From: Nonlinear dynamical analysis of GNSS data: quantification, precursors and synchronisation
%recurrence, %REC | Percentage of recurrent points falling within the specified radius, ε. | \( \%\mathrm{REC}=100\frac{number\ of\ points\ in\ triangle}{\varepsilon \left(\varepsilon -1\right)/2} \) |
%determinism, %DET | Percentage of recurrent points forming diagonal line structures. This is a measure of determinism in the signal. | \( \%\mathrm{DET}=100\frac{number\ of\ points\ in\ diagonal\ lines}{number\ of\ recurrent\ points} \) |
Linemax, DMAX | The length of the longest diagonal line in the plot (except main diagonal). | DMAX = length of longest diagonal line in the recurrence plot |
Entropy, ENT | The Shannon information entropy of all diagonal line lengths over integer bins in a histogram. This is a measure of signal complexity with units bits/bin. | ENT = − ∑ (P_{bin})log_{2}(P_{bin}) |
Trend. TND | A measure of system stationarity. | \( \mathrm{TND}=1000\left(\begin{array}{l} slope\ of\% local\ recurrence\ \\ {}\kern2.25em vs. displacement\end{array}\right) \) |
%laminarity, %LAM | The percentage of recurrent points forming vertical line structures. | \( \%\mathrm{LAM}=100\frac{number\ of\ points\ in\ vertical\ lines}{number\ of\ recurrent\ points} \) |
VMAX | The length of the longest vertical line in the plot. | VMAX = length of longest vertical line in the recurrence plot |
Trapping time, TT | The average length of vertical line structures. | TT = Average length of vertical lines ≥ parameter line |