Dynamic Range Enhancement Research Articles

Dynamic range enhancements in radio receivers by means of frequency retranslation

In this study, a receiver architecture is presented that may be used for linearisation or for large signal interference suppression. In linearisation mode, an error signal that consists of intermodulation distortion products is obtained and used for predistorting the receiver. Experimental results demonstrate >;16 dB improvement of third-order input intercept point when used in a superheterodyne topology. When used in a direct conversion receiver topology, 7-dB improvement of second-order input intercept point is obtained. In interference suppression mode, an error signal that consists of high-level interferers spectrally close to a small wanted signal is obtained and used for predistorting the receiver. Experimental results demonstrate 14-dB enhancement of spurious-free dynamic range of the receiver.

Selective recognition of arsenic by tailoring ion-imprinted polymer for ICP-MS quantification

A novel arsenic-ion imprinted polymer (As-IIP) was firstly synthesized for the separation and recovery of trace elemental As from environmental water samples. Polymers prepared from bifunctional monomers with intrinsic metal-binding capability are a platform for tailoring ion-selectivity via imprinting moiety–template interaction, without complex formation and ligand immobilization. In the present study, As-IIPs based on 1-vinylimidazole, 4-vinylpyridine and styrene were designed to investigate the imprinting mechanism in relation to their structural and functional properties. In terms of selectivity as well as imprinting effects compared with the non-imprinted polymer (NIP), 1-vinylimidazole-based As-IIP exhibited superior analyte recognition for As ion among 23 competing elements, with a 25-fold enhancement in the practical dynamic and static adsorption capacity range (0.048–4.925μmolg−1). The robust As-IIP sorbent features good reusability up to 20 cycles and a wide working pH 5–7 for a firstly reported solid-phase extraction (SPE) application. As a result of selective sample clean-up, As-IIP-SPE offered limits of detection (LOD) and quantification (LOQ) down to 0.025 and 0.083μmolL−1, respectively, for environmental sample analysis using inductively coupled plasma-mass spectrometry.

Timing Mismatch Compensation in Time-Interleaved ADCs Based on Multichannel Lagrange Polynomial Interpolation

In this paper, the timing mismatch compensation problem in the implementation of a time-interleaved analog-to-digital converter (TIADC) is investigated. The investigation leads to a novel multichannel Lagrange polynomial interpolation timing-mismatch compensation algorithm (MLPI-TMCA). A multichannel Lagrange compensation filter (MLCF) in the form of a finite-impulse response (FIR) filter is also developed for real-time implementation. The design of the compensation system is done in three steps. First, the coefficients of the MLCF are computed based on the mismatch parameters of the TIADC. Second, an Nth order FIR filtering process is performed for each sub-ADC. Third, a multiplexer is used to combine the output of each compensation filter in an orderly manner into the final compensated output signal. The computational complexity of this timing mismatch compensation system is of order N. Computer simulation results showed that MLPI-TMCA is computationally efficient and not sensitive to timing mismatch fluctuations. The actual implementation of a four-channel 320-MHz 12-bit TIADC showed that the MLPI-TMCA is able to efficiently compensate the timing mismatch in a real-time manner and produced about 30-dB spurious-free dynamic range (SFDR) enhancement when the input signal frequency is 70 MHz, whereas the multirate filter banks compensation method produced about 19 dB of SFDR enhancement under the same condition. Thus, the MLPI-TMCA and its multichannel filter implementation provides a good solution for TIADC real-time timing mismatch compensation and may be employed in TIADC chip design due to its implementation advantages.

Accurate mass 및 isotope ratio 측정을 위한 GC-TOF 질량분석기에서의 화학적 이온화방법

An accurate mass and isotope ratio were determined using a gas chromatography/time of flight mass spectrometer in CI positive mode for the identification of unknown metabolites. High mass tune was used to improve the ion intensity of . Chromatographic resolution and dynamic range enhancement were performed to obtain more reliable accurate masses and correct isotope abundance ratios. Average absolute errors of mass and isotope ratios for 24 reference metabolite -TMS (trimethylsilyl) derivatives were 6.8 ppm, 1.5% of (M+1/M ratio) and 1.7% of (M+2/M ratio), respectively. The correct formulas of twenty one compound were retrieved within top-2 hit from the heuristic algorithm for elemental composition using each accurate mass and isotope abundance ratio.

Targeted in Vivo O-GlcNAc Sensors Reveal Discrete Compartment-specific Dynamics during Signal Transduction

β-O-N-acetyl-D-glucosamine (O-GlcNAc) is a post-translational modification involved in a plethora of biological systems ranging from cellular stress to insulin signaling. This modification shares many hallmarks with phosphorylation, including its dynamic cycling onto a host of proteins such as transcription factors, kinases, and phosphatases, and regulation of cellular functions, including cell signaling. Herein, we report the development of an improved genetically based O-GlcNAc FRET sensor and compartmentalized targeted variants for the characterization of the spatiotemporal dynamics of O-GlcNAc. During serum-stimulated signal transduction, rapid increases in O-GlcNAc activity were observed at both the plasma membrane and the nucleus, with a concomitant decrease detected in the cytoplasm. These findings suggest the existence of compartment specific dynamics for O-GlcNAc in response to signal-inducing stimuli, pointing to complex regulation of this modification. In addition, inhibition of the PI3K pathway by wortmannin abolished the O-GlcNAc response, suggesting that the activity observed is modulated downstream of the PI3K pathway. Taken together, our data argues that O-GlcNAc is a rapidly induced component of signaling and that the interplay between O-GlcNAc and kinase signaling may be more akin to the complex relationship between kinase pathways.

PIM-linearity improvement by the size of a diode mounting hole

A new method for the dynamic range enhancement of the PIM-producing patch antenna with diode is proposed, and its effectiveness is verified by experiment. In 2GHz-band experiment, we shows that the size reduction of the diode-mounted hole has an equivalent effect of the diode-rotation in the previous work, and contributes to the linearity improvement in the high power excitation. Through the testing result of 800MHz-band antenna, it is demonstrated that good linearity is obtained up to 43dBm excitation in swept-power test when Dh=4.6mm. The frequency characteristics of the employed diode are also verified through a frequency-swept test. The resultant PIM-level variation is less than 2dB, which is negligibly small in comparison with the difference between 800MHz- and 2GHz-antennas.

A Microcontroller-Based IR Range Finder System With Dynamic Range Enhancement

The present paper describes the development of a microcontroller-based infrared (IR) range finder system, employing two IR light-emitting diodes (LEDs) and an IR sensor. The system employs a software array-based approach where both the burst frequency of IR energy transmitted by the IR LEDs and the duration of this energy transmission in one sweep are progressively reduced, in a bid to increase the possibility of sensing the IR energy reflected back from the object. The proposed system can perform dynamic range enhancement, by utilizing an intelligent scheme, where, the output from the IR sensor system is used as a feedback to adaptively switch one of the IR LEDs. Experimental studies confirm that our developed system can indeed implement dynamic range enhancement, when compared to a conventional IR range finder system.

Enhancement of Input Power Dynamic Range for Multiwavelength Amplification and Optical Signal Processing in a Semiconductor Optical Amplifier Using Holding Beam Effect

We demonstrate a considerable enhancement of input power dynamic range (IPDR) for multiwavelength amplification and optical signal processing in a semiconductor optical amplifier (SOA) by using holding beam effect. The effect is used in SOA gain region at power level well below 10 dBm, which is much smaller than the required power as the setting at transparency wavelength. The IPDR is extended not only to high power range due to the reduction of nonlinear crosstalks, but also to low power range due to the compression of amplified spontaneous emission (ASE) noise. The technique is first applied to the amplification of wavelength-division multiplexed (WDM) channels using a continuous wave (CW) holding beam. The holding beam is particularly useful for the amplification of large number of channels thanks to the suppression effect of interactions among WDM channels. It is then carried out for one of extensively-used optical processing schemes, terahertz optical asymmetric demultiplexer (TOAD), for multiwavelength data format conversion without the need of an external CW light. The IPDR of TOAD reaches over 20 dB as control clock behaves simultaneously as the holding beam. We also present that the patterning effect and the impact of ASE noise on the converted signal are strongly dependent on the TOAD's switching window, which is optimized at 40% duty ratio for the largest IPDR.

Using Gas Chromatography with Ion Mobility Spectrometry to Resolve Explosive Compounds in the Presence of Interferents*

Ion mobility spectrometry (IMS) is a valued field detection technology because of its speed and high sensitivity, but IMS cannot easily resolve analytes of interest within mixtures. Coupling gas chromatography (GC) to IMS adds a separation capability to resolve complex matrices. A GC-IONSCAN® operated in IMS and GC⁄ IMS modes was evaluated with combinations of five explosives and four interferents. In 100 explosive/interferent combinations, IMS yielded 21 false positives while GC⁄ IMS substantially reduced the occurrence of false positives to one. In addition, the results indicate that through redesign or modification of the preconcentrator there would be significant advantages to using GC⁄ IMS, such as enhancement of the linear dynamic range (LDR) in some situations. By balancing sensitivity with LDR, GC⁄ IMS could prove to be a very advantageous tool when addressing real world complex mixture situations.

Dynamic range enhancement of nonlinear nanomechanical resonant cantilevers for highly sensitive NEMS gas/mass sensor applications

This paper describes a comprehensive nonlinear multiphysics model based on the Euler–Bernoulli equation that remains valid up to large displacements in the case of electrostatically actuated nanocantilevers. This purely analytical model takes into account the fringing field effects which are significant for thin resonators. Analytical simulations show very good agreement with experimental electrical measurements of silicon nanodevices using wafer-scale nanostencil lithography (nSL), monolithically integrated with CMOS circuits. Close-form expressions of the critical amplitude are provided in order to compare the dynamic ranges of NEMS cantilevers and doubly clamped beams. This model allows designers to cancel out nonlinearities by tuning some design parameters and thus gives the possibility of driving the cantilever beyond its critical amplitude. Consequently, the sensor performance can be enhanced by being optimally driven at very large amplitude, while maintaining linear behavior.

A Computational Study on the Role of Gap Junctions and Rod Ih Conductance in the Enhancement of the Dynamic Range of the Retina

Recent works suggest that one of the roles of gap junctions in sensory systems is to enhance their dynamic range by avoiding early saturation in the first processing stages. In this work, we use a minimal conductance-based model of the ON rod pathways in the vertebrate retina to study the effects of electrical synaptic coupling via gap junctions among rods and among AII amacrine cells on the dynamic range of the retina. The model is also used to study the effects of the maximum conductance of rod hyperpolarization activated current Ih on the dynamic range of the retina, allowing a study of the interrelations between this intrinsic membrane parameter with those two retina connectivity characteristics. Our results show that for realistic values of Ih conductance the dynamic range is enhanced by rod-rod coupling, and that AII-AII coupling is less relevant to dynamic range amplification in comparison with receptor coupling. Furthermore, a plot of the retina output response versus input intensity for the optimal parameter configuration is well fitted by a power law with exponent . The results are consistent with predictions of more theoretical works and suggest that the earliest expression of gap junctions along the rod pathways, together with appropriate values of rod Ih conductance, has the highest impact on vertebrate retina dynamic range enhancement.

High dynamic range colour imaging using complementary metal-oxide-semiconductor (CMOS) sensors with non-destructive readout

We present a novel colour reconstruction approach for a high dynamic range camera based on a CMOS sensor with non-destructive readout. The output of such a sensor consists of a sequence of noisy mosaic images that can be combined to create a colour image having a high dynamic range. We show that intuitive sequential processing, where dynamic range enhancement is followed by conventional demosaicing, is prone to introduce extra errors due to ‘stepped gradient’ artefacts and residual system noise. We propose an alternative joint reconstruction algorithm that utilizes all available data to improve the quality of the resulting full colour image. Conventional colour reconstruction quality evaluation, camera noise tests and visual observations show that the proposed method does not produce ‘stepped gradient’ artefacts and generally outperforms a sequential approach based on traditional demosaicing routines for a wide range of system noise values. It also provides a steady increase in dynamic range when the number of non-destructive samples grows.

Active Dendrites Enhance Neuronal Dynamic Range

Since the first experimental evidences of active conductances in dendrites, most neurons have been shown to exhibit dendritic excitability through the expression of a variety of voltage-gated ion channels. However, despite experimental and theoretical efforts undertaken in the past decades, the role of this excitability for some kind of dendritic computation has remained elusive. Here we show that, owing to very general properties of excitable media, the average output of a model of an active dendritic tree is a highly non-linear function of its afferent rate, attaining extremely large dynamic ranges (above 50 dB). Moreover, the model yields double-sigmoid response functions as experimentally observed in retinal ganglion cells. We claim that enhancement of dynamic range is the primary functional role of active dendritic conductances. We predict that neurons with larger dendritic trees should have larger dynamic range and that blocking of active conductances should lead to a decrease in dynamic range.

Analysis and Design of a Robust Floating Point CMOS Image Sensor

A robust floating point CMOS image sensor (CIS) is designed and tested. A detailed analysis for signal-to-noise ratio (SNR) of the floating point CIS including the effect of the exponent detection error is presented. Based on the analysis, a simple way to effectively remove the optimum integration time detection error is proposed. In addition, the proposed imager obtains the exponent at the beginning of the image capturing cycle, which provides a logarithmic image of the scene. A 32 times 24 prototype sensor including 4 transistors pixel array, 4 bit static random access memory (SRAM) array, 8 bit ADC and CDS block, and integration time control block was designed and fabricated using standard 0.5 mum CMOS process. It achieved 50.5 dB of dynamic range (DR) enhancement with 32 dB of peak SNR at 30 frames/s.

Theoretical investigation of the input power dynamic range enhancement of XPM wavelength converter using a CW holding beam

The performance of pre-amplified cross-phase modulation (XPM) wavelength converter with a continuous wave (CW) holding beam has been theoretically investigated. To increase the input power dynamic range of the pre-amplified XPM wavelength converter, we apply a CW holding beam to the pre-amplifier of XPM wavelength converter. In our proposed scheme, the input power dynamic range with negative power penalty of 20dB was obtained.

Applications of digital micro-mirror devices to digital optical microscope dynamic range enhancement

In this paper, we present a method of using digital micro-mirror devices to dynamic range enhancement of a digital optical microscope images. Our adaptive feedback illumination control generates a high dynamic range image through an algorithm that combines the DMD-to-camera pixel geometrical mapping and a feedback operation. The feedback process automatically generates an illumination pattern in an iterative fashion that spatially modulates the DMD array elements on pixel-by-pixel level. Via experiment, we demonstrate a system that uses precise DMD control of the projector to enhance the dynamic range ideally by a factor of 573. Results are presented showing approximately 5 times the camera dynamic range, enabling visualization over a wide range of specimen characteristics.

Pre-binding dynamic range and sensitivity enhancement for immuno-sensors using nanofluidic preconcentrator

Almost all immuno-biosensors are inherently limited by the quality of antibodies available for the target molecule, and obtaining a highly sensitive antibody for a given target molecule is a challenge. We describe a highly efficient and flexible way to enhance immunoassay detection sensitivity and binding kinetics using a nanofluidic based electrokinetic preconcentrator. The device is a microfluidic integration of charge-based biomolecule concentrator and a bead-based immunoassay. Because the preconcentrator can increase the local biomolecule concentration by many orders of magnitude, it gives the immuno-sensor better sensitivity and faster binding kinetics. With a 30 min preconcentration, we were able to enhance the immunoassay sensitivity (with molecular background) by more than 500 fold from higher 50 pM to the sub 100 fM range. Moreover, by adjusting the preconcentration time, we can switch the detection range of the given bead-based assay (from 10-10 000 ng ml(-1) to 0.01-10 000 ng ml(-1)) to have a broader dynamic range of detection. As the system can enhance both detection sensitivity and dynamic range, it can be used to address the most critical detection issues in the detection of common disease biomarkers.

Dynamic-Range Enhancement and Linearization in Electrooptically Modulated Coherent Optical Links

We present a general analysis of various electrooptic-modulation configurations on the system performance of a coherent analog optical link. We evaluate the dependence of the modulation scheme of the optical modulator and its properties on the system dynamic range and linearity. Linearization of a coherent optical link based on extending the length of a directional-coupler modulator is also described, illustrating the unique considerations when linearizing a coherent link. System-level modeling of an analog coherent optical link under different modulation configurations is presented.

Averaging of Replicated Pulses for Enhanced-Dynamic-Range Single-Shot Measurement of Nanosecond Optical Pulses

Measuring optical pulse shapes beyond the dynamic range of oscilloscopes is achieved by temporal pulse stacking in a low-loss, passive, fiber-optic network. Optical pulses are averaged with their time-delayed replicas without introducing additional noise or jitter, allowing for high-contrast pulse-shape measurements of single-shot events. A dynamic-range enhancement of 3 bits is experimentally demonstrated and compared with conventional multishot averaging. This technique can be extended to yield an increase of up to 7 bits of additional dynamic range over nominal oscilloscope performance.

Quantification and screening of pesticide residues in food by gas chromatography–exact mass time-of-flight mass spectrometry

A gas chromatography–exact mass time-of-flight mass spectrometry (GC–TOF-MS) method has been developed for the quantification of approximately one hundred pesticides in baby food, pear and lettuce samples. Prior to analysis, co-extractives were removed from acetonitrile:toluene (80:20) extracts using dispersive solid-phase extraction with primary secondary amine (50mg) and carbon sorbent (50mg). The concentration of pesticides in the extracts was measured using an extracted mass chromatogram window of 0.05Th. Samples spiked with pesticides at 0.01 and 0.1mgkg−1 yielded average recoveries in the range of 70–109% with relative standard deviations less than 26% and displayed good linearity for the majority of the analytes. The method was applied to the screening of pear and lettuce samples for pesticide residues. Targeted quantification and exact mass peak detection, deconvolution and library searching packages were used successfully to detect and identify incurred residues present in the samples at concentrations above 0.01mgkg−1. The new feature dynamic range enhancement, improved mass accuracy, and hence detection and quantification of the analytes across the concentration range studied.