Thanks for the response. I looked at the code and from what I can tell, it’s just using various ham radio rigs built in CTCSS facilities and programming them via RS232. Am I missing something?

Chris

On Dec 7, 2013, at 3:22 AM, Sdr Guru sdrguru1@gmail.com wrote:

Hi

GPL DCS source http://yo3iiu.ro/blog/?p=779

CTCSS & Noise Squelch http://svn.ohnosec.org/viewvc/projects/allstar/astsrc-1.4.23-pre/trunk/aster... http://svn.ohnosec.org/viewvc/projects/allstar/astsrc-1.4.23-pre/trunk/aster... http://svn.ohnosec.org/viewvc/projects/allstar/astsrc-1.4.23-pre/trunk/aster...

SG

On Wed, Nov 13, 2013 at 2:59 PM, Chris Hanson lightningbolts@gmail.com wrote: Has anyone considered adding this or found a work around for those noisy stations that keep breaking the squelch?

Thanks Chris

For transmitters that don't use tone squelch, the best FM squelch is a noise squelch, which detects the "quieting" an FM signal causes. The gr-scanner project (which is incomplete/work-in-progress, don't bug me about functionality yet) has one, albeit written for Gnuradio:

https://github.com/bistromath/gr-scanner/blob/master/python/standard_squelch...

It's a rewrite of Gnuradio's "standard squelch".

--n

On Mon, Dec 9, 2013 at 10:17 AM, James Sharp james@fivecats.org wrote:

On 12/9/2013 7:33 AM, Chris Hanson wrote:

...

Thanks for the response. I looked at the code and from what I can tell, it’s just using various ham radio rigs built in CTCSS facilities and programming them via RS232. Am I missing something?

The app_rpt file has some functions to detect tones in an audio stream that can be used to detect the CTCSS tones. Look through the "tone_detect" function along with the goertzel_* functions.

They're not specifically tagged as functions to decode CTCSS tones, but they should be able to be used as such.

Those functions are expecting to be fed a 16-bit signed linear mono audio stream.