Speaker
Description
A read-out system, comprising a local oscillator (LO) and down-conversion electronics [1], was developed to process the signals from a cavity beam-position monitor (cBPM) installed at the end of the Accelerator Test Facility (ATF) linac at KEK, Japan. The cBPM [2] operates with a dipole mode signal centered at 1.725 GHz, which must be down-converted to a lower frequency suitable for digital processing via an embedded ADC in FPGA. Preliminary test carried at ATF were performed by measuring the down-converted waveforms with an 2GS/s oscilloscope.
A local oscillator with frequency 1.875 GHz was synthesized with an n-fractional PLL [3] from the 10 MHz reference signal of ATF in order to obtain an intermediate frequency (IF) of 150 MHz. Minor changes were made in LO Signal configuration to achieve proper synchronization between the LO and RF signals, which enables to get a good consistency of measurements and high resolution of the BPM system. Future work will focus on full digitization of the signal in a custom programmed FPGA
embedded system with a high speed ADC.
[1] O. Friar, A. Lyapin, Building, Optimizing and Measuring the Performance of Downconverting Electronics Using X Microwave Modules, PH4100 Major Project Report, RHUL (2022).
[2] C. Simon et al., Performance of a Reentrant Cavity Beam Position Monitor, Phys. Rev. ST Accel. Beams, 11, 082802 (2008).
[3] Texas Instruments, LMX2592EVM Evaluation Module (EVM) User’s Guide, SN AU195, December 2015. [Online]. Available: https://www.ti.com/lit/ug/snau195/snau195.pdf?ts=1752555860184
