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

Mike McLernon Mike.McLernon at mathworks.com
Mon Feb 13 08:10:24 EST 2012


Hi Salman,

The Simulink SDRu driver is built on top of the UHD driver, so any limitations imposed by UHD will be encountered in Simulink.  Also, note that the SDRu Receiver block supports int16 complex data outputs.  That math implies a max rate of 25 Msps ( (16 bits/sample real + 16 bits/sample imaginary) * 25 Msps = 800 Mbps.

Mike


From: usrp-users-bounces at lists.ettus.com [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of salman dinani
Sent: Sunday, February 12, 2012 11:01 PM
To: Ian Buckley
Cc: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] SBX daughtercard bandwidth problem..!!

Thanks Josh and Ian Buckley....:) So it means:
1. I cannot set the decimation or interpolation to "1" in simulink SDRu block? or in other words i        cannot get the sampling rate of 100 MSPS?? :(

2. Is there any way using Simulink SDRu block??

Regards

Salman Dinani
On Mon, Feb 13, 2012 at 2:06 AM, Ian Buckley <ianb at ionconcepts.com<mailto:ianb at ionconcepts.com>> wrote:
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<mailto: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<mailto:USRP-users at lists.ettus.com>
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>


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