CF-3000 Frequently Asked Questions

Data analysis can be performed without any problems.
The question then becomes how many data points (lines) can be obtained.
The CF-3000's FFT calculation speed is approximately 40ms, meaning it can capture 25 data points per second. If the rotational upward time of the object being measured is 30 seconds, then 30 seconds x 25 = 750 data points can be captured, which is more than enough to reach the upper limit of 400 tracking lines.

<Notes>
One thing to be careful about with tracking measurements is at low RPMs. At low RPMs, the sampling clock is slower, which causes order shifts (because the data capture time ratio is longer than the rotational fluctuation, the order peak moves within a single frame). Ideally, you should increase the rotational speed slowly at low RPMs. Depending on the engine, precise rotational control may not be possible, so at low RPMs, it is best to display the power spectrum waveform and check for any order shifts.

<1> Rotational increase and calculation time
Converted at 1 P/R
0 to 35000 rpm = 0 to 583 Hz (increase)
Rate of change per line
583÷400=1.46Hz (=0.6s)
Since the calculation time is 40ms, the FFT calculation time is not a problem.

<2> Sampling time
The sampling time is 1200 r/min in the 25th order range.
2048 points ÷ (1200r/min ÷ 60×1p/r×64 multiplication) = 1.6s
The sampling time is also a problem (it's prone to causing order shifts).

(1) At low RPMs, raise slowly.
(2) Set the degree setting to a high value.
(3) Reduce the sample size to 1024 or less.

These measures are necessary.