week 2 individual beginning of project paper

· Analyze the technologies for analog-to-digital and digital-to-analog conversions in telecommunications.

· In analog technology, compare and contrast the advantages and disadvantages of amplitude modulation, frequency modulation, phase modulation, and Quadrature Amplitude Modulation (QAM).

Introduction

Analog to digital and digital to analog conversions are processes that are transparent to the naked eyed but is complex in nature and require careful conversions. There are distinct advantages to both and their uses depend on the task at hand. Both are still in use today with digital being more prevalent because of large amounts of data that it can easily transmit over great distances. Both of these two communication mediums are not going away anytime soon and each has a place in today’s networking community.

Analog-to-digital and digital-to-analog conversions in telecommunications

Analog signal is one that increases or decreases in nature due to the fluctuations of the item being transmitted. This can be compared to the highs and lows of a radio signal in which the analog signal will rise and drop based on the radio signal being transmitted. Analog to digital conversion happens all of the time in telecommunications. For example an analog phone call made from home is converted to a digital signal at the main office switch. This conversion happens again when you scan a photo with a scanner by converting the image into digital information.

Digital to analog conversion occurs when a Digital to Analog Converter known as a (DAC) converts digital data into an analog signal (Goleniewski, 2007). This is heard when listening to a CD; the digital data on the CD is converted in to analog signal thus producing the music. Digital to analog conversion does occur but the use of digital signal far exceeds the use of analog for multiple reasons. Digital is preferred over analog because it uses less power, use of encryption can, discrete signal, and high bandwidth capabilities just to name a few.

Advantages and disadvantages of amplitude modulation, frequency modulation, phase modulation, and Quadrature Amplitude Modulation (QAM).

Amplitude and frequency modulation both use electromagnetic waves to transmit information. Amplitude modulation (AM) varies the amplitude wave based on the data being sent with frequency remaining unchanged. Frequency modulation (FM) happens by encoding sound by varying frequency of wave with amplitude remaining the same. Its advantages are it is resistant to noise, resilient to fluctuations in signal strength, and does not need a linear amplifier.

Phase modulation happens when a carrier signal is varied to match the phase of modulated signal keeping the frequency unchanged. The phase shift will depend on amplitude or modulation of the signal used. It advantage is there is less static interference than in frequency modulation. Its disadvantages are there is data loss, high degree of phase ambiguity, and specialized equipment needed.

Quadrature Amplitude Modulation (QAM) is both analog and digital in nature. Two analog and digital signals are modulated out of phase by 90 degrees using amplitude shift-keying modulation. Advantages of QAM are it allows for multiple signals to be sent over the same channel simultaneously and it can be used with analog and digital formats. Its disadvantages are that it has distortion, attenuation, channel interference.

References

Goleniewski, L. (2007). Telecommunications Essentials: The Complete Global Source, Second Edition. Upper Saddle River, NJ: Pearson Education, Inc.