nanocrystalline zno particles were prepared by a novel sonochemical route from zinc acetate and sodium hydroxide without any requirement of calcination steps at high temperature and without surfactants. variations in several parameters and their effects on the structural (crystal size and morphology) properties of nanoparticles were investigated. characterizations were carried out by x-ray diff...

Multiple – output transmitter implementation based on Direct Digital Synthesis (DDS) architecture is presented and investigated. A particular number of identical and independent units compose the proposed device. DDS technology is applied on the first stage of these units and provides amplitude, phase and frequency adjustments on the corresponding output signals. Quadrature mixers are driven by...

Spurious performance of direct digital synthesis (DDS) is partly caused by two quantization operations in its numerical (i.e. digital) part. These errors are deterministic and periodic in the time domain, therefore they appear as line spectra (undesired components: spurs) in the frequency domain. Hence it is quite natural to analyze the effects by DFT (discrete Fourier transform). The amplitude...

National Bureau of Standards Gaithersburg, MD 20899 To provide a phase meter calibration service, a phase angle calibration standard has been developed at NBS. This standard is a signal. generator with two sinusoidal outputs and uses direct digital synthesis to generate the signals. The phase angle between the two sinusoids is determined by the input parameters in the calculation of the sets of...

introduction: various systems for intraoral digital radiography have been available as an alternative to film–based radiography. in consideration of several advantages of digital radiography such as less patient absorbed dose, manipulation of im age quality and elimination of processing, it has been extensively used in different fields of denti stry in recent years. the purpose of this study wa...

Objectives: An efficient, safe, affordable and easily accessible measuring instrument for quantitative assessment of bone prior to dental implant placement enables more accurate treatment planning. Costly imaging modalities are neither widely available, nor affordable for some patients. This study sought to assess the efficacy of a newly designed digital bone gauge for measurement of bone width...

Waveform generators employed in college laboratories are often purchased instruments with ultra precision, which may cause unnecessary expenditure since the prices are often high whilst some functionalities are not required. By analyzing the principle of existing products, a simple waveform generator based on DDS (direct digital synthesis) technology has been developed using AT89S52 single chip...

In this paper, architecture of residue number system used in FIR filters, is presented. For many years residue number coding has been recognized as a system which provides capability for implementation of a high speed addition and multiplication. These advantages of residue number system coding for the high speed FIR filters design results from the fact that an digital FIR filter requires only ...

We report on the generation of a frequency comb around 4330 nm with an unprecedented coherence of the single teeth. Generating the comb within a Ti:sapphire laser cavity by a difference-frequency process and using a phase-lock scheme based on direct digital synthesis, we achieve a tooth linewidth of 2.0 kHz in a 1-s timescale (750 Hz in 20 ms). The generated per-tooth power of 1 μW ranks this c...

This demonstration shows how VESNA wireless sensor nodes can be used for cognitive radio experiments involving wireless sensor networks. SNE-ISMTV is a radio frontend that has been developed for this purpose. Spectrum sensing capability in the TV white-spaces and 2.4 GHz ISM band is demonstrated by running receivers in a swept-tuned spectrum analyzer configuration and displaying measured spectr...