diff --git a/pyrelacs/ui/plots/calibration.py b/pyrelacs/ui/plots/calibration.py
new file mode 100644
index 0000000..8264b2d
--- /dev/null
+++ b/pyrelacs/ui/plots/calibration.py
@@ -0,0 +1,113 @@
+from IPython import embed
+import pyqtgraph as pg
+import numpy as np
+from scipy.signal import welch, find_peaks
+from scipy.integrate import romb
+
+
+class CalibrationPlot:
+    def __init__(self, figure: pg.GraphicsLayoutWidget, nix_file):
+        self.figure = figure
+        self.nix_file = nix_file
+
+    def plot(self):
+        self.figure.setBackground("w")
+        self.beat_plot = self.figure.addPlot(row=0, col=0)
+        self.power_plot = self.figure.addPlot(row=1, col=0)
+        self.beat_plot.addLegend()
+        self.power_plot.addLegend()
+        # self.power_plot.setLogMode(x=False, y=True)
+
+        block = self.nix_file.blocks[0]
+        colors = ["red", "green", "blue", "black", "yellow"]
+        for i, (stim, fish) in enumerate(
+            zip(list(block.data_arrays)[::2], list(block.data_arrays)[1::2])
+        ):
+            f_stim, stim_power = welch(
+                stim[:],
+                fs=40_000.0,
+                window="flattop",
+                nperseg=100_000,
+            )
+            stim_power = self.decibel(stim_power)
+            stim_max_power_index = np.argmax(stim_power)
+            freq_stim = f_stim[stim_max_power_index]
+
+            f_fish, fish_power = welch(
+                fish[:],
+                fs=40_000.0,
+                window="flattop",
+                nperseg=100_000,
+            )
+            fish_power = self.decibel(fish_power)
+            fish_max_power_index = np.argmax(fish_power)
+            freq_fish = f_fish[fish_max_power_index]
+
+            beat_frequency = np.abs(freq_fish - freq_stim)
+
+            beat = stim[:] + fish[:]
+            beat_squared = beat**2
+
+            f, powerspec = welch(
+                beat_squared,
+                window="flattop",
+                fs=40_000.0,
+                nperseg=100_000,
+            )
+            powerspec = self.decibel(powerspec)
+
+            padding = 20
+            integration_window = powerspec[
+                (f > beat_frequency - padding) & (f < beat_frequency + padding)
+            ]
+
+            peaks = find_peaks(powerspec, prominence=40)[0]
+
+            pen = pg.mkPen(colors[i])
+
+            self.beat_plot.plot(
+                np.arange(0, len(beat)) / 40_000.0,
+                beat,
+                pen=pen,
+                name=stim.name,
+            )
+            self.power_plot.plot(f, powerspec, pen=pen, name=stim.name)
+            self.power_plot.plot(f[peaks], powerspec[peaks], pen=None, symbol="x")
+
+    def decibel(self, power, ref_power=1.0, min_power=1e-20):
+        """Transform power to decibel relative to ref_power.
+
+        \\[ decibel = 10 \\cdot \\log_{10}(power/ref\\_power) \\]
+        Power values smaller than `min_power` are set to `-np.inf`.
+
+        Parameters
+        ----------
+        power: float or array
+            Power values, for example from a power spectrum or spectrogram.
+        ref_power: float or None or 'peak'
+            Reference power for computing decibel.
+            If set to `None` or 'peak', the maximum power is used.
+        min_power: float
+            Power values smaller than `min_power` are set to `-np.inf`.
+
+        Returns
+        -------
+        decibel_psd: array
+            Power values in decibel relative to `ref_power`.
+        """
+        if np.isscalar(power):
+            tmp_power = np.array([power])
+            decibel_psd = np.array([power])
+        else:
+            tmp_power = power
+            decibel_psd = power.copy()
+        if ref_power is None or ref_power == "peak":
+            ref_power = np.max(decibel_psd)
+        decibel_psd[tmp_power <= min_power] = float("-inf")
+        decibel_psd[tmp_power > min_power] = 10.0 * np.log10(
+            decibel_psd[tmp_power > min_power] / ref_power
+        )
+        if np.isscalar(power):
+            return decibel_psd[0]
+        else:
+            return decibel_psd