PT Journal
AU Aliaga, RJ
TI Real-Time Estimation of Zero Crossings of Sampled Signals for Timing Using Cubic Spline Interpolation
SO IEEE Transactions on Nuclear Science
JI IEEE Trans. Nucl. Sci.
PY 2017
BP 2414
EP 2422
VL 64
IS 8
DI 10.1109/TNS.2017.2721103
LA English
DE Digital arithmetic; digital circuits; digital timing; field-programmable gate array (FPGA); interpolation; signal processing algorithms; splines time estimation; time resolution
AB A scheme is proposed for hardware estimation of the location of zero crossings of sampled signals with subsample resolution for timing applications, which consists of interpolating the signal with a cubic spline near the zero crossing and then finding the root of the resulting polynomial. An iterative algorithm based on the bisection method is presented that obtains one bit of the result per step and admits an efficient digital implementation using fixed-point representation. In particular, the root estimation iteration involves only two additions, and the initial values can be obtained from finite impulse response (FIR) filters with certain symmetry properties. It is shown that this allows online real-time estimation of timestamps in free-running sampling detector systems with improved accuracy with respect to the more common linear interpolation. The method is evaluated with simulations using ideal and real timing signals, and estimates are given for the resource usage and speed of its implementation.
ER