Multi-Rate DSP/FPGA-Based Real-Time Acquisition and Control on the ISTTOK Tokamak

Data acquisition on the ISTTOK tokamak is being upgraded from VME to PCI using a general purpose especially developed transient recorder PCI acquisition board with 8 galvanic isolated 14 bit, 2 MSamples/sec channels, 512 Mbytes of SDRAM, and integrated FPGA/DSP capabilities. Due to the wide range of ISTTOK signal spectrum, data-reduction is crucial to efficiently use data retrieval and analysis systems. To avoid long latency offline processing and also to allow real-time control implemented in the DSP, multi-rate real time decimation in the FPGA has been implemented. This paper describes the data processing techniques developed using either FIR or cascaded-integrator-comb CIC filters. A digital DC baseline restorer was also implemented in the FPGA.