diff --git a/src/algorithms/channel/adapters/channel.cc b/src/algorithms/channel/adapters/channel.cc
index f4c7fa77d..353f5a080 100644
--- a/src/algorithms/channel/adapters/channel.cc
+++ b/src/algorithms/channel/adapters/channel.cc
@@ -197,7 +197,13 @@ void Channel::set_signal(const Gnss_Signal& gnss_signal)
 
 void Channel::start_acquisition()
 {
-    channel_fsm_.Event_start_acquisition();
+    bool result = false;
+    result = channel_fsm_.Event_start_acquisition();
+    if(!result)
+        {
+            LOG(WARNING) << "Invalid channel event";
+            return;
+        }
     DLOG(INFO) << "Channel start_acquisition()";
 }
 
diff --git a/src/algorithms/channel/libs/channel_fsm.cc b/src/algorithms/channel/libs/channel_fsm.cc
index 499d55881..935c696ce 100644
--- a/src/algorithms/channel/libs/channel_fsm.cc
+++ b/src/algorithms/channel/libs/channel_fsm.cc
@@ -53,53 +53,88 @@ ChannelFsm::ChannelFsm(std::shared_ptr<AcquisitionInterface> acquisition) :
 }
 
 
-
-void ChannelFsm::Event_start_acquisition()
+bool ChannelFsm::Event_start_acquisition()
 {
-    mx.lock();
-    d_state = 1;
-    start_acquisition();
-    DLOG(INFO) << "CH = " << channel_ << ". Ev start acquisition";
-    mx.unlock();
+    std::lock_guard<std::mutex> lk(mx);
+    if((d_state == 1) || (d_state == 2))
+        {
+            return false;
+        }
+    else
+        {
+            d_state = 1;
+            start_acquisition();
+            DLOG(INFO) << "CH = " << channel_ << ". Ev start acquisition";
+            return true;
+        }
 }
 
 
-void ChannelFsm::Event_valid_acquisition()
+bool ChannelFsm::Event_valid_acquisition()
 {
-    mx.lock();
-    d_state = 2;
-    start_tracking();
-    DLOG(INFO) << "CH = " << channel_ << ". Ev valid acquisition";
-    mx.unlock();
+    std::lock_guard<std::mutex> lk(mx);
+    if(d_state != 1)
+        {
+            return false;
+        }
+    else
+        {
+            d_state = 2;
+            start_tracking();
+            DLOG(INFO) << "CH = " << channel_ << ". Ev valid acquisition";
+            return true;
+        }
 }
 
 
-void ChannelFsm::Event_failed_acquisition_repeat()
+bool ChannelFsm::Event_failed_acquisition_repeat()
 {
-    mx.lock();
-    d_state = 1;
-    start_acquisition();
-    DLOG(INFO) << "CH = " << channel_ << ". Ev failed acquisition repeat";
-    mx.unlock();
-}
-
-void ChannelFsm::Event_failed_acquisition_no_repeat()
-{
-    mx.lock();
-    d_state = 3;
-    request_satellite();
-    DLOG(INFO) << "CH = " << channel_ << ". Ev failed acquisition no repeat";
-    mx.unlock();
+    std::lock_guard<std::mutex> lk(mx);
+    if(d_state != 1)
+        {
+            return false;
+        }
+    else
+        {
+            d_state = 1;
+            start_acquisition();
+            DLOG(INFO) << "CH = " << channel_ << ". Ev failed acquisition repeat";
+            return true;
+        }
 }
 
 
-void ChannelFsm::Event_failed_tracking_standby()
+bool ChannelFsm::Event_failed_acquisition_no_repeat()
 {
-    mx.lock();
-    d_state = 0;
-    notify_stop_tracking();
-    DLOG(INFO) << "CH = " << channel_ << ". Ev failed tracking standby";
-    mx.unlock();
+    std::lock_guard<std::mutex> lk(mx);
+    if(d_state != 1)
+        {
+            return false;
+        }
+    else
+        {
+            d_state = 3;
+            request_satellite();
+            DLOG(INFO) << "CH = " << channel_ << ". Ev failed acquisition no repeat";
+            return true;
+        }
+}
+
+
+bool ChannelFsm::Event_failed_tracking_standby()
+{
+    std::lock_guard<std::mutex> lk(mx);
+    if(d_state != 2)
+        {
+            return false;
+        }
+    else
+        {
+            d_state = 0;
+            notify_stop_tracking();
+            DLOG(INFO) << "CH = " << channel_ << ". Ev failed tracking standby";
+            return true;
+        }
 }
 
 void ChannelFsm::set_acquisition(std::shared_ptr<AcquisitionInterface> acquisition)
diff --git a/src/algorithms/channel/libs/channel_fsm.h b/src/algorithms/channel/libs/channel_fsm.h
index 29f741bfc..23b92c394 100644
--- a/src/algorithms/channel/libs/channel_fsm.h
+++ b/src/algorithms/channel/libs/channel_fsm.h
@@ -54,11 +54,11 @@ public:
     void set_channel(unsigned int channel);
 
     //FSM EVENTS
-    void Event_start_acquisition();
-    void Event_valid_acquisition();
-    void Event_failed_acquisition_repeat();
-    void Event_failed_acquisition_no_repeat();
-    void Event_failed_tracking_standby();
+    bool Event_start_acquisition();
+    bool Event_valid_acquisition();
+    bool Event_failed_acquisition_repeat();
+    bool Event_failed_acquisition_no_repeat();
+    bool Event_failed_tracking_standby();
 
 private:
 
diff --git a/src/algorithms/channel/libs/channel_msg_receiver_cc.cc b/src/algorithms/channel/libs/channel_msg_receiver_cc.cc
index d22f2dd73..a88fc6d88 100644
--- a/src/algorithms/channel/libs/channel_msg_receiver_cc.cc
+++ b/src/algorithms/channel/libs/channel_msg_receiver_cc.cc
@@ -44,26 +44,27 @@ channel_msg_receiver_cc_sptr channel_msg_receiver_make_cc(ChannelFsm* channel_fs
 
 void channel_msg_receiver_cc::msg_handler_events(pmt::pmt_t msg)
 {
+    bool result = false;
     try
     {
             long int message = pmt::to_long(msg);
             switch (message)
             {
             case 1: //positive acquisition
-                d_channel_fsm->Event_valid_acquisition();
+                result = d_channel_fsm->Event_valid_acquisition();
                 break;
             case 2: //negative acquisition
                 if (d_repeat == true)
                     {
-                        d_channel_fsm->Event_failed_acquisition_repeat();
+                        result = d_channel_fsm->Event_failed_acquisition_repeat();
                     }
                 else
                     {
-                        d_channel_fsm->Event_failed_acquisition_no_repeat();
+                        result = d_channel_fsm->Event_failed_acquisition_no_repeat();
                     }
                 break;
             case 3: // tracking loss of lock event
-                d_channel_fsm->Event_failed_tracking_standby();
+                result = d_channel_fsm->Event_failed_tracking_standby();
                 break;
             default:
                 LOG(WARNING) << "Default case, invalid message.";
@@ -74,6 +75,10 @@ void channel_msg_receiver_cc::msg_handler_events(pmt::pmt_t msg)
     {
             LOG(WARNING) << "msg_handler_telemetry Bad any cast!";
     }
+    if(!result)
+        {
+            LOG(WARNING) << "msg_handler_telemetry invalid event";
+        }
 }