[USRP-users] [Discuss-gnuradio] Bandpass Sampling

Marcus Müller marcus.mueller at ettus.com
Thu Dec 11 11:03:38 EST 2014


www.ni.com/white-paper/14311/en/

Greetings,
Marcus

On 12/11/2014 04:54 PM, Richard Bell wrote:
> That's perfect. Thanks a lot. I'm curious to know where this document came
> from, so I can help myself later. Can you tell me?
>
> v/r,
> Rich
>
> On Tue, Dec 9, 2014 at 8:52 AM, Marcus Müller <marcus.mueller at ettus.com>
> wrote:
>
>> Hi Ian,
>> thanks, I was looking for that.
>> Richard: Everything left of the ADC/DAC is on the WBX daughterboard.
>>
>> Greetings,
>> Marcus
>>
>> On 12/09/2014 05:41 PM, Ian Buckley wrote:
>>> Block diagram USRP N210 + WBX:
>>>
>>>
>> http://www.ni.com/white-paper/app/largeimage?lang=en&imageurl=%2Fcms%2Fimages%2Fdevzone%2Ftut%2FUSRP_Advanced_Diagram_smaller.png
>>> On Dec 9, 2014, at 8:24 AM, Marcus Müller via USRP-users <
>> usrp-users at lists.ettus.com> wrote:
>>>> Hi Richard,
>>>> it's a 300+-page PDF file, which works quite well on any computer that
>> I tried -- maybe you need to wait a second for your PC to load that
>> document?
>>>> It doesn't contain a block diagram of the WBX, however.
>>>>
>>>> Greetings,
>>>> Marcus
>>>>
>>>> On 12/09/2014 02:00 AM, Richard Bell wrote:
>>>>> I've seen the the UHD manual but not the performance measures doc. It
>> is
>>>>> not opening for me. If it has a block diagram of the WBX board, then
>> that
>>>>> is what I was looking for.
>>>>>
>>>>> There is no more information I need at this time. Your previous answer
>> was
>>>>> helpful and what I was looking for.
>>>>>
>>>>> Yes you can move this to the usrp list.
>>>>>
>>>>> Thanks again,
>>>>> Rich
>>>>>
>>>>> On Mon, Dec 8, 2014 at 12:24 PM, Marcus Müller <
>> marcus.mueller at ettus.com>
>>>>> wrote:
>>>>>
>>>>>>  There's so much Marcus in here ;) so here's my answer: usually,
>> you'd use
>>>>>> the USRP+WBX as direct conversion receiver, not an IF one.
>>>>>>
>>>>>> Regarding WBX documentation: have you seen the performance
>> measurements
>>>>>> [1], and the UHD manual [2]?
>>>>>>
>>>>>> Is there some specific information you're missing?
>>>>>>
>>>>>> Best regards,
>>>>>> Marcus
>>>>>>
>>>>>> PS: if you'd agree, I'd like to shift this discussion to
>>>>>> usrp-users at lists.ettus.com .
>>>>>>
>>>>>> [1] http://files.ettus.com/performance_data/wbx/
>>>>>> [2] http://files.ettus.com/manual/page_dboards.html#dboards_wbx
>>>>>>
>>>>>>
>>>>>> On 12/08/2014 08:57 PM, Richard Bell wrote:
>>>>>>
>>>>>> I think Marcus answered my question. Thank you.
>>>>>>
>>>>>> On Mon, Dec 8, 2014 at 11:53 AM, Richard Bell <
>> richard.bell4 at gmail.com> <richard.bell4 at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>
>>>>>>  I'm apologize. I am using a WBX card.
>>>>>>
>>>>>> I forgot to mention that I've been looking for a datasheet for the
>> WBX,
>>>>>> but all I can find is the PCB schematic doc on the ettus website which
>>>>>> isn't very useful. So I don't know what the IF frequency coming out
>> of the
>>>>>> WBX is. Does the WBX tune itself given the UHD source settings so
>> that the
>>>>>> IF it produces is proper for the USRP ADC?
>>>>>>
>>>>>> Rich
>>>>>>
>>>>>> On Mon, Dec 8, 2014 at 11:28 AM, <mleech at ripnet.com> <
>> mleech at ripnet.com> wrote:
>>>>>>
>>>>>>   The N2xx series use a fixed sample rate, so there's no "deciding
>> what
>>>>>> sample rate to use based on Fc".
>>>>>>
>>>>>> There's also the analog bandwidth of the ADC to consider.  If you
>> aren't
>>>>>> going to use a downconverter card, then the analog bandwidth of the
>> ADC
>>>>>> will start to roll-off at some point, so even if you narrowband
>> filter your
>>>>>> input signal to remove aliasing possibilities, you will end up in the
>>>>>> roll-off skirts of the analog bandwidth of the ADC.
>>>>>>
>>>>>> Is there some reason not to use a downconverter card, like the WBX for
>>>>>> your application?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 2014-12-08 14:23, Richard Bell wrote:
>>>>>>
>>>>>>   I have a binary FSK signal centered at 300 MHz with 160 kHz offset
>>>>>> peaks from the center freak. Therefore the lowest signal frequency of
>>>>>> interest is 300-0.16 = 299.84 MHz and the highest is 300.16 MHz.
>>>>>>
>>>>>> I know the maximum sampling rate of the USRPN210 ADC is 100 MSPS. If
>> the
>>>>>> USRP uses that sample rate of 100 MSPS, it will alias my signal onto
>> itself
>>>>>> in an unwanted manor.
>>>>>>
>>>>>> My question is, how does the USRPN210 decide what sample rate to set
>> the
>>>>>> ADC to? Is it a function of both the center frequency and the sample
>> rate
>>>>>> setting of the UHD source block?
>>>>>>
>>>>>> Thanks,
>>>>>> Rich
>>>>>>
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