diff --git a/iridiumtk/reassembler/mtpos.py b/iridiumtk/reassembler/mtpos.py
new file mode 100644
index 0000000..9f52642
--- /dev/null
+++ b/iridiumtk/reassembler/mtpos.py
@@ -0,0 +1,96 @@
+#!/usr/bin/env python3
+# vim: set ts=4 sw=4 tw=0 et pm=:
+
+import sys
+import datetime
+import re
+import crcmod
+import os
+
+from util import fmt_iritime, xyz, dt
+
+from .base import *
+from .ida import ReassembleIDA
+from ..config import config, outfile
+
+class ReassembleIDAMap(ReassembleIDA):
+    """Extract coordinates from access decision messages"""
+
+    intvl = 60
+    exptime = 60 * 8
+    last_output = 0
+
+    mt_pos = []
+
+    def __init__(self):
+        super().__init__()
+        global json
+        import json
+        if config.stats:
+            from util import curses_eol
+            global eol
+            eol=curses_eol()
+
+
+    def consume(self, q):
+        (data, time, ul, _, freq)=q
+        if len(data) < 2:
+            return
+
+        m_type = data[:2].hex()
+
+        if m_type !="0605" and m_type != "7605":
+            return
+
+        if ul:
+            ul="UL"
+        else:
+            ul="DL"
+
+
+        if m_type == "7605":
+            if data[2] == 0 and data[3]&0xf0 == 0x40:
+                type = 'sbd'
+                pos=xyz(data[3:], 4)
+            elif data[3] == 0x50: # ack only
+                return
+            else: # no match
+                return
+        elif m_type == "0605":
+            off = (2+1+20+1+3+3+2+2+2)
+            if len(data) > off and data[off] == 0x1b:
+                type = 'gsm'
+                pos=xyz(data[off+1:], 0)
+                #lac_o=2+1+20
+                #if data[lac_o] == 0x04:
+                #    print("lac=",data[lac_o+1:lac_o+3].hex())
+                #if data[lac_o+3] == 0x61:
+                #    print("sca=",data[lac_o+4:lac_o+6].hex())
+            else: # no match
+                return
+        else:
+            raise ValueError
+
+        self.mt_pos.append({"xyz": [pos['x']*4+2, pos['y']*4+2, pos['z']*4+2], "type": type, "ts": int(time)})
+
+        if time >= self.last_output + self.intvl:
+            self.last_output = time
+            self.mt_pos = [x for x in self.mt_pos if x['ts'] > time - self.exptime]
+
+            ofile=config.output
+            if ofile is None:
+                ofile="mt.json"
+            temp_file_path="%s.tmp"%(ofile)
+            with open(temp_file_path, "w") as f:
+                print(json.dumps({"time": int(time), "interval": self.intvl, "mt_pos": self.mt_pos}, separators=(',', ':')), file=f)
+            os.rename(temp_file_path, ofile)
+            if config.stats:
+                sts=dt.epoch(int(time))
+                mts=len(self.mt_pos)
+                print("%s: %d MTs"%(sts,mts), end=eol, file=sys.stderr)
+
+
+
+modes=[
+["live-mt-map",        ReassembleIDAMap, ],
+]