[USRP-users] The receiver ADC goes into saturation

Marcus D. Leech mleech at ripnet.com
Sat Oct 25 16:46:05 EDT 2014


On 10/25/2014 03:47 PM, Marcus Müller wrote:
> Hi Dan,
>
> On October 25, 2014 8:25:36 PM CEST, Dan CaJacob via USRP-users <usrp-users at lists.ettus.com> wrote:
>> Everything The Marci said.
> The Marci with a capital M and a capital T. I suddenly feel meaningful :)
> We're going to need a logo and a motto.
>
> Cheers,
> Marcus The Less Experienced
This either needs to be handled by George Lucas  ("Return of the 
Marci"), or a renaissance painter ("The Beatification of the Marci").
>
>> Specifically,
>>
>> 1. Reduce your TX amplitude to a maximum of 0.2, which should guarantee
>> linearity across many modulation types.
>> 2. Reduce your TX gain to 0.  (You could even go a bit negative on some
>> daughtercards, I do sometimes)
>> 3. Reduce your RX gain to 0.
>>
>> If you have test equipment, you can now check the OTA (over the air)
>> power
>> of the TXsignal nearby with an antenna.
>>
>> I assume that you are using an antenna for both the TX and RX sides and
>> that the units are a decent distance apart to avoid damaging the front
>> end
>> of the RX with too much power.
>>
>> If your RX side is not working, incrementally increase the RX gain
>> until it
>> does.  If you reach the maximum RX gain and it still doesn't work, only
>> then try increasing your TX gain.
>>
>> Very Respectfully,
>>
>> Dan CaJacob
>>
>> On Sat, Oct 25, 2014 at 10:35 AM, Marcus D. Leech via USRP-users <
>> usrp-users at lists.ettus.com> wrote:
>>
>>>   On 10/25/2014 08:28 AM, w xd via USRP-users wrote:
>>>
>>>   Hi all:
>>>         Environment:USRP N210,14bit ADC
>>>         According the formula:DR(dynamic range):6.02*14=84.28dB.
>>>         And now two USRP N210 close to each other,while one is used
>> for transmitting and the other is used for receiving.The amplitude of
>> the signal which to be send is 1.The gain in the transmitter I set
>> 31.5dB.And the gain in the receiver I set also 31.5dB.The
>> 31.5dB*2=63<DR(dynamic range).Why the receiver goes in saturation so
>> easily?The signal saturates the ADC and gets clipped.Can someone
>> explain it to me?
>>>         Thank you.
>>> Best regards,
>>> xd
>>>
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing
>> listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>   To use a simple physical world analogy, you're *screaming loudly*
>> into
>>> your friends ear, and wondering why they have gone temporarily
>> deaf...
>>> Reduce your TX power and/or RX gain.
>>>
>>>
>>>
>>> _______________________________________________
>>> 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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