[App_rpt-users] RTCM falsing DTMF

[Tim Sawyer]

In simpleusb.conf or voter.conf or as in your case, usbradio.conf you can add a statement:

plfilter = yes

which will place a 300Hz high pass filter on the receive audio. 
--
Tim
:wq

On Jun 4, 2012, at 5:12 PM, Ken wrote:

> Tim – what do you mean by “filtering PL”?
>  
> Do you just mean ctcssfrom=dsp
> Or is it something else?
>  
> Ken
>  
>  
> From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Tim Sawyer
> Sent: Monday, June 04, 2012 11:10 AM
> To: Chuck Henderson
> Cc: app_rpt mailing list
> Subject: Re: [App_rpt-users] RTCM falsing DTMF
>  
> What one says on the internet never goes away. I posted that before I found that not filtering PL was causing a problem. That older post is still valid if RADIO_RELAX is too loose for your system. 
> --
> Tim
> :wq
>  
> On Jun 3, 2012, at 10:00 PM, Chuck Henderson wrote:
> 
> 
>  
> //  My fix for the DTMF falsing problem is to make one change to the file dsp.c
> //  /usr/src/trunk/asterisk/main/dsp.c
> //  Change this line in dsp.c (find the line by searching for 26.0)
> #define DTMF_TO_TOTAL_ENERGY    ((digitmode & DSP_DIGITMODE_RELAXDTMF) ? 26.0 : 42.0)
> //  To look like this line
> #define DTMF_TO_TOTAL_ENERGY    ((digitmode & DSP_DIGITMODE_RELAXDTMF) ? 38.0 : 42.0)
> //  The result for our 2 repeaters, 
> //  one on VHF using the USB fob, 
> //  and the other on UHF using multiple RTCM's,
> //  is a reduction of DTMF falsing from hundreds per day to only 2 or 3 per day and 
> //  no problems decoding DTMF.
> //  I do not turn off RADIO_RELAX because doing so caused problems with DTMF decode.
> //  The only problem with my fix is that I have to re-edit dsp.c every time I update.
> //  Remember to do the usual "makes" after editing this file.
>  
>  
> On Sun, Jun 3, 2012 at 4:01 PM, Tim Sawyer <tim.sawyer at me.com> wrote:
> First I would update from svn, might as well as you have to recompile anyway. The instructions to update from svn are at https://allstarlink.org/support.html#astupgrade
>  
> Before you do the make up grade edit /usr/src/astsrc/asterisk/menuselect.makeopts 
> change the line that says
>  
> MENUSELECT_CFLAGS=RADIO_RELAX LOADABLE_MODULES
> to
> MENUSELECT_CFLAGS=LOADABLE_MODULES
>  
> then do make upgrade or make upgrade-acid as appropriate. 
> --
> Tim
> :wq
>  
> On Jun 3, 2012, at 1:51 PM, Tim Sawyer wrote:
> 
> 
> I am one of those that found setting RADIO_RELAX off works much better. TT falsing has been reduced to near zero and decoding is still as fast as I can push the buttons. 
>  
> One thing I found was that I had to turn on the PL filter. Before I did that TT decoding was unbearably show with RADIO_RELAX off. 
> --
> Tim
> :wq
>  
> On Jun 3, 2012, at 12:48 PM, Jim Duuuude wrote:
> 
> 
> This has nothing to do with the RTCM. The DTMF receiver is the same one that is used in all the other
> channel drivers for the other types of interfaces also.
> 
> When the app_rpt stuff was first being developed (10+ years ago), the default parameters
> for the DTMF receiver seemed too "tight" for radio use. There were a number of combinations
> that were found of receivers and transmitting devices (HT's mobiles, etc) that did not seem to
> work reliably with the parameters the way they were, so we developed the "RADIO_RELAX" set
> of parameters, which are more "relaxed" then the normal ones.
> 
> As time has gone on, there have been cases where using these "relaxed" parameters have seemed
> to do more harm then good. I dont know if your case is one of those. If you wish to try, I suggest
> re-compiling Asterisk with the RADIO_RELAX compile parameter turned off, and see if you like it
> that way better. I can guarantee you that you will have less "falsing" if you do that. What I can not
> guarantee is that you will get all the "real" digits decoded reliably (if you do that).
> 
> Jim WB6NIL
> 
> From: adamson_alan at hotmail.com
> To: app_rpt-users at ohnosec.org
> Date: Sun, 3 Jun 2012 15:26:06 -0400
> Subject: [App_rpt-users] RTCM falsing DTMF
> 
> ok, so is it normal for the RTCM to get false DTMF when voice is doing over the link?  I adjusted the RX audio so that the 2 lights were off with a 3khz tone generated from a service monitor.
> I see oh between 6-8 DTMF's detected over the voter channel during use…. How do you fix that issue?
> Alan
> 
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