On 16/12/2024 13:47, Christophe Grimault wrote:
I followed your advice and I'm getting closer !-)
I tried this :
usrp = uhd.usrp.MultiUSRP(f"addr=192.168.30.2")
duration =10.0 start_time_spec =
uhd.libpyuhd.types.time_spec(usrp.get_time_now().get_real_secs() +1.0)
rx_rates = [390625.0*2,390625.0]
# --------------- # Craft commands # --------------- # Start with chan
0 ... usrp.set_rx_rate(rx_rates[0],chan=0)
rx_tune_request0 = uhd.types.TuneRequest(1100.0e6)
usrp.set_rx_freq(tune_request=rx_tune_request0,chan=0)
usrp.set_rx_gain(45.0,chan=0)
num_samps0 = math.ceil(int(usrp.get_rx_rate(chan=0)) * duration)
rx_streamer_args0 = uhd.usrp.StreamArgs("fc32","sc16")
rx_streamer_args0.channels = [0]
rx_streamer0 = usrp.get_rx_stream(rx_streamer_args0)
max_samps_per_packet = rx_streamer0.get_max_num_samps()
L0 = math.ceil(num_samps0 / max_samps_per_packet) * max_samps_per_packet
recv_buffer0 = np.zeros(L0,dtype=np.complex64)
stream_cmd0 = uhd.types.StreamCMD(uhd.types.StreamMode.start_cont)#num_done)
stream_cmd0.stream_now =False stream_cmd0.num_samps = num_samps0
stream_cmd0.time_spec = start_time_spec
# Then chan 1, which is 2 times slower. usrp.set_rx_rate(rx_rates[1],chan=1)
rx_tune_request1 = uhd.types.TuneRequest(1100.0e6)
usrp.set_rx_freq(tune_request=rx_tune_request1,chan=1)
usrp.set_rx_gain(35.0,chan=1)
num_samps1 = math.ceil(int(usrp.get_rx_rate(chan=1)) * duration)
rx_streamer_args1 = uhd.usrp.StreamArgs("fc32","sc16")
rx_streamer_args1.channels = [1]
rx_streamer1 = usrp.get_rx_stream(rx_streamer_args1)
max_samps_per_packet = rx_streamer1.get_max_num_samps()
L1 = math.ceil(num_samps1 / max_samps_per_packet) * max_samps_per_packet
recv_buffer1 = np.zeros(L1,dtype=np.complex64)
stream_cmd1 = uhd.types.StreamCMD(uhd.types.StreamMode.start_cont)#num_done)
stream_cmd1.stream_now =False stream_cmd1.num_samps = num_samps1
stream_cmd1.time_spec = start_time_spec
# -------------------------------------------------- # Launch sampling
on both streamers, i.e. channels #
-------------------------------------------------- rx_streamer0.issue_stream_cmd(stream_cmd0)
rx_streamer1.issue_stream_cmd(stream_cmd1)
metadata0 = uhd.types.RXMetadata()
nb_samples0 = rx_streamer0.recv(recv_buffer0, metadata0,3.0)
metadata1 = uhd.types.RXMetadata()
nb_samples1 = rx_streamer1.recv(recv_buffer1, metadata1,3.0)
metadata0.time_spec.get_real_secs() - metadata1.time_spec.get_real_secs()
And got the attached figures.
Over the 10 s of capture, I switch of the signal at the same time on
both channels (exact same time because the switch is before the RF
coupler). Both capture are roughly aligned in time, but when I zoom, I
see 26 us of delay (which is roughly 10 samples at rx_rate_1 of
390625). Am I wrong expecting a "perfect timing" ? And when I compute :
metadata0.time_spec.get_real_secs() - metadata1.time_spec.get_real_secs()
still I get 0.0 us.
What am I doing wrong ? Shall I launch threads ?
Any thoughts ?
Thanks in advance
Chris
A cursory inspection of your code doesn't indicate any glaring errors,
but your start-time is only 1 second ahead of when
you get the time from the device. That MAY not be enough to get both
streamers set-up so that they'll "trigger" at the
same time.
What device type is this?
Christophe Grimault
NovaGrid SAS
Les Jardins de la Teillais
3, allée de la grande égalonne
35740 Pacé, France
Tel : (33)2 23 41 37 97
Mob: (33)6 82 22 46 93
www.novagrid.com
Le 16/12/2024 à 15:15, Christophe Grimault a écrit :
Dear users,
I'm using python wrappers with UHD >= 4.5 and a X300 with 2 twinRx.
I would like to know if it is possible to create a streamer, for more
than N channels, with a sampling rate which different for each channel.
As for now, when I try this, I get all my 4 channels with the same
sampling rate, which is the one of the last channel added.
Is it just possible to do it ? Say, for example, have a streamer
with 2 channels :
* chan 0 on fc = 140 Mhz, rx_rate=20 MS/s
* chan 1 on fc = 140 MHz, rx_rate=1 MS/s
Thanks in advance
Chris
--
Christophe Grimault
NovaGrid SAS
Les Jardins de la Teillais
3, allée de la grande égalonne
35740 Pacé, France
Tel : (33)2 23 41 37 97
Mob: (33)6 82 22 46 93
www.novagrid.com
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