Sporadic E mode for TX search

Add sporadic E mode for TX search, to optimise for 1500km distance if recent activity has been reported in server region.

server/tx_search.js

@@ -46,6 +46,7 @@ function processData(data, piCode, rdsPs) {
     let maxScore = -Infinity; // Initialize maxScore with a very low value
     let txAzimuth;
     let maxDistance;
+    let esMode = checkEs();
 
     for (const cityId in data.locations) {
         const city = data.locations[cityId];
@@ -53,7 +54,13 @@ function processData(data, piCode, rdsPs) {
             for (const station of city.stations) {
                 if (station.pi === piCode.toUpperCase() && !station.extra && station.ps && station.ps.toLowerCase().includes(rdsPs.replace(/ /g, '_').replace(/^_*(.*?)_*$/, '$1').toLowerCase())) {
                     const distance = haversine(serverConfig.identification.lat, serverConfig.identification.lon, city.lat, city.lon);
-                    const score =  (10*Math.log10(station.erp*1000)) / distance.distanceKm; // Calculate score
+                    let weightDistance = distance.distanceKm
+                    if (esMode && distance.distanceKm > 200) {
+                        weightDistance = Math.abs(distance.distanceKm-1500);
+                    } else {
+                        weightDistance = distance.distanceKm;
+                    }
+                    const score =  (10*Math.log10(station.erp*1000)) / weightDistance; // Calculate score
                     if (score > maxScore) {
                         maxScore = score;
                         txAzimuth = distance.azimuth;
@@ -82,6 +89,29 @@ function processData(data, piCode, rdsPs) {
     }
 }
 
+function checkEs() {
+    const url = "https://fmdx.org/includes/tools/get_muf.php";
+    let esSwitch = false;
+
+    fetch(url)
+        .then(response => response.json())
+        .then(data => {
+            if (serverConfig.identification.lon < -32) {
+                if (data.north_america.max_frequency != "No data") {
+                    esSwitch = true;
+                }
+            } else {
+                if (data.europe.max_frequency != "No data") {
+                    esSwitch = true;
+                }
+            }
+        })
+        .catch(error => {
+            console.error("Error fetching data:", error);
+        });
+    return esSwitch;
+}
+
 function haversine(lat1, lon1, lat2, lon2) {
     const R = 6371; // Earth radius in kilometers
     const dLat = deg2rad(lat2 - lat1);