That seems like it would explain a good part of the overlap grunge you are experiencing, even though you seem extremely confident when you say that the OCXO driving the RTCM still "isn't enough" in overlap areas. Out of curiosity do you have any firsthand experience with what we are talking about? I'm not meaning to condescend here, but you seem very confident that an OCXO driving the RTCM won't help on overlap areas, despite what Jim has said multiple times on the list (see my links). Are we missing something? On Monday, June 6, 2016, Jeff Carrier <k0jsc.jeff@gmail.com> wrote:
Sam,
I'm not injecting 9.6 MHz into the RTCM. At some point I'd like to give that a whirl but I'd need another device to take the 10 MHz and change it to 9.6. That's another device that could fail on a mountain top. One of my sites still isn't accessible and take 6 hours round trip in good weather.
On Mon, Jun 6, 2016 at 1:57 PM, Sam Skolfield <kj6qfs@gmail.com <javascript:_e(%7B%7D,'cvml','kj6qfs@gmail.com');>> wrote:
Jeff, are you using the RTCMs internal crystal or are you injecting an external GPSDO derived 9.6MHz?
On Monday, June 6, 2016, Jeff Carrier <k0jsc.jeff@gmail.com <javascript:_e(%7B%7D,'cvml','k0jsc.jeff@gmail.com');>> wrote:
Trust me, a GPS-discipline OCXO isn't enough in your overlap areas. Mine have 50+ ,miles between overlap zones (transmitters are 100+ miles apart) and you'll still hear garbled signals in the overlap.
Keep in mind, public safety spends tens even hundreds of thousands of dollars to do this very same thing!
Am I saying don't try it. Not even a little! Experiment and have fun! I'm just sharing my own experiences.
I had the rare opportunity to speak with Jim on the phone a while back and this came up. If I could only remember, comprehend and apply even 25% of what we talked about I'd be light years ahead!
On Mon, Jun 6, 2016 at 10:23 AM, <app_rpt-users-request@ohnosec.org> wrote:
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Today's Topics:
1. Re: RTCM Simulcast question (David McGough) 2. Current signal strength (Skyler F) 3. Re: App_rpt-users Digest, Vol 88, Issue 16 (Jeff Carrier)
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Message: 1 Date: Mon, 6 Jun 2016 12:06:57 -0400 (EDT) From: David McGough <kb4fxc@inttek.net> To: App_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] RTCM Simulcast question Message-ID: <Pine.LNX.4.44.1606061158330.10347-100000@goliath.inttek.net> Content-Type: TEXT/PLAIN; charset=US-ASCII
If you GPS-discipline that OCXO, I think it would be more than adequate. Since you've already got the 1 PPS GPS signal, all that should be needed in addition to the OCXO/Si5351 is a little $3 Arduino board (like: http://www.ebay.com/itm/131702108124 ) to program the desired output frequency(s) and perform compensation.
$16 for an OCXO ---NICE! ...The whole project maybe $25!
On Mon, 6 Jun 2016, Joe Moskalski wrote:
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
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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:
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?
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Message: 2 Date: Mon, 6 Jun 2016 10:23:34 -0600 From: Skyler F <electricity440@gmail.com> To: "app_rpt-users@ohnosec.org" <app_rpt-users@ohnosec.org> Subject: [App_rpt-users] Current signal strength Message-ID: < CAJNyT0-e-NbcP-JQpf83yeAWJ0RE2CuZ0H69B3ivEd2Xbm4x1w@mail.gmail.com> Content-Type: text/plain; charset="utf-8"
So I just had this idea to analyze 2 meter band openings, find a weak 162MHz weather station and have a dummy app_rpt node Receive that signal. Using DSP, Then print the current strength to a file, and graph it.
Is there any way to get the current signal strength and store it in a bash variable or something?
73 Skyler kd0whb