Re: [Discuss-gnuradio] Squelch and the KSHT sounds ...

[Mike Jameson]

The 'Power Squelch' block in GRC is my favourite and I would recommend using this one.

Have a look at the following GRC flow graph for a working example that uses the power squelch block:

https://raw.githubusercontent.com/m0mik/scanoo/master/apps/scanoo.com_rx.grc

Note that the 'Ramp' setting is the number of samples it takes at the start and end of a detected signal for the volume to go from 0% to 100% and 100% to 0%, and the 'Alpha' setting is the signal average alpha just like in the FFT WX GUI widget. 1 disables the averaging and will give you the fastest cutoff at the end, however if you have signal flutter then the audio will be choppy.  I'd recommend using between '0.01' and '0.001' in the power squelch block for the 'alpha' setting.

Mike

--
Mike Jameson M0MIK BSc MIET
Ettus Research Technical Support
Email: address@hidden
Web: http://ettus.com

On Sun, Jul 13, 2014 at 12:05 AM, <address@hidden> wrote:

I've deployed a gnuradio application which records a morning maritime radio program in a Caribbean community. The recording can be played back online for people who missed the 'news'. 

The application works famously. However, I've got a request for an enhancement that comes up a lot! Everyone is used to hearing the 'ksht' sound after the mike is unkeyed. However, the squelch function I use in GnuRadio 3.7.1 doesn't seem to have a setting which affects how quickly the squelch gate closes (its instantaneous). There is an Alpha and a Ramp function, but they don't seem to affect the result (wouldn't expect Alpha to).

Does anyone have any insight into the code for this block?

Jim

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