What Is A Carrier

Discussion of Carriers

1. What is a Carrier
Discussion

2. Carrier Signal
4A frequency in a communications channel
modulated to carry analog or digital signal
information. For example, an FM radio
transmitter modulates the frequency of a
carrier signal and the receiver processes the
carrier signal to extract the analog
information. An AM radio transmitter
modulates the amplitude of a carrier signal.

3. Carrier System
4A communications system providing a
number of point-to-point channels through
some type of multiplexing. T-1 and
T-3 carrier services are examples of carrier
systems that can be used between points in
a Wide Area Network (WAN).

4. carrier service provider:
4A company offering telephone and data
communications between points in a state or
in one or more countries. The Regional Bell
Operating Companies (RBOCs) are
example of carriers.

5. Modulation
4Technique for impressing information
(voice, music, picture, or data) on a radio-
frequency carrier wave by varying one or
more characteristics of the wave in
accordance with the intelligence signal

6. Modulation Types
4b) Amplitude modulation (AM)
4b) Frequency Modulation (FM)
4c) Phase Modulation (PM)
4d) Pulse coded Modulation (PCM)
4e) Pulse Duration Modulation (PDM)

7. Amplitude Modulation (AM)
4Auditory or visual information is
impressed on a carrier wave by
varying the amplitude of the
carrier to match the fluctuations in
the audio or video signal being
transmitted

8. Frequency Modulation (FM)
4The amplitude of the carrier is kept
constant, but its frequency is
altered in accordance with
variations in the audio signal being
sent.

9. Phase Modulation
4The phase of a carrier wave is
varied in response to the
vibrations of the sound source in
phase modulation (PM).

10. Pulse-coded modulation
(PCM),
4In the intelligence signal converts
the carrier into a series of
constant-amplitude pulses spaced
in such a manner that the desired
intelligence is contained in coded
form.

11. Pulse-duration modulation
(PDM),
4Another kind of pulse modulation
is in which intelligence is
represented by the length and
order of regularly recurring pulses.

12. What is a wavelength?
4The distance between the peak of one wave
to the next.

13. Adding intelligence to the
waveform
4By modulating a waveform we can add
intelligence to the transmitted wave.

14. Carrier
4The Carrier is the portion of the wave which
carries no inteligence
4the unmodulated single-frequency
electromagnetic wave that carries the
desired information