Ooops! A break statement went missing when I merged my two patches (rtl_fm-cal 
and print_deviation). Attatched to this mail is a new combined patch, sm0svx-
combined-v2.patch.gz.

Regards,
Tobias


Thursday, August 07, 2014 Tobias wrote:
> Hi,
> 
> I've implemented a FM deviation measurement mode in rtl_fm. It's turned
> on using the -D command line switch.
> 
>          [-D [tone freq]] Print the deviation of an FM signal.
>              If given without a tone frequency, the whole bandwidth
>              is used in the measurement. This include a lot of noise on
>              weak signals so the measurement will not be so good.
>              If a deviation measurement is done on a single tone the
>              tone frequency should be given to improve the accuracy
>              of the estimate.
> 
> If measuring on the whole bandwidth a simple min/max measurement is done
> on the demodulated signal and the deviation is determined from the
> difference. This work ok for very strong signals but just a little bit
> of noise will mess up the estimate. This mode can be used to get an
> approximate estimate for a voice signal for example.
> 
> If a tone frequency is given then the Goertzel single bin DFT algorithm
> is used to find out the amplitude of the tone. This is much better since
> all noise outside of the binwidth (100Hz) will be removed.
> 
> The patch is attached to this mail (sm0svx-print_deviation.patch.gz). I
> have also attached a patch that is a combination of my previous patch
> and the print_deviation patch (sm0svx-combined.patch.gz). I did this
> since the two patches conflict with each other in quite a few places.
> Hopefully this will make it easier for the maintainer to merge.
> 
> The code is also available on GitHub but I didn't create a pull request
> since that does not seem to be the way you want to work with patches.
> Tell me if you want me to create a pull request after all.
> 
>      https://github.com/sm0svx/librtlsdr/tree/print_deviation
>      https://github.com/sm0svx/librtlsdr/tree/sm0svx
> 
> Regards,
> Tobias

Attachment: sm0svx-combined-v2.patch.gz
Description: GNU Zip compressed data

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