From 54d6b9281dc233e0b2acf26884073d973b7663de Mon Sep 17 00:00:00 2001
From: jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Tue, 4 Sep 2007 02:43:56 +0000
Subject: Merged r6271:6278 from jcorgan/t182 into trunk. Implements
ticket:182.
Created new top-level component, gr-utils, to hold commonly used utility
scripts (originally in gnuradio-examples). These now install into the
system path, allowing their use from wherever.
Reorganization of gnuradio-examples component:
* Commonly used utility scripts moved from python/usrp into gr-utils.
* Examples now install into $(prefix)/share/gnuradio/examples/...
* Channel coding examples moved into gr-trellis/src/examples, now install
from there, only if gr-atsc itself is going to built and installed.
* ATSC example scripts now install into example hierarchy
* Cruft has been moved into 'limbo' in repository, do not get installed
Trunk passes 'make distcheck'.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@6279 221aa14e-8319-0410-a670-987f0aec2ac5
---
gnuradio-examples/python/usrp/limbo/am_rcv.py | 115 ++++++++++++++++++++++++++
1 file changed, 115 insertions(+)
create mode 100755 gnuradio-examples/python/usrp/limbo/am_rcv.py
(limited to 'gnuradio-examples/python/usrp/limbo/am_rcv.py')
diff --git a/gnuradio-examples/python/usrp/limbo/am_rcv.py b/gnuradio-examples/python/usrp/limbo/am_rcv.py
new file mode 100755
index 0000000000..2908dcbf54
--- /dev/null
+++ b/gnuradio-examples/python/usrp/limbo/am_rcv.py
@@ -0,0 +1,115 @@
+#!/usr/bin/env python
+
+from gnuradio import gr, eng_notation
+from gnuradio import audio
+from gnuradio import usrp
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+import sys
+import math
+
+from gnuradio.wxgui import stdgui, fftsink
+import wx
+
+class am_rx_graph (stdgui.gui_flow_graph):
+ def __init__(self,frame,panel,vbox,argv):
+ stdgui.gui_flow_graph.__init__ (self,frame,panel,vbox,argv)
+
+ station = parseargs(argv[1:])
+ offset_freq = 30e3
+ IF_freq = offset_freq - station
+
+ adc_rate = 64e6
+ usrp_decim = 250
+ if_rate = adc_rate / usrp_decim # 256 kHz
+ if_decim = 4
+ demod_rate = if_rate / if_decim # 64 kHz
+ audio_decimation = 2
+ audio_rate = demod_rate / audio_decimation # 16 kHz
+
+ # usrp is data source
+ src = usrp.source_c (0, usrp_decim)
+ src.set_rx_freq (0, IF_freq)
+ actual_IF_freq =src.rx_freq(0)
+ actual_offset = actual_IF_freq + station
+
+ #print actual_IF_freq
+ #print actual_offset
+
+ src.set_pga(0,20)
+ # sound card as final sink
+ audio_sink = audio.sink (int (audio_rate))
+
+ channel_coeffs = \
+ gr.firdes.low_pass (1.0, # gain
+ if_rate, # sampling rate
+ 9e3, # low pass cutoff freq
+ 10e3, # width of trans. band
+ gr.firdes.WIN_HANN)
+
+ ddc = gr.freq_xlating_fir_filter_ccf (if_decim,channel_coeffs,-actual_offset,if_rate)
+
+ magblock = gr.complex_to_mag()
+ volumecontrol = gr.multiply_const_ff(.003)
+
+ # Deemphasis. Is this necessary on AM?
+ TAU = 75e-6 # 75us in US, 50us in EUR
+ fftaps = [ 1 - math.exp(-1/TAU/if_rate), 0]
+ fbtaps= [ 0 , math.exp(-1/TAU/if_rate) ]
+
+ deemph = gr.iir_filter_ffd(fftaps,fbtaps)
+
+ # compute FIR filter taps for audio filter
+ width_of_transition_band = audio_rate / 8
+ audio_coeffs = gr.firdes.low_pass (1.0, # gain
+ if_rate, # sampling rate
+ 9e3, #audio_rate/2 - width_of_transition_band,
+ 4e3, # width_of_transition_band,
+ gr.firdes.WIN_HANN)
+
+ # input: float; output: float
+ audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
+
+
+
+
+ print len(channel_coeffs)
+ print len(audio_coeffs)
+
+ # now wire it all together
+ self.connect (src, ddc)
+ self.connect (ddc, magblock)
+ self.connect (magblock, volumecontrol)
+ self.connect (volumecontrol,deemph)
+ self.connect (deemph,audio_filter)
+ self.connect (audio_filter, (audio_sink, 0))
+
+ if 1:
+ pre_demod = fftsink.fft_sink_c (self, panel, title="Pre-Demodulation", fft_size=128, sample_rate=if_rate)
+ self.connect (src, pre_demod)
+ vbox.Add (pre_demod.win, 1, wx.EXPAND)
+
+ if 0:
+ post_demod = fftsink.fft_sink_c (self, panel, title="Post Demodulation", fft_size=256, sample_rate=demod_rate)
+ self.connect (ddc, post_demod)
+ vbox.Add (post_demod.win, 1, wx.EXPAND)
+
+ if 0:
+ post_filt = fftsink.fft_sink_f (self, panel, title="Post Filter", fft_size=512, sample_rate=audio_rate)
+ self.connect (magblock,post_filt)
+ vbox.Add (post_filt.win, 1, wx.EXPAND)
+
+def parseargs (args):
+ nargs = len (args)
+ if nargs == 1:
+ freq1 = float (args[0]) * 1e3
+ else:
+ sys.stderr.write ('usage: am_rcv freq1\n')
+ sys.exit (1)
+
+ return freq1
+
+if __name__ == '__main__':
+ app = stdgui.stdapp (am_rx_graph, "AM RX")
+ app.MainLoop ()
+
--
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