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

Marcus Müller marcus.mueller at ettus.com
Tue Dec 9 11:52:31 EST 2014


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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