Abstract Accurate frequency measurement at low frequencies remains a persistent challenge in many technical domains. While classical methods such as zero-crossing detection perform adequately at higher frequencies, observational studies have shown that these methods exhibit increasing instability and systematic deviation as frequencies decrease. These deviations are primarily linked to discretization, quantization effects, finite observation windows, and implicit reset behavior at signal crossings. This publication presents a measurement instrument concept specifically designed for low-frequency signal analysis. The proposed instrument does not replace existing frequency meters, but instead complements them by providing a diagnostic measurement layer that exposes deviations and instabilities that remain hidden in classical approaches. The concept is derived from previously published observational results and focuses on measurement behavior rather than theoretical reformulation. The proposed instrument treats frequency as a continuous directional process over time, allowing local deviations, drift, and asymmetry to be observed directly instead of being averaged out. By preserving continuity across measurement windows, the instrument avoids artificial resets that occur in classical zero-crossing-based estimators, particularly in low-frequency regimes. The instrument concept is intended as a practical measurement tool rather than a theoretical model. It is designed to operate alongside conventional frequency estimation techniques, offering additional insight into signal behavior at frequencies typically ranging from standard grid frequencies (50–60 Hz) down to very low-frequency domains. The framework is reproducible and implementation-agnostic, allowing independent evaluation across different platforms and datasets. Potential application areas include power grid monitoring, electromechanical systems, vibration analysis, long-period oscillations, and other domains where low-frequency measurement accuracy is critical. This work aims to provide a structured measurement proposal that enables engineers and researchers to observe and quantify low-frequency measurement artifacts more transparently.
Eddy De Neve (Sat,) studied this question.