[App_rpt-users] App_rpt-users Digest, Vol 99, Issue 9

Jeff Carrier k0jsc.jeff at gmail.com
Sun May 7 21:32:02 EDT 2017


Joe,

Did you lock it to a GPSDO?  Jim mentioned this mod to me about a year ago
and I never had a chance to give it a try.  My previous overlap area was
tolerable but I've added a third transmitter so it may be time to try this
finally.

On Sun, May 7, 2017 at 10:00 AM, <
app_rpt-users-request at lists.allstarlink.org> wrote:

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> Today's Topics:
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>    1. RTCM Simulcast and 9.6 MHz Phase locking (Joe Moskalski)
>    2. Re: RTCM Simulcast and 9.6 MHz Phase locking (Joe Leikhim)
>
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Sun, 7 May 2017 03:13:26 -0400
> From: Joe Moskalski <kc2irv at gmail.com>
> To: app_rpt mailing list <App_rpt-users at ohnosec.org>
> Subject: [App_rpt-users] RTCM Simulcast and 9.6 MHz Phase locking
> Message-ID:
>         <CAES28qyXLtJMUoGqAYk5bKU_eE2Nciq_9QQC48rBDSeZigtgHA@
> mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> I wanted to throw this email out to the group for all those who want to
> simulcast with the RTCM. For those who don't know, in order to make the
> RTCM suitable for simulcast you must have a more accurate 9.6 MHz clock for
> the RTCM in order to ensure the audio sounds acceptable in the overlap
> areas. I did this a few months ago using 9.6 MHz OCXO's. This worked
> reasonably well. Not as well as I would have liked but the system was very
> usable, but of course I wanted it to be better. Since the PCGM
> (Programmable Clock Generation Module) is no longer available, I decided to
> roll my own as some say.
> I created a PLL circuit that can accept a 10 MHz, 1 MHz or 100 KHz
> reference input and produce a phase locked 9.6 MHz out for the RTCM. I have
> been testing this over the past few days and it has made an great
> improvement in the audio quality in the overlap. The quality of the audio
> in the overlap areas sounds very, very good, it's very similar to what I
> expect to hear in commercial simulcast systems. My circuit is heavily based
> off of an old Motorola MSF5000 HSO PLL circuit that I was able to adapt and
> modify to my needs.  There are other uses for this circuit that make it
> attractive for simulcasting but I wont get into them here. I am will to
> share my schematic and bill of materials (digikey) with anyone. Please send
> me an email and I will be willing to share all of my information on the
> project.
>
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> ------------------------------
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> Message: 2
> Date: Sun, 7 May 2017 03:42:25 -0400
> From: Joe Leikhim <rhyolite at leikhim.com>
> To: Users of Asterisk app_rpt <app_rpt-users at lists.allstarlink.org>
> Subject: Re: [App_rpt-users] RTCM Simulcast and 9.6 MHz Phase locking
> Message-ID: <35ee60f8-a760-363b-0d28-1b6c9967cebd at leikhim.com>
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>
> Thanks Joe;
>
> I would certainly be interested in your documentation. Does this solve
> the problem of transmit PL tone jumping phase on key up, as Hayden
> encountered?
>
> Joe L
>
> On 5/7/2017 3:13 AM, Joe Moskalski wrote:
> > I wanted to throw this email out to the group for all those who want
> > to simulcast with the RTCM. For those who don't know, in order to make
> > the RTCM suitable for simulcast you must have a more accurate 9.6 MHz
> > clock for the RTCM in order to ensure the audio sounds acceptable in
> > the overlap areas. I did this a few months ago using 9.6 MHz OCXO's.
> > This worked reasonably well. Not as well as I would have liked but the
> > system was very usable, but of course I wanted it to be better. Since
> > the PCGM (Programmable Clock Generation Module) is no longer
> > available, I decided to roll my own as some say.
> > I created a PLL circuit that can accept a 10 MHz, 1 MHz or 100 KHz
> > reference input and produce a phase locked 9.6 MHz out for the RTCM. I
> > have been testing this over the past few days and it has made an great
> > improvement in the audio quality in the overlap. The quality of the
> > audio in the overlap areas sounds very, very good, it's very similar
> > to what I expect to hear in commercial simulcast systems. My circuit
> > is heavily based off of an old Motorola MSF5000 HSO PLL circuit that I
> > was able to adapt and modify to my needs.  There are other uses for
> > this circuit that make it attractive for simulcasting but I wont get
> > into them here. I am will to share my schematic and bill of materials
> > (digikey) with anyone. Please send me an email and I will be willing
> > to share all of my information on the project.
> >
> > <https://www.avast.com/sig-email?utm_medium=email&utm_
> source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon>
> >       Virus-free. www.avast.com
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> >
> >
> >
> >
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> --
> Joe Leikhim
>
>
> Leikhim and Associates
>
> Communications Consultants
>
> Oviedo, Florida
>
> JLeikhim at Leikhim.com
>
> 407-982-0446
>
> WWW.LEIKHIM.COM
>
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