diff --git a/libraries/AP_Math/chirp.cpp b/libraries/AP_Math/chirp.cpp
index b01250bca6..eb3c7e2fff 100644
--- a/libraries/AP_Math/chirp.cpp
+++ b/libraries/AP_Math/chirp.cpp
@@ -46,6 +46,8 @@ void Chirp::init(float time_record, float frequency_start_hz, float frequency_st
 
     B = logf(wMax / wMin);
 
+    // Mark as incomplete
+    complete = false;
 }
 
 // determine chirp signal output at the specified time and amplitude
@@ -83,5 +85,8 @@ float Chirp::update(float time, float waveform_magnitude)
         waveform_freq_rads = wMax;
         output = 0.0f;
     }
+
+    complete = time > record;
+
     return output;
 }
diff --git a/libraries/AP_Math/chirp.h b/libraries/AP_Math/chirp.h
index 23487e21e5..0208503293 100644
--- a/libraries/AP_Math/chirp.h
+++ b/libraries/AP_Math/chirp.h
@@ -16,6 +16,9 @@ public:
     // accessor for the current waveform frequency
     float get_frequency_rads() {return waveform_freq_rads; }
 
+    // Return true if chirp is completed
+    bool completed() const { return complete; }
+
 private:
     // Total chirp length in seconds
     float record;
@@ -50,4 +53,7 @@ private:
     // output of chirp signal at the requested time
     float output;
 
+    // True if chirp is complete, reset to false on init
+    bool complete;
+
 };