diff --git a/analytics/analytics/detectors/threshold_detector.py b/analytics/analytics/detectors/threshold_detector.py
index 8d92130..ad4fd13 100644
--- a/analytics/analytics/detectors/threshold_detector.py
+++ b/analytics/analytics/detectors/threshold_detector.py
@@ -1,6 +1,7 @@
 import logging as log
 
 import pandas as pd
+import numpy as np
 from typing import Optional
 
 from detectors import Detector
@@ -30,44 +31,47 @@ class ThresholdDetector(Detector):
     def detect(self, dataframe: pd.DataFrame, cache: ModelCache) -> dict:
         if cache is None or cache == {}:
             raise ValueError('Threshold detector error: cannot detect before learning')
+        if len(dataframe) == 0:
+            return None
+
         value = cache['value']
         condition = cache['condition']
 
-        now = convert_sec_to_ms(time())
         segments = []
+        for index, row in dataframe.iterrows():
+            current_timestamp = convert_pd_timestamp_to_ms(row['timestamp'])
+            segment = { 'from': current_timestamp, 'to': current_timestamp }
+            # TODO: merge segments
+            if pd.isnull(row['value']):
+                if condition == 'NO_DATA':
+                    segment['params'] = { value: None }
+                    segments.append(segment)
+                continue
 
-        dataframe_without_nans = dataframe.dropna()
-        if len(dataframe_without_nans) == 0:
-            if condition == 'NO_DATA':
-                segments.append({ 'from': now, 'to': now , 'params': { value: 'NO_DATA' } })
-            else:
-                return None
-        else:
-            last_entry = dataframe_without_nans.iloc[-1]
-            last_time = convert_pd_timestamp_to_ms(last_entry['timestamp'])
-            last_value = float(last_entry['value'])
-            segment = { 'from': last_time, 'to': last_time, 'params': { value: last_value } }
-
+            current_value = row['value']
+            segment['params'] = { value: row['value'] }
             if condition == '>':
-                if last_value > value:
+                if current_value > value:
                     segments.append(segment)
             elif condition == '>=':
-                if last_value >= value:
+                if current_value >= value:
                     segments.append(segment)
             elif condition == '=':
-                if last_value == value:
+                if current_value == value:
                     segments.append(segment)
             elif condition == '<=':
-                if last_value <= value:
+                if current_value <= value:
                     segments.append(segment)
             elif condition == '<':
-                if last_value < value:
+                if current_value < value:
                     segments.append(segment)
 
+        last_entry = dataframe.iloc[-1]
+        last_detection_time = convert_pd_timestamp_to_ms(last_entry['timestamp'])
         return {
             'cache': cache,
             'segments': segments,
-            'lastDetectionTime': now
+            'lastDetectionTime': last_detection_time
         }
 
     def consume_data(self, data: pd.DataFrame, cache: Optional[ModelCache]) -> Optional[dict]: