Re: [Discuss-gnuradio] GRC 3.6 / 802.11 a/g test signal

[Ernest Szczepaniak]

So... After going deep into Annex L i found that my scrambler fails. Also
MATLAB built-in scrambler gives wrong results. Could you pls check this code
fragment?

Asumme that we have 20 data bits to scramble. Initial scrambler state is [1
0 1 1 1 0 1] (bit nr 7 left side).

scrambler_register=[1 0 1 1 1 0 1];                                   %
scrambler seed
data_bits=randi([0 1],1,20);                                             %
data to be scrambled

for i=1:20
   temp=xor(scrambler_register(1),scrambler_register(4));  % x7 and x4 xor
operation
   data_scrambled(i)=xor(data_bits(i),temp);                      % output
bit
   register=circshift(scrambler_register',-1,1)';                    % shift
left register
   register(7)=data_scrambled(i);                                       %
insert data to register
end

To clarify, left side of register has index (1), right side has index (7).

Best, 
Ernest



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