diff --git a/README.md b/README.md
index f1a3f6e..d712e75 100644
--- a/README.md
+++ b/README.md
@@ -383,6 +383,20 @@ for i in *; do if [ -f "../conf-available/$i" ]; then sudo ln -s -f "../conf-ava
 After that rerun the install script.
 If you still have history loading issues, get back to me via the github issues or the various forums i frequent.
 
+## heatmap in conjunction with readsb wiedehopf fork --heatmap feature:
+
+First parameter after /tar1090 in the URL mandatory, rest are optional
+- maximum number of dots to draw: /?heatmap=200000
+- duration in hours that shall be displayed: &heatDuration=48 (default: 24)
+- set the end of the duration 48 hours into the past: &heatEnd=48 (default:0)
+- radius of the dots: &heatRadius=2
+- opacity of the dots: &heatAlpha=2
+- only redraw the dots when pressing R on the keyboard: &heatManualRedraw
+
+alternative display style: &realHeat
+- blurryness: &heatBlur=2
+- weight of each dot for the heatmap: &heatWeight=4
+
 ## NO WARRANTY - Excerpt from the License:
 
   11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
diff --git a/html/early.js b/html/early.js
index c878aa5..59e96a7 100644
--- a/html/early.js
+++ b/html/early.js
@@ -146,6 +146,8 @@ if (usp.has('heatmap')) {
     let val;
     if (val = parseInt(usp.get('heatmap'), 10))
         heatmap.max = val;
+    if (usp.has('heatManualRedraw'))
+        heatmap.manualRedraw = true;
 }
 
 if (usp.has('pTracks')) {
diff --git a/html/script.js b/html/script.js
index 1476d87..40a78ac 100644
--- a/html/script.js
+++ b/html/script.js
@@ -1271,6 +1271,10 @@ function startPage() {
 
     drawUpintheair();
     mapRefresh();
+
+    if (heatmap) {
+        drawHeatmap();
+    }
 }
 
 //
@@ -3898,7 +3902,8 @@ function checkMovement() {
     const elapsed = Math.abs(ts - lastMovement);
 
     if (!checkMoveDone && heatmap && elapsed > 300) {
-        drawHeatmap();
+        if (!heatmap.manualRedraw)
+            drawHeatmap();
         checkMoveDone = 1;
     }
     if (elapsed > 500 || (!onMobile && elapsed > 45)) {
@@ -3938,7 +3943,7 @@ function checkRefresh() {
     }
 }
 function mapRefresh() {
-    if (!mapIsVisible)
+    if (!mapIsVisible || heatmap)
         return;
     //console.log('mapRefresh()');
     let addToMap = [];