[USRP-users] Random long duration noise at the start of UBX captures

Michael West michael.west at ettus.com
Mon Oct 12 19:06:40 EDT 2015


Hi Nathan,

I am unable to reproduce what you are seeing.  I have an N210+GPSDO+UBX
with a 3A power supply and I ran the rx_samples_to_file command you
provided with RX2 terminated and all my data looks clean over multiple
runs.  Are you getting any O's, errors, or warnings during your runs?

Regards,
Michael

On Mon, Oct 12, 2015 at 2:19 PM, Perelman, Nathan <
nperelman at lgsinnovations.com> wrote:

> Sorry, forgot to mention that, RX2 is terminated. I am also using a 3 amp
> power supply not the recommended 4 amp as I don’t have a 4 amp one.
>
>
>
> I tried setting the reference to internal without disconnecting the GPSDO
> and then again after disconnecting the GPSDO, and saw the same issue. In
> the second case, the noise lasted 1.6 seconds, although I don’t suspect the
> duration has anything to do with the test setup, it seems random.
>
> -Nathan
>
>
>
> *From:* Michael West [mailto:michael.west at ettus.com]
> *Sent:* Monday, October 12, 2015 4:51 PM
> *To:* Perelman, Nathan
> *Cc:* Ben Hilburn via USRP-users
> *Subject:* Re: [USRP-users] Random long duration noise at the start of
> UBX captures
>
>
>
> To be clear, when I say disconnect the GPSDO, I mean disconnect the GPSDO
> power.  The data cables can be left in place.
>
> Regards,
>
> Michael
>
>
>
> On Mon, Oct 12, 2015 at 1:43 PM, Michael West <michael.west at ettus.com>
> wrote:
>
> Hi Nathan,
>
> The simple answer is no, that is not expected.  What do you have connected
> to the RX2 port?  Also, do you see the same effect if you disconnect the
> GPSDO?
>
>
>
> Regards,
>
> Michael
>
>
>
> On Mon, Oct 12, 2015 at 1:26 PM, Perelman, Nathan via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>
> I’ve been having issues with UBX daughter-boards for a little while, and I
> finally traced them down to a reproducible issue. Running:
>
> ./rx_samples_to_file --duration 2 --rate 25000000 --freq 1e9 --gain 38
> --ref gpsdo --setup 0
>
>
>
> I frequently see large amounts of random noise (up to +/- 0.5 out of 1.0),
> for up to 0.5 seconds. I have tested with 2 different UBX daughter-boards
> and seen similar noise. Is this expected with the UBX? I do not see similar
> noise with the SBX.
>
>
>
> I am using UHD 3.8.5 with an N210.
>
> -Nathan
>
>
>
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>
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