Hi,
I have an interesting observation to share, and I want to see if
anybody
can help me shed some light. When I measure time in python in the
following
way:
t1 = datetime.now()
self.start()
t2=datetime.now()
diff = t2.microsecond - t1.microsecond
print “Difference %d”, diff
I get very different time benchmarks…it goes from 309 microseconds
(minimum) to all the way 1 second(max). Do you know why this thread
spawning
is taking such a variety of time after flowgraph start()??
====Code Below=====
#!/usr/bin/env python
from gnuradio import gr, gru, modulation_utils
from gnuradio import usrp
from gnuradio.eng_option import eng_option
from gnuradio import eng_notation
from optparse import OptionParser
from datetime import datetime
import sys
class my_top_block(gr.top_block):
def init(self):
gr.top_block.init(self)
self.interp = 64
self.waveform_type = gr.GR_GAUSSIAN
self.waveform_ampl = 32000
self.waveform_freq = 2.5e9
self.waveform_offset = 0
self.nsamples = 0
self._instantiate_blocks ()
self.set_waveform_type (self.waveform_type)
def usb_freq (self):
return self.u.dac_freq() / self.interp
def usb_throughput (self):
return self.usb_freq () * 4
def set_waveform_type (self, type):
self._configure_graph (type)
self.waveform_type = type
def set_waveform_ampl (self, ampl):
self.waveform_ampl = ampl
self.siggen.set_amplitude (ampl)
self.noisegen.set_amplitude (ampl)
def set_waveform_freq (self, freq):
self.waveform_freq = freq
self.siggen.set_frequency (freq)
def set_waveform_offset (self, offset):
self.waveform_offset = offset
self.siggen.set_offset (offset)
def set_interpolator (self, interp):
self.interp = interp
self.siggen.set_sampling_freq (self.usb_freq ())
self.u.set_interp_rate (interp)
def _instantiate_blocks (self):
self.src = None
self.u = usrp.sink_c (0, self.interp)
self.noisegen = gr.noise_source_c (gr.GR_GAUSSIAN,
self.waveform_ampl)
self.head = None
if self.nsamples > 0:
self.head = gr.head(gr.sizeof_gr_complex,
int(self.nsamples))
def _configure_graph (self, type):
try:
self.lock()
self.disconnect_all ()
if self.head:
self.connect(self.head, self.u)
tail = self.head
else:
tail = self.u
if type == gr.GR_UNIFORM or type == gr.GR_GAUSSIAN:
self.connect (self.noisegen, tail)
self.noisegen.set_type (type)
self.src = self.noisegen
else:
raise ValueError, type
finally:
self.unlock()
def set_freq(self, target_freq):
r = self.u.tune(self.subdev.which(),self.subdev,2.5e9)
if r:
#print "r.baseband_freq =",
eng_notation.num_to_str(r.baseband_freq)
#print “r.dxc_freq =”,
eng_notation.num_to_str(r.dxc_freq)
#print “r.residual_freq =”,
eng_notation.num_to_str(r.residual_freq)
#print “r.inverted =”, r.inverted
return True
return False
def build_graph(self):
demods = modulation_utils.type_1_demods()
parser = OptionParser (option_class=eng_option)
parser.add_option ("-T", "--tx-subdev-spec", type="subdev",
default=(0, 0),
help=“select USRP Tx side A or B”)
parser.add_option ("-f", “–rf-freq”, type=“eng_float”,
default=None,
help=“set RF center frequency to FREQ”)
parser.add_option ("-i", “–interp”, type=“int”, default=64,
help=“set fgpa interpolation rate to INTERP
[default=%default]”)
parser.add_option ("-d", “–decim”, type=“int”, default=32,
help=“set fgpa decimation rate to DECIM
[default=%default]”)
parser.add_option ("–sine", dest=“type”, action=“store_const”,
const=gr.GR_SIN_WAVE,
help=“generate a complex sinusoid [default]”,
default=gr.GR_SIN_WAVE)
parser.add_option ("–const", dest=“type”, action=“store_const”,
const=gr.GR_CONST_WAVE,
help=“generate a constant output”)
parser.add_option ("–gaussian", dest=“type”,
action=“store_const”,
const=gr.GR_GAUSSIAN,
help=“generate Gaussian random output”)
parser.add_option ("–uniform", dest=“type”, action=“store_const”,
const=gr.GR_UNIFORM,
help=“generate Uniform random output”)
parser.add_option ("-w", "--waveform-freq", type="eng_float",
default=0,
help=“set waveform frequency to FREQ
[default=%default]”)
parser.add_option ("-a", “–amplitude”, type=“eng_float”,
default=16e3,
help=“set waveform amplitude to AMPLITUDE
[default=%default]”, metavar=“AMPL”)
parser.add_option ("-g", “–gain”, type=“eng_float”, default=None,
help=“set output gain to GAIN
[default=%default]”)
parser.add_option ("-o", “–offset”, type=“eng_float”, default=0,
help=“set waveform offset to OFFSET
[default=%default]”)
parser.add_option ("-N", “–nsamples”, type=“eng_float”,
default=0,
help=“set number of samples to transmit
[default=+inf]”)
(options, args) = parser.parse_args ()
if len(args) != 0:
parser.print_help()
raise SystemExit
if options.rf_freq is None:
sys.stderr.write("usrp_siggen: must specify RF center
frequency
with -f RF_FREQ\n")
parser.print_help()
raise SystemExit
if options.tx_subdev_spec is None:
options.tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
m = usrp.determine_tx_mux_value(self.u, options.tx_subdev_spec)
print "mux = %#04x" % (m,)
self.u.set_mux(m)
self.subdev = usrp.selected_subdev(self.u, options.tx_subdev_spec)
print "Using TX d'board %s" % (self.subdev.side_and_name(),)
if options.gain is None:
self.subdev.set_gain(self.subdev.gain_range()[1]) # set max
Tx
gain
else:
self.subdev.set_gain(options.gain) # set max Tx gain
if not self.set_freq(options.rf_freq):
sys.stderr.write('Failed to set RF frequency\n')
raise SystemExit
self.subdev.set_enable(True) # enable
transmitter
- def start_graph(self):
t1 = datetime.now()
self.start()
t2 = datetime.now()
diff = t2.microsecond - t1.microsecond
print “Time it takes to start the flowgraph%d” % diff*
def stop_graph(self):
self.subdev.set_enable(False)
self.stop()