diff --git a/README.md b/README.md
index 7234d88..1308d2b 100644
--- a/README.md
+++ b/README.md
@@ -24,8 +24,30 @@ Same as Fizzy I have not done any of the coding. My only idea with this fork is
 
 Further modifications added by [tmiklas](https://github.com/tmiklas/tbeam-helium-mapper):
 
+**2021-11-18** - Introducing **distance target** mode (a.k.a. TX window scaling)
+
+Verison: `1.1-tm`
+
+Most mappers usually operate in **time target** mode, where they send data to network every set interval (i.e. `SEND_INTERVAL`). There is however a different use case for fast moving mappers - like in a car at motorway speeds...
+
+This feature allows you to switch mapping mode from time target to distace target and back. You can configure your desierd distance target in `configuration.h` and turn ON/OFF by pressing the `USR` button for over 1sec:
+
+```
+#define DISTANCE_TARGET          200.0     // MUST be decimal number; distance target in meters
+```
+
+![T-Beam buttons](img/t-beam-buttons.jpeg)
+
+Once moving, you will be able to see it operating properly and reporting TX window:
+
+![TX Window Scaling](img/TX-window-scaling.jpeg)
+
+In simple terms, with distance target set to 200m (as default in this code), window scaling starts working once you travel at speed over 10m/s (36k/h or 22.3mph). There's also a lower limit - do not transmit more often than every 2sec... so with 200m target you are good up to 100m/s (360k/h or 223mph) - good luck :-P
+
 **2021-11-14** - Added some new features
 
+Verison: `1.0-tm`
+
 > Send Now - transmit on deman by short-pressing 2nd button
 
 Reacts to short-press of the central button and overrides any travel distance requirement (see 2 below).
@@ -41,11 +63,13 @@ This is controlled by 2 variables in `configuration.h` file, `MIN_DIST` and `STA
 Example:
 
 ```
+#define SEND_INTERVAL           (20 * 1000)     // Sleep for these many millis
+
 // -----------------------------------------------------------------------------
 // LoRa send criteria
 // -----------------------------------------------------------------------------
 #define MIN_DIST                 50.0      // MUST be decimal number; minimum distance in meters from the last sent location before we can send again. A hex is about 340m, divide by this value to get the pings per hex.
-#define STATIONARY_TX_INTERVAL   60        // If stationary the LoRa frame will be sent once every N cycles... with 30sec cycle, interval of 60 means to transmit once every 30min
+#define STATIONARY_TX_INTERVAL   60        // If stationary the LoRa frame will be sent once every N cycles... with 20sec cycle, interval of 60 means to transmit once every 20min
 
 ```
 
diff --git a/img/TX-window-scaling.jpeg b/img/TX-window-scaling.jpeg
new file mode 100644
index 0000000..979d4fc
Binary files /dev/null and b/img/TX-window-scaling.jpeg differ
diff --git a/img/t-beam-buttons.jpeg b/img/t-beam-buttons.jpeg
new file mode 100644
index 0000000..4c3a657
Binary files /dev/null and b/img/t-beam-buttons.jpeg differ
diff --git a/main/configuration.h b/main/configuration.h
index 5063e91..3d271ee 100644
--- a/main/configuration.h
+++ b/main/configuration.h
@@ -33,7 +33,7 @@ void ttn_register(void (*callback)(uint8_t message));
 // -----------------------------------------------------------------------------
 
 #define APP_NAME                "Helium TTGO"
-#define APP_VERSION             "1.0-tm"
+#define APP_VERSION             "1.1-tm"
 
 // -----------------------------------------------------------------------------
 // Configuration
@@ -80,6 +80,7 @@ void ttn_register(void (*callback)(uint8_t message));
 // -----------------------------------------------------------------------------
 #define MIN_DIST                 50.0      // MUST be decimal number; minimum distance in meters from the last sent location before we can send again. A hex is about 340m, divide by this value to get the pings per hex.
 #define STATIONARY_TX_INTERVAL   60        // If stationary the LoRa frame will be sent once every N cycles... with 30sec cycle, interval of 60 means to transmit once every 30min
+#define DISTANCE_TARGET          200.0     // MUST be decimal number; distance target in meters
 
 
 // -----------------------------------------------------------------------------
diff --git a/main/main.ino b/main/main.ino
index 9bb0363..c77947b 100644
--- a/main/main.ino
+++ b/main/main.ino
@@ -31,6 +31,7 @@
 
 */
 
+#include <Arduino.h>
 #include "configuration.h"
 #include "rom/rtc.h"
 #include <TinyGPS++.h>
@@ -45,8 +46,12 @@ float         last_send_lat           = 0;
 float         last_send_lon           = 0;
 float         min_dist_moved          = MIN_DIST;
 float         dist_moved              = UINT32_MAX;
+unsigned int  adjusted_SEND_INTERVAL  = SEND_INTERVAL;
 //
 
+// do we want to auto-scale transmit window size?
+bool autoScaleTX = false;
+
 AXP20X_Class axp;
 bool pmu_irq = false;
 String baChStatus = "No charging";
@@ -120,6 +125,22 @@ bool trySend() {
         screen_print(buffer);
       }
 
+      // TX window auto-scaling
+      // desired ping distance is 200m
+      if (autoScaleTX && !justSendNow) {
+        float newWindow = DISTANCE_TARGET / (dist_moved / adjusted_SEND_INTERVAL);  // seconds
+        if (newWindow > SEND_INTERVAL) { // both are in millis!
+          // we're too slow... default back to old mode with ping every SEND_INTERVAL
+          newWindow = SEND_INTERVAL;
+        } else if (newWindow < 2000) {
+          // this is 100m/s movement or 360kph or 220mph :-o
+          newWindow = 2000;
+        }
+        snprintf(buffer, sizeof(buffer), "TX window: %4.1fsec\n", newWindow / 1000);
+        screen_print(buffer);
+        adjusted_SEND_INTERVAL = newWindow; // millis
+      }
+
       // set back to normal mode
       justSendNow = false;
 
@@ -472,27 +493,50 @@ void loop() {
   static bool wasPressed = false;
   static uint32_t minPressMs; // what tick should we call this press long enough
   if (!digitalRead(BUTTON_PIN)) {
+
     if (!wasPressed) { // just started a new press
-      Serial.println("pressing");
+      // Serial.println("pressing");
       wasPressed = true;
-      minPressMs = millis() + 3000;
+      minPressMs = millis();
     }
+
   } else if (wasPressed) {
+
     // we just did a release
     wasPressed = false;
-    if (millis() > minPressMs) {
+    if (millis() > minPressMs + 1000) {
       // held long enough
-#ifndef PREFS_DISCARD
-      screen_print("Discarding prefs disabled\n");
-#endif
-#ifdef PREFS_DISCARD
-      screen_print("Discarding prefs!\n");
-      ttn_erase_prefs();
-      delay(5000); // Give some time to read the screen
-      ESP.restart();
-#endif
+      Serial.println("Long press!");
+      if (autoScaleTX) {
+        // turn off auto scaling to static trigger
+        autoScaleTX = false;
+        adjusted_SEND_INTERVAL = SEND_INTERVAL;
+        char buffer[40];
+        snprintf(buffer, sizeof(buffer), "TX scaling OFF\n");
+        screen_print(buffer);        
+        // screen_print("TX Scaling OFF");
+      } else {
+        // enable auto-scaling
+        autoScaleTX = true;
+        char buffer[40];
+        snprintf(buffer, sizeof(buffer), "TX scaling ON\n");
+        screen_print(buffer);        
+        // screen_print("TX Scaling ON");
+      }
+// #ifndef PREFS_DISCARD
+//       screen_print("Discarding prefs disabled\n");
+// #endif
+// #ifdef PREFS_DISCARD
+//       screen_print("Discarding prefs!\n");
+//       ttn_erase_prefs();
+//       delay(5000); // Give some time to read the screen
+//       ESP.restart();
+// #endif
+
     } else {
+
       // short press, send beacon
+      Serial.println("Short press :-P");
       justSendNow = true;
       trySend();
     }
@@ -501,7 +545,7 @@ void loop() {
   // Send every SEND_INTERVAL millis
   static uint32_t last = 0;
   static bool first = true;
-  if (0 == last || millis() - last > SEND_INTERVAL) {
+  if (0 == last || millis() - last > adjusted_SEND_INTERVAL) {
     if (trySend()) {
       last = millis();
       first = false;