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Bugfix?: changed sign detection of root calculation

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This commit is contained in:
Jan Käberich 2021-02-23 21:02:04 +01:00
parent aac1429793
commit 05ca7e6434
1 changed files with 9 additions and 3 deletions
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12
Software/PC_Application/VNA/Deembedding/twothru.cpp
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@ -306,9 +306,15 @@ std::vector<TwoThru::Point> TwoThru::calculateErrorBoxes(std::vector<Protocol::D
p221x.push_back((p112x[i]-p111x[i])/p212x[i]);
test = sqrt(p212x[i]*(1.0-p221x[i]*p221x[i]));
if(i > 0) {
if(arg(test) - arg(last_test) > 0) {
// according to the octave script, the next line should be if(arg(test) - arg(last_test) > 0)
// but that leads to 180° degree phase shift and also doesn't make much sense:
// we want to figure out the correct sign for the root so that no phase jumps occur. The
// phase difference from one to the next point is allowed to be positive, it just should be smaller
// than PI/2 (otherwise we got the wrong sign for the root)
if(abs(arg(test) - arg(last_test)) > M_PI / 2) {
k = -k;
}
qDebug() << "angle at point" << i << "(" << arg(test) - arg(last_test) << ")";
}
last_test = test;
p211x.push_back(k*test);
@ -362,7 +368,7 @@ std::vector<TwoThru::Point> TwoThru::calculateErrorBoxes(std::vector<Protocol::D
p221x.push_back((p112x[i]-p111x[i])/p212x[i]);
test = sqrt(p212x[i]*(1.0-p221x[i]*p221x[i]));
if(i > 0) {
if(arg(test) - arg(last_test) > 0) {
if(abs(arg(test) - arg(last_test)) > M_PI / 2) {
k = -k;
}
}
@ -555,7 +561,7 @@ std::vector<TwoThru::Point> TwoThru::calculateErrorBoxes(std::vector<Protocol::D
for(unsigned int i=0;i<f.size();i++) {
test = sqrt(s212x[i]*(1.0-s221x[i]*s221x[i]));
if(i > 0) {
if(arg(test) - arg(last_test) > 0) {
if(abs(arg(test) - arg(last_test)) > M_PI / 2) {
k = -k;
}
}