Attempt 2. Sorry for breaking mailing list rules with the attachments. Here is a google drive link to the screenshots, GRC file, and binary files. (3 MB zip)
https://drive.google.com/a/eng.ucsd.edu/file/d/1TvmHuEMFb2QpkiMMdiUEW6aVoUfLYayi/view?usp=sharing We have three sliders in GNUradio. 1. TX gain 2. RX gain 3. Digital Gain (multiply constant block between our binary file and the UHD block. We also have one TX connected directly to an RX with a 30 dB analog attenuation for safety. Our binary files were generated in MATLAB and are normalized to unity magnitude. Attached, please find the GRC file and our binary files. For reference, the waveform we made is a multitone signal so it should be a bunch of evenly spaced spikes. I have included some screenshots too. Additionally we have verified this strange behavior with a spectrum analyzer. By playing around with the sliders you can see how narrow the zone is for good results. Intuitivly it seems like TX and RX gain don't really matter. They just shift the narrow usability zone for Digital gain. On Wed, Oct 17, 2018 at 12:45 PM Ali Dormiani <sdorm...@eng.ucsd.edu> wrote: > We have three sliders in GNUradio. > > 1. TX gain > > 2. RX gain > > 3. Digital Gain (multiply constant block between our binary file and the > UHD block. > > We also have one TX connected directly to an RX with a 30 dB analog > attenuation for safety. > > Our binary files were generated in MATLAB and are normalized to unity > magnitude. > > Attached, please find the GRC file and our binary files. For reference, > the waveform we made is a multitone signal so it should be a bunch of > evenly spaced spikes. I have included some screenshots too. Additionally we > have verified this strange behavior with a spectrum analyzer. > By playing around with the sliders you can see how narrow the zone is for > good results. Intuitivly it seems like TX and RX gain don't really matter. > They just shift the narrow usability zone for Digital gain. > > > > On Wed, Oct 10, 2018 at 6:20 PM Marcus D. Leech via USRP-users < > usrp-users@lists.ettus.com> wrote: > >> On 10/10/2018 03:08 PM, Ali Dormiani via USRP-users wrote: >> >> Hello, >> >> We have the exact same problem. My lab is waiting on some sfp+ cables so >> in a few days I will share our screenshots, code, and data binary files in >> order to provide this thread with a second example of this issue. For now, >> all I can say is this problem is not isolated to your N310 or Windows. >> >> We have two N310's running with the same version of UHD (and GNUradio >> 3.7.13.4) on Linux kernel 4.18. By using amplitude sliders in GNUradio we >> found that there is a very small and strange gain "Goldilocks" zone around >> .002 that gives good results. Going higher starts to raise the noise floor >> until all signal definition is gone. >> >> Ali Dormiani >> UCSD Noiselab >> >> What is your RF gain set to in these examples? Does that change things? >> >> If you raise things to a level where non-linearity is apparent, does >> placing a 10dB attenuator in-line fix it (trying to distinguish between >> the transmitter being non-linear, and your receiver/spectrum analyser). >> >> >> >> On Wed, Oct 10, 2018 at 11:33 AM Mathieu Lizée via USRP-users < >> usrp-users@lists.ettus.com> wrote: >> >>> Hi, >>> >>> When using the UHD "tx_waveforms" example, I can see that the signal >>> emitted by my N310 USRP is saturated when it’s not supposed to be. >>> >>> Here's a snapshot of the signal when I set the amplitude to 0.003: >>> .\tx_waveforms.exe --rate 12.5e6 --nsamps 1250000000 --freq 1575.42e6 >>> --ampl 0.003 --otw sc16 --wave-type SINE --wave-freq 10e3 --channels 2 >>> >>> [image: tx_waveforms_3e-3_amp] >>> <https://user-images.githubusercontent.com/15334138/46685506-a7424700-cbc3-11e8-926e-b0da5f416652.png> >>> >>> Here's a snapshot of the signal when I set the amplitude to 0.03: >>> .\tx_waveforms.exe --rate 12.5e6 --nsamps 1250000000 --freq 1575.42e6 >>> --ampl 0.03 --otw sc16 --wave-type SINE --wave-freq 10e3 --channels 2 >>> >>> [image: tx_waveforms_3e-2_amp] >>> <https://user-images.githubusercontent.com/15334138/46685468-9265b380-cbc3-11e8-9ce7-42908cf9bf2e.png> >>> >>> As you can see from the pictures above, it seems that there's a >>> saturation in the signal when the amplitude is set to 0.03 (which is >>> unexpected with such a small amplitude). We have double-checked with a X300 >>> device, and the signal is normal in both cases. >>> >>> Do you have an idea of what could be wrong, or a suggestion to try on >>> our side? >>> >>> Technical Information: >>> >>> - Windows 10 >>> - USRP N310 >>> - UHD 3.13.0.3-rc1 >>> >>> >>> Thank you! >>> >>> -- >>> *Mathieu Lizee* >>> *Software Development Intern* >>> >>> *Skydel Solutions* >>> WeWork 5th Floor (Skydel) >>> 1275 Av des Canadiens-de-Montreal >>> Montreal, QC >>> H3B 0G4 >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >> >> >> _______________________________________________ >> USRP-users mailing >> listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >
_______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
