Method in which lock-in detectors process signals from standard ac susceptometers, particularly in the detection of higher harmonics, is analyzed in details. The exact formulas have been derived and checked experimentally by measurements on soft ferromagnetic sample, using several available lock-in amplifiers. The reasons why the proper phase adjustment has to be implemented in the protocol of ...

Lock-in amplifier (LIA) is the most important and essential instrument in signal recovery in the presence of large amount of noise. In this paper an indigenously designed microcontroller based advanced lock-in amplifier is proposed. The lock-in detection is done by quadrature sampling method. It is designed to work for the frequency range of 10Hz to 100kHz. The microcontroller based lock-in amp...

None of the conventionally displayed images of lock-in thermography (in-phase or 0° image, out of phase or -90° image, amplitude image, phase image) is able to become inverted in the presence of emissivity contrast. The phase signal is inherently emissivity-corrected, but here contributions of different heat sources superimpose very nonlinearly, which prevents any meaningful deconvolution. It i...

We consider the problem of nonlinear filtering of one-dimensional diffusions from noisy measurements. The filter is said to lose lock if the estimation error exits a prescribed region. In the case of phase estimation this region is one period of the phase measurement function, e.g., [−π, π]. We show that in the limit of small noise the causal filter that maximizes the mean time to loose lock is...

In this article we will show that the phase-pock equations of Superconductivity have backward uniqueness. Backward uniqueness guarantees that the semi group generated by the solutions of phase-lock equations is injective, which plays an important role in understanding the long time dynamic properties of the solutions. INTRODUCTION In the previous article [1-3], we proposed the following phase-l...

Phase-lock loops (PLLs) have been one of the basic building blocks in modern electronic systems. They have been widely used in communications, multimedia and many other applications. The theory and mathematical models used to describe PLLs come in two types: linear and non-linear. Non-linear theory is often complicated and difficult to deal with in real-world designs. Analog PLLs have been well...

OBJECTIVES The purpose of this study was to explore the relationship between EEG phase reset and performance on the Wechsler Intelligence test. METHODS The electroencephalogram (EEG) was recorded from 19 scalp locations from 378 subjects ranging in age from 5 years to 17.6 years. The Wechsler Intelligence test (WISC-R) was administered to the same subjects on the same day but not while the EE...

In this study we explore how music can entrain human walkers to synchronise to the musical beat without being instructed to do so. For this, we use an interactive music player, called D-Jogger, that senses the user's walking tempo and phase. D-Jogger aligns the music by manipulating the timing difference between beats and footfalls. Experiments are reported that led to the development and optim...