmonic content, as well [7].
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