Background:Aiming at precise beam position measurement of next generation FEL facility

Shanghai institute of applied physics developed 5712 MHz high Q CBPM prototype.Purpose:ADC bits and data length of data acquisition system are key parameters influencing spatial resolution of CBPM.In order to find the optimized configuration parameters

dedicated beam experiments and corresponding Monte Carlo simulations were used to solve the problems.Methods:The position calibration factors of CBPM prototype have been obtained through beam based calibration experiment at the Shanghai deep ultraviolet FEL facility.The dependence between system spatial resolution and ADC bits and the data length have been simulated with the measured position calibration factors by using Monte Carlo method.Results:Equipped with 14bits or better ADCs IF sampling technique is capable to achieve submicron position resolution

which is the optimal choice for CBPM on-line data acquisition system. Applying FFT signal processing algorithm

optimal data lengths in RF and IF sampling techniques were respectively 8192 and 256 points.Conclusions:RF sampling technique is hard to accomplish precise measurement of submicron level due to limited bits of present ultra- high-speed ADC

but suitable for plug & play prototype parameter test and evaluation.