Füge PRMS-Fehlerbehandlung hinzu und implementiere Partialresponse-Kodierung
This commit is contained in:
Silas Oettinghaus
199
Classes/04_DSP/Coding/Partialresponse.m
Normal file
199
Classes/04_DSP/Coding/Partialresponse.m
Normal file
@@ -0,0 +1,199 @@
|
||||
classdef Partialresponse
|
||||
%PARTIALRESPONSE Generalized symbol-domain partial-response coding.
|
||||
|
||||
properties
|
||||
order = 1
|
||||
end
|
||||
|
||||
methods
|
||||
function obj = Partialresponse(options)
|
||||
arguments
|
||||
options.order (1,1) double = 1
|
||||
end
|
||||
|
||||
obj.order = options.order;
|
||||
end
|
||||
|
||||
function signal = precode(obj, signal, options)
|
||||
arguments
|
||||
obj
|
||||
signal
|
||||
options.M = []
|
||||
end
|
||||
|
||||
[data, issignal, signalclass] = obj.unpackSignal(signal);
|
||||
M = obj.resolveM(data, options.M);
|
||||
a = obj.amplitudeToIndex(data, M);
|
||||
|
||||
h = arrayfun(@(k) nchoosek(obj.order, k), 0:obj.order);
|
||||
u = zeros(size(a));
|
||||
state = zeros(1, obj.order);
|
||||
|
||||
start_idx = 1;
|
||||
if obj.order == 1
|
||||
% Match the legacy Duobinary class exactly: keep the first
|
||||
% precoded symbol at zero state and start the recursion at k=2.
|
||||
start_idx = 2;
|
||||
end
|
||||
|
||||
for k = start_idx:numel(a)
|
||||
u(k) = mod(a(k) - sum(h(2:end).*state), M);
|
||||
state = [u(k) state(1:end-1)];
|
||||
end
|
||||
|
||||
data_out = obj.indexToPamAmplitude(u, M);
|
||||
signal = obj.packSignal(data_out, issignal, signalclass);
|
||||
end
|
||||
|
||||
function signal = encode(obj, signal, options)
|
||||
arguments
|
||||
obj
|
||||
signal
|
||||
options.M = []
|
||||
end
|
||||
|
||||
[data, issignal, signalclass] = obj.unpackSignal(signal);
|
||||
M = obj.resolveM(data, options.M);
|
||||
u = obj.amplitudeToIndex(data, M);
|
||||
|
||||
h = arrayfun(@(k) nchoosek(obj.order, k), 0:obj.order);
|
||||
y = zeros(size(u));
|
||||
state = zeros(1, obj.order);
|
||||
center = ((M - 1) * sum(h)) / 2;
|
||||
|
||||
for k = 1:numel(u)
|
||||
pr_state = [u(k) state];
|
||||
y(k) = sum(h .* pr_state) - center;
|
||||
state = pr_state(1:end-1);
|
||||
end
|
||||
|
||||
y = y ./ obj.encodedScaling(M, obj.order);
|
||||
|
||||
signal = obj.packSignal(y, issignal, signalclass);
|
||||
end
|
||||
|
||||
function signal = decode(obj, signal, options)
|
||||
arguments
|
||||
obj
|
||||
signal
|
||||
options.M = []
|
||||
end
|
||||
|
||||
[data, issignal, signalclass] = obj.unpackSignal(signal);
|
||||
M = obj.resolveEncodedM(data, options.M);
|
||||
|
||||
h = arrayfun(@(k) nchoosek(obj.order, k), 0:obj.order);
|
||||
idx_to_amp = nan(1, (M-1)*sum(h) + 1);
|
||||
center = ((M - 1) * sum(h)) / 2;
|
||||
scaling = obj.encodedScaling(M, obj.order);
|
||||
|
||||
for n = 0:(M^(obj.order+1)-1)
|
||||
state = zeros(1, obj.order+1);
|
||||
tmp = n;
|
||||
for k = 1:numel(state)
|
||||
state(k) = mod(tmp, M);
|
||||
tmp = floor(tmp/M);
|
||||
end
|
||||
y_idx = sum(h .* state);
|
||||
idx_to_amp(y_idx + 1) = (y_idx - center) / scaling;
|
||||
end
|
||||
|
||||
alphabet = unique(idx_to_amp);
|
||||
a = zeros(size(data));
|
||||
|
||||
for k = 1:numel(data)
|
||||
[~, pos] = min(abs(data(k) - alphabet));
|
||||
y_idx = find(idx_to_amp == alphabet(pos), 1) - 1;
|
||||
a(k) = mod(y_idx, M);
|
||||
end
|
||||
|
||||
data_out = obj.indexToPamAmplitude(a, M);
|
||||
signal = obj.packSignal(data_out, issignal, signalclass);
|
||||
end
|
||||
end
|
||||
|
||||
methods (Access=private)
|
||||
function [data, issignal, signalclass] = unpackSignal(~, signal)
|
||||
issignal = isa(signal, 'Signal');
|
||||
if issignal
|
||||
signalclass = signal;
|
||||
data = signal.signal;
|
||||
else
|
||||
signalclass = [];
|
||||
data = signal;
|
||||
end
|
||||
data = double(data(:));
|
||||
end
|
||||
|
||||
function signal = packSignal(~, data, issignal, signalclass)
|
||||
if issignal
|
||||
signalclass.signal = data;
|
||||
signal = signalclass;
|
||||
else
|
||||
signal = data;
|
||||
end
|
||||
end
|
||||
|
||||
function M = resolveM(~, data, M)
|
||||
if isempty(M)
|
||||
M = numel(unique(round(data, 12)));
|
||||
end
|
||||
end
|
||||
|
||||
function M = resolveEncodedM(obj, data, M)
|
||||
if isempty(M)
|
||||
I = numel(unique(round(data, 12)));
|
||||
if obj.order == 1
|
||||
M = (I + 1) / 2;
|
||||
else
|
||||
error('Partialresponse:NeedM', ...
|
||||
'Specify M when decoding higher-order partial-response signals.');
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
function a = amplitudeToIndex(obj, data, M)
|
||||
levels = obj.pamLevels(M);
|
||||
scaling = obj.pamScaling(M);
|
||||
amp = round(data(:) * scaling);
|
||||
a = (amp + (M - 1)) / 2;
|
||||
end
|
||||
|
||||
function data = indexToPamAmplitude(obj, a, M)
|
||||
scaling = obj.pamScaling(M);
|
||||
data = (2*a(:) - (M - 1)) / scaling;
|
||||
end
|
||||
|
||||
function levels = pamLevels(~, M)
|
||||
levels = -(M-1):2:(M-1);
|
||||
end
|
||||
|
||||
function scaling = pamScaling(~, M)
|
||||
try
|
||||
mapper = PAMmapper(M, 0);
|
||||
scaling = mapper.scaling;
|
||||
catch ME
|
||||
error('Partialresponse:UnsupportedM', ...
|
||||
'Unsupported PAM order for Partialresponse: %s', ME.message);
|
||||
end
|
||||
end
|
||||
|
||||
function scaling = encodedScaling(~, M, order)
|
||||
h = arrayfun(@(k) nchoosek(order, k), 0:order);
|
||||
center = ((M - 1) * sum(h)) / 2;
|
||||
y = zeros(M^(order+1), 1);
|
||||
|
||||
for n = 0:(numel(y)-1)
|
||||
state = zeros(1, order+1);
|
||||
tmp = n;
|
||||
for k = 1:numel(state)
|
||||
state(k) = mod(tmp, M);
|
||||
tmp = floor(tmp/M);
|
||||
end
|
||||
y(n + 1) = sum(h .* state) - center;
|
||||
end
|
||||
|
||||
scaling = sqrt(mean(y.^2));
|
||||
end
|
||||
end
|
||||
end
|
||||
Reference in New Issue
Block a user