added preference for AFSK preamble

res/values/strings.xml

@@ -173,6 +173,9 @@
 <string name="p_aprs_path_hint">hop 1, hop 2, ...</string>
 <string name="p_aprs_path_summary">Sequence of digipeaters</string>
 <string name="p_aprs_path_entry">Enter the comma separated digi path</string>
+<string name="p_afsk_prefix">Frame Sync Prefix</string>
+<string name="p_afsk_prefix_summary">No-Op Preamble (e.g. for VOX control)</string>
+<string name="p_afsk_prefix_entry">Enter the prefix time [ms]</string>
 
 <!-- TCP server settings -->
 <string name="p_tcp_server_summary">APRS-IS TCP server (port 14580) to contact</string>

res/xml/pref_afsk.xml

@@ -13,6 +13,15 @@
 		android:summary="@string/p_aprs_path_summary"
 		android:dialogTitle="@string/p_aprs_path_entry" />
 
+        <EditTextPreference
+                android:key="afsk.prefix"
+		android:inputType="number"
+		android:defaultValue="1000"
+		android:hint="1000"
+		android:title="@string/p_afsk_prefix"
+		android:summary="@string/p_afsk_prefix_summary"
+		android:dialogTitle="@string/p_afsk_prefix_entry" />
+
     </PreferenceCategory>
 
 </PreferenceScreen>

src/backend/AfskUploader.scala

@@ -6,7 +6,8 @@ import com.nogy.afu.soundmodem.{Message, APRSFrame, Afsk}
 
 class AfskUploader(prefs : PrefsWrapper) extends AprsIsUploader(prefs) {
 	val TAG = "AprsAfsk"
-	var FrameLength = 150	//1200Bits = 1sec to open VOX
+	// frame prefix: bytes = milliseconds * baudrate / 8 / 1000
+	var FrameLength = prefs.getStringInt("afsk.prefix", 1000)*1200/8/1000
 	var Digis = prefs.getString("digi_path", "WIDE1-1")
 	
 	def start() {
@@ -27,12 +28,4 @@ class AfskUploader(prefs : PrefsWrapper) extends AprsIsUploader(prefs) {
 	def stop() {
 	}
 
-	// Non Interface methods
-	def set_FrameLength(length: Int) = {
-		FrameLength = length
-	}
-
-	def set_Digis(Digipeaters : String) = {
-		Digis = Digipeaters
-	}
 }