[App_rpt-users] Motorola MSF / Voting / Receivers;

Sat May 9 17:51:51 UTC 2015

One more thing, if I may.

Can I use a USB and a Beagle Board or does I need to use a RTCM for voting? The cost comes out about the same but the Beagle has more options like the ability to stream the audio to an Icecast server.

From: Chuck Henderson 
Sent: Saturday, May 09, 2015 8:44 AM
To: R. Wayne 
Subject: Re: [App_rpt-users] Motorola MSF / Voting / Receivers;

With the RTCM at each receiver and with it receiving unfiltered discriminator audio, you can get perfect voting.  The amount of delay is going to need to be just a little more than the path with the greatest delay.  For a repeater that uses all private point to point 5 ghz links I have an almost constant 2 ms delay due to the data link, but once in a while it goes up to 30ms.  But for a repeater that uses the Internet I have delays of 30 to 140ms for the network path and once in a while up to 300ms on the Internet.  On the all private links repeater I can set it for about 100ms of overall delay and have no problems, but for the Internet connected system I have to set it for 400ms overall delay.  The delay is sometimes noticed on unkey when a person hears the last syllable of what they said.  And it makes it impossible for a person using 2 radios in their car to listen to the output of the repeater while transmitting into the repeater input, unless they have an amazing brain that can deal with hearing them self delayed and still be able to talk.  I can't. 
So just give up listening to yourself talk and the delay is no issue.  No audio is lost due to the delay.

I did think about the doubling that can happen due to the delay, so I modified the main site so that as soon as it detects carrier, and even before it detects PL, it keys the transmitter through a timer for 500ms max, that lets everyone listening to the repeater know that someone may be about to talk so don't double.  If PL is not detected and the AllstarLink never sends a key down signal, then the transmitter drops after the first 500 ms.  It has worked great at almost completely eliminating doubling. 

As for the main transmit site, it will have a receiver and a transmitter connected to the same RTCM and if the RTCM looses contact with the asterisk system due to a network outage, then the repeater becomes a single site repeater with a simple CW ID'r and preset hang time.  When the network is restored then the AllStarLink controller computer can take over again.
Chuck  WB9UUS

On Sat, May 9, 2015 at 9:19 AM, R. Wayne <allstar at controlservers.net> wrote:

  Great answer, Jeff! We KNOW that the MSF is designed for a 2nd receiver tray and it would be nice if we had some direction. At least a schematic on that sub-section. Nope. “It won’t work. Don’t waste your time... (or ours by asking.) Thank you for your reply.

  There is another say that we can go. We can use a RC-210 controller or even a Zetron 38, a RC-100 – any number of external hardware controllers. But then how will Allstar like this? With the RC210 we can put the repeater on port 1, the receiver on port 2, and the RTCM on port 3 and then tell them all to talk to one another? We even have some Vertex VX-4100’s that have 20 KHz channel spacing and similar spec’s as the CDM750. Wouldn’t it be great to just solve the problem rather than adding more hardware complexity?

  It seems that Allstar is the solution as long as we can speed up the audio delay. But then again if we vote will it matter? I mean , won’t they all have some delay caused by the internet itself? Our biggest concern is with the “primary” receiver going out to the internet and then back just for the repeater to TX. What if the internet goes down? So then would our repeater. Our site vendor has 25 sites connected over 5.8 GHz and if we used a VPN this wouldn't be an issue. But we have receivers that will be remoted and this will require internet rather than a VPN right?

  From: Jeff Carrier 
  Sent: Saturday, May 09, 2015 6:49 AM
  To: R. Wayne 
  Subject: Re: [App_rpt-users] Motorola MSF / Voting / Receivers;

  I'll leave part 2 to one of the experts but as for part 1  

  The CDM makes a great receiver.  Though it's less desirable to me than an MTR2000 those just aren't in the budget.  Its certainly easier to interface to than the MASTR III's that I have on the bench now.  It is a mobile radio but in my installation I have 12 commercial UHF DMR MTR3000's all running nearly 100 watts at the same site as my UHF receiver and they're only separated horizontally and not vertically.  My CDM receiver also has a preamp and I've had almost no trouble.  I did have a mixing product but only when a 2 meter remote base transmitted on 144.890.  I'll add I have a pretty crappy duplexer on this but it is BP/BR and also has a pre-selector between the preamp and the receiver.  Still, they seem to have a "decent" front end for a mobile radio.  

  73 de K0JSC

  On Sat, May 9, 2015 at 7:33 AM, R. Wayne <allstar at controlservers.net> wrote:

    We have learned the hard way that our Motorola MSF 5000 repeaters with 30 KHz channel spacing and a 2 MHz wide front-end just cannot handle southern California’s 15 KHz channel spacing. We’ve tried using the 15 KHz replacement crystals with miserable results. We have not located 20 KHz crystals and even if we could we don't know what circuit changes would be necessary to tailor the audio response. We have asked on a site how to interface a Motorola CDM 750 mobile transceiver with 20 KHz channel spacing and instead of an answer we’re told it won’t work. It’s a mobile. Don’t waste your time. Well, its our time to experiment. I know of several popular repeaters here on SoCal built using the CDM 750 / 1250.

    OK. About Allstar. It seems if we can’t get an answer about directly interfacing a second receiver to a MSF 5000 that is designed for a second receiver we need to look at how Allstar can allow us to use an external receiver. Besides the obvious of a USB or RTCM is there any way to create like a LOCALHOST situation at the repeater site where we can almost eliminate any audio delay? We know that, and plan to use, off-site voting to cover our rather large footprint. That will have to be on an external Internet IP rather than an internal IP (192.168.x.x). Can we have both? An internal network and an external network? Or do we have to use one network especially if we plan on doing voting?

    Thank you in advance.

    R. Wayne

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