Lect-AM-5_07 - Spectrum of AM: t c t m c A t AM x cos ] cos...

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

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Spectrum of AM: t c t m c A t AM x cos ] cos 1 [ ) ( + = t m c c A t m c c A t c c A ) cos( ) 2 / 1 ( ) cos( ) 2 / 1 ( cos + +- + = Taking the Fourier transform )} ( ) ( ){ 2 / ( ) ( c f f c f f c A f AM x + +- = )]} ( [ )] ( [ { ) 2 / 1 ( m f c f f m f c f f c A- + +-- + )]} ( [ )] ( [ { ) 2 / 1 ( m f c f f m f c f f c A + + + +- + Along with the carrier there are two frequency components f c-f m is called the LOWER SIDEBAND(LSB) f +f is called the UPPER SIDEBAND(USB) Shows the plot of a 100% modulated message signal. Carrier freq.: 504 KHz ; Message signal freq. : 4.6 KHz POWER EFFICIENCY: Power in the carrier = 2 ) 2 / 1 ( c A Power in the LSB = 2 2 ) 8 / 1 ( 2 2 / ) ( ) 2 / 1 ( c A c A = Power in the USB = 2 2 ) 8 / 1 ( 2 2 / ) ( ) 2 / 1 ( c A c A = Power Efficiency = Sideband power/Total power 2 2 ) 4 / 1 ( 2 ) 2 / 1 ( _______ __________ 2 2 ) 4 / 1 ( c A c A c A + = 2 2 _______ 2 + = When = 1, i.e.., for 100% modulation power efficiency is only 33% Generation Of AM: V 1 (t) R L m(t) A c cos c t V 2 (t) )] ( cos [ ) ( 1 t m t c c A t V + = The switching action of the diode may be approximated by a pulse train, which expressed as a Fourier series is as follows: ] 5 cos ) 5 / 1 ( 3 cos ) 3 / 1 ( )[cos / 2 ( ) 2 / 1 ( ) ( t c t c t c t p g +- + = } cos ) / 2 ( ) 2 / 1 )]{( ( cos [ ) ( 2 t c t m t c c A t V + + = The higher harmonics can be filtered out after passing...
View Full Document

This note was uploaded on 09/24/2010 for the course MATHEMATIC AAOC C222 taught by Professor Prof.dilipkumarsatpathi during the Fall '07 term at Birla Institute of Technology & Science, Pilani - Hyderabad.

Page1 / 26

Lect-AM-5_07 - Spectrum of AM: t c t m c A t AM x cos ] cos...

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