Re: [Discuss-gnuradio] problem with send() function making OOT

[Marcus Müller]

Hi Sanjoy,

you're both setting the time for both the USRP with the GPSDO (which 
will get it from GPSDO) and the one without. You don't have to do that, 
remove these lines. There should be no set_time_** in your code if you 
want to use the time as it comes from your GPSDO.

Then, although you use a time in the streamer command, you don't do 
set_command_time() before setting the frequencies. That's what I 
recommended.

Best regards,
Marcus



On 19.07.2015 00:20, Sanjoy Basak wrote:
> Hi Marcus,
>
> I need help regarding the phase sync part that you mentioned in your
> previous post here.
>
> "There's one thing that could use improvement in the echotimer code: If
> the set_?x_freq() were done after the time and clock sources had been
> set as a timed command (i.e. after calling set_command_time()), then the
> SBX daughterboards would always have the same phase relationship after
> tuning to the same frequency, which might be really handy in MIMO."
>
> This part I tried in python, however, I am not actually getting any
> phase sync between the receive files. I am not really sure whether
> defining freq after set_command_time() in python can really help.
> However, please let me know what modification should I make or what
> exactly I need to do.
>
> I am putting the python code here that I am using right now for 2 usrps.
> 2 TXs are in one x310 (on gpsdo) and 2 RXs are on the other one
> (external ref).
> and the connection is TX-wire-30_dB_attenuator-wire-RX, I am taking
> wired measurement. I am using 2.45 GHz freq.
>
> ---------------------------
>          self.usrp_source0 = uhd.usrp_source(
>            ",".join(("addr=172.xx.xx.73", "")),
>            uhd.stream_args(
>              cpu_format="fc32",
>              channels=range(2),
>            ),
>          )
>
>          self.usrp_sink0 = uhd.usrp_sink(
>            ",".join(("addr=172.xx.xx.75", "")),
>            uhd.stream_args(
>              cpu_format="fc32",
>              channels=range(2),
>            ),
>          )
>
>
>          self.usrp_source0.set_clock_source("external", 0)
>          self.usrp_source0.set_time_source("external", 0)
>          self.usrp_source0.set_subdev_spec("A:0 B:0", 0)
>          self.usrp_source0.set_time_unknown_pps(uhd.time_spec())
>          self.usrp_source0.set_samp_rate(samp_rate)
>          self.usrp_source0.set_gain(26, 0)
>          self.usrp_source0.set_antenna("RX2", 0)
>          self.usrp_source0.set_gain(26, 1)
>          self.usrp_source0.set_antenna("RX2", 1)
>
>          self.usrp_sink0.set_clock_source("gpsdo", 0)
>          self.usrp_sink0.set_time_source("gpsdo", 0)
>          self.usrp_sink0.set_subdev_spec("A:0 B:0", 0)
>          self.usrp_sink0.set_time_unknown_pps(uhd.time_spec())
>          self.usrp_sink0.set_samp_rate(samp_rate)
>          self.usrp_sink0.set_gain(0, 0)
>          self.usrp_sink0.set_antenna("TX/RX", 0)
>          self.usrp_sink0.set_gain(0, 1)
>          self.usrp_sink0.set_antenna("TX/RX", 1)
>
>    time.sleep(1)
>    print "receiver pps time:"
>    cmd_time = self.usrp_source0.get_time_last_pps()
>    print "transmitter pps time:"
>    cmd_time0 = self.usrp_sink0.get_time_last_pps()
>    real_seconds = uhd.time_spec_t.get_real_secs(cmd_time)
>    real_seconds0 = uhd.time_spec_t.get_real_secs(cmd_time0)
>
>    print real_seconds
>     print real_seconds0
>
>
>    self.usrp_source0.set_time_next_pps(uhd.time_spec_t(0.0))
>    self.usrp_sink0.set_time_next_pps(uhd.time_spec_t(0.0))
>
>    now = self.usrp_source0.get_time_now()
>    starttime = now + uhd.time_spec(1.5)
>    self.usrp_source0.set_start_time(starttime)
>    self.usrp_sink0.set_start_time(starttime)
>
>          self.usrp_source0.set_center_freq(f, 0)
>          self.usrp_source0.set_center_freq(f, 1)
>          self.usrp_sink0.set_center_freq(f, 0)
>          self.usrp_sink0.set_center_freq(f, 1)
>
>          self.blocks_throttle_0_1 =
> blocks.throttle(gr.sizeof_gr_complex*1, samp_rate,True)
>          self.blocks_throttle_0_0_0 =
> blocks.throttle(gr.sizeof_gr_complex*1, samp_rate,True)
>          self.blocks_throttle_0_0 =
> blocks.throttle(gr.sizeof_gr_complex*1, samp_rate,True)
>          self.blocks_throttle_0 = blocks.throttle(gr.sizeof_gr_complex*1,
> samp_rate,True)
>          self.blocks_file_source_0_0 =
> blocks.file_source(gr.sizeof_gr_complex*1,
> "/home/sanjoy/Desktop/new/siso with new preamble
> 3/20150603_siso_echotimer/floatgen.bin", True)
>          self.blocks_file_source_0 =
> blocks.file_source(gr.sizeof_gr_complex*1,
> "/home/sanjoy/Desktop/new/siso with new preamble
> 3/20150603_siso_echotimer/floatgen.bin", True)
>          self.blocks_file_sink_0_0 =
> blocks.file_sink(gr.sizeof_gr_complex*1,
> "/home/sanjoy/Desktop/siso2.bin", False)
>          self.blocks_file_sink_0_0.set_unbuffered(False)
>          self.blocks_file_sink_0 =
> blocks.file_sink(gr.sizeof_gr_complex*1,
> "/home/sanjoy/Desktop/siso1.bin", False)
>          self.blocks_file_sink_0.set_unbuffered(False)
> -----------------------------
>
> My system config is usrp X310, daughterboard SBX-120, uhd 3.9.
>
> best regards
> Sanjoy