One method that would improve the simulcast performance without going nuts designing, troubleshooting and building a completely separate device to clock the RTCM to the GPSDO would be to replace the the 9.6 Mhz crystal with a TCXO. There are several available with a square wave 9.6 Mhz output with an accuracy of .3 ppm. Of course this won't make it perfect but its minimally invasive, cheap, easy and most importantly.... readily available. Another question I have is would an external oscillator with a sine wave output work? If so then there are 9.6 Mhz OCXO's (I found some on ebay) that would be an even further improvement. On Mon, Jun 6, 2016 at 1:15 PM, Jeff Carrier <k0jsc.jeff@gmail.com> wrote:
You are correct Joe. The RTCM is a contender though it wouldn't exist or would be useless without Jim's software.
As Robert mentioned, and his friend is right. I was warned by a local and very knowledgeable elmer also. Personally I'm simulcasting but fortunately there is a node smack dab in the middle that "most" users will switch to so they don't hear the issues in the overlap zones.
I haven't yet cracked the RTCM's open to modify them and I may not ever do it just cause i'm lazy. It depends on how picky your users are. That's sort of a loaded question though. When folks get used to allstar (especially if you're running a high quality codec) and they travel into one of these overlap zones they'll probably complain because they're used to so much more fidelity!
Does it work without jumping through all the hoops...? Yes, it's just way more ugly in the areas that have overlapping coverage.
blah blah...i'm delirious and I still have two more night shifts to go!
73 de K0JSC
On Mon, Jun 6, 2016 at 10:59 AM, <app_rpt-users-request@ohnosec.org> wrote:
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Today's Topics:
1. Re: RTCM Simulcast question (Robert Newberry) 2. Re: App_rpt-users Digest, Vol 88, Issue 16 (Joe Leikhim)
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Message: 1 Date: Mon, 6 Jun 2016 12:56:57 -0400 From: Robert Newberry <N1XBM@amsat.org> To: app_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] RTCM Simulcast question Message-ID: < CAM09xEagKzHhFhw94cqe7oDKWkhr51fdTKt0CuQB2DMz7OH4Gg@mail.gmail.com> Content-Type: text/plain; charset="utf-8"
Please don't flame me.
I have a friend who used to work in the paging industry. When I talked to him about simulcast he was telling me about the paging industry the pains they went thru. He was saying that they used all of the same transmitters made around the same time. A signal can go from point A to B in transmitter a different lengths of time.
He basically told me the same thing, that go do it and enjoy. He just warned me about PL sync and all of the details to getting it right. He just said at the end of the day that he was confident I could get it to work, but probably will not be satisfied with the results.
N1XBM Apparare Scientor Paratus Communicare Allstar Node # 27086, 41540, 41812, 42086, 42658, 42657 www.radioguysrepeaternetwork.com