diff --git a/fsw_params.h b/fsw_params.h
--- a/fsw_params.h
+++ b/fsw_params.h
@@ -418,9 +418,13 @@ typedef struct{
     float cp_rpw_sc_rw4_f4;
 } rw_f_t;
 
-#define NB_ACQUISITION_DURATION 3
+#define MATRIX_IS_POLLUTED      0
+#define MATRIX_IS_NOT_POLLUTED  1
 #define ACQUISITION_DURATION_F0 683     // 256 / 24576 * 65536
 #define ACQUISITION_DURATION_F1 4096    // 256 /  4096 * 65536
 #define ACQUISITION_DURATION_F2 65536   // 256 /   256 * 65536
+#define HALF_ACQUISITION_DURATION_F0 341     // 256 / 24576 * 65536 / 2
+#define HALF_ACQUISITION_DURATION_F1 2048    // 256 /  4096 * 65536 / 2
+#define HALF_ACQUISITION_DURATION_F2 32768   // 256 /   256 * 65536 / 2
 
 #endif // FSW_PARAMS_H_INCLUDED