Re: [Discuss-gnuradio] Trying to use the complex int16 option of the UHD blocks

[Josh Blum]

On 07/26/2012 05:09 PM, Nazmul Islam wrote:
> Hi Josh,
> 
> I am just wondering how the USRP performs the 8 bit mapping for I & Q
> samples. The ADC & DAC have 12 - 14 bit precision, I think. When I select
> the sc8 wire format, does the USRP divide the entire received signal range
> into 2^8 sectors and uses one number to represent each of those?
> 

Technically, there is just a multiply and slice operation. You can
specify peak to optimize for the best use of t 8 bits of dynamic range.
See:
http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1stream__args__t.html#a4463f2eec2cc7ee70f84baacbb26e1ef

-josh

> Thanks,
> 
> Nazmul
> 
> On Sun, Jul 22, 2012 at 4:22 PM, Josh Blum <address@hidden> wrote:
> 
>>
>>
>> On 07/22/2012 01:14 PM, Nazmul Islam wrote:
>>> Hello,
>>>
>>>  I am trying to use the complex int16 option of the UHD (source/sink)
>>> blocks in my GRC generated python codes. I am doing wide band spectral
>>> analysis in my experiments. Therefore, 50 MS/s will be very helpful for
>> me.
>>>
>>
>> The host format and the wire format are totally independent options
>> here. Both of these properties also configurable properties in the GRC
>> USRP source/sink blocks.
>>
>> * You need to set the wire format to sc8 (thats 2 bytes per complex
>> sample) to achieve 50 Msps over gigabit ethernet.
>>
>> * The desired host format does not have to change. fc32 (complex floats)
>> is a perfectly valid setting
>>
>> -josh
>>
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> 
> 
>