I am not observing one individual channel but phase difference between two channels. I very well know individual channel would show random phases but not the phase difference when same signal is injected in two channels. I hope you are aware that phase difference = 2pi/lambda* path_difference. Path difference is constant as that’s the difference between two paths of two daughterboards and hence this phase difference is constant. Remember same signal is injected so initial phases would be same for two channels and only the difference in the signal path lengths bring the difference which is constant
Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: Marcus D. Leech <patchvonbr...@gmail.com> Sent: Sunday, August 16, 2020 10:39 PM To: Koyel Das (Vehere); usrp-users@lists.ettus.com Subject: Re: [USRP-users] Incorrect data from usrp 2955 On 08/16/2020 12:46 PM, Koyel Das (Vehere) wrote: The measurement is not initial phase but the phase difference between two channels Get Outlook for iOS<https://aka.ms/o0ukef> Are you using an external reference, or using the internal clock in the X310? If you observe an individual channel, is it "sane" ? That is, apparently on-frequency, and with correct amplitudes and low distortion? ________________________________ From: Koyel Das (Vehere) <koyel....@vehere.com><mailto:koyel....@vehere.com> Sent: Sunday, August 16, 2020 10:15:48 PM To: Marcus D. Leech <patchvonbr...@gmail.com><mailto:patchvonbr...@gmail.com>; usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> <usrp-users@lists.ettus.com><mailto:usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Incorrect data from usrp 2955 the phase difference between two channels of USRP as a function of frequency and time, when measured by splitting the same signal and feeding two channels of usrp, are wandering around wrt one another which was not happening before. I had given demo more than 30 times based on this principle and tested previously more than 50 times and I got correct result every time. Now only suddenly it started happening. The frequency is 2.4 GHz and bandwidth I tried from 1 MHz to 100 MHz. Previously the whole bandwidth was showing similar values but then suddenly started behaving abnormally giving near to correct result sometimes and sometimes junk. Regards, Koyel Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: Marcus D. Leech <patchvonbr...@gmail.com><mailto:patchvonbr...@gmail.com> Sent: Sunday, August 16, 2020 10:05 PM To: Koyel Das (Vehere); usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Incorrect data from usrp 2955 On 08/15/2020 11:59 PM, Koyel Das (Vehere) wrote: No it doesn’t look better again after reducing gain. Sometimes the phase differences are closeby but not so same as we were getting before and most of the times they are totally incorrect. Strength of the signal when we tried with maximum gain was near -40 dbm. Regards, Koyel To clarify some things. (A) The phase errors are just the initial phases--they don't wander around with respect to one another during a run? (B) What frequency range? Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: USRP-users <usrp-users-boun...@lists.ettus.com><mailto:usrp-users-boun...@lists.ettus.com> on behalf of Marcus D. Leech via USRP-users <usrp-users@lists.ettus.com><mailto:usrp-users@lists.ettus.com> Sent: Sunday, August 16, 2020 12:25:37 AM To: usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> <usrp-users@lists.ettus.com><mailto:usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Incorrect data from usrp 2955 On 08/15/2020 01:16 PM, Koyel Das (Vehere) via USRP-users wrote: Hi, We are using USRP 2955. Something has gone wrong. Before we were getting constant phase difference across channels for limited bandwidth and with time when we split single antenna signal using splitter and fed two channels of USRP but now it is not doing so. This happened on Friday that after getting a series of correct results : constant phase difference across channels by feeding signal using splitter as mentioned above, we suddenly started to receive wrong data: random phase across channels and with time using the same setup with splitter. The thing we did was setting gain to near maximum and receiving 100 MHz sample rate. But I don't think amplifier has damaged because in this usrp we have four independent channels and when we connected the splitter to unused channels then also we got wrong data. What can go wrong that USRP is streaming data but phases are wrong? What do you think? Please let me know. Regards, Koyel Get Outlook for iOS<https://aka.ms/o0ukef> _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com<mailto:USRP-users@lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com Does it look better again when you reduce the gain? What is the magnitude of the signals going to the RX ports?
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