From 2cd2cf5cf1f00cf39497b3ca10ccf075c0e2473a Mon Sep 17 00:00:00 2001
From: Adam Wisher <37659188+mrwish7@users.noreply.github.com>
Date: Mon, 21 Apr 2025 08:22:36 +0100
Subject: [PATCH] TX ID Algorithm tweaks and config options

Fix bug when TX ERP is 1W and allow user choice of algorithms in webserver config
---
 server/server_config.js |  3 ++-
 server/tx_search.js     | 27 ++++++++++++++++++++++++---
 web/setup.ejs           | 10 ++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/server/server_config.js b/server/server_config.js
index 1be8796..8c6ae9b 100644
--- a/server/server_config.js
+++ b/server/server_config.js
@@ -30,7 +30,8 @@ let serverConfig = {
     ],
     defaultTheme: "theme1",
     bgImage: "",
-    rdsMode: false
+    rdsMode: false,
+    txIdAlgorithm: 0
   },
   xdrd: {
     wirelessConnection: true,
diff --git a/server/tx_search.js b/server/tx_search.js
index 38220e5..cf48bcd 100644
--- a/server/tx_search.js
+++ b/server/tx_search.js
@@ -12,6 +12,21 @@ var currentRdsPs = '';
 const usStatesGeoJsonUrl = "https://raw.githubusercontent.com/PublicaMundi/MappingAPI/master/data/geojson/us-states.json";
 let usStatesGeoJson = null;  // To cache the GeoJSON data for US states
 
+// Get weighting values based on algorithm setting.
+// Defaults = algorithm 1
+let weightedErp = 10;
+let weightedDist = 400;
+const algorithms = [
+    [10, 400],
+    [30, 500]
+];
+const algoSetting = parseInt(serverConfig.webserver.txIdAlgorithm);
+
+if (typeof algorithms[algoSetting] !== 'undefined') {
+    weightedErp = algorithms[algoSetting][0];
+    weightedDist = algorithms[algoSetting][1];
+}
+
 // Load the US states GeoJSON data
 async function loadUsStatesGeoJson() {
     if (!usStatesGeoJson) {
@@ -121,8 +136,14 @@ async function processData(data, piCode, rdsPs) {
             weightDistance = Math.abs(distance.distanceKm - 1500);
         }
         let erp = station.erp && station.erp > 0 ? station.erp : 1;
-        let extraWeight = erp >= 10 && distance.distanceKm <= 400 ? 0.3 : 0;
-        const score = ((10 * Math.log10(erp * 1000)) / weightDistance) + extraWeight;
+        let extraWeight = erp >= weightedErp && distance.distanceKm <= weightedDist ? 0.3 : 0;
+        let score = 0;
+        // If ERP is 1W, use a simpler formula to avoid zero-scoring.
+        if (erp === 0.001) {
+            score = erp / distance.distanceKm;
+        } else {
+            score = ((10 * Math.log10(erp * 1000)) / weightDistance) + extraWeight;
+        }
         if (score > maxScore) {
             maxScore = score;
             txAzimuth = distance.azimuth;
@@ -247,4 +268,4 @@ function deg2rad(deg) {
 
 module.exports = {
     fetchTx
-};
+};
\ No newline at end of file
diff --git a/web/setup.ejs b/web/setup.ejs
index f63edfd..207e671 100644
--- a/web/setup.ejs
+++ b/web/setup.ejs
@@ -296,6 +296,16 @@
                         <p>You can switch between American (RBDS) / Global (RDS) mode here.</p>
                         <%- include('_components', {component: 'checkbox', cssClass: 'bottom-20', iconClass: '', label: 'American RDS mode (RBDS)', id: 'webserver-rdsMode'}) %><br>
                     </div>
+                    <div class="panel-33 p-bottom-20" style="padding-left: 20px; padding-right: 20px;">
+                        <h3>Transmitter Search Algorithm</h3>
+                        <p>Different modes may help with more accurate transmitter identification depending on your region.</p>
+                        <%- include('_components', { component: 'dropdown', id: 'server-tx-id-algo', inputId: 'webserver-txIdAlgorithm', label: 'Transmitter ID Algorithm', cssClass: '', placeholder: 'Algorithm 1', 
+                        options: [
+                            { value: '0', label: 'Algorithm 1' },
+                            { value: '1', label: 'Algorithm 2' },
+                        ]
+                        }) %>
+                    </div>
                 </div>
 
             </div>