diff --git a/README b/README
index add8645..8c6712e 100644
--- a/README
+++ b/README
@@ -1,9 +1,9 @@
 TETRA MAC/PHY layer experimentation code
-(C) 2010 by Harald Welte <laforge@gnumonks.org>
+(C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
 ======================================================================
 
-This code aims to implement the (so far) sending and (in the future)
-receiving part of the TETRA MAC/PHY layer.
+This code aims to implement the sending and receiving part of the
+TETRA MAC/PHY layer.
 
 If you read the ETSI EN 300 392-2 (TETRA V+D Air Interface), you will
 find this code implementing the parts between the MAC-blocks (called
@@ -12,23 +12,58 @@ type-1 bits) and the bits that go to the DQPSK-modulator (type-5 bits).
 It is most useful to look at Figure 8.5, 8.6, 9.3 and 19.12 in conjunction
 with this program.
 
+You will need libosmocore (http://bb.osmocom.org/trac/wiki/libosmocore) to link.
+
+
+== Demodulator ==
+
+src/demod/python/cpsk.py
+	* contains a gnuradio based pi4/DQPSK demodulator, courtesy of KA1RBI
+src/demod/python/tetra-demod.py
+	* call demodulator on a 'cfile' containing complex baseband samples
+src/demod/python/usrp1-tetra_demod.py
+	* use demodulator in realtime with a USRP1 SDR
+src/demod/python/usrp2-tetra_demod.py
+	* use demodulator in realtime with a USRP2 SDR
+
+The output of the demodulator is a file containing one float value for each symbol,
+containing the phase shift (in units of pi/4) relative to the previous symbol.
+
+You can use the "float_to_bits" program to convert the float values to unpacked
+bits, i.e. 1-bit-per-byte
+
+
+== PHY/MAC layer ==
+
+=== library code ===
+
 Specifically, it implements:
-	lib_crc.[ch]
-		* CRC16-CCITT (currently defunct/broken as we need it for
-		  non-octet-aligned bitfields)
-	tetra_rm3014.[ch]
-		* (30, 14) Reed-Muller code for the ACCH (broadcast block of
-		  each downlink burst)
-	tetra_conv_enc.[ch]
-		* 16-state Rate-Compatible Punctured Convolutional (RCPC) coder
-	tetra_interleave.[ch]
-		* Block interleaving (over a single block only)
-	tetra_scramb.[ch]
-		* Scrambling
-	tetra_burst.[ch]
-		* Routines to encode continuous normal and sync bursts
-	testpdu.[ch]
-		* Routines to build some example SYNC-PDU and SYSINFO-PDU
+lower_mac/crc_simple.[ch]
+	* CRC16-CCITT (currently defunct/broken as we need it for
+	  non-octet-aligned bitfields)
+lower_mac/tetra_conv_enc.[ch]
+	* 16-state Rate-Compatible Punctured Convolutional (RCPC) coder
+lower_mac/tetra_interleave.[ch]
+	* Block interleaving (over a single block only)
+lower_mac/tetra_rm3014.[ch]
+	* (30, 14) Reed-Muller code for the ACCH (broadcast block of
+	  each downlink burst)
+lower_mac/tetra_scramb.[ch]
+	* Scrambling
+lower_mac/viterbi*.[ch]
+	* Convolutional decoder for signalling and voice channels
+phy/tetra_burst.[ch]
+	* Routines to encode continuous normal and sync bursts
+phy/tetra_burst_sync.[ch]
+
+
+=== Receiver Program ===
+
+The main receiver program 'tetra-rx' expects an input file containing a
+stream of unpacked bits, i.e. 1-bit-per-byte.
+
+
+=== Transmitter Program ===
 
 The main program conv_enc_test.c generates a single continuous downlinc sync
 burst (SB), contining:
@@ -38,13 +73,14 @@ burst (SB), contining:
 
 Scrambling is set to 0 (no scrambling) for all elements of the burst.
 
-You will need libosmocore (http://bb.osmocom.org/trac/wiki/libosmocore) to link.
-
-
+It does not actually modulate and/or transmit yet.
 
-USAGE:
 
-	src/float_to_bits data/dqpsk-float.dat data/out.bits
+== Quick example ==
 
-	src/burst_test data/out.bits
+	# assuming you have generated a file samples.cfile at a sample rate of
+	# 195.312kHz (100MHz/512 == USRP2 at decimation 512)
+	src/demod/python/tetra-demod.py -i /tmp/samples.cfile -o /tmp/out.float -s 195312 -c 0
+	src/float_to_bits /tmp/out.float /tmp/out.bits
+	src/tetra-rx /tmp/out.bits