Fermilab booster low level RF system upgrades

Status of and plans for upgrades to the aging Booster Low Level RF phase and frequency control system are described. The central feature of the new system is replacement of the existing analog voltage controlled oscillator (VCO) with a direct digital synthesizer (DDS) operating directly at the Booster 37-53 Mhz frequency. This eliminates historically chronic problems with VCO frequency drift and setting inaccuracies. Initial implementation consists of the DDS operating under digital signal processor (DSP) control to generate the open loop frequency sweep profile and to close the beam phase-locked frequency loop. Further iterations will bring synchronous phase control, RF station counter-phasing operations at injection and extraction times, and the Booster to Main Ring beam transfer synchronization and phase-lock process under precise and programmable digital control. These improvements will facilitate and provide the enhanced flexibility for features, including new transfer synchronization options, expected to be necessary for continued high intensity operation from now into the Fermilab Main Injector era