[App_rpt-users] RTCM Simulcast and 9.6 MHz Phase locking

Pierre Martel petem001 at gmail.com
Tue Jun 6 21:00:37 UTC 2017


after reading on gps locked clock and  pll found this.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=234

Low-jitter GPS-locked precision frequency reference
450 Hz to 800 MHz output

this could be usefull to steer about any radio model no?

Is it worth the time and money to try with this device?

Le ven. 12 mai 2017 à 17:39, Pierre Martel <petem001 at gmail.com> a écrit :

> A big thanks Tim. I feel less uneducated ;-) Will have to get a look at
> this..
>
> 2017-05-12 12:03 GMT-04:00 Tim Sawyer <tisawyer at gmail.com>:
>
>> Political Correctness Gone Mad. 😄
>>
>> Actually it's Programmable Clock Generator Module.
>>
>> K
>>
>> On Thu, May 11, 2017 at 8:38 PM Pierre Martel <petem001 at gmail.com> wrote:
>>
>>> I know there is always the one that ask the obvious question but, what
>>> is a pcgm?
>>>
>>>
>>> Le lun. 8 mai 2017 à 23:10, Tim Sawyer <tisawyer at gmail.com> a écrit :
>>>
>>>> The PCGM were noisy. I know of a case where a ham using one was shut
>>>> down by the site owner. Seems the PCGM was emitting a interfering signal on
>>>> high band, around 158 Mhz.
>>>>
>>>> On Mon, May 8, 2017 at 1:33 PM, Bryan Fields <bryan at bryanfields.net>
>>>> wrote:
>>>>
>>>>> I've been following this with some interest.  One of the fundamental
>>>>> issues with the PCGM was the master clock going to the radio was unable to
>>>>> be modulated.  This made low frequency signals (PL) distort, and digital PL
>>>>> was even worse.
>>>>>
>>>>> Typically most radios use two point modulation, with modulation on the
>>>>> reference oscillator.  When you add an external reference you loose this.
>>>>>
>>>>> Some base stations are designed to do two point modulation even on an
>>>>> external clock, the Quantar for example.  This station will even phase lock
>>>>> it's PL and DPL generation if provided a 1 PPS in addition to a clock.
>>>>>
>>>>> If we could inject modulation into the clock generator simulcast
>>>>> performance would vastly improve.  I'd be interested to see your design to
>>>>> see if this would be a possibility.
>>>>>
>>>>> Thoughts?
>>>>>
>>>>> --
>>>>> Bryan Fields
>>>>> M: +1-727-409-1194 <(727)%20409-1194>
>>>>>
>>>>> On May 8, 2017, at 14:15, Reid Brandon <rfpowerguy at yahoo.com> wrote:
>>>>>
>>>>> Hi Joe,
>>>>> I got a page with a pic of a man that rotated  around saying DOWNLOAD
>>>>> NOT FOUND.
>>>>> Try again!?
>>>>> Tks  Reid
>>>>>
>>>>>
>>>>> On Sunday, May 7, 2017 12:25 PM, Pierre Martel <petem001 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>
>>>>> I am very interrested in all this project. My email is VE2PF @ VE2MRC
>>>>> dot com!
>>>>>
>>>>> what radio did you used for the project?
>>>>>
>>>>> Thanks for sharing!
>>>>>
>>>>> Pierre
>>>>> VE2PF
>>>>>
>>>>>
>>>>> 2017-05-07 12:32 GMT-04:00 Kevin Custer <kuggie at kuggie.com>:
>>>>>
>>>>> Joe,
>>>>>
>>>>> Why not consider do it as an article for Repeater Builder?
>>>>>
>>>>> Thanks,
>>>>> Kevin
>>>>>
>>>>>
>>>>> 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.
>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>> --
>>>> --
>>>> Tim
>>>> _______________________________________________
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>> --
>> --
>> Tim
>>
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>
>
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