نتایج جستجو برای: direct digital synthesis
تعداد نتایج: 1109471 فیلتر نتایج به سال:
This paper presents a low distortion signal generator with a frequency range from 0 to 10 kHz using the direct digital synthesis (DDS) method for ADC characterization. The results show that the maximum distortion in the whole frequency range is -80.37 dB, the frequency resolution is 1.421 nHz (with a 48-bits DDS chip), the stability in frequency is 25 μHz/Hz and the amplitude stability is 13 μV/V.
A new transmit architecture for digital radios is proposed that emphasizes the use of pre-computed waveforms stored in memory instead of real-time computation. We present results that show how direct synthesis techniques can be extended to directly generate many types of digitally modulated waveforms such as PSK or QAM. These techniques are especially appropriate for software radios implemented...
The paper reports on some experiments with implementing positional digital image filters using field programmable devices. It demonstrates that a single field programmable device may be used to build such a filter. By using extensive pipelining in the design, the filter can achieve performance of 50 million pixels per second (using Xilinx XC4000E devices) and almost 90 MHz (in case of Virtex-2 ...
A key requirement across a multitude of industries is to accurately produce, easily manipulate, and quickly change waveforms of various frequencies and types. Whether a wideband transceiver requires an agile low-phase-noise frequency source with excellent spurious-free dynamic performance or an industrial measurement and control system needs a stable frequency stimulus, the ability to quickly, ...
|This work presents results that show how direct digital synthesis (DDS) techniques can be extended to produce frequency modulated (FM) waveforms as well as many types of digitally modulated waveforms, such as PSK or QAM. We show how digitally modulated wave-forms can be eeciently synthesized from tables of pre-computed samples. This work also reports on the implementation of these algorithms i...
CereProc R ©Ltd. have recently released a beta version of a commercial unit selection synthesiser featuring XML control of speech style. The system is freely available for academic use and allows fine control of the rendered speech as well as full timings to interface with avatars and other animation. With reference to this system we will discuss current state-of-theart commercial expressive sy...
We describe a Direct Digital Synthesiser (DDS) which provides three frequency-locked synchronised outputs to generate frequencies from DC to 160 MHz. Primarily designed for use in a heterodyning range imaging system, the flexibility of the design allows its use in a number of other applications which require any number of stable, synchronised high frequency outputs. Frequency tuning of 32 bit l...
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
Partial randomization dynamic element matching (DEM) was recently introduced as a promising DEM technique for low harmonic distortion digital-to-analog conversion. The DEM technique is well suited for applications such as direct digital synthesis in wireless communication systems for which low hardware complexity is essential in addition to low harmonic distortion. Previously reported simulatio...
سابقه و هدف: اکثریت پوسیدگی های دندانی، ضایعاتی با حدود نامشخص اند که برای مشاهده آنها بر روی رادیوگراف های conventional باید حدود 40 درصد فرآیند دمینرالیزاسیون صورت بگیرد. تصاویر رادیوگرافی معمول، عمق نفوذ یک ضایعه پوسیدگی را کمتر از مقدار واقعی آن نشان می دهند در حالیکه با استفاده از روش digital subtraction radiography تشخیص تقلیل مواد معدنی به میزان 5-1 درصد در واحد حجم امکان پذیر است. هدف ا...
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