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Merge branch 'fm_filter' into 'master' 

FM Demod Flowgraph - Add Low-Pass filter prior to Demod

See merge request librespacefoundation/satnogs/gr-satnogs!110
This commit is contained in:
Corey Shields 2017-09-23 13:02:27 +00:00
parent e494299bba 6b4f593661
commit 00ca01c9d9
2 changed files with 141 additions and 17 deletions
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121
apps/flowgraphs/fm_demod.grc
View File

@ -1,5 +1,5 @@
<?xml version='1.0' encoding='utf-8'?>
<?grc format='1' created='3.7.11'?>
<?grc format='1' created='3.7.10'?>
<flow_graph>
<timestamp>Thu May 5 00:22:45 2016</timestamp>
<block>
@ -178,7 +178,7 @@ SDR received samples</value>
</param>
<param>
<key>_coordinate</key>
<value>(781, 865)</value>
<value>(928, 1028)</value>
</param>
<param>
<key>_rotation</key>
@ -220,6 +220,33 @@ SDR received samples</value>
<value>250000</value>
</param>
</block>
<block>
<key>variable</key>
<param>
<key>comment</key>
<value></value>
</param>
<param>
<key>_enabled</key>
<value>True</value>
</param>
<param>
<key>_coordinate</key>
<value>(1040, 1028)</value>
</param>
<param>
<key>_rotation</key>
<value>0</value>
</param>
<param>
<key>id</key>
<value>max_modulation_freq</value>
</param>
<param>
<key>value</key>
<value>3000</value>
</param>
</block>
<block>
<key>variable</key>
<param>
@ -369,7 +396,7 @@ TX sampling rate</value>
</param>
<param>
<key>_coordinate</key>
<value>(1085, 410)</value>
<value>(864, 412)</value>
</param>
<param>
<key>_rotation</key>
@ -941,6 +968,84 @@ we shift the LO a little further</value>
<value>100e3</value>
</param>
</block>
<block>
<key>low_pass_filter</key>
<param>
<key>beta</key>
<value>6.76</value>
</param>
<param>
<key>alias</key>
<value></value>
</param>
<param>
<key>comment</key>
<value>Using the Carson bandwidth rule for filter width:
width = 2*(deviation + max_modulation_freq).
For the majority of FM transmissions we can expect
max_modulation_freq = 3000</value>
</param>
<param>
<key>affinity</key>
<value></value>
</param>
<param>
<key>cutoff_freq</key>
<value>deviation+max_modulation_freq</value>
</param>
<param>
<key>decim</key>
<value>1</value>
</param>
<param>
<key>_enabled</key>
<value>True</value>
</param>
<param>
<key>type</key>
<value>fir_filter_ccf</value>
</param>
<param>
<key>_coordinate</key>
<value>(1064, 368)</value>
</param>
<param>
<key>_rotation</key>
<value>180</value>
</param>
<param>
<key>gain</key>
<value>1</value>
</param>
<param>
<key>id</key>
<value>low_pass_filter_0</value>
</param>
<param>
<key>interp</key>
<value>1</value>
</param>
<param>
<key>maxoutbuf</key>
<value>0</value>
</param>
<param>
<key>minoutbuf</key>
<value>0</value>
</param>
<param>
<key>samp_rate</key>
<value>audio_samp_rate</value>
</param>
<param>
<key>width</key>
<value>3000</value>
</param>
<param>
<key>win</key>
<value>firdes.WIN_HAMMING</value>
</param>
</block>
<block>
<key>osmosdr_source</key>
<param>
@ -2681,7 +2786,7 @@ we shift the LO a little further</value>
</param>
<param>
<key>_coordinate</key>
<value>(877, 394)</value>
<value>(432, 396)</value>
</param>
<param>
<key>_rotation</key>
@ -2865,7 +2970,7 @@ we shift the LO a little further</value>
</connection>
<connection>
<source_block_id>blks2_rational_resampler_xxx_1</source_block_id>
<sink_block_id>analog_quadrature_demod_cf_0</sink_block_id>
<sink_block_id>low_pass_filter_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
@ -2887,6 +2992,12 @@ we shift the LO a little further</value>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
<connection>
<source_block_id>low_pass_filter_0</source_block_id>
<sink_block_id>analog_quadrature_demod_cf_0</sink_block_id>
<source_key>0</source_key>
<sink_key>0</sink_key>
</connection>
<connection>
<source_block_id>osmosdr_source_0</source_block_id>
<sink_block_id>satnogs_coarse_doppler_correction_cc_0</sink_block_id>

37
apps/flowgraphs/satnogs_fm_demod.py
View File

@ -5,7 +5,7 @@
# Title: FM Generic Demodulation
# Author: Manolis Surligas (surligas@gmail.com)
# Description: A generic FM demodulation block
# Generated: Wed Aug 9 13:41:22 2017
# Generated: Thu Sep 21 10:50:12 2017
##################################################
from gnuradio import analog
@ -51,9 +51,10 @@ class satnogs_fm_demod(gr.top_block):
##################################################
self.samp_rate_rx = samp_rate_rx = satnogs.hw_rx_settings[rx_sdr_device]['samp_rate']
self.xlate_filter_taps = xlate_filter_taps = firdes.low_pass(1, samp_rate_rx, 125000, 25000, firdes.WIN_HAMMING, 6.76)
self.taps = taps = firdes.low_pass(12.0, samp_rate_rx, 100e3, 60000, firdes.WIN_HAMMING, 6.76)
self.max_modulation_freq = max_modulation_freq = 3000
self.filter_rate = filter_rate = 250000
self.deviation = deviation = 5000
self.audio_samp_rate = audio_samp_rate = 48000
@ -79,7 +80,9 @@ class satnogs_fm_demod(gr.top_block):
self.osmosdr_source_0.set_bb_gain(satnogs.handle_rx_bb_gain(rx_sdr_device, bb_gain), 0)
self.osmosdr_source_0.set_antenna(satnogs.handle_rx_antenna(rx_sdr_device, antenna), 0)
self.osmosdr_source_0.set_bandwidth(samp_rate_rx, 0)
self.low_pass_filter_0 = filter.fir_filter_ccf(1, firdes.low_pass(
1, audio_samp_rate, deviation+max_modulation_freq, 3000, firdes.WIN_HAMMING, 6.76))
self.freq_xlating_fir_filter_xxx_0 = filter.freq_xlating_fir_filter_ccc(int(samp_rate_rx/filter_rate), (xlate_filter_taps), lo_offset, samp_rate_rx)
self.blks2_rational_resampler_xxx_1 = filter.rational_resampler_ccc(
interpolation=24,
@ -92,14 +95,15 @@ class satnogs_fm_demod(gr.top_block):
##################################################
# Connections
##################################################
self.msg_connect((self.satnogs_tcp_rigctl_msg_source_0, 'freq'), (self.satnogs_coarse_doppler_correction_cc_0, 'freq'))
self.connect((self.analog_quadrature_demod_cf_0, 0), (self.satnogs_ogg_encoder_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.analog_quadrature_demod_cf_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.satnogs_iq_sink_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.satnogs_waterfall_sink_0, 0))
self.connect((self.freq_xlating_fir_filter_xxx_0, 0), (self.blks2_rational_resampler_xxx_1, 0))
self.connect((self.osmosdr_source_0, 0), (self.satnogs_coarse_doppler_correction_cc_0, 0))
self.connect((self.satnogs_coarse_doppler_correction_cc_0, 0), (self.freq_xlating_fir_filter_xxx_0, 0))
self.msg_connect((self.satnogs_tcp_rigctl_msg_source_0, 'freq'), (self.satnogs_coarse_doppler_correction_cc_0, 'freq'))
self.connect((self.analog_quadrature_demod_cf_0, 0), (self.satnogs_ogg_encoder_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.low_pass_filter_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.satnogs_iq_sink_0, 0))
self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.satnogs_waterfall_sink_0, 0))
self.connect((self.freq_xlating_fir_filter_xxx_0, 0), (self.blks2_rational_resampler_xxx_1, 0))
self.connect((self.low_pass_filter_0, 0), (self.analog_quadrature_demod_cf_0, 0))
self.connect((self.osmosdr_source_0, 0), (self.satnogs_coarse_doppler_correction_cc_0, 0))
self.connect((self.satnogs_coarse_doppler_correction_cc_0, 0), (self.freq_xlating_fir_filter_xxx_0, 0))
def get_antenna(self):
return self.antenna
@ -234,6 +238,13 @@ class satnogs_fm_demod(gr.top_block):
def set_taps(self, taps):
self.taps = taps
def get_max_modulation_freq(self):
return self.max_modulation_freq
def set_max_modulation_freq(self, max_modulation_freq):
self.max_modulation_freq = max_modulation_freq
self.low_pass_filter_0.set_taps(firdes.low_pass(1, self.audio_samp_rate, self.deviation+self.max_modulation_freq, 3000, firdes.WIN_HAMMING, 6.76))
def get_filter_rate(self):
return self.filter_rate
@ -245,6 +256,7 @@ class satnogs_fm_demod(gr.top_block):
def set_deviation(self, deviation):
self.deviation = deviation
self.low_pass_filter_0.set_taps(firdes.low_pass(1, self.audio_samp_rate, self.deviation+self.max_modulation_freq, 3000, firdes.WIN_HAMMING, 6.76))
self.analog_quadrature_demod_cf_0.set_gain((2*math.pi*self.deviation)/self.audio_samp_rate)
def get_audio_samp_rate(self):
@ -252,6 +264,7 @@ class satnogs_fm_demod(gr.top_block):
def set_audio_samp_rate(self, audio_samp_rate):
self.audio_samp_rate = audio_samp_rate
self.low_pass_filter_0.set_taps(firdes.low_pass(1, self.audio_samp_rate, self.deviation+self.max_modulation_freq, 3000, firdes.WIN_HAMMING, 6.76))
self.analog_quadrature_demod_cf_0.set_gain((2*math.pi*self.deviation)/self.audio_samp_rate)
def get_audio_gain(self):