[App_rpt-users] Simulcast (was: posted on repeater builder)

Bryan Fields Bryan at bryanfields.net
Wed Feb 13 23:47:26 EST 2019


On 2/13/19 5:59 PM, Jonathan Weirmeir wrote:
> On Wed, Feb 13, 2019, 2:59 PM Bryan Fields <Bryan at bryanfields.net wrote:
> 
<snip>
>> The traditional way to use the RTCM/voter is to remove the crystal
>> reference
>> on the transmitter PLL replacing it with the generated GPS clock.  In most
>> radios this will remove the dual point modulation provided by a diode
>> across
>> the crystal.  Now modulation balance will be way off, and it will be much
>> harder to get audio to line up.
>
>
> Could this device give new life to old crystalled repeaters, such as
> Motorola Micor, GE MASTR II, etc? If so, anyone have any notes to share?


I've fixed quoting for you.

No, this will not work, as the crystal is directly modulated in these old
radios; you would need some way to modulate the incoming clock signal.  Now
some higher end products you can do this with, but not the SIlabs chips.  If
you could directly modulate it, then you can do dual point modulation in a PLL
based radio too :)

It's a great option if you have a radio where you can replace the reference of
a PLL (and it has filtering in there), but not great to replace a directly
modulated crystal.

Micor's are dead, long live the synthesized radios :D

-- 
Bryan Fields

727-409-1194 - Voice
http://bryanfields.net


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