diff --git a/repeater/src/python/tsbk.py b/repeater/src/python/tsbk.py
new file mode 100644
index 0000000..6000c79
--- /dev/null
+++ b/repeater/src/python/tsbk.py
@@ -0,0 +1,167 @@
+
+# P25 TSBK and MBT message decoder (C) Copyright 2013 KA1RBI
+# 
+# This file is part of OP25
+# 
+# OP25 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 3, or (at your option)
+# any later version.
+# 
+# OP25 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 OP25; see the file COPYING. If not, write to the Free
+# Software Foundation, Inc., 51 Franklin Street, Boston, MA
+# 02110-1301, USA.
+
+def crc16(dat,len):	# slow version
+        poly = (1<<12) + (1<<5) + (1<<0)
+        crc = 0
+        for i in range(len):
+                bits = (dat >> (((len-1)-i)*8)) & 0xff
+                for j in range(8):
+                        bit = (bits >> (7-j)) & 1
+                        crc = ((crc << 1) | bit) & 0x1ffff
+                        if crc & 0x10000:
+                                crc = (crc & 0xffff) ^ poly
+        crc = crc ^ 0xffff
+        return crc
+
+class tsbk (object):
+    def __init__(self, debug=0):
+	self.debug = debug
+	self.freq_table = {}
+	self.stats = {}
+	self.stats['tsbks'] = 0
+	self.stats['crc'] = 0
+
+    def format_channel_id(self, id):
+	table = (id >> 12) & 0xf
+	channel = id & 0xfff
+	if table not in self.freq_table:
+		return "%x-%d" % (table, channel)
+	return "%f" % (self.freq_table[table]['frequency'] + self.freq_table[table]['step'] * channel)
+
+    def decode_mbt_data(self, opcode, header, mbt_data):
+	# print "decode_mbt_data: %x %x" %(opcode, mbt_data)
+	if opcode == 0x0:  # grp voice channel grant
+		ch1  = (mbt_data >> 32) & 0xffff
+		ch2  = (mbt_data >> 16) & 0xffff
+		ga   = (mbt_data      ) & 0xffff
+		print "mbt00 voice grant ch1 %x ch2 %x addr 0x%x" %(ch1, ch2, ga)
+	elif opcode == 0x3c:  # adjacent status
+		rfid = (header >> 24) & 0xff
+		stid = (header >> 16) & 0xff
+		ch1  = (mbt_data >> 48) & 0xffff
+		ch2  = (mbt_data >> 32) & 0xffff
+		print "mbt3c adjacent rfid %x stid %x ch1 %x ch2 %x" %(rfid, stid, ch1, ch2)
+	elif opcode == 0x3b:  # network status
+		wacn = (mbt_data >> 44) & 0xfffff
+		ch1  = (mbt_data >> 24) & 0xffff
+		ch2  = (mbt_data >> 8) & 0xffff
+		print "mbt3b net stat wacn %x ch1 %x ch2 %x" %(wacn, ch1, ch2)
+	elif opcode == 0x3a:  # rfss status
+		rfid = (mbt_data >> 56) & 0xff
+		stid = (mbt_data >> 48) & 0xff
+		ch1  = (mbt_data >> 32) & 0xffff
+		ch2  = (mbt_data >> 16) & 0xffff
+		print "mbt3a rfss stat rfid %x stid %x ch1 %x ch2 %x" %(rfid, stid, ch1, ch2)
+	#else:
+	#	print "mbt other %x" % opcode
+
+    def decode_tsbk(self, tsbk):
+	self.stats['tsbks'] += 1
+	if crc16(tsbk, 12) != 0:
+		self.stats['crc'] += 1
+		return	# crc check failed
+	opcode = (tsbk >> 88) & 0x3f
+	#print "TSBK: 0x%02x 0x%024x" % (opcode, tsbk)
+	if opcode == 0x02:   # group voice chan grant update
+		ch1  = (tsbk >> 64) & 0xffff
+		ga1  = (tsbk >> 48) & 0xffff
+		ch2  = (tsbk >> 32) & 0xffff
+		ga2  = (tsbk >> 16) & 0xffff
+		print "tsbk02 grant update: chan %s %d %s %d" %(self.format_channel_id(ch1), ga1, self.format_channel_id(ch2), ga2)
+	elif opcode == 0x16:   # sndcp data ch
+		ch1  = (tsbk >> 48) & 0xffff
+		ch2  = (tsbk >> 32) & 0xffff
+		print "tsbk16 sndcp data ch: chan %x %x" %(ch1, ch2)
+	elif opcode == 0x34:   # iden_up vhf uhf
+		iden = (tsbk >> 76) & 0xf
+		bwvu = (tsbk >> 72) & 0xf
+		toff0 = (tsbk >> 58) & 0x3fff
+		spac = (tsbk >> 48) & 0x3ff
+		freq = (tsbk >> 16) & 0xffffffff
+		toff_sign = (toff0 >> 13) & 1
+		toff = toff0 & 0x1fff
+		if toff_sign == 0:
+			toff = 0 - toff
+		txt = ["mob Tx-", "mob Tx+"]
+		self.freq_table[iden] = {}
+		self.freq_table[iden]['offset'] = float(toff) * float(spac) * 0.125
+		self.freq_table[iden]['step'] = float(spac) * 0.000125
+		self.freq_table[iden]['frequency'] = float(freq) * 0.000005
+		print "tsbk34 iden vhf/uhf id %d toff %f spac %f freq %f [%s]" % (iden, toff * spac * 0.125 * 1e-3, spac * 0.125, freq * 0.000005, txt[toff_sign])
+	elif opcode == 0x3d:   # iden_up
+		iden = (tsbk >> 76) & 0xf
+		bw   = (tsbk >> 67) & 0x1ff
+		toff0 = (tsbk >> 58) & 0x1ff
+		spac = (tsbk >> 48) & 0x3ff
+		freq = (tsbk >> 16) & 0xffffffff
+		# toff_sign = (toff0 >> 13) & 1
+		# toff = toff0 & 0x1fff
+		# if toff_sign == 0:
+		# 	toff = 0 - toff
+		toff = toff0
+		txt = ["mob xmit < recv", "mob xmit > recv"]
+		self.freq_table[iden] = {}
+		self.freq_table[iden]['offset'] = float(toff) * 0.25
+		self.freq_table[iden]['step'] = float(spac) * 0.000125
+		self.freq_table[iden]['frequency'] = float(freq) * 0.000005
+		print "tsbk3d iden id %d toff %f spac %f freq %f" % (iden, toff * 0.25, spac * 0.125, freq * 0.000005)
+	elif opcode == 0x3a:   # rfss status
+		syid = (tsbk >> 56) & 0xfff
+		rfid = (tsbk >> 48) & 0xff
+		stid = (tsbk >> 40) & 0xff
+		chan = (tsbk >> 24) & 0xffff
+		print "tsbk3a rfss status: syid: %x rfid %x stid %d ch1 %x(%s)" %(syid, rfid, stid, chan, self.format_channel_id(chan))
+	elif opcode == 0x39:   # secondary cc
+		rfid = (tsbk >> 72) & 0xff
+		stid = (tsbk >> 64) & 0xff
+		ch1  = (tsbk >> 48) & 0xffff
+		ch2  = (tsbk >> 24) & 0xffff
+		print "tsbk39 secondary cc: rfid %x stid %d ch1 %x(%s) ch2 %x(%s)" %(rfid, stid, ch1, self.format_channel_id(ch1), ch2, self.format_channel_id(ch2))
+	elif opcode == 0x3b:   # network status
+		wacn = (tsbk >> 52) & 0xfffff
+		syid = (tsbk >> 40) & 0xfff
+		ch1  = (tsbk >> 24) & 0xffff
+		print "tsbk3b net stat: wacn %x syid %x ch1 %x(%s)" %(wacn, syid, ch1, self.format_channel_id(ch1))
+	elif opcode == 0x3c:   # adjacent status
+		rfid = (tsbk >> 48) & 0xff
+		stid = (tsbk >> 40) & 0xff
+		ch1  = (tsbk >> 24) & 0xffff
+		print "tsbk3c adjacent: rfid %x stid %d ch1 %x(%s)" %(rfid, stid, ch1, self.format_channel_id(ch1))
+	#else:
+	#	print "tsbk other %x" % opcode
+
+def main():
+	q = 0x3a000012ae01013348704a54
+	rc = crc16(q,12)
+	print "should be zero: %x" % rc
+
+	q = 0x3a001012ae01013348704a54
+	rc = crc16(q,12)
+	print "should be nonzero: %x" % rc
+
+	t = tsbk()
+	q = 0x3a000012ae01013348704a54
+	t.decode_tsbk(q)
+	
+
+if __name__ == '__main__':
+	# run tests, if this code is invoked as a program
+	main()