SDR & NFM

[nosoup4u]

Trying to set this up for the first time. I am able to tune to a local FM station and the audio sounds fine, but if I try to tune to the local NOAA station, I get nothing but noise on the NFM setting, but on WFM I can hear it (similar to setting WFM on a scanner). Do I need to make change to the filter bandwith or something?

[rbm]

Here are the settings I typically use for NFM on NOAA.

Rich

[nosoup4u]

That made all the difference, thanks for the screen shots.

[rbm]

Glad it worked out for you.

Better a picture than a thousand words.

Rich

[Xourque]

Thanks that helped me for nearly the same thing!

[Unitrunker]

I thought the NWS was 50 khz FM, not the typical 12.5 khz narrow FM.

[rbm]

Originally Posted by Unitrunker

I thought the NWS was 50 khz FM, not the typical 12.5 khz narrow FM.

Yes, that's true.
"The NWS recommends the public purchase receivers with a 0.5 to 1.0 microvolt sensitivity for 20 decibels (dB) quieting, a selectivity of 45 to 70 dB down at +/- 25 kilohertz (kHz)"

However, as in my case, when you receive multiple, adjacent NOAA broadcasts, that's not feasible.

If you're only trying to recover audio (and not data) you can use whatever bandwidth works best for you.

Rich

[rbm]

To put it visually ....
Here's a screen capture with the BW set to 50 khz.

Notice that there are three signals within that bandwidth and they're now totally garbled.

As long as you don't go so narrow that you start clipping, or so wide that your recovered audio is too low, I find that narrower is better. It also reduces some of the noise.

Rich