  The bunch-by-bunch BPM signal array has to be reshaped into a turn-by-turn
(TBT) matrix in order to make the TBT beam position information of a single
bunch available for further data analysis, such as via the Fourier transform to
obtain the synchrotron tune and betatron tune, etc. Since the RF frequency
sweeps more than 10 MHz in the first 8 ms of a Booster cycle, the revolution
time decreases more than 20%. The number of data points for each Booster turn
(BT) should be varied in the same pace with the revolution time since the
sampling rate of a digital oscilloscope is usually fixed. And this can be done
by pre-determining the relationship between the RF frequency and the time in a
cycle via the curve fit.
