Fixed atsc_field_sync_demux to consume input even when not creating

output. Added python files to make a complete 2.x atsc receiver, but
it is not fully working. It will happily produce the exact same amount of
transport stream output as a working system but has errors in the data.


git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@5081 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 84 insertions, 0 deletions

diff --git a/gr-atsc/src/python/fpll.py b/gr-atsc/src/python/fpll.py
new file mode 100755
index 000000000..0788d0fb0
--- /dev/null
+++ b/gr-atsc/src/python/fpll.py
@@ -0,0 +1,84 @@
+#!/usr/bin/env python
+#
+# Copyright 2004,2005 Free Software Foundation, Inc.
+# 
+# This file is part of GNU Radio
+# 
+# GNU Radio 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.
+# 
+# GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+# 
+
+from gnuradio import gr, atsc
+import math
+
+def main():
+
+	fg = gr.flow_graph()
+
+        u = gr.file_source(gr.sizeof_float,"/tmp/atsc_pipe_2")
+
+        input_rate = 19.2e6
+	IF_freq = 5.75e6
+
+
+	# 1/2 as wide because we're designing lp filter
+	symbol_rate = atsc.ATSC_SYMBOL_RATE/2. 
+	NTAPS = 279
+	tt = gr.firdes.root_raised_cosine (1.0, input_rate, symbol_rate, .115, NTAPS)
+  # heterodyne the low pass coefficients up to the specified bandpass
+  # center frequency.  Note that when we do this, the filter bandwidth
+  # is effectively twice the low pass (2.69 * 2 = 5.38) and hence
+  # matches the diagram in the ATSC spec.
+	arg = 2. * math.pi * IF_freq / input_rate
+	t=[]
+	for i in range(len(tt)):
+	  t += [tt[i] * 2. * math.cos(arg * i)]
+	rrc = gr.fir_filter_fff(1, t)
+
+	fpll = atsc.fpll()
+
+	pilot_freq = IF_freq - 3e6 + 0.31e6
+	lower_edge = 6e6 - 0.31e6
+	upper_edge = IF_freq - 3e6 + pilot_freq
+	transition_width = upper_edge - lower_edge
+	lp_coeffs = gr.firdes.low_pass (1.0,
+			   input_rate,
+			   (lower_edge + upper_edge) * 0.5,
+                           transition_width,
+                           gr.firdes.WIN_HAMMING);
+
+	lp_filter = gr.fir_filter_fff (1,lp_coeffs)
+
+	alpha = 1e-5
+	iir = gr.single_pole_iir_filter_ff(alpha)
+	remove_dc = gr.sub_ff()
+
+	out = gr.file_sink(gr.sizeof_float,"/tmp/atsc_pipe_3")
+	# out = gr.file_sink(gr.sizeof_float,"/mnt/sata/atsc_data_float")
+
+        fg.connect(u, fpll, lp_filter)
+	fg.connect(lp_filter, iir)
+	fg.connect(lp_filter, (remove_dc,0))
+	fg.connect(iir, (remove_dc,1))
+	fg.connect(remove_dc, out)
+
+	fg.run()
+
+
+if __name__ == '__main__':
+    main ()
+
+
+