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

Marcus Müller marcus.mueller at ettus.com
Tue Dec 9 11:24:21 EST 2014


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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