NTC362 Week 2 Learning Team Assignment- Analog and Digital Comparison Paper
NTC362 Week 2 Learning Team Assignment- Analog and Digital Comparison Paper
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Analog and Digital Technology 1 Analog and Digital Technology: A Comparison NTC362 University of Phoenix Analog and Digital Technology 2 Analog and Digital Technology: A Comparison Analog to digital conversions techniques begin with the transmission of the information without reproduction of the original information minus the degradation with signal distortion or noise by the binary signal. T. T. (2011). “The binary signal consists of two values characterized by binary digits or bits 1 and 0. Unless the noise and distortion is picked up during transmission then the binary signal will not change. The value is measure by the receiver so that the reception is clear. If the information to be transferred is already in binary form as in data communications there isn’t any need for the signal to be encoded. Voice communication thru the method of the telephone is not in binary form. These signals vary in range of values are analog and within the digital communications system analog signals must be converted to digital form.” Digital to Analog conversions involve a conversion process with DAC. This devise takes the binary code converting it to the analog signal. Digital to analog signals can compromise the quality of the signal, if it is not actively monitored. Analog lines, which are also known as POTS lines usually support standard phone lines, fax machines or alarm lines, keeping them separate from the digital PBX equipment. An example of digital to an analog signal would be the use of a modem for Internet use that converts computer digital signals using POTS lines. Advantages and Disadvantages of Common Modulation Techniques Amplitude Modulation Analog and Digital Technology 3 Analogsignals have four modulation techniques. The most simple of the four is Amplitude Modulation (AM). AM transmits data by varying the intensity of the waves. The most common use for AM is transmitting radio stations. AM is very simple by design thatmakes it the least costly method of transmitting data. The main disadvantage with AM is how easily the transmission can contain interference. AM signals also use more energy than other types of modulation methods. Frequency Modulation Frequency Modulation (FM) is also most commonly used in broadcasting radio stations. FM transmits data by using multiple frequencies of the signal as opposed to the varying the intensity wave. Using multiple frequencies makes FM transmissions less susceptible to line interference. Disadvantages of FM are the amount of bandwidth required. It is much higher than that of other methods. FM is also much more complicated and requires more complicated equipment. Phase Modulation Phase Modulation (PM) is similar to FM. PM; however, uses two waves, whereas FM only uses one. The first wave sends out the signal normally, and the second sends out the signal up to 180 degrees out of phase. PM is much simpler than FM because only the phase varies, not the frequencies. Many of the complex circuits needed to measure the frequencies in FM are not needed in PM. A disadvantage of PM is the creation of phase ambiguity when the modulation signal exceeds 180 degrees. Quadrature Amplitude Modulation Analog and Digital Technology 4 Quadrature Amplitude Modulation (QAM) can send multiple signals on one carrier. When using QAM in modems both the amplitude and the phase of the signals vary, this causes the transmissions to be much faster than any of the other modulation techniques. A disadvantage is how susceptible QAM is to noise and interference. Another disadvantage is that QAM requires the use of linear amplifiers. Linear amplifiers use much more energy and makes them not very popular in mobile devices. Applications of Modern Modulation Techniques From dialup to DSL to WiFi, modulation techniques continue to increase throughput and improve quality through optimization. The current networking technologies are 100 plus years in the making, but it seems as though each year brings about a new advancement, and each new generation of networking technology can be marked by a new or improved modulation technique. Although hardware is significant, as it often makes new modulation techniques possible, with the current developmental stateof communication technology, it is advancements in modulation that get noticed as significant. V.90 Starting with dialup connections, as it was a major milestone of information technology as it is know today, the creation of the 56k (V.90) modem marked the peak of the technology. If fact, after a decade, V.90 modems are still widely used still. V.90 modems use a very simple PAM consisting of 8000 symbols per second each coded from seven bits of each eight bit PCM word. The result is 128 amplitude levels in the signal. Upstream of V.90 modems are limited to the older V.34 modulation and is only capable of 33.6 Kbps. ADSL Analog and Digital Technology 5 Asymmetric Digital Subscriber Lines (ADSL) marked a huge step forward in consumer connectivity, and the best part about it was that it made use of current twisted pair telephone lines, which at the time almost every home in America already had active. The advancement from Dialup to DSL was made possible by a combination of modulation techniques.Carrierless Amplitude Phase CAP, a form of QAM developed by AT&T, was used in early implementations of ADSL; however, it has been replaced by Discrete Multitone Modulation (DMT), which is currently the universally standardized ADSL modulation method. Therefore, only DMT is covered in detail. DMT, also a form of multicarrier modulation, splits available bandwidth into sub channels, each using QAM modulation on a separate carrier to maximize throughput. DMT for ADSL divides the downstream bandwidth into 4.3125 kHz wide channels and the upstream bandwidth into 32 4.3125 kHz wide channels (Alturayef & Rodriguez, 2007). The result is a throughput of about 8.1 Mbps downstream and a 1.5mbps upstream.Because it has to coexist with POTS, the first six channels are reserved for voice allowing ADSL and POTS to function simultaneously. 802.11(x) 802.11 commonly referred to as WiFi, marked a huge step forward in modern connectivity, one people are still working to build upon. Once again, modulation has played a very important role in the development of 802.11 from its original throughput of one to two Mbps to the 504 Mbps capabilities of today’s standard 802.11n. The first widely adopted WiFi standard was 802.11b operating in the 2.4 GHz spectrum. To reach its top speed of 11Mbs, 802.11b used Direct Spread Spectrum Sequencing (DSSS), also found in CDMA cellular Analog and Digital Technology 6 networks and GPSs, and Complementary Code Keying (CCK) (Bhatia, 2007). CCK consisted of 64, eight bit channels, making it similar to the modulation techniques used by ADSL. With 802.11a, introduced a new revolutionary modulation technique that we are still current trying to push it its limits, Orthogonal Frequency Division Multiplexing (OFDM). Using OFDM 802.11a split each of its eight available channels, each 20MHz wide, into multiple subchannels each with its own signal able to transmit independently of one another. Operating the 5GHz spectrum, 802.11a was not widely adopted because it was not compatible with the already successful 802.11b, which quickly made way to its successor. 802.11g also utilized OFDM; however, it brought it to the 2.4GHz spectrum and offered backward compatibility with 802.11b. Like 802.11a, though, 802.11g transmits a fourmicrosecond symbol with an 800 nanosecond interval, and at the full transmission rate of 54Mbps, each symbol contains 288 bits including 72 error correction bits, whichis managed by using 64 QAM on each subcarrier with a ¾ rate encoder (Cisco, 2011). As mentioned before, OFDM carries into the latest 802.11 standard 802.11n, and it is still getting pushed to greater limits. With a 5/6 rate encoder and more subcarriers per channel 802.11n increased the data rate to a maximum of 65Mbps over a solitary transmission using the same 20MHz wide channels as 802.11a/g. With the capability to transmit four channels simultaneously, the maximum throughput with 20MHz channels is 260Mhz. While 260MHz alone is a significant leap forward, there is more. The 802.11n standard also brought 40MHz channels to the mix and an available 108 subcarriers: in total bringing the maximum data rate of all four channels to an outstanding 540Mbps. It makes one wonder what the next advancement in modulation will bring to the table. Analog and Digital Technology 7 Hierarchy of T(X) and SONET Concerning the use of SONET and T(X) there are some advantages and disadvantages, but before we cover what those are we need first to understand what each is and what each has to offer. SONET or what is also known as Synchronous Optical Networking is the standardized multiplexing protocol that transfers multiple digital bit streams over optical fiber using lasers or coherent light from lightemitting diodes (LEDs). In this mode of transmission less transmission rates are required. SONET equipment is managed by the TL1 protocol. TL1 is a telecom language used for managing and reconfiguring SONET network elements. Some of the key advantages of SONET are: Provides highcapacity fiber optic transport Defines a system of synchronous signal level Includes a highlevel of OAM&P (Operations, Administration, Maintenance, and Provisioning) capability Supports automatic protection switching Allows a highdegree of interoperability between different vendor platforms SONET offers fault tolerance and reliability. Network costs are lower However, there are disadvantages to using SONET. This is something that is almost hard to believe with what seems to be the perfect answer. The following are the disadvantages: SONET is not for the everyday home network. It is primarily utilized in carrier networks such as Verizon, Cox, and Comcast in their highspeed backbones. Analog and Digital Technology 8 Requires strict synchronization schemes SONET is not cheap because of the complex and costly equipment. On the flipside to Synchronous Optical Networking (SONET) we also have the T(X), which is another name for the T1or T3 data lines and so on. These lines use adigital transmission to transfer “digitaldata” over point to point or point to multipoint communication channel. The various ways for these lines to communicate are copper wire, optical fiber, or wireless. For the digital transmission to take place, forms of data information such as voice, text,or image data is converted into binary code, which is nothing other than a combination of ones and zeros. At the receiver end, binary code is converted back into original format. It provides clearer and faster transmission, using less bandwidth to transmit more information than analog transmission.For instance University of Phoenix spelled in binary code would look like the following: 0101010101101110011010010111011001100101011100100111001101101001 0111010001111001001000000110111101100110001000000101000001101000 0110111101100101011011100110100101111000 This is only what three words look like just image the entire document spelled out this way. Here are some advantages to using these lines. The T3 line cantransport a mass amount of data. “The T3 internet line has 672 separate channels that can allow 672 people to simultaneously browse the net at a very high speed”(Theodorou, 2008). T1 are fast at 1.5 mbps, but T3 provides connection speeds as high as 44.6 mbps. Analog and Digital Technology 9 With these speeds and the ability to transport a vast amount of data the T(x) data lines seem to provide all the answers we are looking for. However, there is always a downfall, “According to Data Connect Enterprise, a networking company based in Olney, Maryland, T3 bandwidth can cost as much as $15,000 per month”(Johnson, 2011). This means that using a T3 line can be very expensive to use. Using a T1 line is around a fraction of the cost at about $1,000 a month; however, this is not for a home network. The other downfall is that adding a dedicated T1 line to a home or a T3 line to a business will require physical installation of the line. The bottom line is that T(X)lines are expensive and only medium to large companies can afford the upgrade. In contrast the one thing to remember about both of these types of data and communication lines is that they are not for the home network. Cost of installation can run very high, and they are meant for the networks that need the speed and bandwidth. So unless one is a millionaire it is safe to leave these data line to the big dogs. Analog and Digital Technology 10 References Alturayef, M., Rodriguez, D.(2007).ADSL Technology, Retrieved January 13, 2012 from http://ecee.colorado.edu/~ecen4242/adsl/adsltechnology.htm Bhatia, A (2007) 802.11 Retrieved January 13 , from http://it.toolbox.com/wiki/index.php/802.11 Gao, F (1998) An Introduction to the V.90 (56K) Modem. January 13, 2012 from http://www.eetimes.com/design/communicationsdesign/4018048/AnIntroductionto theV9056KModem KVEDARAS, R. R., KVEDARAS, V. V., & USTINAVICIUS, T. T. (2011). Retrieved January 13, 2012 from Settling Time Testing of Fast DACs. Acta Physica Polonica, A, 119(4), 521527. Johnson, J. (2011, July 11). What is t3 bandwidth?Retrieved January 13, 2012 from Analog and Digital Technology 11 http://www.ehow.com/info_8720239_t3bandwidth.html Theodorou, V. (2008, April 30). T3 internet. Retrieved January 13, 2012 from http://www.squidoo.com/t3internet
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