diff --git a/pyproject.toml b/pyproject.toml
index 74445cc..0a57f44 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,11 @@ classifiers = [
 	"Development Status :: 2 - Pre-Alpha",
 	"Topic :: Scientific/Engineering",
 ]
+dependencies = [
+	"numpy",
+	"scipy",
+	"rich",
+]
 
 [project.urls]
 Homepage = "https://git.linarphy.net/linarphy/backscattering-analyzer"
diff --git a/src/backscattering_analyzer/analyzer.py b/src/backscattering_analyzer/analyzer.py
index 128326f..bcced61 100644
--- a/src/backscattering_analyzer/analyzer.py
+++ b/src/backscattering_analyzer/analyzer.py
@@ -187,29 +187,14 @@ class Analyzer:
         """
         coupling = self.modelisation[self.settings.coupling_name()]
 
-        coupling_1, coupling_2 = (
-            array(
-                [
-                    self.modelisation["freq"][0],
-                    coupling[0],
-                ]
-            ),
-            array(
-                [
-                    self.modelisation["freq"][0],
-                    coupling[1],
-                ]
-            ),
-        )
+        nperseg = int(len(coupling[0]) * 2) - 1
 
         rate = 1 / (self.movement[0, 1] - self.movement[0, 0])
 
-        result = zeros(self.bench_movement.shape[1])
+        result = zeros(coupling.shape[1])
         scattering_factor = [0, 0]
 
-        for index in range(
-            len(self.modelisation[self.settings.coupling_name()])
-        ):
+        for index in range(len(coupling)):
             argument = (
                 self.movement[1]
                 * 4
@@ -226,7 +211,7 @@ class Analyzer:
                         psd(
                             sin(argument),
                             fs=rate,
-                            nperseg=2999,
+                            nperseg=nperseg,
                         )[1]
                         * abs(coupling[0])
                     )
@@ -235,7 +220,7 @@ class Analyzer:
                         psd(
                             cos(argument),
                             fs=rate,
-                            nperseg=2999,
+                            nperseg=nperseg,
                         )[1]
                         * abs(coupling[1])
                     )