The RTCM and simulcast DOES work. As mentioned before, you have to be using a transmitter that can accept a 10 mHz (or whatever) reference signal. You also need 1 PPS for your receivers and transmitter. You also need to sync the RTCM to your GPSDO (which I have not done). If you have not done all this you WILL hear some “funk” in the overlap areas.
That “funk” can go from usable to un-usable depending on how strong the transmitters are in the overlap region.
Pardon the “non-technical” terms. It does work but the law of physics do apply here.
de K0JSC
···
On Mon, Jun 6, 2016 at 9:54 AM, app_rpt-users-request@ohnosec.org wrote:
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Today’s Topics:
Re: audio for direct VCO FM (Joe Leikhim) (Steve Wright)
Re: RTCM Simulcast question (Steve Wright)
Re: audio for direct VCO FM: Si5351B (David McGough)
Re: RTCM Simulcast question (Joe Moskalski)
Re: RTCM Simulcast question (David McGough)
Re: RTCM Simulcast question (Joe Moskalski)
Message: 1
Date: Mon, 6 Jun 2016 19:40:50 +1200
From: Steve Wright info@meshnetworks.co.nz
Subject: Re: [App_rpt-users] audio for direct VCO FM (Joe Leikhim)
Message-ID: 57552902.9070008@meshnetworks.co.nz
Content-Type: text/plain; charset=windows-1252; format=flowed
On 04/06/16 04:00, Joe Leikhim rhyolite@leikhim.com wrote:
Assuming the VCO is part of a PLL, the PLL will tend to “correct” the
modulation, […]
Was planning to use the Si5351B - has VCO input.
S
Message: 2
Date: Mon, 6 Jun 2016 20:22:36 +1200
From: Steve Wright info@meshnetworks.co.nz
Subject: Re: [App_rpt-users] RTCM Simulcast question
Message-ID: 575532CC.2020304@meshnetworks.co.nz
Content-Type: text/plain; charset=windows-1252; format=flowed
On Sat, Jun 4, 2016 at 6:03 PM, Joe Moskalski kc2irv@gmail.com wrote:
I will be setting up a 2 site UHF simulcast system in the coming months
Huh? I was told (on this list) that simulcast TX “doesn’t work”.
S
Message: 3
Date: Mon, 6 Jun 2016 10:46:38 -0400 (EDT)
From: David McGough kb4fxc@inttek.net
Subject: Re: [App_rpt-users] audio for direct VCO FM: Si5351B
Message-ID:
<Pine.LNX.4.44.1606060946450.4196-100000@goliath.inttek.net>Content-Type: TEXT/PLAIN; charset=US-ASCII
Hi Steve,
We’re getting way off topic for the mailing list, but, I thought I’d post
this reply here if there are any other interested hams out there, perhaps
who are also experimenting in this area.
I haven’t played with the Si5351B version of this interesting chip, yet. I
wonder whether the voltage control input of this chip would be suitable
for AF FM modulation? Assuming that you could modulate the VCXO at audio
frequencies (the datasheet isn’t completely clear to me about that), an
immediate issue would be that everytime you change the fractional-N
division ratio, you’ll change the modulation index. This will have to be
compensated for, one way or another.
I’ve been playing with several boards with Si5351 chips. They’re pretty
neat. They’re also pretty noisy! …With both spurious and phase noise.
The phase noise can be improved somewhat with a better external crystal
oscillator, the spurs seem more challenging. Using the on-board VCXO with
the 5351B, you can’t use a high quality external oscillator, so phase
noise and overall frequency stability could be an issue, too.
Anyhow, for my applications, I’m following the Si5351 with a secondary
clean-up VCO/PLL, which was already in the radios. I just needed a
frequency-agile reference oscillator, so to speak. I think the Si5351 will
work well for this, based on my preliminary tests! (I’d certainly like to
hear the experiences from anyone who has already been down this road!)
I guess you’re not finding any local sources of surplus radios? Do you
have any 6m power amps available?
73, David KB4FXC
On Mon, 6 Jun 2016, Steve Wright wrote:
On 04/06/16 04:00, Joe Leikhim rhyolite@leikhim.com wrote:
Assuming the VCO is part of a PLL, the PLL will tend to “correct” the
modulation, […]
Was planning to use the Si5351B - has VCO input.
S
Message: 4
Date: Mon, 6 Jun 2016 11:03:11 -0400
From: Joe Moskalski kc2irv@gmail.com
Subject: Re: [App_rpt-users] RTCM Simulcast question
Message-ID:
<CAES28qxB06niu+nL4Y5QfUvgZFf-y8s=uZdH2afzxKnwr0HV+w@mail.gmail.com>Content-Type: text/plain; charset=“utf-8”
It seems clear that in order for simulcast to work properly with the RTCM
I will need to clock the CPU to the GPSDO. Is there a device available to
give you the 9.6 mhz reference from the 10 mhz out from the GPSDO or does
anyone have a schematic available so that I can build them myself?
Virus-free.
<#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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Message: 5
Date: Mon, 6 Jun 2016 11:36:01 -0400 (EDT)
From: David McGough kb4fxc@inttek.net
Subject: Re: [App_rpt-users] RTCM Simulcast question
Message-ID:
<Pine.LNX.4.44.1606061122550.4196-100000@goliath.inttek.net>Content-Type: TEXT/PLAIN; charset=US-ASCII
Hi Joe,
While on the subject of the Si5351 chips, the application of converting
one reference clock to a secondary frequency is what they were designed
for. So, since you’ve already got a GPS reference, this -might- be an
inexpensive starting point…For this application, you obviously won’t
need all the bells and whistles presented in this article! See:
http://www.knology.net/~gmarcus/Si5351/Si5351_VFO_QEX.pdf
http://www.knology.net/~gmarcus
Note that I would replace the Si5351 25MHz reference with a decent TCXO
(available on ebay, etc.)…Note that I haven’t used the Si5351 with an
RTCM, there may be simpler/better ways???
73, David KB4FXC
On Mon, 6 Jun 2016, Joe Moskalski wrote:
It seems clear that in order for simulcast to work properly with the RTCM
I will need to clock the CPU to the GPSDO. Is there a device available to
give you the 9.6 mhz reference from the 10 mhz out from the GPSDO or does
anyone have a schematic available so that I can build them myself?
Virus-free.
<#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
Message: 6
Date: Mon, 6 Jun 2016 11:54:11 -0400
From: Joe Moskalski kc2irv@gmail.com
To: David McGough kb4fxc@inttek.net
Subject: Re: [App_rpt-users] RTCM Simulcast question
Message-ID:
<CAES28qx-G3wytTXKMRVvzMNm+498_c-aeNB6JrTWmZOR7A7ZcA@mail.gmail.com>Content-Type: text/plain; charset=“utf-8”
I mentioned this to someone else, QRP Labs has a kit that creates a OCXO
around the Si5351 chip. here is the link:
http://www.qrp-labs.com/ocxokit.html
If you couple this with another kit of theirs you can program it it any
frequency you want. My only thought is would it be accurate/stable enough.
http://www.qrp-labs.com/progrock.html
Virus-free.
<#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
On Mon, Jun 6, 2016 at 11:36 AM, David McGough kb4fxc@inttek.net wrote:
Hi Joe,
While on the subject of the Si5351 chips, the application of converting
one reference clock to a secondary frequency is what they were designed
for. So, since you’ve already got a GPS reference, this -might- be an
inexpensive starting point…For this application, you obviously won’t
need all the bells and whistles presented in this article! See:
Note that I would replace the Si5351 25MHz reference with a decent TCXO
(available on ebay, etc.)…Note that I haven’t used the Si5351 with an
RTCM, there may be simpler/better ways???
73, David KB4FXC
On Mon, 6 Jun 2016, Joe Moskalski wrote:
It seems clear that in order for simulcast to work properly with the
RTCM
I will need to clock the CPU to the GPSDO. Is there a device available
to
give you the 9.6 mhz reference from the 10 mhz out from the GPSDO or
does
anyone have a schematic available so that I can build them myself?
<
Virus-free.
<
<#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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