Analog and Digital Comparison

Topics: Modulation, Synchronous optical networking, Modem Pages: 7 (1568 words) Published: June 2, 2014
Analog and Digital Comparison


February 3, 2014

Dr. Phillip Coleman





Analog and Digital Comparison

Telecommunications is a term used to describe any type of long distance communication techniques. In the digital age, telecommunications describes the use of electronic devices that facilitate communications between people, computers, and other machines. There are several technologies used today that enable these communications and allow them to perform efficiently. The basis behind these technologies is the process of converting analog signals, or signals that can have an infinite number of values that encapsulates the data stream, to digital signals, signals that generally can only have a value of zero or one, and digital signals to analog signals.

There are many different devices in use that convert the different signal types and transmit the data. Some of the devices are used to facilitate longer distance communications and others are used to allow short distance communications. An example of the digital-to-analog conversion process is the use of a data modem to convert the digital signals that a computer generates to an analog signal that can be transmitted over the twisted pair telephone lines. This is also an example of analog-to-digital conversion as the modem does double duty by decoding the information coming in across the telephone lines into data that is usable by the computer. Other types of modems include Digital Subscriber Line (DSL) modems, Cable Modems, and satellite radio modems. All of these devices convert digital signals into analog for transmission and when they are receiving information they convert the analog signals back to digital for computer processing.

The techniques used to convert the digital signals to analog signals and back to digital vary with the application of the network. In many cases the same information gets converted from digital to analog and back multiple times and using multiple methods before it reaches its final destination. Cable modems are a ubiquitous form of this process and can be found in many homes across the United States and the world. Cable internet is made possible by utilizing the bandwidth allotted for one or more cable TV channels and modulating the signal to allow for internet data transmission as well. Utilizing this method it is possible to achieve speeds between 56.6K and 10mbps (Kiniry 1998). The cable modem houses both a modulator and a demodulator which is how the term "modem" (MOulator DEModulator) came about. The signal is received and demodulated to allow for the information to be used on an IP based network, and the data from the computers is converted from IP based data to the modulated carrier signal to be sent out across the cable network.


Analog signals have been around for a long time and are used more frequently than most people may think. There are different types of analog signals that many of us are familiar with: AM (amplitude modulation), FM (frequency modulation), and PM (phase modulation) which is not very popular. These signals are most commonly used for today's radio broadcasts but they have also been used in the transference of data as well. QAM (quadrature amplitude modulation) is considered more of a digital signal but it uses two AM signals which is the reason why it is mentioned here.

AM (AMPLITUDE MODULATION). This was one of the first analog signals created and used by the first radio stations. One of the advantages of AM signals is that they are very easily detected. "There have even been reports of people hearing some nearby radio station from their stainless steel kitchen sink" (Olofson, 2007). This also means that the components used to make the receivers are cheap which also made it popular. One of the biggest disadvantages of the AM signal is that it picks up a lot of noise or...

References: A Brief Overview of SONET Technology. (2005). Retrieved from
Baker, Kevin
Goleniewski, L. (2007). _Telecommunications essentials_. (2nd ed.) Boston, MA: Pearson.
John Wiley & Sons Inc. . (2005). Wide Area Networks (WAN) [PowerPoint slides]. Retrieved from
Kiniry, J. R., & Metz, C. (1998). Cable modems: Cable TV delivers the internet. _IEEE Internet Computing, 2_(3), 12-15. doi:
Olofsson, M
Sharma, D.K., Mishra, A., Saxena, R. (2010). _Analog & Digital Modulation Techniques:_
_An Overview_
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