diff --git a/pasada-lib/include/step_detector.h b/pasada-lib/include/step_detector.h
index d27c23e..b8999e3 100644
--- a/pasada-lib/include/step_detector.h
+++ b/pasada-lib/include/step_detector.h
@@ -54,8 +54,15 @@ protected:
     double fps;
 
 public:
+    /**
+     * @param fps Initial guess for sampling rate - this is recomputed internally after the first 100 samples
+     * @param listener Listener to send step events to
+     * @param debug collect debug buffers (used in unit tests)
+     */
     StepDetector(double fps, StepListener *listener, bool debug = false);
+    /** filter using raw accel samples (unevenly spaced and 3-dimensional) */
     void filter(double ts, std::vector<float> values);
+    /** filter using scalar accel samples in \vec{e_g} direction */
     void filter_a(double s1);
     std::vector<double> getBufSsd();
     std::vector<double> getBufSqi();