Analog and Digital Technologies
To understand the technologies of analog and digital conversions we must first understand what analog and digital transmissions are. Analog transmissions are a continuous variable in amplitude and frequency. The frequency band that they operate over defines analog circuits. People generally produce a bandwidth of 9,900Hz with frequencies in the range of 100Hz to 10,000Hz. Speech that falls between 250Hz and 3,400Hz is considered intelligible speech and therefore the network circuits use bandwidth-limiting filters designed to filter out all frequencies above 4,000Hz. For these reasons, analog circuits are low-speed data communications, with a maximum data rate of 33.6Kps when analog loops are at both ends of the circuit.
Digital transmissions are very different from analog transmission. A digital transmission is a series of pulses that are ones or zeroes and these ones and zeroes make up combinations to create characters in characters sets. The way the signal is carried depends on whether the network is electrical or optical. In an electrical network, the ones and zeroes are either high voltage or low voltage. With an optical network, it is either the presents of light or no light.
Communications today are transmitted over a mix of digital and analog networks. Conversion is necessary for data to be transmitted across the various networks. Codecs are the devices that convert the transmissions from analog to digital. Modems are other devices that infuse digital signal onto transmission conveniences. Modems control the variables of electromagnetic wave to determine the ones and zeroes. Conversions are weak points in the network and errors and distortions can occur at these points.
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COMP09022 Network Design BSc COMPUTER NETWORKING COMP09022 ICMPv6 Prepared by B00270675 13-03- 2015 WORD COUNT (0000) TABLE OF CONTENTS TITLE PAGE……………………………………………... 1 TABLE OF CONTENTS………………………………….. 2 INTRODUCTION TO THE REPORT……………………. 3 TABLE OF FEATURES.......................................................4
After compression, the structure data, audio and video must be multiplexed. A number of compressed TV signals are combined by a multiplexer and put unto a shared transition medium. This is done by one of the two possible kinds of multiplexers that result in either a transport or a program stream, which is suited for secure transmission paths since it can contain large amounts of information. In addition multiplexing can be done using various methods. Time division multiplexing allocates a distinct time interval for each channel in a set; with the help of synchronization and a fixed interval order the channels take turns using the common line.
Communication between people is done in two ways: verbally and nonverbally. Those are layman terms. The language of verbal communication is described as digital code, whereas nonverbal communication is called analog code. The main difference that you could probably presume is that verbal communication involves a language, or better yet, spoken words. Inversely, nonverbal communication integrates the use of symbols or gestures to communicate an idea or feeling.
Recording technology wasn’t always a digital process. Before the 1970s, all recordings depended on capturing a physical analogue sound with microphones. This was done on either tape or disk. Analogue recordings lacked the sonic integrity that the 21st century demanded; it was becoming increasingly problematic and expensive in reducing noise and distortion that plagued analogue recordings. As a result, audio researchers began to study digital conversion techniques. They discovered that digitizing an electrical audio signal consisted of sampling the audio wave thousands of times a second, measuring the peak amplitude of each sample, and then assigning one of a limited number of binary values to each.
ATM is geared toward high speed voice and video transmission, much like a telephone network. It uses a cell-switching and multiplexing technology. The data (this refers to data, voice and video) is transferred between two points on a dedicated circuit in 53 byte cells. Each cell is the exact same size, no matter what data is being sent. The cells consist of 5 bits of header information and 48 bits of actual data. Using a smaller, consistent cell size means there's less delay between when each cell processes at the other end. Using dedicated circuits via virtual circuits ensures there is no interruption in the data transfer. This is extremely important to voice and video transmissions, because they are highly intolerant to data delays. This improves the Quality of Service (QoS) and speed of transfer, which can be between 25 Mbps to 622 Mbps.
This digital data takes the form of binary numbers, physically transferred by sending zero volts for zero or off and plus five volts for one or on. Certain binary numbers convey certain types of information, for example a certain binary number will tell the device that a note on a keyboard has been pressed. This is called a note on event and the
There are a great number of applications for Digital Signal Processing and in order to better understand why DSP has such a large impact on multiple aspects of society, it helps to better understand the wide variety of applications it can be used for. Here we will briefly look into the following applications of Digital Signal Processing and their uses; speech and audio compression, communications, biomedical signal processing and applications in the automobile manufacturing industry. Li Tan [1] goes into detail with each of these applications in his book, Digital Signal Processing, and explains how each are used on a daily basis.
Digital signals convert regular signals into strings of ones and zeros, which is much more efficient than analog signals. Broadcasters can maximize their use of channel space because digital signals carry significantly more information than analog signals. Several digital programs and services can be sent in the space occupied by a single analog channel. The result of this is that the consumer is provided with more channel choices(FCC).
In the Using the pulse modulation technique, the analog signal is converted into the digital signal. The process of quantization and companding of a signal is carried on the spreadsheets. To attain a clear signal to quantization noise ratio, the number of samples should be increased. By increasing the sampling depth, the quantization error can be minimized. By companding process, the quantization noise and distortion levels can be minimized. Companding improves response for low amplitude signals.
Communication begins with transmitting information to another person and the way one format of transmi...
According to Pew Research Center's Journalism Project, the overall drop in newspaper circulation began in 1989 and has been at a gradual decline of 1% a year since (Pew Research Center's Journalism Project, 2007). 1989 is also the year of the birth of the World Wide Web(Home.web.cern.ch, 2014).
A multiplexer is a form of transmission in which allows multiple signals to travel simultaneously over one medium. The signals are carried into smaller channels called subchannels. There are many types of multiplexing, for example, time division multiplexing, statistical multiplexing, and etc. The types that are used depends on what the media, transmission, and reception devices can handle. A multiplexer transmits at the end of a channel and demultiplexers are at the receiving end separating the combined signals and restores them to their original form. Multiplexing also comes in hand with networking to increase the data that is sent and shared over a given time span on a given bandwidth.
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Over time the different means of receiving the internet have changed several years ago, a phone line would proved a slow connection to the internet, but would not be useful when storing and...
Speech coding can be defined as the act of transforming the speech signal to a more compact form in smaller memory. The access to unlimited bandwidth is impossible. Thus, code and compressing of speech signal are needed. Since speech compression required in long-distance communication, high-quality speech storage, and message encryption, many users need to share the same frequency bandwidth in digital cellular technology. The solution is by utilizing speech compression makes it possible for more users to share the available system. Speech coding is a lossy type of coding. The output signal does not exactly sound like the input. Audio coding tries to code the audio in a perceptually lossless way. The sound at the output is the similar as the input even though the input and output signals are not mathematically equivalent. This type of coding is commonly used for audio storage, broadcasting as well as Internet streaming . There are several techniques of speech coding for example Linear Predictive Coding (LPC), waveform coding and subband coding (Abdul et.al ,2003).