with real-time change of rate capability, were implemented on a
field programmable gate array. The interpolator main building
blocks are a cascaded integrator-comb (CIC) filter and the respective
compensation filter. The latter performs a fixed rate change of
4 and was implemented as a 129 taps finite impulse response (FIR)
filter. The FIR filter coefficients were attained from theMATLAB®
simulation, based on the inverse sinc(x) function. The CIC was
designed to have six stages ( ), a differential delay ( ) of 1, and
a variable rate change factor ( ) ranging from 10 up to 10 000.
Each interpolator over-samples the multiple data rate digital
signals stored at the Joint European Torus (JET) pulse database to
a fixed sampling rate of 40 MSPS. These signals are subsequently
converted to the analog domain by 16 bit digital-to-analog converters
to be used as stimulus for testing real-time control tools
and systems at JET.