A carrier signal is a frequency that is modulated to carry analog or digital information for communication. Common examples are radio transmitters that modulate the frequency or amplitude of a carrier signal to transmit audio information. A carrier system provides multiple point-to-point communication channels using a technique like time-division multiplexing. Carrier service providers offer telephone and data communication between locations using networks like those built by Regional Bell Operating Companies. Modulation involves impressing voice, music, pictures or data onto a radio frequency carrier wave by varying its amplitude, frequency or phase. Common modulation types include amplitude modulation, frequency modulation, phase modulation, pulse code modulation and pulse duration modulation.

1. What is a Carrier Discussion

2. Carrier Signal A 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 A 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 : A 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 Technique 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 b) Amplitude modulation (AM) b) Frequency Modulation (FM) c) Phase Modulation (PM) d) Pulse coded Modulation (PCM) e) Pulse Duration Modulation (PDM)

7. Amplitude Modulation (AM) Auditory 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) The 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 The 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), In 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), Another kind of pulse modulation is in which intelligence is represented by the length and order of regularly recurring pulses.

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

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

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