Bringing README_fsk.txt up to date, examples now work, but some open TODO questions

git-svn-id: https://svn.code.sf.net/p/freetel/code@2872 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/README_fsk.txt b/codec2-dev/README_fsk.txt
index 1e63af1065e126ea5a743b2a72a56a03696fe8d9..00531935242331bf6645cecdbb5a6033f35a6c98 100644 (file)
--- a/codec2-dev/README_fsk.txt
+++ b/codec2-dev/README_fsk.txt
@@ -4,8 +4,8 @@ David Rowe
 Created Jan 2016
 
 A FSK modem with a non-coherent demodulator.  Performance is within a
-fraction of a dB of ideal.  The demodulator can estimate and track
-frequency offsets.
+fraction of a dB of ideal.  The demodulator can estimate the tone
+frequencies and track drift.
 
 Credits
 -------
@@ -18,18 +18,40 @@ Quickstart
 
 Built as part of codec2-dev, see README for build instructions.
 
-1. Using a random bit stream input generate 100 bit/s FSK and play out
-   speaker:
+1. Using 10 test frames as a source of bits, generate 2FSK using a
+   8000 Hz sample rate, at 100 symbols/s (== 100 bits/ for 2FSK), with
+   two frequencies of 1200 and 2400 Hz, and stream via stdout to
+   "play" out speaker:
     
     $ cd build_linux/src
-    $ /fsk_get_test_bits - 10 | ./fsk_mod 8000 100 1200 2400 - - | play -t raw -r 8000 -s -2 
+    $ ./fsk_get_test_bits - 10 | ./fsk_mod 2 8000 100 1200 2400 - - | play -t raw -r 8000 -s -2 -
 
-2. Check the bit error rate of 100 frames of 1200 bit/s FSK:
+    Notes:
+      i) TODO explain structure of test frame and how many bits are in it.
 
-    $ ./fsk_get_test_bits - 100 | ./fsk_mod 9600 1200 1200 2400 - - | ./fsk_demod 9600 1200 - - | ./fsk_put_test_bits -
+2. Measure the bit error rate of 100 frames of 100 bit/s 2FSK:
+
+    $ ./fsk_get_test_bits - 100 | ./fsk_mod 2 8000 100 1200 2400 - - | ./fsk_demod 2 0 8000 100 - - | ./fsk_put_test_bits -
+       FSK BER 0.003108, bits tested 39899, bit errors 124
+
+    Notes:
+      i) The "P" parameter is don't care when mode is 2 or 4, so we set it to 0
+      ii) TODO: waht are the source of errors?  Can we remove them with no noise?
+
+3. Measure the bit error rate of 100 frames at 1200 bits/s, samples at 9600 Hz:
+
+    $ ./fsk_get_test_bits - 100 | ./fsk_mod 2 9600 1200 1200 2400 - - | ./fsk_demod 2X 8 9600 1200 - - | ./fsk_put_test_bits -
       FSK BER 0.000000, bits tested 9499, bit errors 0
 
-3. Automatically check C implementation against Octave using a variety of test conditions and 
+    Notes: i) The 2X option is used in the demod, which narrows the
+              window for parameter estimation window.  In 2X/4X mode
+              the P parameter is used so we set it to 8 (TODO: explain why)
+           ii) TODO explain Restrictions to bit rate ie integer P, so we changed Fs to suit?
+
+4.  (TODO High bit rate example like 115k project Horus)
+
+
+5. Automatically check C implementation against Octave using a variety of test conditions and 
    channel impairments.
 
     $ cd octave