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:
1. Re: audio for direct VCO FM (Joe Leikhim) (Steve Wright) 2. Re: RTCM Simulcast question (Steve Wright) 3. Re: audio for direct VCO FM: Si5351B (David McGough) 4. Re: RTCM Simulcast question (Joe Moskalski) 5. Re: RTCM Simulcast question (David McGough) 6. Re: RTCM Simulcast question (Joe Moskalski)
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Message: 1 Date: Mon, 6 Jun 2016 19:40:50 +1200 From: Steve Wright <info@meshnetworks.co.nz> To: app_rpt-users@ohnosec.org 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
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Message: 2 Date: Mon, 6 Jun 2016 20:22:36 +1200 From: Steve Wright <info@meshnetworks.co.nz> To: app_rpt-users@ohnosec.org 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
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Message: 3 Date: Mon, 6 Jun 2016 10:46:38 -0400 (EDT) From: David McGough <kb4fxc@inttek.net> To: app_rpt-users@ohnosec.org 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
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Message: 4 Date: Mon, 6 Jun 2016 11:03:11 -0400 From: Joe Moskalski <kc2irv@gmail.com> To: App_rpt-users@ohnosec.org 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?
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