Forum: GNU Radio measure of the SNR in a packet

Announcement (2017-05-07): www.ruby-forum.com is now read-only since I unfortunately do not have the time to support and maintain the forum any more. Please see rubyonrails.org/community and ruby-lang.org/en/community for other Rails- und Ruby-related community platforms.
635b8cf1ca106f565815ca16ccc438ae?d=identicon&s=25 Matteo Campanella (Guest)
on 2006-04-26 11:56
(Received via mailing list)
Hello, I would like to write some code to calculate the SNR of a signal;
in my case this signal is a packet radio AX25 1200 baud packet burst
received thru TV RX and usrp.

Is there anything ready for use or has anyone good suggestions to
implement this?

thanks
Matteo
5e81c66258333eb8e665cc4814d0a6d5?d=identicon&s=25 Greg Troxel (Guest)
on 2006-04-26 14:51
(Received via mailing list)
Hello, I would like to write some code to calculate the SNR of a signal;
  in my case this signal is a packet radio AX25 1200 baud packet burst
  received thru TV RX and usrp.

First you need to define SNR.  If you measure the noise power of the
background within the passband when there is no signal, and then
measure the power of the signal+noise while receiving, you can
calculate an estimate.

Or, you can do coherent demod of the signal, and then regenerate a
perfect signal at an amplitude that best matches the received data.
Then you can subtract that and look at the residuals, and calculate
power of the reconstructed signal and the residuals.  The residuals
will have not only noise and receiver distortion, but also components
due to amplitude variations over the estimation period.


This is probably much easier if you don't try to get accurate values
at low SNR.  But it's down low that it's a more interesting problem,
at least to me.


--
        Greg Troxel <gdt@ir.bbn.com>
635b8cf1ca106f565815ca16ccc438ae?d=identicon&s=25 Matteo Campanella (Guest)
on 2006-04-26 21:51
(Received via mailing list)
The first method looks interesting, the only problem I find with it is
that
I cannot tell wether what I am getting from the channel is noise or
noise
plus some weak signal I cannot identify as such. When it comes to very
busy
channels (eg on APRS frequency, you have signals almost all of the
time...)

Matteo
----- Original Message -----
From: "Greg Troxel" <gdt@ir.bbn.com>
To: "Matteo Campanella" <matteo@matcam.net>
Cc: <Discuss-gnuradio@gnu.org>
Sent: Wednesday, April 26, 2006 2:47 PM
Subject: Re: [Discuss-gnuradio] measure of the SNR in a packet
This topic is locked and can not be replied to.