# Is Sentinel able to obtain wave spectrum by interferometric Data?

I have recently read many articles on recovering wave spectrum from the AT-INSAR image spectrum (through interferometric images). However, it is not clear to me whether Sentinel is a viable option, although it is theoretically feasible. I know it is possible with satellites of two antennas, and these antennas are used to calculate the phase difference of the waves. But since the sentinel has only one antenna, it uses the technique of interferometry using two distinct orbits to calculate this phase difference.

A non linear transform from the article "On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum"

$$\begin{multline}\label{eq:tfasecomplete} P^S_P (\mathbf{k})= \left(\frac{k_xB}{\pi V}\right)^2\int d\mathbf{r} \exp(-j\mathbf{k}\cdot \mathbf{r}) \exp\left[\left(\frac{k_xR}{ V}\right)^2(f^u(\mathbf{r})-f^u(\mathbf{0}))\right] \\ \times\left[f^u(\mathbf{r})+\left(\frac{k_xR}{ V}\right)^2(f^u(\mathbf{r})-f^u(\mathbf{0}))^2\right] \left(1-\frac{\partial^2 f^u(\mathbf{r})}{\partial\mathbf{r}^2}\right)\left(\frac{k_xR}{V}\right)^2+2j\left(\frac{k_xR^2}{ V^2}\right) \\ \times \left(\frac{R}{V}\right)^2\left(\frac{\partial f^u(\mathbf{r})}{\partial\mathbf{r}}\right)^2 \left(\frac{\partial f^u(\mathbf{r})}{\partial\mathbf{r}}\right)\left[2f^u(\mathbf{r})-f^u(\mathbf{0})+(\frac{k_xR}{V})^2(f^u(\mathbf{r})-f^u(\mathbf{0})^2)\right]\\ - \left[1+\left(\frac{k_xR}{V}\right)^2 (3f^u(\mathbf{r}) -2f^u(\mathbf{0}))+(f^u(\mathbf{r})-f^u(\mathbf{0}^2)\left(\frac{k_xR}{V}\right)^4\right]. \end{multline}$$

Acctually, i want to know if a can use this transform for sentinel's interfometric data.

Thanks any help

So they use phase. With 2 antenna on the same platform, offset in the direction of motion, you are basically taking 2 snaps shots of the surface (with phase info), and then you can compare those and see how much the surface shifted in the brief interval between image formation, leading to an ocean wave power spectrum vs the wavenumber $$k$$.