Transcript Amplitude Modulation AM Generation (DSBFC)

EEE 3223
COMMUNICATION PRINCIPLES
AMPLITUDE MODULATION
AM GENERATION (DSBFC)
AM GENERATION
 Direct
Method
𝑣𝐴𝑀 𝑡 = 𝐸𝑐 𝑐𝑜𝑠𝜔𝑐 𝑡 + 𝑣𝑠 𝑡 𝑐𝑜𝑠𝜔𝑐 𝑡
= (𝐸𝑐 + 𝑣𝑠 𝑡 )𝑐𝑜𝑠𝜔𝑐 𝑡
AM GENERATION

Indirect Method
Input signal :
𝑣𝑖 𝑡 = 𝑣𝑠 𝑡 + 𝑣𝑐 (𝑡)
=𝐸𝑠 𝑐𝑜𝑠𝜔𝑠 𝑡 + 𝐸𝑐 𝑐𝑜𝑠𝜔𝑐 𝑡
Output of non linear device :
𝑣𝑘 = 𝐸0 + 𝑚1 𝑣𝑖 + 𝑚2 𝑣𝑖 2 + 𝑚3 𝑣𝑖 3 +.....
AM GENERATION
The signal,vk(t) was then filtered using band pass filter (BPF) tuned at the
resonance (salun) frequency, fo = fc
AM GENERATION