Dynamic range of bit-rate-independent pulse timing measurement technique

A variable-temperature homodyne reflectometry measurement technique for detecting nanoscale mechanical motion has recently been developed. We have extended this technique to make the first all-electrical measurements of an ensemble of as-grown, c-axis, single-crystal gallium nitride (GaN) nanowires. These nanowires are approximately 15 μm in length and 100 nm in diameter, and have fundamental resonance frequencies near 1 MHz, and mechanical quality factors, Q, (resonance frequency divided by resonance width) in excess of 104. These high-Q values are sensitive to surface conditions and offer the opportunity to study intrinsic damping mechanisms in the nanoscale resonators. The new microwave measurement technique has allowed us to study the ensemble behavior of nanowire resonances while varying extrinsic variables (e.g., temperature) and obtain statistics on nanowire resonance behavior. Our apparatus allows measurements to be made in either a two-phase lock-in mode, or in a power-spectrum mode, both of which have unique advantages. Our measurements demonstrate a position-spectral noise floor of 0.3 nm/ Hz, largely set by the dynamic range of our microwave readout system.

Download Full-text

Wideband chirp measurement technique for high bit rate sources

Electronics Letters ◽

10.1049/el:19940917 ◽

1994 ◽

Vol 30 (16) ◽

pp. 1336-1338 ◽

Cited By ~ 84

Author(s):

R.A. Saunders ◽

I. Hardcastle ◽

J.P. King

Keyword(s):

Measurement Technique ◽

Bit Rate ◽

High Bit Rate

Download Full-text

Analysis of Relative Intensity to Noise Ratio for Lasers at Different Bias Currents

International Journal of Electronics and Telecommunications ◽

10.2478/v10177-012-0035-1 ◽

2012 ◽

Vol 58 (3) ◽

pp. 255-259

Author(s):

Kamaljit Singh Bhatia ◽

Tara Singh Kamal

Keyword(s):

Relative Intensity ◽

Optical Transmission ◽

Dynamic Range ◽

Single Mode ◽

Bit Rate ◽

Optimal Value ◽

Spurious Free Dynamic Range ◽

Transmission Link ◽

High Bit Rate ◽

Free Dynamic

Abstract In this paper, we have carried out the simulative analysis for averaging out the optimal value of RIN for better performance in high bit rate optical transmission link. We have found that for single mode VCSEL, the bias of 2 mA has the highest Spurious Free Dynamic Range (SFDR) and low RIN. For multimode VCSEL, the bias of 6 mA has the highest SFDR and low RIN.

Download Full-text

Quantization of Weights of Neural Networks with Negligible Decreasing of Prediction Accuracy

Information Technology And Control ◽

10.5755/j01.itc.50.3.28468 ◽

2021 ◽

Vol 50 (3) ◽

pp. 558-569

Author(s):

Zoran Peric ◽

Bojan Denic ◽

Milan Savic ◽

Milan Dincic ◽

Darko Mihajlov

Keyword(s):

Neural Network ◽

Neural Networks ◽

Prediction Accuracy ◽

Network Performance ◽

Dynamic Range ◽

Mean Squared Error ◽

Real Data ◽

Quantization Noise ◽

Bit Rate ◽

The Impact

Quantization and compression of neural network parameters using the uniform scalar quantization is carried out in this paper. The attractiveness of the uniform scalar quantizer is reflected in a low complexity and relatively good performance, making it the most popular quantization model. We present a design approach for the memoryless Laplacian source with zero-mean and unit variance, which is based on iterative rule and uses the minimal mean-squared error distortion as a performance criterion. In addition, we derive closed-form expressions for SQNR (Signal to Quantization Noise Ratio) in a wide dynamic range of variance of input data. To show effectiveness on real data, the proposed quantizer is used to compress the weights of neural networks using bit rates from 9 to 16 bps (bits/sample) instead of standardly used 32 bps full precision bit rate. The impact of weights compression on the NN (neural network) performance is analyzed, indicating good matching with the theoretical results and showing negligible decreasing of the prediction accuracy of the NN even in the case of high variance-mismatch between the variance of NN weights and the variance used for the design of quantizer, if the value of the bit-rate is properly chosen according to the rule proposed in the paper.

Download Full-text

Slow-Scan CCD Observation of Backscattering Patterns in SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131176 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1308-1309

Author(s):

F. Ouyang ◽

D. A. Ray ◽

O. L. Krivanek

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Scanning Electron Microscope ◽

Dynamic Range ◽

High Sensitivity ◽

Lens System ◽

Wide Dynamic Range ◽

Peltier Cooler ◽

Diffraction Patterns ◽

Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

Download Full-text

Quantitative energy-filtered electron diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172693 ◽

1994 ◽

Vol 52 ◽

pp. 992-993

Author(s):

R. Vincent

Keyword(s):

Electron Diffraction ◽

Inelastic Scattering ◽

Dynamic Range ◽

Electron Optics ◽

Surface Layers ◽

High Brightness ◽

Inclined Surfaces ◽

Perfect Symmetry ◽

Amorphous Surface ◽

The Ideal

Microanalysis and diffraction on a sub-nanometre scale have become practical in modern TEMs due to the high brightness of field emission sources combined with the short mean free paths associated with both elastic and inelastic scattering of incident electrons by the specimen. However, development of electron diffraction as a quantitative discipline has been limited by the absence of any generalised theory for dynamical inelastic scattering. These problems have been simplified by recent innovations, principally the introduction of spectrometers such as the Gatan imaging filter (GIF) and the Zeiss omega filter, which remove the inelastic electrons, combined with annual improvements in the speed of computer workstations and the availability of solid-state detectors with high resolution, sensitivity and dynamic range.Comparison of experimental data with dynamical calculations imposes stringent requirements on the specimen and the electron optics, even when the inelastic component has been removed. For example, no experimental CBED pattern ever has perfect symmetry, departures from the ideal being attributable to residual strain, thickness averaging, inclined surfaces, incomplete cells and amorphous surface layers.

Download Full-text

Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155311 ◽

1989 ◽

Vol 47 ◽

pp. 668-669

Author(s):

A. G. Jackson ◽

M. Rowe

Keyword(s):

Thermal Effects ◽

Dynamic Range ◽

Scattering Amplitude ◽

Dynamical Theory ◽

Site Symmetry ◽

Proof Of Concept ◽

Parallel Acquisition ◽

Kinematic Approximation ◽

Speed Up ◽

Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

Download Full-text