Tuesday, December 15, 2015

Re: [Discuss-gnuradio] using USRP to get scattering parameters

Hi Yan,

to be completely honest, at this point it might really be better to point you at a lecture on transmission line and antenna theory. We really don't often do that, but it's not much use that we explain to you how a network analyzer works, if you're the one who wants to build one. I'm also not very optimistic that I could explain the operational principle of a network analyzer, S matrices, directional couplers, isolators, calibration fixtures … better than a textbook. A network analyzer is a complex device, and the math involved for the estimation of the S-Matrices isn't really stuff for a mailing list email.

Basically: Consider this system:
https://en.wikipedia.org/wiki/Network_analyzer_%28electrical%29#/media/File:Vna3.png

I colored all the components that you could implement using a single B210 USRP in green, and what you'd have to implement on your computer in orange. Coincidentially, all the green parts would be the parts that need calibration. Everything that is neither orange nor green will need to be designed, built, analyzed and calibrated by you:


Best regards,
Marcus

On 15.12.2015 18:35, Yan Huang wrote:
Hi,    I mean S-parameters in wireless network. How can I  use  directional couplers in wireless network to do this?    Thanks a lot,  Yan    From: discuss-gnuradio-bounces+eexyh22=nottingham.ac.uk@gnu.org [mailto:discuss-gnuradio-bounces+eexyh22=nottingham.ac.uk@gnu.org] On Behalf Of Marcus D. Leech  Sent: 15 December 2015 17:16  To: discuss-gnuradio@gnu.org  Subject: Re: [Discuss-gnuradio] using USRP to get scattering parameters    On 12/15/2015 11:31 AM, Yan Huang wrote:  Hi all,    I have tried to use USRP B210 and GNUradio to send and receive signal, and now I want to get the network's scattering parameters. But I don't know how to get them using the software.    Is there anybody can give me some advice?    Thanks in advance.      Yan    You mean S-parameters, such as you'd get from an RF network analyser?    You need extra hardware to do that--directional couplers for measuring forward and reflected power, etc.            This message and any attachment are intended solely for the addressee  and may contain confidential information. If you have received this  message in error, please send it back to me, and immediately delete it.     Please do not use, copy or disclose the information contained in this  message or in any attachment.  Any views or opinions expressed by the  author of this email do not necessarily reflect the views of the  University of Nottingham.    This message has been checked for viruses but the contents of an  attachment may still contain software viruses which could damage your  computer system, you are advised to perform your own checks. Email  communications with the University of Nottingham may be monitored as  permitted by UK legislation.      


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