Re: [Discuss-gnuradio] Multipath Fading

[Marcus Müller]

Hello Ritvik,

I have a few questions, could you find a quick answer to each of them, so that I understand the situation better?

I'm very confused, because you have a screenshot of a Flowgraph that has multiple QT GUI sinks, but is set to WX. And then you have a screenshot of QT Gui visualizations and also one of WX GUI visualizations.

Would you mind explaining these graphs a bit better? In which file do you show what?

Why are you using real-world measured signal from a USRP source to test the fading simulator in GNU Radio? Why not simply use a noise source?

>But as a result there is increment in the signal power which is excatly the opposite of the theory.
What is it that you were expecting?

Thanks,
Marcus

On 05/07/2015 10:42 AM, Ritvik Pandey wrote:

---------- Forwarded message ----------
From: Ritvik Pandey <address@hidden>
Date: Fri, May 1, 2015 at 9:59 AM
Subject: Re: [Discuss-gnuradio] Multipath Fading
To: Mostafa Alizadeh <address@hidden>

Hey, 

I tried applying multipath fading in Gnu radio.

But as a result there is increment in the signal power which is excatly the opposite of the theory.

kindly find the attachments for the images.

On Sat, Apr 25, 2015 at 10:28 PM, Ritvik Pandey <address@hidden> wrote:

Thank You so much

On Sat, Apr 25, 2015 at 10:22 PM, Mostafa Alizadeh <address@hidden> wrote:

I think this block is just a single tap channel. If you want to have multipath channel use channel_model2 instead: 

http://gnuradio.org/doc/doxygen/classgr_1_1channels_1_1channel__model2.html

Best, 

Mostafa

On Sat, Apr 25, 2015 at 8:44 PM, Ritvik Pandey <address@hidden> wrote:

Okay ill work on this and get back to you if i face any problems...for now one last thing according to the theory fading is a result of multipath so does this block implements multipath and then shows the faded result or it just filters the fading output of an input signal.

On Sat, Apr 25, 2015 at 9:41 PM, Mostafa Alizadeh <address@hidden> wrote:

The frequency measurement doesn't give any insight rather to see just time variation of the power of the signal (i think you're using a single tone source ). I prefer to plot the singal in time domain to see fading effects.

The fading block has different parameters as said:
http://gnuradio.org/doc/doxygen/classgr_1_1channels_1_1fading__model.html

Set like this:
N = 8
FTds = .01
LOS = false
K = 4
Seed = 1

On Apr 25, 2015 8:27 PM, "Ritvik Pandey" <address@hidden> wrote:

See i am using a signal source and fast noise source as inputs...adding these it passes through the fading block and then towards the fft sink or waterfall sink. 

Input Parameters in signal source: 

Freq: 1 M

Amplitude: 1

Noise Source:

Amplitude: 1

Fading Block:

Normalized Doppler: 10.0

Rayleigh

This for testing the fading block initially in the final stage i have to take the signal from usrp.

On Sat, Apr 25, 2015 at 9:23 PM, Mostafa Alizadeh <address@hidden> wrote:

What is the input of the gnuradio's block you've set??
I think you're using the gnuradio's block wrongly!

Dear Mostafa,

I have tried making a flowgraph using the fading blocks, but i am not able to understand the output. I have compared the input and output it seems almost the same. Can you guide to the mathematical model of the fading block in gnu radio, so that i can understand what actually is happening to the input signal?

Regards

On Sat, Apr 25, 2015 at 9:07 PM, Mostafa Alizadeh <address@hidden> wrote:

Hi Ritvik,

If you have enough background knowledge you need classify channels as follow:

1) Rician channel: which has a line-of-sight(LOS) path between a transmitter and a receiver.

2) Rayleigh fading channel: which doesn't have any LOS. 

3) Something between Rayleigh and Ricean channel: using Nakagami distribution with parameter K varying 0-inf.

You need to first generate samples of these distributions.

On Sat, Apr 25, 2015 at 4:06 PM, Ritvik Pandey <address@hidden> wrote:

Regarding my last post i want to bring it to your notice that i have to implement a multipath fading channel emulator so can you tell me how can i do that?

On Sat, Apr 25, 2015 at 5:03 PM, Ritvik Pandey <address@hidden> wrote:

Dear Sir/Mam,

Hello, i am a student working on the development of a channel emulator, Can you tell me how can you make one in GNU Radio?

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

--

***********************************************************

Department of Electrical Engineering

Aboureyhan Building

MMWCL LAB

Amirkabir University Of Technology

Tehran

IRAN

Tel: +98 (919) 158-7730

LAB: http://ele.aut.ac.ir/~mmwcl/?page_id=411

Homepage: http://ele.aut.ac.ir/~alizadeh/

***********************************************************

--

***********************************************************

Department of Electrical Engineering

Aboureyhan Building

MMWCL LAB

Amirkabir University Of Technology

Tehran

IRAN

Tel: +98 (919) 158-7730

LAB: http://ele.aut.ac.ir/~mmwcl/?page_id=411

Homepage: http://ele.aut.ac.ir/~alizadeh/

***********************************************************

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio