[App_rpt-users] RTCM audio interfacing options

Sam Skolfield kj6qfs at gmail.com
Tue Jan 23 20:40:24 EST 2018


Hi Tim,

>f you are using discriminator audio you don't have to set deemp=yes in
> voter.conf because 13 - COR type = 0 (normal) will switch in the RTCM's
> filter. With 13 - COR type = 1 >>(Ignore) the filter is not switched in.
>

> >You can use COR type 0 in non-voting applications if you want to use the
> RTCM's squelch circuit which is quite good and MICOR quality. This has 2
> advantages. You'll be able to >see the RTCM's RSSI rather than just 0 and
> 255. Second, you can use turn the P/L on and off as the only output PIN
> isn't 'anded' COR and PL. In this case you likely will need to >set
> deemp=yes in voter.conf.
>

 I didn't know either of those things! Very good to know.

>
> Transmit audio is not pre-emphasize unless you have CTCSS enabled. If you
> need pre-emphasis but no tone you can set a freq with 0 level.
>

Yep! That's what I was eluding to in examples 1 and 4 of my original post.

Thanks for the 411, it's much appreciated as always.

>
>
> On Tue, Jan 23, 2018 at 12:04 PM, Sam Skolfield <kj6qfs at gmail.com> wrote:
>
>> Hi Jessie.
>> Yes, for voting and/or simulcasting, you obviously need to provide raw
>> discriminator audio and modulator audio.
>>
>> This is will be a non-voted repeater.
>>
>> On Tue, Jan 23, 2018 at 7:41 AM Jesse Lloyd <ve7lyd at gmail.com> wrote:
>>
>>> Well, if you want it to vote it'll have to be discriminator rx audio. If
>>> not, I'll use which ever squelch I deem to be superior. The motorola 2
>>> level squelches are typically pretty good, but you have to open the lid on
>>> a GM300 to adjust it. If that's ok, then I'd use that.
>>>
>>> For pre-emph, if you want simulcast with PL you have to let the voter
>>> make the PL tone. Otherwise I prefer using the mic in as it has nice a nice
>>> audio filter response and limiter circuit. Just a note for the GM300 you
>>> should adjust the max deviation when programming them into the ham band.
>>> The UHF ones I find change quite a bit with frequency. Sometimes you'll
>>> also have to make an adjustment to the PLL reference voltage to get it to
>>> lock up for Tx.
>>>
>>> Cheers,
>>> Jesse
>>>
>>> > On Jan 23, 2018, at 3:32 AM, Sam Skolfield <kj6qfs at gmail.com> wrote:
>>> >
>>> > Greetings,
>>> > I've been playing with RTCMs and VOTER boards for almost 5 years now,
>>> and I'm very happy with what I have in service. I've built a multi-site
>>> voted system, and more recently a non-voted hub that ties together repeater
>>> controllers at a few sites.
>>> >
>>> > I'm helping a friend but together a RTCM / pair of GM300 repeater, and
>>> got to thinking about audio options. There is more than one right way!
>>> >
>>> > 1. Discriminator audio to RTCM, set deemp=yes in voter.conf (causes
>>> hardware de-emphasis in RTCM circuitry)
>>> > RTCM TX audio to GM300 Flat audio input, use chan_voter software
>>> preemphasis by specifying txctcss and txctcsslevel=0 in rpt.conf
>>> >
>>> > 2. 1. Discriminator audio to RTCM, set deemp=yes in voter.conf (causes
>>> hardware de-emphasis in RTCM circuitry)
>>> > RTCM TX audio to mic audio, letting radio do pre-emphasis.
>>> >
>>> >
>>> > 3. 1.De-emphased audio from GM300 (JU551 set to B)  RTCM
>>> > RTCM TX audio to mic audio, letting radio do pre-emphasis.
>>> >
>>> > 4. 1.De-emphased audio from GM300 (JU551 set to B)  RTCM
>>> > RTCM TX audio to Flat audio input, use chan_voter software preemphasis
>>> by specifying txctcss and txctcsslevel=0 in rpt.conf
>>> >
>>> >
>>> > All four of these combinations should theoretically produce "flat"
>>> system response, but I'm sure all four yield slightly different results,
>>> given different corner frequencies in hardware/software de-emphasis /
>>> pre-emphasis and different input/output impedance combinations.
>>> >
>>> > Has anyone experimented with these combinations?
>>> >
>>> > 73
>>> > --
>>> > KJ6QFS
>>> > Sam Skolfield
>>> > _______________________________________________
>>> > App_rpt-users mailing list
>>> > App_rpt-users at lists.allstarlink.org
>>> > http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
>>> >
>>> > To unsubscribe from this list please visit
>>> http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users and
>>> scroll down to the bottom of the page. Enter your email address and press
>>> the "Unsubscribe or edit options button"
>>> > You do not need a password to unsubscribe, you can do it via email
>>> confirmation. If you have trouble unsubscribing, please send a message to
>>> the list detailing the problem.
>>> _______________________________________________
>>> App_rpt-users mailing list
>>> App_rpt-users at lists.allstarlink.org
>>> http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
>>>
>>> To unsubscribe from this list please visit http://lists.allstarlink.org/
>>> cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of
>>> the page. Enter your email address and press the "Unsubscribe or edit
>>> options button"
>>> You do not need a password to unsubscribe, you can do it via email
>>> confirmation. If you have trouble unsubscribing, please send a message to
>>> the list detailing the problem.
>>
>> --
>> KJ6QFS
>> Sam Skolfield
>>
>> _______________________________________________
>> App_rpt-users mailing list
>> App_rpt-users at lists.allstarlink.org
>> http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
>>
>> To unsubscribe from this list please visit http://lists.allstarlink.org/
>> cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of
>> the page. Enter your email address and press the "Unsubscribe or edit
>> options button"
>> You do not need a password to unsubscribe, you can do it via email
>> confirmation. If you have trouble unsubscribing, please send a message to
>> the list detailing the problem.
>>
>
>
>
> --
> Tim WD6AWP
> _______________________________________________
> App_rpt-users mailing list
> App_rpt-users at lists.allstarlink.org
> http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
>
> To unsubscribe from this list please visit http://lists.allstarlink.org/
> cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of
> the page. Enter your email address and press the "Unsubscribe or edit
> options button"
> You do not need a password to unsubscribe, you can do it via email
> confirmation. If you have trouble unsubscribing, please send a message to
> the list detailing the problem.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.allstarlink.org/pipermail/app_rpt-users/attachments/20180123/5560bee7/attachment.html>


More information about the App_rpt-users mailing list