Test the use of a reverse burst at the end of a transmission.

FM.cpp

@@ -45,6 +45,7 @@ m_kerchunkTimer(),
 m_ackMinTimer(),
 m_ackDelayTimer(),
 m_hangTimer(),
+m_reverseTimer(),
 m_filterStage1(  724,   1448,   724, 32768, -37895, 21352),//3rd order Cheby Filter 300 to 2700Hz, 0.2dB passband ripple, sampling rate 24kHz
 m_filterStage2(32768,      0,-32768, 32768, -50339, 19052),
 m_filterStage3(32768, -65536, 32768, 32768, -64075, 31460),
@@ -57,6 +58,8 @@ m_rxLevel(1),
 m_inputRB(4800U),   // 200ms of audio
 m_outputRB(2400U)   // 100ms of audio
 {
+  m_reverseTimer.setTimeout(0U, 150U);
+
   insertDelay(100U);
 }
 
@@ -141,10 +144,9 @@ void CFM::samples(bool cos, const q15_t* samples, uint8_t length)
     if (!m_callsign.isRunning() && !m_rfAck.isRunning())
       currentSample += m_timeoutTone.getAudio();
 
-    currentSample += m_ctcssTX.getAudio();
+    currentSample += m_ctcssTX.getAudio(m_reverseTimer.isRunning());
 
-    if (m_modemState == STATE_FM)
-      m_outputRB.put(currentSample);
+    m_outputRB.put(currentSample);
   }
 }
 
@@ -165,6 +167,7 @@ void CFM::reset()
   m_ackMinTimer.stop();
   m_ackDelayTimer.stop();
   m_hangTimer.stop();
+  m_reverseTimer.stop();
 
   m_ctcssRX.reset();
   m_rfAck.stop();
@@ -254,7 +257,10 @@ void CFM::stateMachine(bool validSignal)
   }
 
   if (m_state == FS_LISTENING && m_modemState == STATE_FM) {
-    if (!m_callsign.isWanted() && !m_rfAck.isWanted()) {
+    if (!m_callsign.isWanted() && !m_rfAck.isWanted() && !m_reverseTimer.isRunning())
+      m_reverseTimer.start();
+
+    if (!m_callsign.isWanted() && !m_rfAck.isWanted() && m_reverseTimer.isRunning() && m_reverseTimer.hasExpired()) {
       DEBUG1("Change to STATE_IDLE");
       m_modemState = STATE_IDLE;
       m_callsignTimer.stop();
@@ -263,6 +269,7 @@ void CFM::stateMachine(bool validSignal)
       m_ackMinTimer.stop();
       m_ackDelayTimer.stop();
       m_hangTimer.stop();
+      m_reverseTimer.stop();
     }
   }
 }
@@ -276,6 +283,7 @@ void CFM::clock(uint8_t length)
   m_ackMinTimer.clock(length);
   m_ackDelayTimer.clock(length);
   m_hangTimer.clock(length);
+  m_reverseTimer.clock(length);
 }
 
 void CFM::listeningState(bool validSignal)
@@ -299,6 +307,7 @@ void CFM::listeningState(bool validSignal)
     beginRelaying();
 
     m_callsignTimer.start();
+    m_reverseTimer.stop();
 
     io.setDecode(true);
     io.setADCDetection(true);

FM.h

@@ -75,6 +75,7 @@ private:
   CFMTimer             m_ackMinTimer;
   CFMTimer             m_ackDelayTimer;
   CFMTimer             m_hangTimer;
+  CFMTimer             m_reverseTimer;
   CFMDirectFormI       m_filterStage1;
   CFMDirectFormI       m_filterStage2;
   CFMDirectFormI       m_filterStage3;

FMCTCSSTX.cpp

@@ -115,11 +115,14 @@ uint8_t CFMCTCSSTX::setParams(uint8_t frequency, uint8_t level)
   return 0U;
 }
 
-q15_t CFMCTCSSTX::getAudio()
+q15_t CFMCTCSSTX::getAudio(bool reverse)
 {
   q15_t sample = m_values[m_n++];
-  if(m_n >= m_length)
+  if (m_n >= m_length)
     m_n = 0U;
   
-  return sample;
+  if (reverse)
+    return -sample;
+  else
+    return sample;
 }

FMCTCSSTX.h

@@ -27,7 +27,7 @@ public:
 
   uint8_t setParams(uint8_t frequency, uint8_t level);
 
-  q15_t getAudio();
+  q15_t getAudio(bool reverse);
 
 private:
   q15_t*   m_values;

SerialPort.cpp

@@ -103,7 +103,7 @@ const uint8_t MMDVM_DEBUG5       = 0xF5U;
 #define	HW_TYPE	"MMDVM"
 #endif
 
-#define DESCRIPTION "20200713 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM)"
+#define DESCRIPTION "20200714 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM)"
 
 #if defined(GITVERSION)
 #define concat(h, a, b, c) h " " a " " b " GitID #" c ""