diff --git a/src/main.c b/src/main.c
--- a/src/main.c
+++ b/src/main.c
@@ -137,12 +137,19 @@ int main(void)
     HAL_GPIO_TogglePin(LED_BLUE);
     HAL_Delay(100);
 
+    uint8_t lastMinute = 0;
 
     while (1)
     {
-        if(HAL_GetTick() - last_wspr > 120000)
+        if(HAL_GetTick() - last_wspr > 500)
         {
-            encode_wspr();
+            volatile uint8_t minute = get_timestamp()[3] - 0x30;
+
+            // If last minute was odd and this minute is even (transition)
+            if(lastMinute%2 == 1 && minute%2 == 0)
+                encode_wspr();
+
+            lastMinute = minute;
             last_wspr = HAL_GetTick();
         }