Lecture_6a

Lecture_6a - Signal Transmission Lecture 6a (basic...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Elec 300u Slide 1 Signal Transmission Lecture 6a (basic concepts) transmission systems modulation, demodulation, filtering frequency division multiplexing heterodyne and homodyne receivers Some content taken with permission from material developed for the course EECS6.02 by C. Sodini, M. Perrot and H. Balakrishnan
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Transmission Systems Analog Communications – Information is from an analog source – Signal waveform changes according to information content – Fidelity is usually defined in terms of SNR. Digital Communications – Information is from a digital source or a digitized analog signal – Signal is made up of discrete symbols selected from a finite set (e.g., binary data). – Fidelity or accuracy is specified in terms of bit error rate (probability of making a bit error).
Background image of page 2
Modulation, Slide 3 Signal Transmission In a communications system signals or messages need to be transmitted from one place to another We say the signals are passed through a channel (e.g. free space, copper wires, optical fibers) We call this signal transmission Channels operate only at certain frequencies and suffer from distortion, interference and noise In the previous lectures we assumed the channel was a simple direct connection Elec 300u Channel
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Modulation, Slide 4 Modulation Modulation ~ Process by which a parameter of a parameter of a carrier carrier is varied varied in one in one -to to -one correspondence with one correspondence with an information-bearing signal usually referred to as the messag e If the modulating signal is continuous , the modulation is continuous wave (analog) modulation . If the modulating signal is a sequence of pulses , the modulation is pulse modulation (leads to digital modulation ) Modulation There are two basic types of continuous -wave modulation: ¾ ¾ Linear modulation Linear modulation (amplitude modulation) (amplitude modulation) ¾ ¾ Angle modulation Angle modulation (frequency, phase modulation) (frequency, phase modulation) A general modulated modulated carrier is given by )] ( cos[ ) ( ) ( 0 t t t A t x c φ ω + =
Background image of page 4
Modulation, Slide 5 Unmodulated carrier frequency Message signal Linear-modulated signal (amplitude- modulated) Angle-modulated signal (frequency- modulated) Analog (Continuous) Modulation Analog (Continuous) Modulation In 300U, we will focus on amplitude modulation.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Modulation, Slide 6 Amplitude Modulation Amplitude Modulation •The amplitude of amplitude of the carrier carrier is varied varied in direct proportion to proportion to the amplitude amplitude
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 26

Lecture_6a - Signal Transmission Lecture 6a (basic...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online