diff --git a/simulations/airshower_beacon_simulation/bb_measure_true_phase.py b/simulations/airshower_beacon_simulation/bb_measure_true_phase.py
index 3fae81a..e9e04b5 100755
--- a/simulations/airshower_beacon_simulation/bb_measure_true_phase.py
+++ b/simulations/airshower_beacon_simulation/bb_measure_true_phase.py
@@ -47,7 +47,13 @@ if __name__ == "__main__":
     N_beacon_freqs = len(antennas[0].beacon_info)
 
     for freq_name in antennas[0].beacon_info.keys():
-        true_phases = lib.antenna_true_phase_diff(tx, antennas, freq_name, c_light=c_light)
+        measured_phases = np.empty( (len(antennas)) )
+        for i, ant in enumerate(antennas):
+            measured_phases[i] = ant.beacon_info[freq_name]['phase']
+
+        f_beacon = antennas[0].beacon_info[freq_name]['freq']
+
+        true_phases = lib.remove_antenna_geometry_phase(tx, antennas, f_beacon, measured_phases, c_light=c_light)
 
         # Remove the phase from one antenna
         # this is a free parameter
diff --git a/simulations/airshower_beacon_simulation/lib/lib.py b/simulations/airshower_beacon_simulation/lib/lib.py
index e6ed9d4..85ddfd5 100644
--- a/simulations/airshower_beacon_simulation/lib/lib.py
+++ b/simulations/airshower_beacon_simulation/lib/lib.py
@@ -53,28 +53,24 @@ def beacon_from(tx, rx, f, t=0, t0=0, c_light=3e8, radiate_rsq=True, amplitude=1
 
     return sine_beacon(f, t, t0=t0, amplitude=amplitude,**kwargs)
 
-def antenna_true_phase_diff(tx, antennas, freq_name, c_light=3e8):
+def remove_antenna_geometry_phase(tx, antennas, f_beacon, measured_phases=None, c_light=3e8):
     """
-    Determine true phases from the antenna phases.
-
-    This removes the geometrical phase from the antenna phase.
+    Remove the geometrical phase from the measured antenna phase.
     """
     if not hasattr(antennas, '__len__'):
-        single_ant = True
         antennas = [antennas]
 
+    if not hasattr(measured_phases, '__len__'):
+        measured_phases = [measured_phases]
+
     true_phases = np.empty( (len(antennas)) )
     for i, ant in enumerate(antennas):
-        beacon_info = ant.beacon_info[freq_name]
-        measured_phase = beacon_info['phase']
-        f_beacon = beacon_info['freq']
+        measured_phase = measured_phases[i]
 
         geom_time = geometry_time(tx, ant, c_light=c_light)
         geom_phase = geom_time * 2*np.pi*f_beacon
 
-        print(ant.name, measured_phase, geom_phase, phase_mod(geom_phase))
-
-        true_phases[i] = phase_mod(phase_mod(measured_phase) - phase_mod(geom_phase) )
+        true_phases[i] = phase_mod(measured_phase - geom_phase)
 
     return true_phases