[App_rpt-users] Allstar RTCM (Radio Thin Client Module)isnowavailable

Thu Dec 22 17:33:14 UTC 2011

The general concept is that since radio waves travel at the speed of light,
if transmitters in a simulcast system are sufficiently far apart, there are "zones"
in which the signals get sufficiently out of phase with each other, based upon
distance from the transmitters. 

"Launch Delay" is a feature, that allows a fixed delay to put put the in the modulation
audio (in the microsecond (and fractions thereof) range) in an attempt to "compensate"
for such areas (attempt to make the signals "meet" in the proper areas).

In practice, sometimes its rather straightforward, and sometimes, its just kinda of a 
"black magic" to get this anywhere near right or reasonable. Sometimes, using this
ends up making things even worse then not having it at all (being that sometimes, when
you "fix" one area, you "break" others). Clearly every case is unique.

JIM WB6NIL

From: tim.sawyer at me.com
Date: Thu, 22 Dec 2011 09:13:49 -0800
To: w7ry at centurytel.net
CC: app_rpt-users at ohnosec.org
Subject: Re: [App_rpt-users] Allstar RTCM (Radio Thin Client Module)isnowavailable

What is launch delay and it's purpose?

--
Tim
:wq

On Dec 22, 2011, at 8:00 AM, Jim W7RY wrote:How do you control launch delay for your simulcast transmitters?  73Jim W7RY 
From: Peter ElkeSent: Thursday, December 22, 2011 1:10 AMTo: app_rpt mailing listSubject: Re: [App_rpt-users] Allstar RTCM (Radio Thin Client Module)isnowavailable
Hi Marshal, We have been running two separate test projects with the module over the last few weeks.  So far they seem very functional and cut down on node management if your goal is “perma-link” nodes. The first project is to take separate sites and merge them into one frequency (and one big node).  At this point we have two of the eight cut over and we have worked out the basic mechanics.  We use Micor receivers and MSX100 transmitters (that may change).  The transmitters are frequency locked using MSF5000 UHSO units with the reference source being a GPS’s 10Mhz output.  The UHSO creates 14.4Mhz that is fed into the MCX units.  In our testing it became very clear that all of the radios need to be identical. The voting is very cool, you can watch as is switches between the receive sites (very quickly, multiple times in a 1 second period) and the toggling goes unnoticed  on the repeater’s output.    Our next phase is to create larger overlapping coverage area to see how it sounds mixed by adding a third site in the middle of the current two.  At this point we don’t have much simulcast data, the overlap area is quite small. The other project is an upgrade to my portable Beagleboard node that I use traveling.  The old version was an Astro portable driven by a LOX board.  The Beagle had a USB WiFi to a Verizon hot spot box.  The upgrade swaps out the beagle for a RTCM and makes the connection from the road automatic.  To create the internet for the module the old USB wifi was switched out for a Ubiquiti PicoStation set up as a bridge.   When there is cell coverage it works and when there is no cell coverage it’s dead, simple, easy, no-dialing.  The first road test was today, all went well other than some LTE Verizon problems. Over all very cool stuff… Pete WI6H… From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Marshall Oldham
Sent: Wednesday, December 21, 2011 12:23 PM
To: 'Jim Duuuude'; 'app_rpt mailing list'
Subject: Re: [App_rpt-users] Allstar RTCM (Radio Thin Client Module) isnowavailable Jim, Okay so one server running Allstar node software at a central location (like my house) can support a dozen RTCM's being used as "Generic" conventionalfull duplex (repeaters) radio interfaces on far away hilltops even if I do not want to use the RTCM GPS-Timing Multi receiver voting or Simulcast Transmitter features?As long as I have some sort of internet connection at the remote sites back to my house? If I understand this correctly this would mean that: 1) No cost of computer at the radio site.2) No worry about the node computer locking up at the remote radio site and having to reboot or reset it.3) No cost other than the RTCM (Radio Thin Client Module) to setup an Allstar node at the remote radio site. (no computer, no URI,  no Sound FOB) 4) If I use the RTCM (Radio Thin Client Module) I have the ability to setup a normal Allstar node at the present time and then later if I want to I can upgrade the hilltop for GPS-Timing Multi receiver voting and Simulcast Transmitter by simply adding a GPS receiver at the site and reconfiguring the software. If so, this seems like a pretty cool little piece of hardware!  Marshall - ke6pcv         From: Jim Duuuude [mailto:telesistant at hotmail.com] 
Sent: Wednesday, December 21, 2011 11:52 AM
To: Marshall Oldham; app_rpt mailing list
Subject: RE: [App_rpt-users] Allstar RTCM (Radio Thin Client Module) is nowavailableYeah, that's the general idea. The location of the Linux server running app_rpt/Asterisk can be
more or less anywhere within Internet connectivity of all of the receiver and/or transmitter sites.
Of course, "Internet" can mean either some sort of public Internet connection, or a privately-provided
Internet connection (low-cost microwave link(s), etc).

The only limitation is that an RTCM/Voter module *must* be located on the same LAN as the Linux
server, to at least provide a GPS-based timing reference. A system could be set up with a server
located in some sort of datacenter "on the ground", and all the radios could have an RTCM "on the
hill" with them, and as long as there is Internet connectivity of some sort between each of them
and the server, the system will work nicely. That is providing that there is an RTCM located at
the server location also (whether or not that particular RTCM has radio hardware connected to it
or not).

One minimal Linux server can easily support 1 or 2 dozen RTCM's (on 1 or 2 allstar nodes),
and a larger server could easily support MANY dozens of them on dozens of allstar nodes.
Of course, you REALLY dont want to put too many of them on a single server, being a potential
single point of failure. For pretty much any practical purpose, the reasonable limitation is
the point of failure/redundancy issue, not technical limitations.

I'm not sure if you were clear on this, so I thought I would mention that the RTCM is not just
usable as a GPS-timing-based Multi-Receiver Voting system and/or a Simulcast Transmitter system.
It can also be used as a "generic" radio interface for a conventional (non-GPS-based) either simplex
or full duplex (repeater) radio. The advantage of doing this would be to not have the Linux
host "on the hill" with the radio (as mentioned above). In addition, the RTCM allows for 
portable/mobile operation with a mobile/portable Internet connection in both the GPS-based
and non-GPS-based environments. 

JIM WB6NIL

From: ke6pcv at cal-net.org
To: app_rpt-users at ohnosec.org
Date: Wed, 21 Dec 2011 10:54:18 -0800
Subject: Re: [App_rpt-users] Allstar RTCM (Radio Thin Client Module) is nowavailableI have been looking at the Allstar RTCM (Radio Thin Client Module) and it really looks like a GREAT product and addition to the already cool Allstar hardware. Among all the other cool features of the RTCM (Radio Thin Client Module) like Transmitter Simulcasting and Receiver Voting, if I understand the documentationcorrectly you can use this very small Radio Thin Client Module at a remote radio site to set up an Allstar repeater node if the site has internet connection without a COMPUTER at the site? Then you can point the node on the hilltop back to a server on the ground somewhere that is easy to get too?  How many total sites can you use Radio Thin Client Modules on and point back to a single server on the ground?   If this is the case, All I can say is WOW, how cool! 73 Marshall    From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Mark Guibord
Sent: Sunday, December 18, 2011 11:03 AM
To: app_rpt-users at ohnosec.org
Subject: [App_rpt-users] Allstar RTCM (Radio Thin Client Module) is nowavailableAllstar RTCM Radio Thin-Client Module, an Open-Source VOIP-Based Voting Multi-Receiver and Simulcast Transmit System is now available for purchase.  For more information visit http://micro-node.com/thin-m1.html  Regards,Mark GuibordMicro-Node International  
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