SSB-SC

1. Demodulation of SSBSC-AM wave
• Coherent detection/Synchronous detection

2. Coherent Detection
• SSBSC wave s(t) is multiplied with local carrier and passed to LPF
• Local oscillator signal is exactly coherent (both frequency and phase) with
the carrier signal used in modulation process

3. Coherent Detection
• The local oscillator signal is given as
Vccos(2fct )     (1)

4. Coherent Detection
• The local oscillator signal is given as
Vccos(2fct )     (1)
• The output of product modulator is given as

5. Coherent Detection
• The local oscillator signal is given as
Vccos(2fct )     (1)
• The output of product modulator is given as
v(t) Vccos(2fct )s(t)      (2)
s(t) VmVc cos2(fc  fm )t      (3)
• Sub Eq.(3) in Eq.(2)

6. Coherent Detection
{cos(4
2
)}   (4)
) cos(2

f t 
 f t 
f t  2
V V V
v(t)  m
m
c
m c c
• The local oscillator signal is given as
Vccos(2fct )     (1)
• The output of product modulator is given as
v(t) Vccos(2fct )s(t)      (2)
s(t) VmVc cos2(fc  fm )t      (3)
• Sub Eq.(3) in Eq.(2)

7. Coherent Detection
{cos(4
2
)}   (4)
) cos(2

f t 
 f t 
f t  2
V V V
v(t)  m
m
c
m c c
• The local oscillator signal is given as
Vccos(2 fct )     (1)
• The output of product modulator is given as
v(t) Vccos(2fct )s(t)      (2)
s(t) VmVc cos2(fc  fm )t      (3)
• Sub Eq.(3) in Eq.(2)
• After passing to LPF,
2
v (t) 
1
V V Vcos(2 f t )   (5)
m
0 m c c

8. Advantages and Disadvantages of SSB-SC

15. Fourier Transform

16. Fourier Transform