The Development of BPM Signal Processor at SSRF

Abstract [Background]:The Beam Position Monitor (BPM) signal processor is essential for achieving low emittance and high brightness in synchrotron radiation sources. To meet the upgrade demands of the Shanghai Synchrotron Radiation Facility (SSRF) after 15 years of operation, a next-generation digital BPM signal processor has been developed.[Purpose]:This study aims to develop and evaluate a next-generation digital BPM signal processor with improved performance, drift compensation, and resolution for the SSRF storage ring.[Methods]:The new generation processor was designed with several key enhancements. First, it adopts a high-performance Field-Programmable Gate Array(FPGA)-based system-on-chip (SoC), optimizes the RF signal processing chain, and integrates a timing interface and pilot module. Second, slow drift compensation techniques, including crosser switching and pilot tone compensation, were implemented with corresponding digital signal processing algorithms in the FPGA. Finally, the processor's performance was assessed through laboratory tests and beam experiments at the SSRF storage ring.[Results]:Laboratory tests showed a turn-by-turn(TBT) position resolution of 290 nm and a fast acquisition(FA) resolution of 85 nm. Beam tests at the SSRF storage ring achieved a closed-orbit resolution of 100 nm with crosser switching compensation and 30 nm with pilot tone compensation. The implementation of slow drift compensation significantly improved the position resolution of the BPM processor. [Conclusions]:The new BPM processor meets and exceeds SSRF’s operational requirements. Long-term stability tests confirmed a closed-orbit resolution below 50 nm with pilot tone compensation, providing a solid foundation for future BPM system upgrades and ensuring high-precision beam position monitoring.