I need to talk to multiple channels simultaneously

Hello everyone. I know nothing about two way radios or anything similar. I own an escape room and in our next room we’re planning we want each player to wear an earpiece that we can communicate to them through. They don’t need to be able to communicate back. Sometimes we want to send messages to the whole group and sometimes we want to send messages to an individual. Is this possible?

Yes it is. Multiple radios, one each freq/channel, selectively switch audio from all to each individual.

You could also use selective calling to individually address individual radios. It would allow you to use a single RF channel and still perform group wide calling.

I would have thought that if everyone in the group set their radios to the same single (simplex) frequency that any transmission from any of the radios will be heard by the others.
73 Doug
MM7DSA

Cost is the only issue really, apart from the number of frequencies required. With decent budget, your control can use digital radios and you can call individuals, groups or everyone. The actual radios don’t have to be hugely expensive, but the control system can be. you’ll need a dedicated control system. Basically a pile of buttons that direct comms to the individuals or the group. Touch screens tend to be the way. At the least though, it will need a digital repeater as control station - these will allow a small number of concurrent comms circuits using repeater times lots, but probably best to consider it as just one really. With analogue the best you can do is multiple CTCSS tones - but on one frequency, you can call any of them, but you’d have to limit the conversations at one time. You could set the radios with two channels, and leave them to can both - one for it’s own tone, but all the radios have the second channel with the same tone - so transmit on that and everyone gets it, transmit on any of the other tones and only one person gets it. That could give you very cheap radios for receive and just one or two frequencies. In broadcast, where I work (or worked) we’d do this all using IEM receivers and rack transmitters and then do the routing in our audio mixers. These would be racked up and these things are what we use for presenter talkback and of course musician monitoring on stage. Perfectly easy to do from the technical perspective, just very difficult with no budget. IEMs are full bandwidth devices and are simply one to one links. If you use comms, then you are going to send multiple channels down a single circuit, which means it gets complicated. So - to do what you want is possible. To do it elegantly, and cheaply is very, very difficult - so it depends on your budget really.

You can do much more with analog Paul.

Some other options:

Two-tone especially for radios that support AB/AC formatting where AB is a generic group call and AC is specific to a radio.

MDC1200 (or FleetSync, GE-STAR, etc) where you can send a regular group call or selectively call (as long as the radios have MDC enabled they will not unmute to individual calls).

ANI is capable of doing the same thing.

5-tone (Select-Call).

If a repeater was in use, you could even do single channel LTR (though dual channel LTR would give you a slightly higher capacity).

MDC or two-tone would be the way I would go about if using analog.

Indeed, but the cost of analogue selcall is still pretty high - I’ve still got 60 or so Kenwood 340 series that can do all these things, but the current crop of DMR kit from TYT, Retevis and the others can do all the digital stuff cheaper.

Me personally - I prefer hi fi sound in my ears. I used to spend 5 hours a day, 5 days a week with one ear full of comms bandwidth and your ears really suffer. I guess this application is just equipment sophistication capability heavy - which in any format makes it pretty expensive.

The easiest and simplest way to do this is the Motorola DTR600. The radio is not cheap but it is exactly what this person requires. It allows full group calls, as well as calls to individual radios. It also allows groups to be sub-divided, so if this is a big operation, clients can all be in one group and staff in another. A call can be made to everyone; one group or just one radio. If a client calls back for whatever reason, it will say right on the screen who is calling.

That being said, the poster has not been back since February so I doubt it is a priority for him. Too bad, because it is exactly where the DTR shines. Also, as a digital radio, the range is impressive and the sound clarity is always perfect.

If I have a situation where I need my own licence-free frequency spectrum and don’t need to communicate with outside radios or frequencies (and I live in Canada or the U.S.), the DTR is still my go-to radio.

I’d have thought, in the digital domain at least, you could really exploit it for what you want, since many systems allow a transmission to be group broadcasted, or selectively subgroup broadcasted and necessary selective TalkBack could done via a different colour code type selectivity (relative to DMR and transceivers equipped to monitor dual frequencies or dual color code traffic).

Back before DMR, DPMR type systems, there were a few oddball hybrid systems that probably would have done all you mentioned from the start - but they weren’t stuff of public knowledge they even existed let alone that they were in service for what was a fairly short life (full digital modes finished those off).

Shame really, because none of what you’re wanting is actually beyond a cheaply affordable set of equipment if you could it legally to use and licensable (assuming it didn’t fall into license free or license exempt arenas - of which are totally different categories of none license exemption).

Back in the 80s, some of us experimented with a similar idea using full duplex CB setups (major wrist slapping territory that was) and had a jury rigged audio scrambler setup for the non-public traffic so everything was heard by all, but the scrambled stuff was indecipherable by few. Those involved nearly got their necks in nooses when the local CB’ers got sick of what was a sanely controlled experiment compared to their chaotic anarchy. Thankfully I only designed the scrambler modules, so didn’t get caught in the resulting backlash.

Still, good luck - if what you need isn’t feasible with off the shelf kit easily or feasibly, there’s always RoIP type voice networking and 'network radio cellular and wifi based potential routes. You may find non of the existing RoIP networks do the whole lot, but if you get someone who’s a code junkie in your corner, they could adapt any existing open source RoIP client/server/p2p framework and maybe end up with something where the handheld radios end up being as cheap as say MMDVM hotspots can be.

You’ll get there if you believe it’s possible, it’s a time and ingenuity game.