Aya2002
Advanced Member level 4
convolutional encoder
hi Friends,
i have this example and i want to understand it but i cant can some body help me please?
Example 2.1: A convolutional encoder has the following parameters:
G=[133 171]
R=1/2
K=7 (constraint length)
Determine the structure of the encoder.
solution:
the two octal number are converted to binary forms as:
133 = 001 011 011 = 1 011 011
171 = 001 111 001 = 1 111 001
g1(x) =1•(x^0)+0•(x^1)+1•(x^2)+1•(x^3)+0•(x^4)+1•(x^5)+1•(x^6)
g2(x) =1•(x^0)+1•(x^1)+1•(x^2)+1•(x^3)+0•(x^4)+0•(x^5)+1•(x^6)
denote the input as i(x), the first digit is computed from i(x)•g1(x). The second digit is computed from i(x)•g2(x).
thus for i(x)=101=1+x^2,
first digit = (1+x^2)(1+x^2+x^3+x^5+x^6)=10 01 10 00 1
second digit=(1+x^2)(1+x+x^2+x^3+x^6)= 11 00 11 10 1
the encoder sequence is 11 01 00 10 11 01 01 00 11
my questions are:
1. the input i(x), in this example it was 101 (how?)
2. how the encoder sequence was calculated?
thanks
hi Friends,
i have this example and i want to understand it but i cant can some body help me please?
Example 2.1: A convolutional encoder has the following parameters:
G=[133 171]
R=1/2
K=7 (constraint length)
Determine the structure of the encoder.
solution:
the two octal number are converted to binary forms as:
133 = 001 011 011 = 1 011 011
171 = 001 111 001 = 1 111 001
g1(x) =1•(x^0)+0•(x^1)+1•(x^2)+1•(x^3)+0•(x^4)+1•(x^5)+1•(x^6)
g2(x) =1•(x^0)+1•(x^1)+1•(x^2)+1•(x^3)+0•(x^4)+0•(x^5)+1•(x^6)
denote the input as i(x), the first digit is computed from i(x)•g1(x). The second digit is computed from i(x)•g2(x).
thus for i(x)=101=1+x^2,
first digit = (1+x^2)(1+x^2+x^3+x^5+x^6)=10 01 10 00 1
second digit=(1+x^2)(1+x+x^2+x^3+x^6)= 11 00 11 10 1
the encoder sequence is 11 01 00 10 11 01 01 00 11
my questions are:
1. the input i(x), in this example it was 101 (how?)
2. how the encoder sequence was calculated?
thanks