A novel comb compensator with a good passband deviation-complexity tradeoff
This paper presents a novel simple multiplierless comb compensator which exhibits a good tradeoff between the resulting passband droop compensation and introduced complexity. The filter is composed of two second order sections, both working at the lowest rate, and with sine squared magnitude characteristics. The first section remains the same for all comb parameters. The second section depends only on the number of the cascaded comb filters. A simple formula which relates compensator parameter and the number of cascaded combs, is derived. The comparisons with some known compensators are also provided in order to demonstrate the benefit of the proposed compensator.
Simple multiplierless CIC compensators providing minimum passband deviation
A simple multiplierless decimation filter is cascaded-integrator-comb (CIC) filter. However, the CIC filter offering high folding-band attenuations introduces a high passband droop. The most popular technique for reducing the droop is connecting a low-order FIR filter called compensator in cascade with CIC filter. In this paper, we present a method for the design of simple multiplierless compensators based on the minimization of the peak-to-peak passband deviation. We form a simple design problem by representing each compensator coefficient as only one signed power of two. The optimum coefficients are found by using the exhaustive search. We show that the proposed compensators with three and five coefficients significantly reduce the droop in wide passbands despite their extremely simple structures, which contain only two and four adders, respectively.
High‐precision U‐Pb zircon age calibration of the global Carboniferous time scale and Milankovitch band cyclicity in the Donets Basin, eastern Ukraine
High‐precision ID‐TIMS U‐Pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic, cyclostratigraphic, and biostratigraphic framework of the Carboniferous Donets Basin of eastern Europe. Chemical abrasion of zircons, use of the internationally calibrated EARTHTIME mixed U‐Pb isotope dilution tracer, and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of <0.05%, or ∼100 ka, for these Carboniferous volcanics. This precision allows the resolution of time in the Milankovitch band and confirms the long‐standing hypothesis that individual high‐frequency Pennsylvanian cyclothems and bundles of cyclothems into fourth‐order sequences are the eustatic response to orbital eccentricity (∼100 and 400 ka) forcing. Tuning of the fourth‐order sequences in the Donets Basin to the long‐period eccentricity cycle results in a continuous age model for the Middle to Late Pennsylvanian (Moscovian‐Kasimovian‐Ghzelian) strata of the basin and their record of biological and climatic changes through the latter portion of the late Paleozoic Ice Age. Detailed fusulinid and conodont zonations allow the export of this age model to sections throughout Euramerica. Additional ages for Mississippian strata provide among the first robust radiometric calibration points within this subperiod and result in variable lowering of the base ages of its constituent stages compared to recent global time scale compilations.