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Connecting a remotely located dispatcher to the local crew's FRS radios

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Connecting a remotely located dispatcher to the local crew's FRS radios
Posted by JohnMarlin on Thursday, February 01, 2018 8:55 PM

Does anyone have experience with running op sessions using a remote dispatcher, and connecting that person in to the FRS radio system used by the local crew? In theory, this looks like it could be done fairly easily using a computer that is running Google Voice, Hangouts, Skype, Mumble, or any other voice-over-IP solution. My thinking is that some fairly basic impedence-matching hardware between the computer and an FRS radio should work. The radio would have to run in VOX mode. (Unless I were to implement some other mechanism for activating push-to-talk on the FRS radio; e.g, JMRI talking to a relay that shorts the required 2.2K resistance across the MIC terminals on the FRS radio.)

I'm still in the brainstorming stage here, but would welcome ideas or feedback from others who've implemented solutions in the past.

Tags: FRS , operations
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Posted by josephbw on Friday, February 02, 2018 12:58 PM

All you need is a matching radio for the dispatcher. And you will soon tire of running in VOX mode. You'll pick up endless chatter from every conversation on the layout.

We use radios in this manner at our club, and the only problem we have is when the operators don't pay attention and try to talk at the same time as someone else.

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Posted by JohnMarlin on Friday, February 02, 2018 5:17 PM

In this case the dispatcher will actually be in another physical location, so the challenge is to link that person over the internet to be able to communicate with the local crew using FRS radios. So, picture a crew of folks onsite at the layout using FRS radios, and then one additional radio which is wired up to transmit the voice traffic over the internet to a dispatcher in another state or country. 

I agree that you wouldn't ever want the crew radios to use VOX mode, but for the single radio connected to the internet, that might use VOX. The Dispatcher, sitting quietly in a room somewhere far away, would need to be aware that anything he says will be picked up and sent to the crew members.

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Posted by josephbw on Saturday, February 03, 2018 10:04 AM

To be able to dispatch properly, the dispatcher is also going to need a track diagram, with the ability to locate all trains, and throw all mainline switches, and possibly also control signals.

It sounds like it would be doable, but it also sounds like it could turn into a huge pain in the butt very quickly.

We have enough trouble with our dispatcher in another room, let alone another state. Smile

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Posted by rrinker on Saturday, February 03, 2018 10:58 AM

 With JMRI this is actually quite easy as the disptacher can view the actual JMRI panel - not just a screen share, the actual thing. Or you can use screen sharing like GoToMyPC or something and remotely access the dispatcher console on the layout from anywhere you can get an internet connection.

                            --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by JohnMarlin on Saturday, February 03, 2018 12:32 PM

Yes, the plan is for the dispatcher to use CATS on JMRI, so I'm hopeful that thisd part is fairly straightforward. I do recognize there risk of things getting messy quickly. Any technical glitch could quickly derail the whole operation. But we'd be prepared to quickly have a local person jump into the dispatcher role if wasn't working. In any case, this wouldn't be a regular thing. I suppose, to be honest, this is as much an exercise in figuring out how we can pull it off, and fun challenge to solve!

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Posted by BMMECNYC on Saturday, February 03, 2018 1:57 PM

JohnMarlin

Yes, the plan is for the dispatcher to use CATS on JMRI, so I'm hopeful that thisd part is fairly straightforward. I do recognize there risk of things getting messy quickly. Any technical glitch could quickly derail the whole operation. But we'd be prepared to quickly have a local person jump into the dispatcher role if wasn't working. In any case, this wouldn't be a regular thing. I suppose, to be honest, this is as much an exercise in figuring out how we can pull it off, and fun challenge to solve!

 

This type of thing is part of what LCC is advertised to do (dispatching from across the country).  I dont know if there are products that can make this happen (well JMRI is part of it) but on the LCC hardware side, I dont think there are products for this application yet. 

 

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
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Posted by rrinker on Saturday, February 03, 2018 4:13 PM

 Don't need any devices or a special bus. The ability to work across HTTP protocol is built in to JMRI. Several big layouts have run operating sessions like this, with the DS on the other side of the country.

 Yet another 'problem' LCC claims to solve, but it's already been solved.

                             --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Overmod on Monday, February 05, 2018 7:10 AM

I believe a considerable amount of work in this general area has already been done by the ARRL (American Radio Relay League).  If I were looking to build computer connectivity into a FRS transceiver, I'd at least study what they've done.

If I understand the question correctly, this has nothing whatsoever to do with the actual dispatching (or layout 'feedback'), only with the communication between the dispatcher and the operators by voice.

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Posted by RR_Mel on Monday, February 05, 2018 8:10 AM

John
 
I spent my entire working career (50 years) in two-way radio communications and related electronics.  I would be happy to help you, if you are interested send me a forum message and I’ll get back to you.
 
The last thing you want is VOX, that is a pain in the you know where.
 
 
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by rrinker on Monday, February 05, 2018 12:57 PM

 For the isolated DS it's ok. Road crews should never be in VOX mode, otherwise you'll kill the channel when talking between the engineer and conductor/brakeman. The DS usially has his hands full lining routes and recording train movements. Need a foot pedal like they really used to have for the phone if you want PTT for the DS.

                                    --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by JohnMarlin on Monday, February 05, 2018 6:01 PM
@Randy: Yes, only the DS would be in VOX mode, not the rest of the crew.
 
An alternative would be to add some additional hardware on the local connections to activate PTT (push-to-talk) when the dispatcher does something on the remote side. Could utilize DTMF tones (can you tell I am old-skool?), or use a JMRI output Light output to throw a relay. If I am not mistaken, I can activate the talk mode by putting 2.2K resistance across the MIC and GND connections,
 
But this certainly adds to the complexity a great deal, vs. just having the Dispatcher in a quiet room using VOX mode.
 
@Overmod: You mentioned the ARRL, and I poked around on their web site a bit, but thus far haven't found anything that really fits my needs...or my budget. If the only way to address this is with the sort of "relay over IP" solutions commericially available, this will likely end up being too costly and complicated.
 
@Mel, I'll reach out to you directly to give more details.
 
Thanks all, for your feedback and suggestions
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Posted by rrinker on Monday, February 05, 2018 9:27 PM

 Check with Bob, owner of the Quaker Valley RR. I'm pretty sure he's done remote DS sessions with JMRI. Actually, i think Ken McCorry has done it as well, although he doesn't use JMRI and he has a physical CTC machine downstairs from the railroad so I'm not sure how he would remotely dispatch the railroad. 

http://www.quaker-valley.com/

                               --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Eric White on Tuesday, February 06, 2018 9:52 AM

Take a look at Model Railroad Planning 2018. Dave Abeles is doing exactly what you're talking about using Skype and FRS radios to dispatch his layout. There's a sidebar about it on page 49.

Sounds like he sets up an FRS base station next to the computer set on VOX, which repeats the Skype messages back and forth between the layout and the dispatcher.

Eric

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Posted by JohnMarlin on Wednesday, February 07, 2018 11:25 PM

Thanks all, for the assistance. My circuitry ended up being pretty simple. I started with a 40 DB pad, but the volume was pretty low. My final circuit ended up just having a 120ohm resistor across the inputs, and 0.1uf capacitor inline with the audio. For the speaker side, I took the FRS headphone wires straight into my computer's Line In port.

Using Google Hangouts for the connection, and it works fine with a dispatcher using a Chromebook or an iPhone.  

Sound is crystal clear, and VOX works fine for a dispatcher in a quiet room. 

The next big test will be doing this live for a mini op session.

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