On 27/02/12 08:30 PM, George Nychis wrote: > It's be good if you can chime in here, Josh :) > > It seems like this is something that should be fixed about tunnel.py > in future GNU Radio releases for use with UHD. I've attached a skeletal piece of GRC that uses the "Burst Tagger" block with a 10Hz trigger input to insert tx_eob/tx_sob tags into the stream. I'm not sure whether this will have the desired effect or not, but at least in theory it should.
> > > I'm trying to do my fair share of research here and tackle it. If what > you say is true, Marcus, the control I need is over the TX chain. > > I did a bunch of reading through the UHD docs here: > http://files.ettus.com/uhd_docs/doxygen/html/annotated.html > > I see various controls using tx_streamer and tx_metadata_t to use tags > to control samples to be part of a burst. Like, marking the start and > end of my TX burst of samples which can construct a packet. > > No prob, I can do that. But it seems like there needs to be some sort > of UHD stream command which turns the TX chain in to an "on-demand" > chain and not continuously streaming. On the other hand, I would like > RX to be continuous. > > I see the RX control to specify stream controls here: > http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1stream__cmd__t.html > > > That is clearly documented as control of samples to the host to be > continuous or not. > > However, I don't see that same control for the TX stream. > Tx_metadata_t and t_streamer control the bursts, but don't seem to > control the overall stream? Maybe I am missing something. > > On Sunday, February 26, 2012, Marcus D. Leech wrote: > > On 02/26/2012 08:54 PM, George Nychis wrote: >> >> >> On Sun, Feb 26, 2012 at 5:01 PM, Marcus D. Leech >> <mle...@ripnet.com <javascript:_e({}, 'cvml', >> 'mle...@ripnet.com');>> wrote: >> >> On 02/26/2012 02:29 PM, Apurv Bhartia wrote: >>> Its an XCVR2450, but I do *not* start any 'packet' >>> transmissions. All I do, is to start both the flowgraphs, >>> and just listen for packets. >>> >> In which case, the TX side is running--even if you aren't >> sending any *data* bits, it's still transmitting, and >> blocking the receiver. >> >> You'll have to get more sophisticated about half-duplex flow >> management, using tagging to tell UHD to turn on/off the TX side. >> >> Josh probably has better words of wisdom on this than I. >> >> >> Hi Marcus, >> >> I'm working with Apurv, so I'm going to chime in here :) >> >> I tried doing some searching on the mailing list, but I wasn't >> really able to find much on this. I also thought that auto tr >> would handle this. I found a post from Josh on the mailing list >> that said Auto TR is always enabled in UHD. >> >> http://www.ruby-forum.com/topic/1527488 >> >> > Yes, it is enabled in UHD. But since Gnu Radio is a *streaming* > model, you need to take special measures to control TX from within a > Gnu Radio flow-graph. YOu need to insert a tag in the stream to > control the transmitter, otherwise, you'll be continuously streaming. > > What you do is insert a burst-tagger into your stream, and set it > to send the appropriate tags for UHD into the stream using the trigger > input. I just can't off the top of my head, remember what those > stream tags are at the moment. But the basic issue is that Gnu Radio > uses a streaming model, and while UHD itself (at the C++ level) > has fine-grianed control over transmitter functions, etc, gr-uhd > doesn't > directly expose any of that, because there's just not mechanism > within Gnu Radio to expose that stuff. The stream tagging, however, > does allow you to control the transmitter state. In the > particular case of the XCVR2450, the hardware is physically > incapable of > TX and RX at the same time. > > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortium > http://www.sbrac.org > > -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
burst_tagger_uhd.grc
Description: application/gnuradio-grc
#!/usr/bin/env python
##################################################
# Gnuradio Python Flow Graph
# Title: Burst Tagger Uhd
# Generated: Mon Feb 27 20:52:20 2012
##################################################
from gnuradio import eng_notation
from gnuradio import gr
from gnuradio import uhd
from gnuradio.eng_option import eng_option
from gnuradio.gr import firdes
from grc_gnuradio import wxgui as grc_wxgui
from optparse import OptionParser
import wx
class burst_tagger_uhd(grc_wxgui.top_block_gui):
def __init__(self):
grc_wxgui.top_block_gui.__init__(self, title="Burst Tagger Uhd")
_icon_path = "/usr/share/icons/hicolor/32x32/apps/gnuradio-grc.png"
self.SetIcon(wx.Icon(_icon_path, wx.BITMAP_TYPE_ANY))
##################################################
# Variables
##################################################
self.samp_rate = samp_rate = 250e3
##################################################
# Blocks
##################################################
self.uhd_usrp_sink_0 = uhd.usrp_sink(
device_addr="",
stream_args=uhd.stream_args(
cpu_format="fc32",
channels=range(1),
),
)
self.uhd_usrp_sink_0.set_samp_rate(samp_rate)
self.uhd_usrp_sink_0.set_center_freq(0, 0)
self.uhd_usrp_sink_0.set_gain(0, 0)
self.gr_sig_source_x_0_0 = gr.sig_source_s(samp_rate, gr.GR_SQR_WAVE, 10, 1, 0)
self.gr_sig_source_x_0 = gr.sig_source_c(samp_rate, gr.GR_COS_WAVE, 25e3, 1, 0)
self.gr_burst_tagger_0 = gr.burst_tagger(gr.sizeof_gr_complex)
self.gr_burst_tagger_0.set_true_tag("tx_eob",True)
self.gr_burst_tagger_0.set_false_tag("tx_sob",True)
##################################################
# Connections
##################################################
self.connect((self.gr_burst_tagger_0, 0), (self.uhd_usrp_sink_0, 0))
self.connect((self.gr_sig_source_x_0, 0), (self.gr_burst_tagger_0, 0))
self.connect((self.gr_sig_source_x_0_0, 0), (self.gr_burst_tagger_0, 1))
def get_samp_rate(self):
return self.samp_rate
def set_samp_rate(self, samp_rate):
self.samp_rate = samp_rate
self.uhd_usrp_sink_0.set_samp_rate(self.samp_rate)
self.gr_sig_source_x_0.set_sampling_freq(self.samp_rate)
self.gr_sig_source_x_0_0.set_sampling_freq(self.samp_rate)
if __name__ == '__main__':
parser = OptionParser(option_class=eng_option, usage="%prog: [options]")
(options, args) = parser.parse_args()
tb = burst_tagger_uhd()
tb.Run(True)
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
