Analog and Digital Comparison Paper
Team
NTC/362
Jun 10, 2015
Analog and Digital Comparison Paper
Analog and digital technologies both have their own advantages as well as disadvantages. This paper will discuss the analog-to-digital and digital-to-analog conversions in telecommunications. For analog, advantages and disadvantages to areas relating to amplitude modulation, frequency modulation, phase modulation, and Quadrature Amplitude Modulation (QAM) will be addressed. Techniques that are used specifically for the 56K modem, Asymmetrical Digital Subscriber Line, and Wi-Fi will be explained, and the last portion will reflect on the T(X) and the synchronous optical network (SONET) digital hierarchy.
To begin, analog technology is used for voice communication, using twisted-pair copper cable as the transmission medium with a maximum bandwidth of 1MHz. With analog communication came a number of historical advancements, ultimately diminishing the desire for such transmission media type alone. Speech, audio, and voice is not in binary form, thus conversion to binary is necessary for transmission. This is the analog-to-digital (A/D) conversion, meaning converting a non-binary signal into binary form. A coding system called Pulse Code Modulation (PCM) is used for analog-to-digital conversion. Filtering, sampling, quantizing, and encoding are the four steps of PCM. Two methods for analog modulation are amplitude modulation (AM) and frequency modulation (FM). In contrast to analog-to-digital conversion, analog modulation is when signals are transmitted directly without conversion. The difference in each is that in AM the amplitude varies according to high (binary 1) and low amplitudes (binary 0) for interpretation of signals, whereas FM will vary in the frequencies of signals, using binary 0s for low frequencies and 1s for high frequencies. The outcome of sampling results in pulse amplitude modulated, or PAM.
A digital signal is a...