Dynamic range

About: Dynamic range is a research topic. Over the lifetime, 7576 publications have been published within this topic receiving 101739 citations. The topic is also known as: DNR & DR.

A novel automatic digital quasi-peak detector for a time domain measurement system

Abstract: An advanced ultra-fast broadband time domain EMI (TDEMI) measurement system is presented Measurements were performed in the 30-1000 MHz range Using digital signal processing for spectral estimation and detection, the measurement time is reduced by a factor of 10 in comparison to a conventional EMI receiver A novel recording routine for TDEMI measurement and digital signal processing for proper quasi-peak detection is described Different amplitude resolutions are selected during the recording to enhance the dynamic range by about 50 dB Measurement results are compared with the results obtained with a conventional EMI receiver

Digital broadband linearization of optical links.

Abstract: We present a digital postprocessing linearization technique to efficiently suppress dynamic distortions added to a wideband signal in an analog optical link. Our technique achieves up to 35 dB suppression of intermodulation distortions over multiple octaves of signal bandwidth. In contrast to conventional linearization methods, it does not require excessive analog bandwidth for performing digital correction. This is made possible by regenerating undesired distortions from the captured output, and subtracting it from the distorted digitized signal. Moreover, we experimentally demonstrate a record spurious-free dynamic range of 120 dB·Hz2/3 over a 6 GHz electrical signal bandwidth. While our digital broadband linearization technique advances state-of-the-art optical links, it can also be applied to other nonlinear dynamic systems.

Active control of the volume acquisition noise in functional magnetic resonance imaging: Method and psychoacoustical evaluation

Abstract: Functional magnetic resonance imaging (fMRI) provides a noninvasive tool for observing correlates of neural activity in the brain while a subject listens to sound. However, intense acoustic noise is generated in the process of capturing MR images. This noise stimulates the auditory nervous system, limiting the dynamic range available for displaying stimulus-driven activity. The noise is potentially damaging to hearing and is distracting for the subject. In an active noise control (ANC) system, a reference sample of a noise is processed to form a sound which adds destructively with the noise at the listener's ear. We describe an implementation of ANC in the electromagnetically hostile and physically compact MRI scanning environment. First, a prototype system was evaluated psychoacoustically in the laboratory, using the electrical drive to a noise-generating loudspeaker as the reference. This system produced 10-20 dB of subjective noise-reduction between 250 Hz and 1 kHz, and smaller amounts at higher frequencies. The system was modified to operate in a real MR scanner where the reference was obtained by recording the acoustic scanner noise. Objective reduction by 30-40 dB of the most intense component in scanner noises was realized between 500 Hz and 3500 Hz, and subjective reduction of 12 dB and 5 dB in tests at frequencies of 600 Hz and at 1.9 kHz, respectively. Although the benefit of ANC is limited by transmission paths to the cochlea other than air-conduction routes from the auditory meatus, ANC achieves worthwhile attenuation even in the frequency range of maximum bone conduction (1.5-2 kHz). ANC should, therefore, be generally useful during auditory fMRI.

Sensitive, highly linear lithium niobate interferometers for electromagnetic field sensing

Abstract: An asymmetric Mach–Zehnder interferometer in Ti:LiNbO3 has been demonstrated to have a 84 dB linear dynamic range and 1.1 μV sensitivity, for a 3 kHz detection bandwidth and a 50 Ω resistance, at the 1.3 μm wavelength. This device is useful for electric and magnetic field sensing. Optimum linearity is achieved with a 90° intrinsic phase bias. The dependence of dynamic range and sensitivity on optical power, phase bias, and modulation voltage is reported. The reasons for, and magnitudes of, deviations from optimum linear behavior are described for many fabricated interferometers.

A 0.7-V 870-μW Digital-Audio CMOS Sigma-Delta Modulator

Abstract: This paper introduces a power-efficient, chopper-stabilized switched-capacitor sigma-delta (ΣΔ) modulator that combines delayed input feedforward and single-comparator tracking multi-bit quantization to achieve high-precision, low-voltage analog-to-digital (A/D) conversion. An experimental prototype of the proposed architecture has been integrated in a 0.18-μm CMOS technology. The prototype operates from a 0.7-V supply voltage with a sampling rate of 5 MSamples/sec and consumes only 870 μW of total power. The converter achieves a dynamic range of 100 dB, a peak signal-to-noise ratio (SNR) of 100 dB and a peak signal-to-noise and distortion ratio (SNDR) of 95 dB for a 25-kHz signal bandwidth.