[USRP-users] Full Duplex w/ X310 & UBX-160

Dave NotTelling dmp250net at gmail.com
Wed Mar 30 13:18:20 EDT 2016


I tuned the RX side to simply pick up some known signals in the area.

On Wed, Mar 30, 2016 at 1:07 PM, <mleech at ripnet.com> wrote:

> If you're transmitting at a frequency other than you're receiving at, why
> would you expect to be able to receive it?  I don't understand.
>
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> On 2016-03-30 13:02, Dave NotTelling wrote:
>
> Oh, sorry, I meant that I no longer see the GFSK transmission.  I also
> should have added that I don't get a correct spectrum from the RX side *at
> all*.  If I disable one of the two chains (disable all TX or RX) then
> everything works fine.
>
> On Wed, Mar 30, 2016 at 1:00 PM, <mleech at ripnet.com> wrote:
>
>> What do you mean by "it all breaks down"?  Error messages?
>>
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>> On 2016-03-30 12:55, Dave NotTelling wrote:
>>
>> Marcus,
>>
>>      This is odd then.  Please see the attached for my example flow graph
>> in GNU Radio.  The basics are that I am transmitting a GFSK (just for
>> giggles) on 1.001 GHz and receiving on 900 MHz.  When the graph starts up,
>> the TX side is working properly.  I can tell this by looking at the output
>> of my B200 which is tuned to 1.001 GHz.  The moment I change a parameter
>> (RX/TX gain/freq) it all breaks down.  Is this possibly an issue with the
>> X300/X310 UHD driver and/or GNU Radio gr-uhd?  Or am I just doing something
>> stupid?
>>
>> Thank you!
>>
>> -Dave
>>
>>
>>
>> On Wed, Mar 30, 2016 at 12:22 PM, <mleech at ripnet.com> wrote:
>>
>>> The RX and TX synthesizers are totally separate on the UBX, so you can
>>> frequency-split however you want.
>>>
>>> The larger the split, the easier it will be to prevent de-sense between
>>> TX and RX, since it would be easy to, for example, insert a notch filter
>>> for your TX band into the RX path, etc.
>>>
>>>
>>>
>>>
>>> On 2016-03-30 11:18, Dave NotTelling via USRP-users wrote:
>>>
>>> Can I transmit at say 100 MHz while simultaneously receiving at say 1
>>> GHz?  If so, can I also use different sampling rates between the TX and RX
>>> paths?  Are there any existing examples of how to do simultaneous TX and RX
>>> in GNU Radio?
>>>
>>> If this is not possible, then what is the max frequency difference?  I
>>> was assuming that if I were transmitting at 1 GHz, then I could tune the RX
>>> side up and down by half the master clock rate.
>>>
>>> Thank you!
>>>
>>> -Dave
>>>
>>> _______________________________________________
>>> USRP-users mailing listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>>
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