Show average period of beacons

src/StationRow.vue

@@ -4,6 +4,7 @@
     <template v-if="status.lastHeard">
       <td>{{ formatTime(status.lastHeard) }}</td>
       <td>{{ formatTime(now - status.lastHeard, true) }}</td>
+      <td>{{ formatTime(Math.round(status.avgDelta), true) }}</td>
       <td>{{ status.lastVoltage || "" }}</td>
       <td>{{ status.lastTemperature || "" }}</td>
     </template>
@@ -12,6 +13,7 @@
       <td>Never Heard</td>
       <td>Never Heard</td>
       <td>Never Heard</td>
+      <td>Never Heard</td>
     </template>
   </tr>
 </template>
@@ -66,9 +68,14 @@ export default {
     messages() {
       Object.assign(
         this.status,
-        this.messages.reduce((acc, message) => {
+        this.messages.reduce((acc, message, idx, arr) => {
           acc.lastHeard = message.date.getTime();
-          acc.delta = message.date - acc.lastHeard;
+          if (idx === 0) {
+            acc.avgDelta = 0;
+          } else {
+            let delta = message.date.getTime() - arr[idx - 1].date.getTime();
+            acc.avgDelta = (acc.avgDelta * (idx - 1) + delta) / idx;
+          }
           if ("data" in message && "analog" in message.data) {
             acc.lastVoltage = message.data.analog[0] / 10;
             acc.lastTemperature = message.data.analog[1];

src/StatusScreen.vue

@@ -5,6 +5,7 @@
         <th>Callsign</th>
         <th>Last Heard</th>
         <th>Time since Last Heard</th>
+        <th>Avg. Period</th>
         <th>Last Voltage</th>
         <th>Last Temperature</th>
       </tr>