Transmitters and Receivers Generalized Transmitter Generalized Receiver The Superheterodyne Receiver Minimum Sampling frequency
Transmitters and Receivers Generalized Transmitter Generalized Receiver The Superheterodyne Receiver Minimum Sampling frequency
Generalized Transmitter Transmitter generate the modulated signal at the frequency fc from the message signal m(t) Any type of modulated signal can be represented by ■ v(t)=Refz(t)e v(t)=V(t)cos(2πft+θt) v(t)=x.(t)cos(2πft)-x,(t)sin(2πft) (h9呢9mp災YPR8 Is function of m(t)
Generalized Transmitter ◼ Transmitter generate the modulated signal at the frequency fc from the message signal m(t) ◼ Any type of modulated signal can be represented by ◼ ◼ where complex envelope ◼ Is function of m(t) 2 ( ) Re{ ( ) } ( ) ( )cos(2 ( )) ( ) ( )cos(2 ) ( )sin(2 ) c j f t c c c s c v t z t e v t V t f t t v t x t f t x t f t = = + = − ( ) ( ) ( ) ( ) ( ) j t c s z t V t e x t jx t = = +
Complex envelope Type of Mapping Corresponding Quadrature modulation modulation z(m(t)) (t) x(t) AM A.[1+m(t] A.1+m(t)] 0 DSB A.m(t) A.m(t) 0 PM Lekmr) A cos(km(t)) 4 sin(km(t)) FM e m A.cos(k,['m(r)dr)Asin(k,fm()dr) SSB A.[m(t)±jm(t)] Am(t)） ±jAm(t)
Complex envelope ( ) ( ) [1 ( )] ( ) [ ( ) ( )] p t f c c jk m t c jk m d c c A m t A m t A e A e A m t jm t − + [1 ( )] ( ) cos( ( )) cos( ( ) ) ( ) c c c p t c f c A m t A m t A k m t A k m d A m t − + 0 0 sin( ( )) sin( ( ) ) ( ) c p t c f c A k m t A k m d jA m t − Type of modulation AM DSB PM FM SSB Mapping z(m(t)) Corresponding Quadrature modulation xc (t) xs (t)
Complex envelope Type of Mapping Corresponding Amplitude and phase modulation modulation z(m(t)) V(t) 0(t) AM A,1+m(t)] A.1+m) 0, m(t)>-1 180°，m(t)<-1 DSB A.m(t) 4m(t) 0, m(t)>0 180°，m(t)<0 PM A.e。mo) A k,m(t) FM A kimr)dr SSB A.[m(t)±jm(t)] AVm2()+m2(0 an'±m m(t)
Complex envelope 2 2 1 ( ) ( ) ( ) ( ) c c c c c A m t A m t A A A m t m t + + 1 0, ( ) 1 180 , ( ) 1 0, ( ) 0 180 , ( ) 0 ( ) ( ) ( ) tan [ ] ( ) p t f m t m t m t m t k m t k m d m t m t − − − − Type of modulation AM DSB PM FM SSB Mapping z(m(t)) Corresponding Amplitude and phase modulation V(t) (t) ( ) ( ) [1 ( )] ( ) [ ( ) ( )] p t f c c jk m t c jk m d c c A m t A m t A e A e A m t jm t − +
Generalized Transmitter ■Two canonical form AM-PM generation technique Quadrature generation technique Choice is up to designer Maximize performance Minimize cost Based upon the available device and circuits
Generalized Transmitter ◼ Two canonical form ◼ AM-PM generation technique ◼ Quadrature generation technique ◼ Choice is up to designer ◼ Maximize performance ◼ Minimize cost ◼ Based upon the available device and circuits