diff --git a/bbn_wave_freq_m5atomS3/WaveFilters.h b/bbn_wave_freq_m5atomS3/WaveFilters.h
index eb8acbe..710ddac 100644
--- a/bbn_wave_freq_m5atomS3/WaveFilters.h
+++ b/bbn_wave_freq_m5atomS3/WaveFilters.h
@@ -5,7 +5,8 @@
 #define FREQ_UPPER 4.0
 #define FREQ_GUESS 0.3 /* freq guess */
 
-#define FREQ_COEF  1.0
+#define FREQ_COEF        1.0
+#define FREQ_COEF_TIGHT  0.05
 #define ARANOVSKIY_SCALE 10.0
 
 #define ACCEL_MAX_G_SQUARE 16.0