Dear All,
We are experiencing unexpected behavior with the time stamps in the meta file
headers. It
appears that in cases where the flowgraph experiences data drops, the timestamp
is properly
updated. However, in cases, where the flowgraph hits the maximum segment size
(4 MB in our case),
the calculation of timestamp is done in such a way that appears to neglect a
decimation factor
in one of our blocks (keep_1_in_n). Details can be found below. Any
suggestions as to what's
going on or what to do about it would be most appreciated.
Sincerely,
Dan Marlow
Details:
OS: Ubuntu 15.04 (GNU/Linux 3.19.0-26-generic x86_64)
H/W: Ettus B210 with GPSDO,
Intel(R) Core(TM) i5-4430 CPU @ 3.00GHz 8GB memory USB3
gnuradio: 3.7.8
Flowgraph: This is provided to give an idea of what we are doing. It is
close to what we
are using, but not exact, since we edited the output
generated by GRC.
B210_2ch_filewriter.grc
Description: Binary data
The actual top_block we are running is attached below.
#!/usr/bin/env python2
##
# GNU Radio Python Flow Graph
# Title: Top Block
# Generated: Thu Jul 23 11:29:50 2015
##
from gnuradio import blocks
from gnuradio import eng_notation
from gnuradio import fft
from gnuradio import gr
from gnuradio import uhd
from gnuradio.eng_option import eng_option
from gnuradio.fft import window
from gnuradio.filter import firdes
from optparse import OptionParser
import specest
import time
import pmt
from DAQ import rxcntl
class top_block(gr.top_block):
def __init__(self, fname1='raw1.dat', fname2='raw2.dat'):
gr.top_block.__init__(self, "Top Block")
##
# Extra Variables
##
self.fname1 = fname1
self.fname2 = fname2
self.nChannels = nChannels = 1
print "Entering top_block: fname1={0:s} fname2={1:s}".format(self.fname1,self.fname2)
##
# Variables
##
self.freq1 = freq1 = 142000
self.freq2 = freq2 = 142000
self.samp_rate = samp_rate = 1/4.
self.gain = gain = 60
self.N_average = N_average = 512
self.FFT_size = FFT_size = 32
self.BW = BW = 2000
self.BW = BW = 2500
##
# Blocks
##
self.uhd_usrp_source_0 = uhd.usrp_source(
",".join(("ser=F61177", "")),
uhd.stream_args(
cpu_format="fc32",
channels=range(self.nChannels),
),
)
self.uhd_usrp_source_0.set_subdev_spec("A:A A:B", 0)
self.uhd_usrp_source_0.set_samp_rate(samp_rate)
self.uhd_usrp_source_0.set_center_freq(self.freq1, 0)
self.uhd_usrp_source_0.set_gain(gain, 0)
self.uhd_usrp_source_0.set_bandwidth(BW, 0)
#sensorNames = self.uhd_usrp_source_0.get_mboard_sensor_names(0)
#print "Sensor names=" + str(sensorNames)
GPStime = self.uhd_usrp_source_0.get_mboard_sensor("gps_time")
GPS_locked = self.uhd_usrp_source_0.get_mboard_sensor("gps_locked")
print "GPS Info: {0:s}; {1:s}".format(str(GPS_locked),str(GPStime))
self.uhd_usrp_source_0.set_time_now(uhd.time_spec(time.time()), uhd.ALL_MBOARDS)
if self.nChannels == 2 :
self.uhd_usrp_source_0.set_center_freq(self.freq2, 1)
self.uhd_usrp_source_0.set_gain(gain, 1)
self.uhd_usrp_source_0.set_bandwidth(BW, 1)
self.specest_moving_average_vff_0 = specest.moving_average_vff(N_average, FFT_size, 1, 4096)
self.fft_vxx_0 = fft.fft_vcc(FFT_size, True, (window.blackmanharris(FFT_size)), True, 1)
self.blocks_vector_to_stream_0 = blocks.vector_to_stream(gr.sizeof_float*1, FFT_size)
self.blocks_stream_to_vector_0 = blocks.stream_to_vector(gr.sizeof_gr_complex*1, FFT_size)
self.blocks_keep_one_in_n_0_0 = blocks.keep_one_in_n(gr.sizeof_float*FFT_size, N_average)
self.blocks_complex_to_mag_squared_0 = blocks.complex_to_mag_squared(FFT_size)
self.blocks_file_meta_sink_0 = blocks.file_meta_sink(gr.sizeof_float*1, self.fname1, self.samp_rate, \
1, blocks.GR_FILE_FLOAT, False, 100, self._extras(), False)
self.blocks_file_meta_sink_0.set_unbuffered(False)
if self.nChannels == 2 :
self.specest_moving_average_vff_1 = specest.moving_average_vff(N_average, FFT_size, 1, 4096)
self.fft_vxx_0_0 = fft.fft_vcc(FFT_size, True, (window.blackmanharris(FFT_size)), True, 1)
self.blocks_vector_to_stream_0_0 = blocks.vector_to_stream(gr.sizeof_float*1, FF
