[USRP-users] USRP X310 motherboard issues

T reffahcs at gmail.com
Wed Dec 10 18:28:28 EST 2014


Marcus - thanks for the feedback. I'm going to wait for the new firmware that Matt mentioned and hopefully that will fix it. If its unsuccessful I will try the steps you mentioned below.

-Tim 

Sent from my iPad

> On Dec 10, 2014, at 14:30, Marcus Müller via USRP-users <usrp-users at lists.ettus.com> wrote:
> 
> Hello Tim,
> 
> this is in fact quite a bit surprising. I have no idea where the 500kHz spaced tones in your QPSK_B.png came from, so I'm really just guessing around how to narrow down reasons: 
> 
> The numeric values seem to be low, but I want to be on the safe side: 
> * How much input power are you providing (please make sure to stay below -15dBm!)?
> * If you reduce input power/voltage, does the effect decrease?
> * Does it get worse when you increase the analog gain?
> * could you please tune to let's say 303.25MHz?
> * If you run the osmocom Spectrum Browser with
> -a "lo_offset=15000000"
> does the picture change dramatically?
> 
> This is all very generic... I can't really explain the little spikes in your multi_tone_B.png, so far.
> Between the daughterboard and the ADC is only a (if I remember correctly) 6GHz RC lowpass; so no active active parts that would explain these spikes.#
> 
> I hope this can be solved fast!
> 
> Best regards,
> Marcus Müller
> 
> 
>> On 12/10/2014 07:02 PM, Timothy Schaffer via USRP-users wrote:
>> I received an X310 from NI last week along with 2 x WBX-120 boards and I've
>> noticed a difference in signal quality between the A and B subdevs of the
>> motherboard. Overall, It seems the signals receive from the B side are
>> generally distorted and prone to harmonics. I naturally assumed this was an
>> issue with the WBX boards, so I swapped them and noticed the same issues.
>> Next I swapped the cables connected to the bulkhead and still the same
>> issue.
>> I''m currently using UHD 3.008.000-52, but have not tried other versions.
>> I've reloaded the FPGA firmware, ran all 3 cal routines on both subdevs.
>> I'm not sure what else to try? I'v eattached a couple of screen shots of
>> some of the tests I performed with an HP E4432B. The tests were done back
>> to back using the same cable from the siggen to the USRP.
>> 
>> You can see in these two screen shots, the actual distortion to the
>> waveform in the scope.
>> [image: Inline image 2].[image: Inline image 1]
>> 
>> Here is a DQPSK(24.3ksps) test signal at 303 MHz
>> 
>> [image: Inline image 3][image: Inline image 4]
>> 
>> Any ideas on what could be wrong, or does it need to go back to NI for
>> repair/replace?
>> 
>> -Tim
>> 
>> 
>> 
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> 
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