diff --git a/sw/ground_segment/multimon/Makefile b/sw/ground_segment/multimon/Makefile
index 3142c0dd96..4ac9650ad3 100644
--- a/sw/ground_segment/multimon/Makefile
+++ b/sw/ground_segment/multimon/Makefile
@@ -29,7 +29,7 @@ STRIP		=strip
 MKDIR		=mkdir
 
 # all:		$(BINDIR) $(BINDIR)/multimon $(BINDIR)/gen
-all:		$(BINDIR)/multimon
+all:		$(BINDIR)/multimon multimon.cma
 
 $(BINDIR)/%.s:	%.c
 		$(CC) $(CFLAGS) -S -o $@ $<
@@ -67,6 +67,9 @@ $(BINDIR)/mkcostab:	$(BINDIR)/mkcostab.o
 costabi.c costabf.c:	$(BINDIR)/mkcostab
 			$(BINDIR)/mkcostab
 
+multimon.cma : pprzlib.o demodml.o demod.ml
+	ocamlmklib -o multimon $^
+
 libtest: pprzlib.o demodml.c demod.ml test.ml
 	ocamlc -custom -o $@ pprzlib.o demodml.c -I +lablgtk2 unix.cma lablgtk.cma demod.ml test.ml
 
diff --git a/sw/ground_segment/multimon/pprzlib.c b/sw/ground_segment/multimon/pprzlib.c
index 0a6919233c..b7103d2357 100644
--- a/sw/ground_segment/multimon/pprzlib.c
+++ b/sw/ground_segment/multimon/pprzlib.c
@@ -187,6 +187,8 @@ afsk48p_demod(struct demod_state *s, float *buffer, int length, char* data)
   float f;
   unsigned char curbit;
 
+  printf("l=%d\n", length);
+
   s->l1.afsk48p.sample_count += length;
   if (s->l1.afsk48p.sample_count > FREQ_SAMP) {
     s->l1.afsk48p.sample_count -= FREQ_SAMP;
@@ -295,6 +297,7 @@ static struct demod_state dem_st[2];
 char data_left[INPUT_BUF_LEN];
 char data_right[INPUT_BUF_LEN];
 char* data_received[2] = {data_left, data_right};
+unsigned int fbuf_cnt = 0;
 
 char**
 pprz_demod_read_data(void) {
@@ -303,7 +306,6 @@ pprz_demod_read_data(void) {
   unsigned char *bp;
   short *sp;
   float fbuf[2][16384];
-  unsigned int fbuf_cnt = 0;
   int data_received_len[2];
 
   if (fmt) {
@@ -337,9 +339,10 @@ pprz_demod_read_data(void) {
     }
     if (i > 0) {
       if (stereo) {
-	for (; i >= sizeof(b.s[0]); i -= (sizeof(b.s[0])*2), sp+=2)
-	  fbuf[LEFT][fbuf_cnt++] = (*sp) * (1.0/32768.0);
+	for (; i >= sizeof(b.s[0]); i -= (sizeof(b.s[0])*2), sp+=2) {
+	  fbuf[LEFT][fbuf_cnt] = (*sp) * (1.0/32768.0);
 	  fbuf[RIGHT][fbuf_cnt++] = (*(sp+1)) * (1.0/32768.0);
+	}
       } else {
 	for (; i >= sizeof(b.s[0]); i -= sizeof(b.s[0]), sp++)
 	  fbuf[LEFT][fbuf_cnt++] = (*sp) * (1.0/32768.0);
diff --git a/sw/ground_segment/tmtc/Makefile b/sw/ground_segment/tmtc/Makefile
index 0f1838c2a2..4fd21ede2a 100644
--- a/sw/ground_segment/tmtc/Makefile
+++ b/sw/ground_segment/tmtc/Makefile
@@ -57,6 +57,12 @@ hw_modem_listen : modem.cmo hw_modem_listen.ml ../../lib/ocaml/lib-pprz.cma
 	@echo 'exec lablgtk2 -I $$PAPARAZZI_SRC/sw/lib/ocaml glibivy-ocaml.cma lib-pprz.cma -I $$PAPARAZZI_SRC/sw/ground_segment/tmtc $$PAPARAZZI_SRC/sw/ground_segment/tmtc/modem.cmo $$PAPARAZZI_SRC/sw/ground_segment/tmtc/hw_modem_listen.ml $$*' >> $@
 	@chmod a+x $@
 
+demod_listen : ../multimon/multimon.cma demod_listen.ml ../../lib/ocaml/lib-pprz.cma
+	$(OCAMLC) $(INCLUDES) -I ../multimon -o $@ lablgtk.cma glibivy-ocaml.cma lib-pprz.cma multimon.cma $^
+	@cat ../../../pprz_src_test.sh > $@
+	@echo 'exec lablgtk2 -I $$PAPARAZZI_SRC/sw/lib/ocaml -I $$PAPARAZZI_SRC/sw/ground_segment/multimon glibivy-ocaml.cma lib-pprz.cma -I $$PAPARAZZI_SRC/sw/ground_segment/tmtc $$PAPARAZZI_SRC/sw/ground_segment/multimon/multimon.cma $$PAPARAZZI_SRC/sw/ground_segment/tmtc/demod_listen.ml $$*' >> $@
+	@chmod a+x $@
+
 receive : receive.ml ../../lib/ocaml/lib-pprz.cma
 	$(OCAMLC) $(INCLUDES) -o $@ lablgtk.cma glibivy-ocaml.cma lib-pprz.cma $^
 	@cat ../../../pprz_src_test.sh > $@
diff --git a/sw/ground_segment/tmtc/demod_listen.ml b/sw/ground_segment/tmtc/demod_listen.ml
new file mode 100644
index 0000000000..975bc4a9ab
--- /dev/null
+++ b/sw/ground_segment/tmtc/demod_listen.ml
@@ -0,0 +1,129 @@
+(*
+ * $Id$
+ *
+ * Hardware modem receiver
+ *  
+ * Copyright (C) 2004 CENA/ENAC, Pascal Brisset, Antoine Drouin
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA. 
+ *
+ *)
+
+open Printf
+
+(** Ivy messages are initially tagged "modem" and with the A/C
+id as soon as it is identified (IDENT message) *)
+let ac_id = ref "modem"
+
+let modem_msg_period = 1000 (** ms *)
+
+module Tele_Class = struct let name = "telemetry_ap" end
+module Tele_Pprz = Pprz.Protocol(Tele_Class)
+module PprzTransport = Serial.Transport(Tele_Pprz)
+
+(** Monitoring of the message reception *)
+type status = {
+    mutable rx_byte : int;
+    mutable rx_msg : int;
+    mutable rx_err : int
+  }
+let status = { rx_byte = 0; rx_msg = 0; rx_err = 0 }
+
+(** Callback for each decoded message *)
+let use_pprz_message = fun (msg_id, values) ->
+  status.rx_msg <- status.rx_msg + 1; (** Monitoring update *)
+  let msg = Tele_Pprz.message_of_id msg_id in
+  if msg.Pprz.name = "IDENT" then
+    ac_id := Pprz.string_assoc "id" values;
+  Tele_Pprz.message_send !ac_id msg.Pprz.name values
+
+(** Listen on a dsp device *)
+let listen_pprz_modem = fun pprz_message_cb devdsp ->
+  let fd = Demod.init devdsp in
+
+  (** Callback for a checksumed pprz message *)
+  let use_pprz_buf = fun buf ->
+    status.rx_byte <- status.rx_byte + String.length buf;
+    Debug.call 'P' (fun f -> fprintf f "use_pprz: %s\n" (Debug.xprint buf));
+    pprz_message_cb (Tele_Pprz.values_of_bin buf) in
+
+  (** Callback for available chars *)
+  let cb =
+    let buffer = ref "" in
+    fun _ ->
+      let (data_left, data_right) = Demod.get_data () in
+      (** Accumulate in a buffer *)
+      let b = !buffer ^ data_left in
+      Debug.call 'M' (fun f -> fprintf f "Pprz buffer: %s\n" (Debug.xprint b));
+      (** Parse as pprz message and ... *)
+      let x = PprzTransport.parse use_pprz_buf b in
+      status.rx_err <- !PprzTransport.nb_err;
+      (** ... remove from the buffer the chars which have been used *)
+      buffer := String.sub b x (String.length b - x);
+      true
+  in
+
+  (** Attach the callback to the channel *)
+  ignore (Glib.Io.add_watch [`IN] cb (Glib.Io.channel_of_descr fd))
+
+(** Modem monitoring messages *)
+let send_modem_msg =
+  let rx_msg = ref 0 
+  and rx_byte = ref 0 
+  and start = Unix.gettimeofday () in
+  fun () ->
+    let dt = float modem_msg_period /. 1000. in
+    let t = int_of_float (Unix.gettimeofday () -. start) in
+    let byte_rate = float (status.rx_byte - !rx_byte) /. dt
+    and msg_rate = float (status.rx_msg - !rx_msg) /. dt in
+    rx_msg := status.rx_msg;
+    rx_byte := status.rx_byte;
+    let vs = ["run_time", Pprz.Int t;
+	      "rx_bytes_rate", Pprz.Float byte_rate; 
+	      "rx_msgs_rate", Pprz.Float msg_rate;
+	      "rx_err", Pprz.Int status.rx_err;
+	      "rx_bytes", Pprz.Int status.rx_byte;
+	      "rx_msgs", Pprz.Int status.rx_msg
+	    ] in
+    Tele_Pprz.message_send !ac_id "DOWNLINK_STATUS" vs
+
+(* main loop *)
+let _ =
+  let ivy_bus = ref "127.255.255.255:2010" in
+  let port = ref "/dev/dsp" in
+  let options =
+    [ "-b", Arg.Set_string ivy_bus, (sprintf "Ivy bus (%s)" !ivy_bus);
+      "-d", Arg.Set_string port, (sprintf "Port (%s)" !port)] in
+  Arg.parse
+    options
+    (fun x -> fprintf stderr "Warning:ignoring %s\n" x)
+    "Usage: ";
+  
+  Ivy.init "Paparazzi hw_modem_listen" "READY" (fun _ _ -> ());
+  Ivy.start !ivy_bus;
+
+  (** Listening on the given port (serial device or multimon fifo)*)
+  listen_pprz_modem use_pprz_message !port;
+
+  (** Sending periodically modem and downlink status messages *)
+  ignore (Glib.Timeout.add modem_msg_period (fun () -> send_modem_msg (); true));
+  
+  let loop = Glib.Main.create true in
+  while Glib.Main.is_running loop do
+    ignore (Glib.Main.iteration true)
+  done