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git-svn-id: http://moon:8086/svn/matlab/trunk@154 801c6759-fa7c-4059-a304-17956f83a07c
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jens
2021-03-22 20:31:27 +00:00
parent b31f3e7435
commit e033d30500
1 changed files with 6 additions and 3 deletions
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iridium.m
+6 -3
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@@ -27,6 +27,9 @@ function iridium (name)
[x, fs] = audioread(name); [x, fs] = audioread(name);
xc = (x(:,1) + i*x(:,2))'; xc = (x(:,1) + i*x(:,2))';
h_rc = fir_rrc(fs, 4/fs, 0.4, 65);
xc = filter(h_rc, 1, xc);
close all; close all;
N = length(x); N = length(x);
@@ -38,7 +41,7 @@ xc_cfo = xc .* lo;
#xc_cfo = xc_cfo .* conj(xc_cfo); #xc_cfo = xc_cfo .* conj(xc_cfo);
phi_cfo_uw = phi_unwrap(angle(xc_cfo)); phi_cfo_uw = phi_unwrap(angle(xc_cfo));
dphi_cfo = [0 diff(phi_cfo_uw)]; dphi_cfo = [0 diff(phi_cfo_uw)];
foff = dphi_cfo*48000; foff = dphi_cfo*fs;
found = find_preamble(dphi_cfo) found = find_preamble(dphi_cfo)
alpha_mean = 0.1; alpha_mean = 0.1;
@@ -58,7 +61,7 @@ subplot(3,1,3)
plot(1:N, dphi_cfo, "-o", 1:N, dphi_mean, 'r-'); legend('dphi'); grid; plot(1:N, dphi_cfo, "-o", 1:N, dphi_mean, 'r-'); legend('dphi'); grid;
start=found(1) start=found(1)
ende=start + 128 ende=start + 400
step=2 step=2
figure figure
@@ -66,7 +69,7 @@ plot(real(xc_cfo(start:step:ende)), imag(xc_cfo(start:step:ende)), 'x'); grid;
function found = find_preamble(phi) function found = find_preamble(phi)
thr = 0.5; thr = 0.5;
nsmp = 16; nsmp = 120;
last = phi(1); last = phi(1);
count = 0; count = 0;
found = []; found = [];