# Wire format: using 8-bit (sc8) vs using 16-bit (sc16) resolution to gnu radio

**URL:** <https://www.ruby-forum.com/t/wire-format-using-8-bit-sc8-vs-using-16-bit-sc16-resolution-to-gnu-radio/242132>\
**Category:** GNU Radio\
**Created:** [May 29, 2015, 6:54pm UTC](https://www.ruby-forum.com/t/wire-format-using-8-bit-sc8-vs-using-16-bit-sc16-resolution-to-gnu-radio/242132 "2015-05-29T18:54:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\
**Post date:** [May 29, 2015, 6:54pm UTC](https://www.ruby-forum.com/t/wire-format-using-8-bit-sc8-vs-using-16-bit-sc16-resolution-to-gnu-radio/242132/1 "2015-05-29T18:54:50Z")

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Hi, i am using usrp N200 and i set to gnu radio the wire format as  
either  
16-bit -\> sc16  
or 8-bit -\>sc8 and host format fc32(complex float) when i use  
a) sc16 the power in the window where i see the spectrum is at -110 dB  
or  
-100 dB, without transmitter sending data (so i see only noise)  
b) sc8 the power in the window where i see the spectrum is at -80 db,  
without transmitter sending data (so i see only noise as before)

Any ideas why i have a bigger starting power in 8-bit? It is -80 dB  
again  
-110 dB.

Thanks

---

<div class="post-metadata">

**Author:** ![klauern](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/96bed5/32.png) [@klauern](https://www.ruby-forum.com/u/klauern)\
**Post date:** [May 29, 2015, 7:59pm UTC](https://www.ruby-forum.com/t/wire-format-using-8-bit-sc8-vs-using-16-bit-sc16-resolution-to-gnu-radio/242132/2 "2015-05-29T19:59:05Z")

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On 29.05.2015 12:53, Nick Kara wrote:

> Hi, i am using usrp N200 and i set to gnu radio the wire format as  
> either 16-bit → sc16  
> or 8-bit -\>sc8 and host format fc32(complex float) when i use  
> a) sc16 the power in the window where i see the spectrum is at -110 dB  
> or -100 dB, without transmitter sending data (so i see only noise)  
> b) sc8 the power in the window where i see the spectrum is at -80 db,  
> without transmitter sending data (so i see only noise as before)
> 
> Any ideas why i have a bigger starting power in 8-bit? It is -80 dB  
> again -110 dB.

Hey Nick,

it’s all kind of arbitrarily scaled anyway (meaning that the absolute  
value, 80 vs 110 is not very meaningful). So this is just an artifact of  
how ADC bits are mapped onto the sc8 bits, and then the scaling. It does  
not mean you’re receiving more power or anything like that.

M