diff --git a/v1.3.1/s15/s15_j17_fon_2012-06-15.txt b/v1.3.1/s15/s15_j17_fon_2012-06-15.txt
index 2ad2649..aacef93 100644
--- a/v1.3.1/s15/s15_j17_fon_2012-06-15.txt
+++ b/v1.3.1/s15/s15_j17_fon_2012-06-15.txt
@@ -26,3 +26,18 @@ Command for listener: owlps-listenerd.semistatic -A -vvvv -i 192.168.11.254 -I 1
 le test se déroule de cette façon :
 
 Durée du test 5 Min avec un temps d'attente de 1 minute à chaque point de mesures. Le fichier de sortie s'appel 2012-06-15_j17_s15.agg
+
+
+> s15 (autocalibration with a human operator in the room but without mobile
+>  terminal): how can I know where is the operator at a given moment?
+
+Very good question! I tried to find a logic and an order in that file but
+I can't. I will explain you the way in which the experiment was made: I
+sit 1 minute in #1 point. After, I walked about 6 seconds to reach the #2
+point where I sit 1 minute. After, I walked 12 seconds to reach the #3
+point where I sit 1 minute. 6 seconds to #4 point and 1 minute there.  6
+seconds to #5 point and 1 minute there.
+
+I had the same question as you, for the begining, about all these
+experiments with autocalibration. It's impossible to know exactly where
+the operator is.