Our final year project is DDS, which was first proposed by J.Tierney in 1971. Direct Digital Synthesis (DDS) is a method used for creating arbitrary digital waveforms and frequencies from a single frequency source. As the VLSI technology is developing also the requirement of the various modern communication systems, direct digital synthesizers have been widely in use like wireless transceivers since the 1980’s. Direct Digital Frequency Synthesis (DDS), consists of a Numerically Controlled Oscillator (NCO), which is a technique which uses digital-data and mixed or analog-signal processing blocks which generate signal waveforms that are repetitive. The DDS achieves very fast frequency switching in very few frequency steps, over a wide band. Also it is used for providing linear phase and frequency shifting with good spectral purity. The DDS is used especially for a high frequency, precise and a phase tunable output. A standard DDS architecture consists of an accumulator, a ROM /lookup table, a DAC and few reconstruction filters.
DDS solutions have been implemented in LSI (large-scale integration) and they play a major role in digital waveform and clock generation. One of the major advantage of a direct digital synthesizer is that the output frequency, amplitude or phase can be precisely and rapidly manipulated under the control of the digital processor . Other important DDS attributes include the ability to tune with extremely precise and fine frequency and phase resolution.
Different modulation capabilities can be very easily included in the DDS by using digital signal processing methods, because the signal is in the digital form. If we program the DDS, adaptive channel bandwidths, modulation formats, frequency hoppin...
... middle of paper ...
... quantized. Frequency is the rate of change in phase, so obviously the frequency is also quantized.
Because of the phase quantization, for a given clock frequency, there are certain frequencies that cannot be exactly achieved.
The frequency tuning word (FTW) is calculated using the equation:
Fig 1.3 DDS Output Waveform
1.4 POPULAR USES FOR DDS
Applications which uses DDS-based waveform generation are divided into two principal categories: Designers of communications systems which require agile (which immediately responds) frequency sources with an excellent phase noise and should have low spurious performance therefore we often choose DDS for its combination of spectral performance and frequency resolution .Some of the applications are which uses a DDS for modulation, as a reference for a PLL to enhance overall frequency, as a local oscillator (LO).
7. Megahertz (MHz, millions of hertz), and Gigahertz (GHz, billions of hertz) measure CPU frequencies, that is the maximum number of CPU pulses per second.
Ex 1 [8.3] Will the frequencies all do the same thing, or will something different happen in each one?
Contents Page Section 3 ……………… …………………… Introduction 3 ……………… …………………… The Pioneers of the Electronic Age 4 ……………… …………………… The Theory of the Synthesiser 5 ……………… …………………… Other Changes Due to Electronic Technology 6 ………………
A general worldview of the United States is a country enriched in luxury, where attaining “the American Dream” is the ultimate goal. America is seen as a country that offers freedom and most importantly provides opportunities. However, behind this façade is the dilemma that exists between the rich and poor neighborhoods in the United States. The socioeconomic status of parents plays a vital role in their offsprings’ future socioeconomic status. The effects of poverty and wealth among children in neighborhoods are examined in Tama Leventhal’s and Jeanne Brooks-Gunn’s article Children and Youth in Neighborhood Context.
In regards to my academic and career goals, I plan to attend a four year university and eventually medical school. After medical school, I hope to become an orthopedic surgeon through residency and specialize in sports medicine. My interest in sports medicine has developed through experiences such as observing my father’s ACL surgery, having an operation on a broken hand, and caring for my grandfather who had prostate cancer. I hope to contribute to the world of sports medicine through research, either on treatments for knee ligament tears or supplement breakthroughs. Additionally, this past summer I spent most of my time at the University of Pittsburgh Health Career Scholars Academy, where I was able to explore various science-related health professions through lectures and gain insight on the medical field. These experiences have secured my interest for healthcare and medicine.
I have had a passion for helping people for as long as I can remember. I think that the earliest influence that I had was my dad. My dad is a very giving and sweet person. He is the kind of person to give you the shirt on his back. It always seemed like he was the happiest when he was helping others and trying to make there life easier, I saw this at a very young age and it inspired my love for helping others.
“After the integrated circuits the only place to go was down—in size that it. Large scale integration (LS) could fit hundreds of components onto one chip. By the 1980’s, very large scale integration (VLSI) squeezed hundreds of thousands of components onto a chip. Ultra-Large scale integration (ULSI) increased that number into millions. The ability to fit so much onto an area about half the size of ...
As a small nonprofit social IT company established in 2001, Digital Divide Data (DDD) has various human resources (HR) challenges. One of such human resources challenges includes lack of financial resources which has prevented the company from attracting unskilled labor. The second human resources challenge facing the Digital Divide Data is the inability to retain its internally-trained managers and high-performing operators. This difficulty comes as a result of the insufficient finance to maintain the internally-trained managers who are highly sought for in both Cambodia and Laos. So overall, the current human resources challenge facing DDD is the difficulty in attracting unskilled
There are 4 unknowns: the coordinate of receiver position X and clock bias b. The Iterative Least Square (ILS) can be used to calculate these unknowns. The following is a brief illustration of process of Iterative Least Square in flowchart as shown in Figure 11. In the appendix, the Iterative Least Square method on Matlab functions is presented.
As electronics is a wide part of the industry now having converted over to a Digital Audio Workspace or D.A.W systems from analogue tape which is a dying art amongst newer budding engineers today from adjusting to the setup skills all are replaced by a computer of some sort and a recording platform such as a D.A.W. Digital Audio workstations’ come on many computer based platforms, though having a good understanding of at least the more commonly found systems seems to benefit all recording studio engineers as this allows them to virtually be able to walk into any studio be it in their own city or abroad in another country an still be able to deliver a quality product to whomever their clients may
This Essay will discuss Codecs; it will explain the definition of codecs and their functions and include a brief history on digital signals, equipment and standards. It will also discuss compression and compression formats such as Lossless and Lossy and files such as FLAC and ALAC
This report will describe the two forms of data communications in terms of the physical interfaces and modes of operation. It will describe the features of data communications equipment in relation to synchronous and asynchronous communication including modems, network terminating units and sending and receiving equipment.
waves are further divided into two groups or bands such as very low frequency (
The Physics Classroom. "Frequency and Period of a Wave." Physic Classroom. The Physics Classroom, 1996. Web. 28 Nov. 2013. .