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1. Install and Repair of Telecom Lines
Telecommunication is the most developing juncture from past 200 years, from drum & smoke signals to
satellite & internet networks. This boom of technology has gone through many phases such as electrical
telegraph, telephone, radio & television, video telephony to mobile (cellular) and computer networks.
In this section, we will cover install and repair for putting up a telephone connection from Central office to a
residential or business place. We will cover its network setup describing each component in detail.
In order to understand what a field technician do, we will go through some basic fundamental principles and
methods.
Sound Waves
When you speak, air is forced from your lungs through your vocal cords, and out your mouth. The
result, of course, is your voice.
Much the same way that a pebble, when thrown into a pool, will create waves of water, the
vibration of your vocal cords produces waves of air. It is these sound waves that make your voice
audible.
The sound waves have various “frequencies” and “amplitudes” that are the result of your
vocalization.
Frequency and Amplitude
Frequency and amplitude are two characteristics that you use to describe a signal. When you listen
to music, or carry on a conversation, you are experiencing both frequency and amplitude, although
those terms are not usually the first ones that come to mind.
People generally interpret frequency as higher or lower tones or pitches. A higher frequency sound,
such as a small dog’s yip, has a “higher” pitch than a lower frequency, such as a big dog’s growl.
We perceive amplitude in terms of how loud or soft a sound is. An ocean liner’s horn has a large
amplitude, where as a whisper is a much lower amplitude.
When you speak, sound waves travel outwards, and will leave an impact on the ear of your listener,
causing their eardrum to vibrate with the same frequencies and amplitudes that were spoken. As a
result of this vibration, your listener will hear what you have said.
As the frequencies and amplitudes of your voice are continuously variable, your voice is considered
to be an analog signal. This fact will become important later on as we discuss how your analog voice
is carried in the telephone circuit.
Frequency is measured in terms of cycles per second. That is, the number of times per second that
the signal will complete a transition from its lowest to highest amplitude and back again. This is
known as oscillation.
Figure 1: Oscillation
