TELECOMMUNICATIONS EXAM 1
QUESTIONS AND ANSWERS
FREQUENTLY TESTED.
What is the biggest difference between frequency division multiplexing
and time division multiplexing?
fdm multiplexes based upon different frequencies using guard bands where
data is wasted; tdm multiplexes based upon time "vertically" and does not
need guard bands
What is a coding scheme and how is it used by a computer to represent
data?
A coding scheme is the language that all computers use to represent data.
They are the set of characters that are the "alphabet" of any given system.
Those characters are represented by bits or binary zeros and ones in
computer systems, grouped together as bytes then translated using three
popular coding schemes
How can bipolar digital signaling be used to represent digital data
Bipolar signaling alternates the ones and zeros from a plus voltage to a minus
voltage. There are three different bipolar techniques, nonreturn to zero (NRZ)
, return to zero (RZ), and alternate mark inversion(AMI). Each technique differs
between returning to zero after each bit or not but each of the techniques
move between a positive and negative voltage potential.
What is modulation?
the transmission of data through telephone lines as a simple sound wave
through circuits and then changing its shape of the wave in different waves to
represent a 1 or a 0
Describe how the three basic modulation techniques discussed in your
book work.
, Amplitude modulation, Frequency modulation and Phase modulation
Amplitude modulation
changes the height or amplitude of the wave to represent a 1 or 0.
Frequency modulation
represents 1's and 0's by changing the number of waves or frequency of the
sound waves
Phase modulation
the direction the wave begins by starting down or up, defined by degrees to
represent a 0 or 1
How can the basic modulation techniques be used to send multiple bits
simultaneously
Each of the basic modulation techniques can be used to send bits
simultaneously by defining two or more different amplitudes, frequencies, or
phases
Symbol rate
the unit of signaling speed used to indicate the number of times per second
the signal on the communication circuit changes
Bit rate
the number of bits per second transmitted
How are the symbol and bit rate related
the bit rate and the symbol rate are the same when only 1 bit is sent on each
symbol during modulation. When the modulation techniques send bits
simultaneously, the bit rate would be, the number of bits sent simultaneously
times the symbol rate
Codec
device is needed to convert analog data to a digital format for storage and
transmission
QUESTIONS AND ANSWERS
FREQUENTLY TESTED.
What is the biggest difference between frequency division multiplexing
and time division multiplexing?
fdm multiplexes based upon different frequencies using guard bands where
data is wasted; tdm multiplexes based upon time "vertically" and does not
need guard bands
What is a coding scheme and how is it used by a computer to represent
data?
A coding scheme is the language that all computers use to represent data.
They are the set of characters that are the "alphabet" of any given system.
Those characters are represented by bits or binary zeros and ones in
computer systems, grouped together as bytes then translated using three
popular coding schemes
How can bipolar digital signaling be used to represent digital data
Bipolar signaling alternates the ones and zeros from a plus voltage to a minus
voltage. There are three different bipolar techniques, nonreturn to zero (NRZ)
, return to zero (RZ), and alternate mark inversion(AMI). Each technique differs
between returning to zero after each bit or not but each of the techniques
move between a positive and negative voltage potential.
What is modulation?
the transmission of data through telephone lines as a simple sound wave
through circuits and then changing its shape of the wave in different waves to
represent a 1 or a 0
Describe how the three basic modulation techniques discussed in your
book work.
, Amplitude modulation, Frequency modulation and Phase modulation
Amplitude modulation
changes the height or amplitude of the wave to represent a 1 or 0.
Frequency modulation
represents 1's and 0's by changing the number of waves or frequency of the
sound waves
Phase modulation
the direction the wave begins by starting down or up, defined by degrees to
represent a 0 or 1
How can the basic modulation techniques be used to send multiple bits
simultaneously
Each of the basic modulation techniques can be used to send bits
simultaneously by defining two or more different amplitudes, frequencies, or
phases
Symbol rate
the unit of signaling speed used to indicate the number of times per second
the signal on the communication circuit changes
Bit rate
the number of bits per second transmitted
How are the symbol and bit rate related
the bit rate and the symbol rate are the same when only 1 bit is sent on each
symbol during modulation. When the modulation techniques send bits
simultaneously, the bit rate would be, the number of bits sent simultaneously
times the symbol rate
Codec
device is needed to convert analog data to a digital format for storage and
transmission
