Re: Calculating SNR of an incoming signal

[Alex Batts]

I'm sampling an incoming signal, but only around 2 MSps. 

I need the signal power to noise power ratio at the receiver as part of my range calculation. So I would need to be able to distinguish between the power of the tone vs the power of the surrounding noise and use those two numerical values in an equation to calculate the range. This is why I referenced the green and red lines on the qt gui freq. display, this would seem to give me signal strength in dB. 

On Thu, Jun 25, 2020 at 2:51 PM Marcus Müller <mueller@kit.edu> wrote:

But you're sampling something, or else you couldn't process this in GNU
Radio. So, I'm a bit confused about what you're actually doing.


On 25/06/2020 20.48, Alex Batts wrote:
> Sorry, I'm new to the mailing list as well.
>
> How would you recommend isolating the tone power? A band pass filter
> wouldn't work at that frequency since there isn't an SDR that can sample
> that high. Would that be where the Phase Locked Loop comes into play?
>
> Thank you for your help to this point,
>
> Alex
>
> On Thu, Jun 25, 2020 at 1:41 PM Marcus Müller <mueller@kit.edu
> <mailto:mueller@kit.edu>> wrote:
>
>     Hi Alex,
>
>     can you make sure to reply to the mailing list, not just me alone?
>     Others usually take interest in discussion, too :)
>
>     Well, then it's easy.
>
>     Total signal power is simply the average magnitude square of your
>     received signal
>     You just need to subtract the power of the tone (that's its squared
>     amplitude) and get the noise power.
>
>     Divide these two, and you get SNR.
>
>     However, since this is the description of a Radar that assumes its
>     targets are stationary, you'd probably use a PLL to remove the noise
>     bandwidth drastically, so not quite sure that kind of SNR
>     measurement is
>     extremely useful for realistic system comparison!
>
>     Best regards,
>     Marcus
>     On 24/06/2020 16.58, Alex Batts wrote:
>      > Hello,
>      >
>      > __ __
>      >
>      > The incoming signal is going to be a specific tone, probably
>     around 5.8
>      > GHz. I am going to be using it for radar range detection. My SDR
>     will
>      > just passively receive the reflected signal off of the object and
>     use
>      > the SNR in the range calculation.
>      >
>      > __ __
>      >
>      > Thank you,
>      >
>      > __ __
>      >
>      > Alex
>      >
>      > __ __
>      >
>