[USRP-users] SBX daughtercard bandwidth problem..!!

Ian Buckley ianb at ionconcepts.com
Sun Feb 12 16:06:31 EST 2012


Clearly I needed more coffee!
You confused me there referring to it as a 16bit mode rather than 8bit complex.

On Feb 12, 2012, at 9:47 AM, Josh Blum wrote:

> 
> 
> On 02/12/2012 09:36 AM, Ian Buckley wrote:
>> Josh, 
>> It's possible you didn't have your Sunday morning coffee yet, or  possibly that the laws of Physics have been shattered...
>> but did you really intend to state that you can now receive 16bits @ 50Msps in UHD...because Cisco would like to offer you a job if so :-)
>> I'm assuming you intended to say 8bits at 50Msps.......or is it not a complex sample stream in this new mode?
> 
> sorry, no coffee yet, but the math seems solid
> 
> 1 byte real, 1 byte imaginary = 16 bits per sample (complex baseband)
> 
> 16 bits per sample * 50 Msps = 800 Mbits per second, which is well
> within gigE rate of 1000 Mbits per second.
> 
> -Josh
> 
>> 
>> -Ian
>> 
>> On Feb 11, 2012, at 10:58 PM, Josh Blum wrote:
>> 
>>> 
>>>> 1. Am i write in this conclusion??
>>> 
>>> Correct.
>>> 
>>> However, it is possible to increase sample rate at the expense of
>>> dynamic range. On the UHD master, you can receive 50Msps with 16 bit
>>> samples. This feature is not yet a part of the SDRu driver.
>>> 
>>>> 2. If yes, than why it is written in application notes tat it has BW of 40
>>>> MHz??
>>> 
>>> This is an analog bandwidth filter. You cannot receive signals outside
>>> LO +/- 20Mhz due to the filter. Consider that some may tune the LO away
>>> from the center frequency for various reasons.
>>> 
>>>> 4. Why i am not able to set decimation or interpolation to 1.??
>>> 
>>> The bandwidth bottleneck is the gigabit ethernet port. Given the recent
>>> advent of 16 bit samples, a decimation of 2 is really the minimum.
>>> 
>>> This is a user mod to burst 100Msps packets, which you may find helpful:
>>> https://lists.gnu.org/archive/html/discuss-gnuradio/2011-03/msg00303.html
>>> 
>>> -Josh
>>> 
>>> _______________________________________________
>>> 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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