# SNR or Other Metrics

**URL:** <https://www.ruby-forum.com/t/snr-or-other-metrics/238094>\
**Category:** GNU Radio\
**Created:** [December 17, 2013, 5:23am UTC](https://www.ruby-forum.com/t/snr-or-other-metrics/238094 "2013-12-17T05:23:33Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [December 17, 2013, 5:23am UTC](https://www.ruby-forum.com/t/snr-or-other-metrics/238094/1 "2013-12-17T05:23:33Z")

</div>

I’d like to report some signal metrics for satellite downlinks. SNR  
would  
seem to be one example, but most algorithms I see for SNR assume that  
you  
are generating a signal from a separate clean signal and noise source,  
each  
with known power. What I have are recordings of real, narrow-band,  
digital  
FM signals. I don’t have a very strong DSP background.

Can anyone point me to a good textbook that covers such practical  
applications?

Thanks for your help!

---

<div class="post-metadata">

**Author:** ![Dan\_CaJacob](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/e68b1a/32.png) [@Dan\_CaJacob](https://www.ruby-forum.com/u/Dan_CaJacob)\
**Post date:** [December 19, 2013, 4:32pm UTC](https://www.ruby-forum.com/t/snr-or-other-metrics/238094/2 "2013-12-19T16:32:17Z")

</div>

On Mon, Dec 16, 2013 at 11:22 PM, Dan CaJacob [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> I’d like to report some signal metrics for satellite downlinks. SNR would  
> seem to be one example, but most algorithms I see for SNR assume that you  
> are generating a signal from a separate clean signal and noise source, each  
> with known power. What I have are recordings of real, narrow-band, digital  
> FM signals. I don’t have a very strong DSP background.
> 
> Can anyone point me to a good textbook that covers such practical  
> applications?
> 
> Thanks for your help!

Hi Dan,

SNR estimations are quite tricky in real life. If you look at the  
digital::mpsk\_snr\_est blocks, there are multiple implementation inside  
that do SNR estimations for M-ary PSK constellations. The different  
algorithms have varying accuracy and (mostly) proportional complexity.  
But as the name implies, this won’t work for FM.

Looking at Google, I found a short paper from Virginia Tech,  
co-authored by Steve Ellingson. I know Steve a bit, though he came  
just as I was finishing up my work there, and he tends to be pretty  
good with these things. So it’s likely a good start mathematically for  
what you need.

[http://www.ece.vt.edu/swe/asmr/docs/ASMR\_R16\_Kumar2.pdf](http://www.ece.vt.edu/swe/asmr/docs/ASMR_R16_Kumar2.pdf)

Tom

---

<div class="post-metadata">

**Author:** ![Dan\_CaJacob](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/e68b1a/32.png) [@Dan\_CaJacob](https://www.ruby-forum.com/u/Dan_CaJacob)\
**Post date:** [December 19, 2013, 5:09pm UTC](https://www.ruby-forum.com/t/snr-or-other-metrics/238094/3 "2013-12-19T17:09:06Z")

</div>

Thanks, Tom! Yeah, I have avoided the MPSK SNR blocks because I figured  
they were specific to PSK.

Very Respectfully,

Dan CaJacob