[App_rpt-users] RTCM txprelim?

[Tim Sawyer]

That's right, there is no txprelem setting for RTCM's. Pre-emphasis is done by setting txctcss which causes chan_voter to turn on DSP pre-emphasis and setting txctcsslevel=0 forces no tone. So yeah, it's sort of a fake out. 

Chan_usbradio txprelim will generate pre-emphasis when using a DMK URI or any other USB audio FOB. The preemp is none in chan_usbradio not in the USB FOB.

That's true, chan_voter and voter.conf is the interface to RTCM's even if not voting.

--
Tim
:wq

On Aug 28, 2013, at 4:21 PM, KJ6KO <kj6ko at innercite.com> wrote:

>  
>  
> AH!  Besides answering another question I had about the "audio standard" on Asterisk being "line level" spkr/mic audio, you are sying the txprelim=yes is not what does it in a RTCM?  Does that still need to be set?
>  
> Sounds like  you are basically "fooling" it by telling it to generate a PL, which makes it think it is connected directly to a modulator, hence it will pre-emphasize the audio automatically? Setting the txctcsslevel=0 just kills the tone.
>  
> Do I have it correct now?
>  
> ALSO,
>   Since chan_simpleusb will not pre-emph, will a DMK URI do it if you use the chan_usbradio to drive it?
>  
> Lets see how many other questions I can cram in here.....
>  
>   I assume since I do not have an RTCM yet, that the chan_voter is what is used for the RTCM?  Even if it is NOT being used as a voter system, just a radio interface?
>  
> Thakns for the help Tim!!
>  
> I'm learnin'
>  
> 73 de Greg
> ----- Original Message -----
> From: Tim Sawyer
> To: KJ6KO
> Cc: App_rpt-users at ohnosec.org
> Sent: Wednesday, August 28, 2013 12:46 PM
> Subject: Re: [App_rpt-users] RTCM txprelim?
> 
> Sorry, this deserves a better expansion. Sometimes I get in a hurry.
> 
> Asterisk ships audio around (on the links, etc) as line-level audio (not pre-emphasized and needs no de-epmhasis). This works out great for telephones, computer clients, voice announcements, etc because Asterisk doesn't have to do any filtering. After all Asterisk is a telephone PBX where you would expect audio to be line-level (speaker/mic) audio. This leaves the pre/de-emphasis up to app_rpt channel drivers. Chan_usbradio and chan_voter can add pre-emphasis. Chan_simpleusb cannot pre-emphasise. 
> 
> With chan_voter the DSP pre-emphasis is turned on by setting txctcss = xxx.x in voter.conf. If you want pre-emphasis but no TX P/L set txctcss =  to some (any) tone and set txctcsslevel = 0.
> 
> Hope that helps.
> --
> Tim
> :wq
> 
> On Aug 28, 2013, at 10:26 AM, Tim Sawyer <tim.sawyer at me.com> wrote:
> 
>> Absolutely, yes. That is it's normal mode. 
>> --
>> Tim
>> :wq
>> 
>> On Aug 28, 2013, at 9:42 AM, KJ6KO <kj6ko at innercite.com> wrote:
>> 
>>> I am looking into an RTCM.  Does it have the capability of driving a modulator directly?  May have to use it with an old Palomar controller which is set up for direct modulator input style TX audio (pre-emphasized)
>>>  
>>> txprelim=yes?
>>>  
>>> I know it has the ability to de-emphasize the DISC audio from the Palomar.
>>>  
>>> Thanks..
>>> 
>>> 
>>> __________ Information from ESET NOD32 Antivirus, version of virus signature database 8738 (20130828) __________
> 
> 
> 
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