Logratio circuit and low frequency feedback system

During the past year, several measures have been tried to improve the stability of injected beam at HLS (Hefei Light Source), which has newly upgraded its injection system. To overcome the evident residual betatron oscillation, one specific betatronoscillation suppressor circuitry is accomplished to take it under control. Means to excite and damp beam motions has been suggested, as well as a PLL circuit in plan to track the variation of tune under various machine states. In addition, works as improving the performance of early version of turnbyturn system and rebuilding the software kit to make it a reliable instrumentation for beam nonlinear dynamics study and machine state monitoring.