264 lines
7.0 KiB
Matlab
264 lines
7.0 KiB
Matlab
classdef Duobinary
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%Duobinary Coding
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% should work
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properties(Access=public)
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end
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methods (Access=public)
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function obj = Duobinary()
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%NAME Construct an instance of this class
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end
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function signal = precode(~,signal)
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if isa(signal,'Signal')
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data = signal.signal;
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else
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data = signal;
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end
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u = unique(data);
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M = numel(u);
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%make unipolar
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if M == 4
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data = data .* sqrt(5);
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elseif M == 6
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data = data .* sqrt(10);
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elseif M == 8
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data = data .* sqrt(21);
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elseif M == 16
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data = data .* sqrt(85);
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warning('Check if PAM16 implementation, mapping and scaling is correct!')
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end
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data = round(data);
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b = min(data);
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data = data - b;
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data = data ./ 2;
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assert(isequal((0:M-1)',unique(data)),'Check Duobinary Precoding'); %seems the signal is not unipolar
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% Pre coding
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bk = zeros(numel(data),1);
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% for k = 1:numel(data)-1
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% bk(k+1) =mod(data(k)-bk(k),M);
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% end
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for k = 2:numel(data)
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bk(k) =mod(data(k)-bk(k-1),M);
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end
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%make bipolar
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bk = bk .* 2;
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bk = bk + b;
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if M == 4
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bk = bk ./ sqrt(5);
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elseif M == 6
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bk = bk ./ sqrt(10);
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elseif M == 8
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bk = bk ./ sqrt(21);
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end
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assert(isequal(unique(bk),u),'Check Duobinary Precoding'); %seems the signal is not the same as before
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if isa(signal,'Signal')
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signal.signal = bk;
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else
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signal = bk;
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end
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end
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function signal = encode(~,signal)
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if isa(signal,'Signal')
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data = signal.signal;
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else
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data = signal;
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end
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data = data./rms(data);
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u = unique(data);
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M = numel(u);
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%make unipolar
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if M == 4
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data = data .* sqrt(5);
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elseif M == 6
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data = data .* sqrt(10);
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elseif M == 8
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data = data .* sqrt(21);
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elseif M == 16
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data = data .* sqrt(85);
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warning('Check if PAM16 implementation, mapping and scaling is correct!')
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end
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data = round(data);
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b = min(data);
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data = data - b;
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data = data ./ 2;
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% assert(isequal((0:M-1)',unique(data)),'Check Duobinary Precoding'); %seems the signal is not unipolar
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% duobinary coding (1+D)
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% coeff = [1,1];
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%
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% data = conv(data,coeff,"same");
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coeff = [1,1];
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data = filter(coeff, 1, data);
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%data = data ./ rms(data);
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% data = ifft(fft(real(data)).*fft(fliplr(coeff'),length(data))) + 1i*ifft(fft(imag(data)).*fft(fliplr(coeff'),length(data)));
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%make bipolar
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data = (data-round(mean(data),1));
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if M == 4
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data = data ./ sqrt(2.5); % 7-level constellation weighted with probability after DB code i.e. mean([-3 3 -2 -2 2 2 -1 -1 -1 1 1 1 0 0 0 0].^2) = 2.5 --> sqrt(2.5) == rms(constellation)
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elseif M == 6
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data = data ./ sqrt(5.8);
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elseif M == 8
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data = data ./ sqrt(10.5); % 15-level constellation weighted with probability after DB code i.e.
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end
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if isa(signal,'Signal')
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signal.signal = data;
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else
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signal = data;
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end
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% Code to evaluate the s in sqrt(s):
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% M=6;
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% c = (0:(2*M)-2) - ((2*M)-2)/2;
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% s = 0;
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% for i = 0:(2*M)-2
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% p(i+1) = M-abs(i-(M-1));
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% s = s+p(i+1)*c(i+1).^2;
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% end
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% s = s/M^2;
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end
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function signalclass = decode(~,signalclass)
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data = signalclass.signal;
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u = unique(data);
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I = numel(u); %number of duobinary coded const. points
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M = (I+1)/2; %PAM-M order
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%make unipolar
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if I == 7
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data = data .* sqrt(2.5);
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elseif I == 11
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%todo
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data = data .* sqrt(5.8);
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warning('Check db decode implementation, mapping and scaling is correct!')
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elseif I == 15
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data = data .* sqrt(10.5);
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elseif I == 16
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warning('Check db decode implementation, mapping and scaling is correct!')
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end
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data = round(data);
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b = min(data);
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data = data - b;
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data = round(data);
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data = mod(data,M);
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%make bipolar
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data = data .* 2;
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data = data - round(mean(data));
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if M == 4
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data = data ./ sqrt(5);
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elseif M == 6
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data = data ./ sqrt(10);
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elseif M == 8
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data = data ./ sqrt(21);
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end
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signalclass.signal = data;
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end
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function signalclass = feedbackdetector(~,signalclass)
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data = signalclass.signal;
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u = unique(data);
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I = numel(u); %number of duobinary coded const. points
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M = (I+1)/2; %PAM-M order
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%make unipolar
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if I == 7
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data = data .* sqrt(2.5);
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elseif I == 11
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%todo
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data = data .* sqrt(5.8);
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warning('Check if PAM16 implementation, mapping and scaling is correct!')
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elseif I == 15
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data = data .* sqrt(10.5);
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elseif I == 16
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warning('Check if PAM16 implementation, mapping and scaling is correct!')
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end
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data = round(data);
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b = min(data);
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data = data - b;
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data = round(data);
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data_out = zeros(length(data),1);
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const = 0:M-1;
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%%FALSCH!
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for k = 1:length(data)-1
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d_ = data(k+1) - data_out(k);
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[~,b] = min(abs(d_-[0:M-1]));
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data_out(k+1) = const(b);
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end
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%make bipolar
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data_out = data_out .* 2;
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data_out = data_out - round(mean(data_out));
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if M == 4
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data_out = data_out ./ sqrt(5);
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elseif M == 6
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data_out = data_out ./ sqrt(10);
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elseif M == 8
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data_out = data_out ./ sqrt(21);
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end
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signalclass.signal = data_out;
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end
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end
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methods (Access=private)
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% Cant be seen from outside! So put all your functions here that can/
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% shall not be called from outside
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end
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end
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