Recently many accelerator parameters are measured by using the digital technology.A data acquisition circuit board adopting software radio technology has been developed.With this circuit board and RF front-end produced i-tech company one can comprise the BPM system.A bunch length monitor composed of the circuit board,power splitter, mix,and band filter has been examined for the bunch length measurement of HLS.The data acquisition circuit board can be further improved,for example,the Ethernet can substitute VME;direct high frequency sampling can substitute medium frequency sampling;using large FPGA.Those will further improve the performance of the data acquisition system,and be the goal of developing this system in the future.
