diff --git a/CentralHub.Api.Tests/MeasurementControllerTests.cs b/CentralHub.Api.Tests/MeasurementControllerTests.cs
index 9e68536..6b14dc0 100644
--- a/CentralHub.Api.Tests/MeasurementControllerTests.cs
+++ b/CentralHub.Api.Tests/MeasurementControllerTests.cs
@@ -100,34 +100,4 @@ public async Task TrackersFilteredFromMeasurements()
 
         Assert.That(addedMeasurements, Has.Count.EqualTo(0));
     }
-
-    [Test]
-    public async Task CalibrateMeasurements()
-    {
-        var measurements = new Measurement[] {
-            new Measurement("12:22:33:44:55:66", Measurement.Protocol.Bluetooth, 10),
-            new Measurement("ab:bb:cc:dd:ee:ff", Measurement.Protocol.Wifi, 20)
-        };
-
-        var addMeasurementsRequest = new AddMeasurementsRequest(_trackerId, measurements);
-        await _measurementController.AddMeasurements(addMeasurementsRequest, default);
-
-        await _localizationService.AggregateMeasurementsAsync(default);
-
-        var measurements3 = new Measurement[] {
-            new Measurement("13:22:33:44:55:66", Measurement.Protocol.Bluetooth, 10),
-            new Measurement("ac:bb:cc:dd:ee:ff", Measurement.Protocol.Wifi, 20),
-            new Measurement("14:22:33:44:55:66", Measurement.Protocol.Bluetooth, 10),
-            new Measurement("ab:bb:cc:dd:ee:ff", Measurement.Protocol.Wifi, 20)
-        };
-
-        var addMeasurementsRequest3 = new AddMeasurementsRequest(_trackerId, measurements3);
-        await _measurementController.AddMeasurements(addMeasurementsRequest3, default);
-        await _localizationService.AggregateMeasurementsAsync(default);
-
-        var lastAggregatedMeasurements = (await _measurementController.GetAggregateMeasurements(_roomId, default)).AggregatedMeasurements.Last();
-
-        Assert.That(lastAggregatedMeasurements.BluetoothCount, Is.EqualTo(1));
-        Assert.That(lastAggregatedMeasurements.WifiCount, Is.EqualTo(1));
-    }
 }
\ No newline at end of file
diff --git a/CentralHub.Api/Controllers/MeasurementController.cs b/CentralHub.Api/Controllers/MeasurementController.cs
index 8810a37..47f420b 100644
--- a/CentralHub.Api/Controllers/MeasurementController.cs
+++ b/CentralHub.Api/Controllers/MeasurementController.cs
@@ -138,19 +138,12 @@ await _occupancySettings.Lock(os =>
 
     private static IReadOnlyList<AggregatedMeasurements> CreateMeasurements(IEnumerable<AggregatedMeasurementDto> aggregatedMeasurements)
     {
-        var recentAggregatedMeasurements = aggregatedMeasurements
-            .Where(am => am.EndTime > (DateTime.UtcNow - TimeSpan.FromDays(1)))
-            .ToImmutableArray();
-
-        var bluetoothCalibrationNumber = recentAggregatedMeasurements.Min(am => am.BluetoothCount);
-        var wifiCalibrationNumber = recentAggregatedMeasurements.Min(am => am.WifiCount);
-
         return aggregatedMeasurements.Select(am => new AggregatedMeasurements(
             am.AggregatedMeasurementDtoId,
             am.StartTime,
             am.EndTime,
-            am.BluetoothCount - bluetoothCalibrationNumber,
-            am.WifiCount - wifiCalibrationNumber)
+            am.BluetoothCount,
+            am.WifiCount)
             ).ToImmutableArray();
     }
 
diff --git a/CentralHub.Api/Services/TrackerRepository.cs b/CentralHub.Api/Services/TrackerRepository.cs
index 6a57ead..9478929 100644
--- a/CentralHub.Api/Services/TrackerRepository.cs
+++ b/CentralHub.Api/Services/TrackerRepository.cs
@@ -110,6 +110,16 @@ public async Task RemoveTrackerAsync(TrackerDto trackerDto, CancellationToken ca
         }
 
         room.Trackers.Remove(trackerDto);
+        var unregisteredTracker = await UnregisteredTrackersMutex.Lock(unregisteredTrackers =>
+        {
+            var unregisteredTracker = new UnregisteredTrackerDto()
+            {
+                BluetoothMacAddress = trackerDto.BluetoothMacAddress,
+                WifiMacAddress = trackerDto.WifiMacAddress,
+            };
+            unregisteredTrackers.Add(unregisteredTracker);
+            return unregisteredTracker;
+        }, cancellationToken);
         _applicationDbContext.Rooms.Update(room);
         try
         {
@@ -120,6 +130,10 @@ public async Task RemoveTrackerAsync(TrackerDto trackerDto, CancellationToken ca
             // Set the roomDto to unchanged
             _applicationDbContext.Rooms.Attach(room).State = EntityState.Unchanged;
             room.Trackers.Add(trackerDto);
+            await UnregisteredTrackersMutex.Lock(unregisteredTrackers =>
+            {
+                unregisteredTrackers.Remove(unregisteredTracker);
+            }, cancellationToken);
             throw;
         }
     }