diff --git a/swash/processing/post.py b/swash/processing/post.py
index 81ac601..a9f6cb5 100644
--- a/swash/processing/post.py
+++ b/swash/processing/post.py
@@ -4,6 +4,7 @@ import pathlib
 import numpy as np
 import pandas as pd
 import matplotlib.pyplot as plt
+import scipy.signal as sgl
 
 from .read_swash import *
 
@@ -17,20 +18,39 @@ root = pathlib.Path(config.get("swash", "out"))
 bathy = pd.read_hdf(cache.joinpath("bathy.h5"), "bathy")
 n = bathy.index.size
 
-# xp = read_nohead_scalar(root.joinpath("xp.dat"), n)
 botl = read_nohead_scalar(root.joinpath("botl.dat"), n)
 dep = np.maximum(0, read_nohead_scalar(root.joinpath("dep.dat"), n))
 vel = read_nohead_vect(root.joinpath("vel.dat"), n)
-# watl = read_nohead_scalar(root.joinpath("watl.dat"), n)
 
+n_t = botl.shape[0]
+
+# Cospectral calculations
+pos_x = n//10
+
+eta = (dep - botl)[n_t//2:, pos_x]
+u = vel[n_t//2:, 0, pos_x]
+
+phi_eta = np.abs(sgl.csd(eta, eta)[1])
+phi_u = np.abs(sgl.csd(u, u)[1])
+phi_eta_u = np.abs(sgl.csd(eta, u)[1])
+
+R = np.sqrt((phi_eta + phi_u - 2*phi_eta_u)/(phi_eta + phi_u + 2*phi_eta_u))
+
+# Plotting
 fig, (ax_dep, ax_vel) = plt.subplots(2)
 
-ax_dep.plot((dep - botl)[:, n//2], label="dep", color="#0066ff")
+ax_dep.plot((dep - botl)[:, pos_x], label="dep", color="#0066ff")
 ax_dep.set(xlabel="t (s)", ylabel="z (m)")
 
-ax_vel.plot(vel[:, 0, n//2], label="vel")
+ax_vel.plot(vel[:, 0, pos_x], label="vel")
 ax_vel.set(xlabel="t (s)", ylabel="U (m/s)")
 
 fig.tight_layout()
-#fig.legend()
+
+fig_r, ax_r = plt.subplots()
+
+ax_r.plot(R)
+ax_r.set(ylim=(0,1))
+ax_r.grid()
+
 plt.show(block=True)