[USRP-users] TX Image rejection B210

Sebastian Held sebastian.held at imst.de
Tue Apr 7 03:47:33 EDT 2015


Hi,

Any news on this?
I have the same problem with two B210 units.
Either the error is my misunderstanding of RF performance parameters,
the example file cannot be used for this performance evaluation or the
hardware design does not meet the performance of the AD chip (which is
hard to believe).

Any hint what I'm doing wrong?

Regards,
Sebastian

Am 31.03.2015 um 09:51 schrieb Sebastian Held via USRP-users:
> forgot to include the list.
>
> Dear Martin,
>
> please see attached figure. Reducing the gain acts on both the wanted
> and unwanted signal in the same manner.
>
> Sebastian
>
> Am 30.03.2015 um 18:46 schrieb Martin Braun via USRP-users:
>> Sebastian,
>>
>> what happens when you turn down the gain (e.g. to 70 dB)?
>>
>> M
>>
>> On 29.03.2015 23:50, Sebastian Held via USRP-users wrote:
>>> Hi,
>>>
>>> I'm currently investigating a problem with my OFDM modulated signals. To
>>> understand, why the spectrum mask is violated, I first checked the basic
>>> TX parameters. The B210 is connected to a R&S FSQ26 via a 20 dB
>>> attenuator.
>>>
>>> I use the examples provided with the
>>> UHD-release_003_008_002-10-ge067c45:
>>> ./tx_waveforms --args="master_clock_rate=20e6" --rate 20000000
>>> --freq=5900000000 --gain=80 --wave-type SINE --ref=gpsdo --int-n
>>> --wave-freq=1000000
>>>
>>> This command results in an expected tone at 5.9 GHz + 1 MHz (approx. -29
>>> dBm) and its image at 5.9 GHz - 1 MHz. The problem is: the image power
>>> is very large: only 26 dB below the wanted 5.901 GHz tone. From the
>>> AD9361 data sheet I would expect a suppression of at least 45 dB.
>>>
>>> To continue to solve my original problem (OFDM spectrum) I first need to
>>> understand, why I get such a large image.
>>> Can I use this example to evaluate the TX image? Any pointers?
>>>
>>> Regards,
>>> Sebastian
>>>
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>
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>
>
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-- 
Sebastian Held (Dipl.-Ing.)
IMST GmbH
Software Engineer
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