Hi all!
I'm working on a "Hello, World!" flow in GRC .... just a simple NBFM
receiver tuned to my local NOAA station.
Using an RTLSDR and the osmocom block ... into a low-pass that
decimates by 5 into the NBFM block and then an audio sink. It doesn't
get any more simple. Here is a image of the flow
http://pabut.org/wiki/images/a/aa/My-fmrcv.grc.png
<http://pabut.org/wiki/images/a/aa/My-fmrcv.grc.png>
So with the sampling rate set to 2M .... works fine ..... if I REDUCE
the sample rate, say 240k, I start to get audio sink underruns
"aUaUaUaUaUaUaUaUaU" and I only get small blurbs of audio.
I'm sure to set the sample rate in the downstream blocks appropriately.
240k samples/sec should be plenty for a 5khz deviation FM signal ...
right??
This is completely counterintuitive to what I was expecting. I
thought by reducing the sample rate I would lower CPU consumption ...
and mitigate the exact problem I'm experiencing at the lower rate.
What am I not grocking here??
Thanks,
--> Rob