On Tue, 06 Nov 2018 12:09:02 -0500 "Marcus D. Leech" <patchvonbr...@gmail.com> wrote:
> On 11/06/2018 10:24 AM, Gwenhael Goavec-Merou wrote: > > On Tue, 06 Nov 2018 09:40:09 -0500 > > "Marcus D. Leech via USRP-users" <usrp-users@lists.ettus.com> wrote: > > > >> On 11/06/2018 04:12 AM, Gwenhael Goavec-Merou via USRP-users wrote: > >>> Hi, > >>> > >>> My environment is: > >>> USRP: X310 with basicRX (currently one but 6 in a near future) > >>> UHD: 3.13.1.0-rc1 > >>> GNURadio: 3.7.13.4-r2 > >>> gr-ettus: master branch, up to date > >>> > >>> I need to sample 4 real signal / USRP and to demodulate / decimate before > >>> transfer to the PC. > >>> > >>> I have created a GNURadio flow with: > >>> - 2 Radio (id 0 and 1), configured with 2 channels > >>> - 2 DDC (id 0 and 1), with 2 channels, with a center frequency fixed to XX > >>> MHz > >>> - 4 complex To Real; > >>> - 1 QT Gui with 4 inputs. > >>> > >>> Each channel of each radio is connected to an DDC input (radio0 channel 0 > >>> to DDC0 input 0, radio0 channel 1 to DDC0 input 1, etc.) > >>> > >>> With this setup and with an input configured as XX + YY MHz (to have a > >>> beatnote) I'm able to see a sinusoid on the qt for all channels (if I > >>> plug / unplug an input signal the corresponding plot is equal to 0 or > >>> displays the signal). > >>> But: > >>> 1/ the console panel display continuouly messages about channels overrun > >>> 2/ the data flow is not continuous (visible in qt plot) (I suppose is due > >>> to 1/ ) > >>> 3/ channels are not aligned (I suppose is due to 1/ and/or 2/ > >>> > >>> Theorically, by reading HDL files for the X310 firmware it's seems > >>> possible to use this configuration. > >>> > >>> Then, how to fix my issue? > >>> - Is it a USRP/UHD limitation? > >>> - gr-ettus seems not heavily upgraded, is something must be modified in > >>> this repository? > >>> - I am just wrong somewhere on my design? > >>> > >>> Thank you very much > >>> > >>> Gwen > >>> > >> What is the sample rate as delivered to the PC? What kind of PC? > > The sample rate is 3MS/s for each channels after DDC (200MS/s before due to > > the ADC). > > My PC is a Lenovo thinkpad x230 with a 1Gb ethernet card. > >> Overrun means that your PC isn't keeping up with the sample flow. > >> > > I've just done several test with only 2 channels : > > - 2 radio, 1 channel/radio and 2 DDC with 1 input (first on radio0, a second > > radio1) : > > - data continuous (but not synchronized) > > - no message on display panel > > - 2 radio, 1 channel/radio and 1 DDC with 2 input : > > - console panel displays continuouly "Ooverrun on chan 0" > > - data not continuous > > - after a short time : freeze > > - 1 radio with 2 channels and 1 DDC with 2 input : > > - console panel displays continuouly "Ooverrun on chan 0" and > > "Ooverrun on chan 1" > > - data not continuous. > > - 1 radio with 2 channels and 2 DDC with 1 input : > > - console panel displays continuouly "Ooverrun on chan 0" > > - data not continuous. > > > > So, the first test seems to show it's possible with my computer to receive 2 > > channel 3MS/s without overrun. Other tests seems to show a problem for radio > > and/or for DDC to send or receive the full speed ADC flow. > > > > Thank. > > > > Gwen > The only immediate comment I have is that 3Msps is not a valid rate for > the DDC with a 200Msps input--rates must be an integer fraction > of the input sample rate. Tested with 2Msps this the same result... > > It would be helpful if you shared your flow-graph for the cases that > don't work. joined Gwen
dualChanPerRadio_1radio_1DDC.grc
Description: application/gnuradio-grc
dualChanPerRadio_1radio_2DDC.grc
Description: application/gnuradio-grc
singleChanPerRadio_2radio_1DDC.grc
Description: application/gnuradio-grc
singleChanPerRadio_2radio_2DDC.grc
Description: application/gnuradio-grc
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