Noise reduction

Filter banks with fixed time-frequency resolution, such as the Short-Time Fourier Transform (STFT), are a common tool for many audio analysis and processing applications allowing effective implementation via the Fast Fourier Transform (FFT). The fixed time-frequency resolution of the STFT can lead to the undesirable smearing of events in both time and frequency. In this paper, we suggest adaptively varying STFT time-frequency resolution in order to reduce filter bank-specific artifacts while retaining adequate frequency resolution. Several strategies for systematic adaptation of time-frequency resolution are proposed. The introduced approach is demonstrated as applied to spectrogram displays, noise reduction, and spectral effects processing.

In order to perform on-line measuring and detection of PD signals, a total solution composing of an HFCT, A/D converter and a complete software package is proposed. The software package includes compensation of HFCT contribution, filtering and noise reduction using wavelet transform and soft calibration routines. The results have shown good performance and high accuracy.

The technical procedure of noise reduction in material cutting by abrasive water-jet is described in this paper. The paper is aimed at the implementation of technical possibilities of noise reduction in the cutting of material by abrasive water-jet technology. Both the theoretical and ...

Capacitively-driven on-chip wires reduce both latency and energy compared to repeaters. A series coupling capacitance offers preemphasis to lower wire delay, reduces the driven load, and lowers the wire voltage swing without a second power supply. A 0.18mum CMOS testchip shows 10.5times energy savings at a 50mV swing compared to full-swing repeated wires, and a 3times gain in wire bandwidth

In order to measure the D structure of a number of objects a comparably new technique in computer vision exists, namely time of flight (TOF) cameras. The overall principle is rather easy and has been applied using sound or light for a long time in all kind of sonar and lidar systems. However in this approach one uses modulated light waves and receives the signals by a parallel pixel array structure. Out of the travelling time at each pixel one can estimate the depth structure of a distant object. The technique requires measuring the intensity differences and ratios of several pictures with extremely high accuracy; therefore one faces in practice rather high noise levels. Object features as reflectance and roughness influence the measurement results. This leads to partly high noise levels with variances dependent on the illumination and material parameters. It can be shown that a reciprocal relation between the variance of the phase and the squared amplitude of the signals exists. On...

We have developed a novel analog front-end part of a wireless brain oxymeter receiver instrument based on near-infrared spectroreflectometry (NIRS). The NIRS receiver makes use of dynamic threshold transistors (DTMOS) for low voltage (1–V), low power and low noise enhancement. The design is composed of a transimpedance amplifier (TIA) and an operational transconductance amplifier (OTA). The OTA differential input pairs are in a class AB configuration, and uses DTMOS devices for input common-mode range enhancement. Post-layout simulations under a 5 pF load, using 0.18 µm CMOS technology results are, for the OTA, an input referred noise of 134 nV/√Hz at 1 kHz, and a power consumption of 16.7 µW without any extra noise reduction technique. Also, the TIA gives 208 pA/√Hz at 1 kHz, while having a power consumption of only 10.9 µW. The proposed analog front-end circuits have been used to implement a NIRS receiver instrument with improved ultra low-light level measurements, high resolution...