diff --git a/numass-core/src/main/java/inr/numass/data/analyzers/TimeAnalyzer.java b/numass-core/src/main/java/inr/numass/data/analyzers/TimeAnalyzer.java
index 682dc712..7eadcfb8 100644
--- a/numass-core/src/main/java/inr/numass/data/analyzers/TimeAnalyzer.java
+++ b/numass-core/src/main/java/inr/numass/data/analyzers/TimeAnalyzer.java
@@ -103,14 +103,17 @@ public class TimeAnalyzer extends AbstractAnalyzer {
             return v1;
         }
 
+
+        double t1 = v1.getDouble(LENGTH_KEY);
+        double t2 = v2.getDouble(LENGTH_KEY);
         double cr1 = v1.getDouble(COUNT_RATE_KEY);
         double cr2 = v2.getDouble(COUNT_RATE_KEY);
-        double w1 = Math.pow(v1.getDouble(COUNT_RATE_ERROR_KEY), -2);
-        double w2 = Math.pow(v2.getDouble(COUNT_RATE_ERROR_KEY), -2);
+        double err1 = v1.getDouble(COUNT_RATE_ERROR_KEY);
+        double err2 = v2.getDouble(COUNT_RATE_ERROR_KEY);
 
-        double countRate = (cr1 * w1 + cr2 * w2) / (1d * w1 + 1d * w2);
+        double countRate = (t1 * cr1 + t2 * cr2) / (t1 + t2);
 
-        double countRateErr = Math.sqrt(1d / (w1 + w2));
+        double countRateErr = Math.sqrt(Math.pow(t1 * err1 / (t1 + t2), 2) + Math.pow(t2 * err1 / (t1 + t2), 2));
 
 
         return ValueMap.of(NAME_LIST,
@@ -141,7 +144,7 @@ public class TimeAnalyzer extends AbstractAnalyzer {
         Stream<NumassEvent> eventStream = super.getEvents(block, config);//using super implementation
 
         return eventStream.map(event -> {
-            long res = lastEvent.get() == null ? -1L : event.getTimeOffset() - lastEvent.get().getTimeOffset();
+            long res = lastEvent.get() == null ? 0L : event.getTimeOffset() - lastEvent.get().getTimeOffset();
 
             if (res < 0) {
                 res = 0L;
diff --git a/numass-main/src/main/groovy/inr/numass/scripts/times/TestAnalyzer.groovy b/numass-main/src/main/groovy/inr/numass/scripts/times/TestAnalyzer.groovy
new file mode 100644
index 00000000..d57b9a77
--- /dev/null
+++ b/numass-main/src/main/groovy/inr/numass/scripts/times/TestAnalyzer.groovy
@@ -0,0 +1,43 @@
+package inr.numass.scripts.times
+
+import hep.dataforge.context.Context
+import hep.dataforge.context.Global
+import hep.dataforge.grind.Grind
+import hep.dataforge.grind.GrindShell
+import hep.dataforge.kodex.fx.plots.PlotManager
+import inr.numass.NumassPlugin
+import inr.numass.actions.TimeAnalyzedAction
+import inr.numass.data.SimpleChainGenerator
+import inr.numass.data.api.SimpleNumassPoint
+import org.apache.commons.math3.random.JDKRandomGenerator
+
+import java.time.Instant
+
+/**
+ * Created by darksnake on 27-Jun-17.
+ */
+
+
+Context ctx = Global.instance()
+ctx.pluginManager().load(PlotManager)
+ctx.pluginManager().load(NumassPlugin.class)
+
+new GrindShell(ctx).eval {
+
+    double cr = 15e3;
+    long length = 30e9;
+    def num = 5;
+
+
+
+    def blocks = (1..num).collect {
+        def generator = new SimpleChainGenerator(1e4 + 1000*num, new JDKRandomGenerator(), { 1000 })
+        generator.generateBlock(Instant.now().plusNanos(it * length), length)
+    }
+
+    def point = new SimpleNumassPoint(10000, blocks)
+
+    def meta = Grind.buildMeta(plotHist: false)
+
+    new TimeAnalyzedAction().simpleRun(point, meta);
+}
\ No newline at end of file
diff --git a/numass-main/src/main/java/inr/numass/utils/NMEventGenerator.java b/numass-main/src/main/java/inr/numass/utils/NMEventGenerator.java
index 26307b47..2d225757 100644
--- a/numass-main/src/main/java/inr/numass/utils/NMEventGenerator.java
+++ b/numass-main/src/main/java/inr/numass/utils/NMEventGenerator.java
@@ -36,6 +36,7 @@ import static inr.numass.data.api.NumassAnalyzer.COUNT_RATE_KEY;
  *
  * @author Darksnake
  */
+@Deprecated
 public class NMEventGenerator {
 
     protected final RandomGenerator rnd;
@@ -169,7 +170,7 @@ public class NMEventGenerator {
     }
 
     private double nextExpDecay(double mean) {
-        return -mean * Math.log(1 - rnd.nextDouble());
+        return - mean * Math.log(1 - rnd.nextDouble());
     }
 
 }
diff --git a/numass-main/src/main/kotlin/inr/numass/actions/TimeAnalyzedAction.kt b/numass-main/src/main/kotlin/inr/numass/actions/TimeAnalyzedAction.kt
index 0c4589bb..5b398f46 100644
--- a/numass-main/src/main/kotlin/inr/numass/actions/TimeAnalyzedAction.kt
+++ b/numass-main/src/main/kotlin/inr/numass/actions/TimeAnalyzedAction.kt
@@ -95,9 +95,19 @@ class TimeAnalyzedAction : OneToOneAction<NumassPoint, Table>() {
             histPlot.add(histogramPlot)
         }
 
-        if(inputMeta.getBoolean("plotStat",true)) {
+        if (inputMeta.getBoolean("plotStat", true)) {
 
-            val statPlotPoints = (1..150).map { 1000 * it }.map { t ->
+            val statPlot = DataPlot(name).configure {
+                "showLine" to true
+                "thickness" to 4
+                "title" to "${name}_${input.voltage}"
+            }.apply {
+                configure(inputMeta.getMetaOrEmpty("plot"))
+            }
+
+            pm.getPlotFrame(getName(), "stat-method").add(statPlot)
+
+            (1..100).map { 1000 * it }.map { t ->
                 val result = analyzer.analyze(input, buildMeta {
                     "t0" to t
                     "window.lo" to loChannel
@@ -111,22 +121,16 @@ class TimeAnalyzedAction : OneToOneAction<NumassPoint, Table>() {
                     1.0
                 }
 
-                XYAdapter.DEFAULT_ADAPTER.buildXYDataPoint(
-                        t / 1000.0,
-                        result.getDouble("cr") / norm,
-                        result.getDouble(NumassAnalyzer.COUNT_RATE_ERROR_KEY) / norm
+                statPlot.append(
+                        XYAdapter.DEFAULT_ADAPTER.buildXYDataPoint(
+                                t / 1000.0,
+                                result.getDouble("cr") / norm,
+                                result.getDouble(NumassAnalyzer.COUNT_RATE_ERROR_KEY) / norm
+                        )
                 )
             }
 
-            val statPlot = DataPlot(name).configure {
-                "showLine" to true
-                "thickness" to 4
-                "title" to "${name}_${input.voltage}"
-            }.apply {
-                configure(inputMeta.getMetaOrEmpty("plot"))
-            }.fillData(statPlotPoints)
 
-            pm.getPlotFrame(getName(), "stat-method").add(statPlot)
         }
 
         return histogram;
diff --git a/numass-main/src/main/kotlin/inr/numass/data/ChainGenerator.kt b/numass-main/src/main/kotlin/inr/numass/data/ChainGenerator.kt
new file mode 100644
index 00000000..04cbbcd7
--- /dev/null
+++ b/numass-main/src/main/kotlin/inr/numass/data/ChainGenerator.kt
@@ -0,0 +1,45 @@
+package inr.numass.data
+
+import inr.numass.data.api.NumassBlock
+import inr.numass.data.api.NumassEvent
+import inr.numass.data.api.SimpleBlock
+import org.apache.commons.math3.random.JDKRandomGenerator
+import org.apache.commons.math3.random.RandomGenerator
+import java.time.Duration
+import java.time.Instant
+import java.util.*
+
+interface ChainGenerator {
+
+    fun next(event: NumassEvent?): NumassEvent
+
+    fun generateBlock(start: Instant, length: Long): NumassBlock {
+        val events = ArrayList<NumassEvent>()
+        var event = next(null)
+        while (event.timeOffset < length) {
+            events.add(event)
+            event = next(event)
+        }
+        return SimpleBlock(start, Duration.ofNanos(length), events)
+    }
+}
+
+class SimpleChainGenerator(val cr: Double, private var rnd: RandomGenerator = JDKRandomGenerator(), private val amp: () -> Short = { 1 }) : ChainGenerator {
+
+    override fun next(event: NumassEvent?): NumassEvent {
+        return if (event == null) {
+            NumassEvent(amp(), Instant.EPOCH, 0)
+        } else {
+            NumassEvent(amp(), event.blockTime, event.timeOffset + generateDeltaTime())
+        }
+    }
+
+    private fun nextExpDecay(mean: Double): Double {
+        return -mean * Math.log(1 - rnd.nextDouble())
+    }
+
+    private fun generateDeltaTime(): Long {
+        return (nextExpDecay(1.0 / cr) * 1e9).toLong()
+    }
+
+}