diff --git a/libowlps-client/libowlps-client.c b/libowlps-client/libowlps-client.c
index 29a4c07..4451097 100644
--- a/libowlps-client/libowlps-client.c
+++ b/libowlps-client/libowlps-client.c
@@ -62,6 +62,10 @@ void owlclient_use_iface(const int sockfd, const char *const iface)
 
 
 
+/*
+ * nb_pkt: number of packets to transmit.
+ * delay: delay between two transmissions, in milliseconds.
+ */
 void owlclient_send_request(const int sockfd,
                             const struct sockaddr_in *const server,
                             const void *const packet,
@@ -84,7 +88,7 @@ void owlclient_send_request(const int sockfd,
   // Transmit remaining packets (if any):
   for (i = 0 ; i < nb_pkt - 1 ; ++i)
     {
-      usleep(delay) ; // Wait during the wanted delay
+      usleep(delay * 1000) ; // Wait during the wanted delay
       owlclient_send_packet(sockfd, server, packet, packet_size) ;
     }
 
diff --git a/owlps-client/owlps-client.c b/owlps-client/owlps-client.c
index d642a7e..173830b 100644
--- a/owlps-client/owlps-client.c
+++ b/owlps-client/owlps-client.c
@@ -20,9 +20,9 @@
 #define DEFAULT_NBPKT_CALIB 20 // 20 packets when calibrating
 #define DEFAULT_NBPKT_NORMAL 10 // 10 packets when requesting the position
 
-/* Delay between two packet transmissions (in microseconds) */
-#define DEFAULT_DELAY_CALIB 50000 // Calibration request
-#define DEFAULT_DELAY_NORMAL 25000 // Localisation request
+/* Delay between two packet transmissions (in milliseconds) */
+#define DEFAULT_DELAY_CALIB 50 // Calibration request
+#define DEFAULT_DELAY_NORMAL 25 // Localisation request
 
 /* Delay between two requests in loop mode (in milliseconds) */
 #define DEFAULT_FLOOD_DELAY 1000
@@ -333,9 +333,9 @@ void print_configuration()
           "\tDestination IP: %s\n"
           "\tDestination port: %"PRIuFAST16"\n"
           "\tInterface: %s\n"
-          "\tDelay: %"PRIdFAST32"\n"
+          "\tDelay (ms): %"PRIdFAST32"\n"
           "\tNumber of packets: %"PRIuFAST16"\n"
-          "\tFlood delay: %"PRIdFAST32"\n"
+          "\tFlood delay (ms): %"PRIdFAST32"\n"
           "\tListening port: %"PRIuFAST16"\n"
           "\tDirection: %"PRIu8"\n"
           "\tX: %f\n"
@@ -464,8 +464,9 @@ void print_usage()
          " request.\n"
          "\t-p dest_port\tDestination port of the localisation request"
          " (default: %d).\n"
-         "\t-t delay\tTime between each packet transmission (default: %d"
-         " µs for a normal request, %d µs for a calibration request).\n"
+         "\t-t delay\tTime between each packet transmission in"
+         " milliseconds (default: %d ms for a normal request,"
+         " %d ms for a calibration request).\n"
          "\t-n nb_packets\tNumber of packet transmitted for the request"
          " (default: %d for a normal request, %d for a calibration"
          " request).\n"
diff --git a/owlps-listener/owlps-listener.h b/owlps-listener/owlps-listener.h
index 3884260..16118fe 100644
--- a/owlps-listener/owlps-listener.h
+++ b/owlps-listener/owlps-listener.h
@@ -60,7 +60,7 @@
 #define DEFAULT_CONFIG_FILE "/usr/local/etc/owlps/owlps-listener.conf"
 enum {MODE_ACTIVE = 'a', MODE_PASSIVE = 'p', MODE_MIXED = 'm'} ;
 #define DEFAULT_AUTOCALIBRATION_HELLO_DELAY 120 // seconds
-#define DEFAULT_AUTOCALIBRATION_DELAY 25000 // ms
+#define DEFAULT_AUTOCALIBRATION_DELAY 25 // milliseconds
 #define DEFAULT_AUTOCALIBRATION_NBPKT 20
 
 
diff --git a/owlps-listener/owlps-listenerd.c b/owlps-listener/owlps-listenerd.c
index 51e7914..7a6ef97 100644
--- a/owlps-listener/owlps-listenerd.c
+++ b/owlps-listener/owlps-listenerd.c
@@ -1421,10 +1421,10 @@ void print_usage()
          "\t-a autocalib_port\tPort on which autocalibration data (hello"
          " & orders) are exchanged with the aggregation server"
          " (default: %d).\n"
-         "\t-H hello_delay\t\tTime between each hello"
-         " message sent to the aggregation server (default: %d s).\n"
+         "\t-H hello_delay\t\tTime between each hello message sent to"
+         " the aggregation server, in seconds (default: %d s).\n"
          "\t-t delay\t\tTime between each autocalibration"
-         " packet transmission (default: %d µs).\n"
+         " packet transmission, in milliseconds (default: %d ms).\n"
          "\t-n nb_packets\t\tNumber of packet transmitted"
          " for one autocalibration request (default: %d).\n"
          "\tdirection x y z\t\tThe coordinates of the listener"