jens
f59fb8f67d
git-svn-id: http://moon:8086/svn/matlab/trunk@100 801c6759-fa7c-4059-a304-17956f83a07c
153 lines
3.2 KiB
Matlab
Executable File
153 lines
3.2 KiB
Matlab
Executable File
## Copyright (C) 2018 Jens Ahrensfeld
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##
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## This program is free software; you can redistribute it and/or modify it
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## under the terms of the GNU General Public License as published by
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## the Free Software Foundation; either version 3 of the License, or
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## (at your option) any later version.
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##
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License
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## along with this program. If not, see <http://www.gnu.org/licenses/>.
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## -*- texinfo -*-
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## @deftypefn {Function File} {@var{retval} =} garage (@var{input1}, @var{input2})
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##
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## @seealso{}
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## @end deftypefn
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## Author: Jens Ahrensfeld <ahrensfeld@w2ess001vm>
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## Created: 2018-12-06
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function [bits, x] = garage_ip (numSamplesPerSym)
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k_n = 0.00; % NOise
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k_s = 1.0; % Sym
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baud_init = 9600;
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fs = baud_init * numSamplesPerSym;
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numSyms = 100;
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numBursts = 3;
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numSymsPauseBetweenBurst = 50;
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syms = rand(numSyms, 1) > 0.5;
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bit = 0;
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% Line coding
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syms_m = manchester(syms);
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% Upconvert
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x = [];
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for k=1:numBursts
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for n=1:2*numSyms,
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for m=1:numSamplesPerSym,
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x = [x syms_m(n)];
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end
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end
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x = [x zeros(1, numSymsPauseBetweenBurst*numSamplesPerSym)];
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end
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% Channel
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[b,a] = butter(2, numSamplesPerSym/4*baud_init/fs);
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y = resample (x, 131, 121);
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%y = x;
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y = k_s*filter(b, a, y) + k_n*randn(1, length(y));
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N = length(y);
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baud = baud_init;
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bit = 0;
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% The master clock counter
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countReload = numSamplesPerSym-1;
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count = countReload;
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smp = [];
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smp_n = [];
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bits = [];
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v_min = 0; % Threshold max
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v_max = 0; % Threshold min
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hyst_thr = 0.5; % Threshold hysteresis
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rho_thr = 1e-5; % Threshold forgetting factor
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alpha_lead = 0.016; % Symbol syncronizer loop filter lead
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alpha_lag = 0.000008; % Symbol syncronizer loop filter lag
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lag_accu = 1; % Symbol syncronizer loop filter
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ns = 1; % Start sample source
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n = 1; % Start sample sink
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err = 0; % Error
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while ns < N
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% Get next interpolated sample
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is = fix(ns);
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mu = ns - is;
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ys = (1-mu).*y(is) + mu.*y(is+1);
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% Calculate threshold
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v_thr = (v_max - v_min) / 2;
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if ys < v_min
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v_min = ys;
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elseif ys > v_max
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v_max = ys;
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end
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v_min = v_min + rho_thr*(v_thr - v_min);
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v_max = v_max - rho_thr*v_max;
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% Detect bit change
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bitChg = 0;
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if (bit == 1)
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if ys < (hyst_thr*v_thr)
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bit = 0;
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bitChg = 1;
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end
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else
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if ys > (hyst_thr*v_thr)
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bit = 1;
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bitChg = 1;
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end
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end
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% Calc error
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if (bitChg)
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err = -(count - fix(numSamplesPerSym/2));
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end
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% Sample bit at baud rate = fs/numSamplesPerSym
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if count == 0
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smp = [smp ys];
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smp_n = [smp_n n];
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bits = [bits bit];
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end;
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if count > 0
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count = count - 1;
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else
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count = countReload;
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end
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vcorr = alpha_lead*err + lag_accu;
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lag_accu = lag_accu + alpha_lag*err;
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baud = vcorr*fs/numSamplesPerSym;
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_err(n) = err;
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_baud(n) = baud;
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_cnt(n) = vcorr;
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_v_tr(n) = v_thr;
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_ys(n) = ys;
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n = n + 1;
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ns = ns + vcorr;
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end
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bits = bits';
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n = 1:length(_ys);
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% Plot
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subplot(3, 1, 1)
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plot(n, _ys, smp_n, smp, 'ro', n, _v_tr, 'y'); grid;
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subplot(3, 1, 2)
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plot(n, _err); grid;
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subplot(3, 1, 3)
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plot(n, _baud); grid;
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endfunction
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