Newbie with an out-of-the-ordinary question

Hi, I’m an absolute beginner to 2 way radios (my background is computing and coding) and have been asked by a charity organisation I volunteer for to investigate and source a 2 way radio solution for our staff and possibly visitors.

I’ve looked at Motorola T92 pmr446 walkie-talkies and they seem to fit the bill. Low power, low cost, no licence, easy to operate, hi-vis, waterproof and able to float (we are a swimming pool). All fine.

The out-of-the-ordinary bit is we also need/would like a second part to the solution if possible. An outdoor PTT public call box for users of the pool to use out-of-hours. It would be great if we could find a pmr446 solution, but it’s not looking very likely.

Does anyone know of a possible solution before I ask my next question?

Not so out-of-the-ordinary, and we will be able to help.

You mentioned the PMR446 radios, which makes us think you are probably in the U.K. Is this correct?

PMR446 radios are similar to the GMRS/FRS radios we have here in the U.S. and Canada. You even have access to some high-end PMR446 radios that we can’t get here, but it seems like the Motorola T92 radios in a PMR446 configuration will work well for you.

Here are a couple of things to understand about two-way radios in general:
#1 - No UHF radio can violate the laws of physics. They are strictly line-of-sight, meaning they will only reliably transmit and receive a distance of a few blocks, regardless of how they are advertised.
#2 - The Motorola T92 is at the high end of consumer-grade radios. They are designed for families to communicate with each other; they are not designed for critical public safety applications. If you are good with that, they will meet your needs. Just be aware that they will not have the lifespan of professional radios, and usually the batteries, charging connectors or headset connectors start to fail after a year or so of hard use.
#3 - PMR446 is a publicly-shared frequency spectrum, and NOTHING you say will be 100% private. GMRS/FRS and PMR446 radios have tones that one can set that will only open the squelch if the calling radio transmits the same tone as the receiving radio, but you are still sharing one public channel. Anyone with the same tone can listen and transmit, and anyone with no tones set can listen to everything you say.

Now the good news. Our forum hosts carry the Ritron series of two-way radio call boxes. They are great quality, and Ritron makes both analog and digital variations. They CAN be programmed for GMRS or FRS here in North America, or PMR446 in Europe. (You want the analog version, with UHF frequency range 450-470 MHz.)

The Motorola radios don’t need programming, but the Ritron callboxes will need programming to match your frequencies that you use. You will need the software and cable, or your radio dealer can program them to your choice of frequencies for you.

With PMR446 radios, there are 16 publicly-shared channels, and if you want to find out if they will work well for you, get one and use the scan mode to listen to all the channels in your area for a few days. If you find some channels not being used in your area, assign them as your primary channel, plus find a backup channel in case there is interference from someone else. Everyone has the ‘right’ to use any public channel, and you cannot ask anyone to stop transmitting or go to another channel, even if you have an incident to report.

Also, it doesn’t need to be said, but do not transmit any private, medical or protected information on the radios. Anyone can listen in.

Hope this helps.

One other UK issue here is around where you are. PMR446 is also used here for enthusiast use, a bit like a CB or ham radio, so while in a small town the only other users could be the local shoe shop or takeaway food place yelling size tens, not nines, or shouting about food orders, in a city there will be people with more power, and continuous talking, and while illegal, nothing you can do.

The tone thing is difficult to grasp. In essence its privacy feature is designed to stop you being annoyed by others, not to keep your stuff private. Remember that you must not pass anything identifiable over the radio on a public band for GDPR reasons. Schools often use these radios and get it wrong. Nobody bothers, of course, but they could.

Your box on the wall? You want the public to be able to call your staff? I’ve never seen a radio that could be powered by mains or a power supply for PMR446 because the rules state batteries, low power and non detachable antennas. Amazingly, many adults cannot get the concept of PTT at all. A mobile number would be safer.

PMR446 will do the job. However, a dedicated professional licence is only £75 for 5 years and will be more reliable, and enable most radios, even cheaper ones to be used legally here. Benefits will be higher reliability and a little more safes as there will be no idiots who think it fun to break into your conversations. Probably no floating ones in the cheap bracket though.

Hi CH,
Thanks for the quick reply and yes, I’m in the UK.
Sorry, if this response is a little staccato - my ultra demanding and too smart for his own good, 3 year old grand-son is here for a few days and he does not take any prisoners when it comes to testing Grandpa’s dinosaur knowledge.

In response.
#1: We are a small rural village. Pop. ~4000. Nothing taller than a 3 storey town-house + trees.
#2: Yes, good advice. May just consider them as replaceable.
#3: This is not even something I considered. We are subject to GDPR here in the UK and our organisation does hold limited private data. Whether we would communicate any of this over a radio is uncertain - something to consider. I have been looking at the Retevis RT648 which has voice scrambling (although not been able to confirm as yet - Bing AI told me). Would this suffice?

As for the RITRON, they are over £500 here in the UK. I will continue to research.
Programming probably required for voice scrambling if we go that way.
We want to avoid a mobile because we don’t want phone numbers becoming known and need a way for a team to respond subject to availability. If we all had a radio(6 of us), we could all provide cover at various times and overlap.

Thanks again.

I’m not sure the PMR446 version has scrambling? Not usually a feature of licence exempt radios. They are waterproof though and chunky. If you can get them for a decent price they’re quite nice.

Normally, I rarely worry about GDPR, but as people listen in as a hobby, if what you say on them is interesting, then you could easily find the transmissions recorded and on Facebook or worse.
The old RT48 - the non-PMR446 version had scrambling, but it seems missing on the 648. Oddly, inversion scrambling IS permitted within the current spec. For £50-60 each, they’re pleasant and tough radios - they don’t use the standard two pin mic/spkr sockets don’t forget - they use the waterproof multi-pad version.

I’ve managed to find which lists scrambling under RT648.
I’d be happy if we can just exclude the casual listeners. Can scrambling be decoded?
On Facebook? wow, I’m such a Newbie.

The scrambling of this type dissuades casual listeners, but also attracts enthusiasts who will want to know who it is? Scrambled signals for some are a bit of a quest, but most people who know what they are doing can defeat it. One warning, though. Because it’s in the spec list doesn’t mean it has it. It’s commonly missed in copy and paste. I sell a few radios that say it’s there, but it’s not. I suspect it’s a Chinese to English thing. CTCSS often seems to be mistaken for scrambling so perhaps just a language thing. Too common for it to be some kind of con.

Scanner users and enthusiasts have groups on social media - so you see things like Anyoine know what the scrambled channel on channel 6 in Macclesfield is - I think it’s the social security people doing raids, I saw a suspicious van around today. Crazy speculation that encourages people to actually listen in, not go away. PMR446, like the US system was supposed to be for those people who want casual use of radios without having to buy licences and spend lots of money - but it’s an easy access hobby radio area now, with people using callsigns and attempting to go far further than the short range idea the Governments all over the world decided was a genuine need. In big cities, the few channels are full! You even hear tales of people listening in to their competitors to see how their sales are going.

The real rule for most businesses seems to be that if you want privacy and lack of interference, and safety is involved, then free to air PMR446 is a bad choice. Somebody calling for help because a person is drowning vs the local kids outside talking about Minecraft between their houses. The privacy tones prevent you hearing the kids, so you don’t know they are active, but if their signal is stronger, you hear silence, not your team member. Licence fees are legitimate expenses in your accounts anyway, as are the purchase of safety radios. a few shared channels in a publicly monitored band that is frequently full of idiots, vs an empty, quiet and reliable licensed channel?

Okay, you’ve convinced me. Scrambling is just a red rag. We are probably a boring target, but they won’t know that.
If we go paid licence, what advantages would that give us - I’m assuming signal power (5w?) which would likely solve the range issue?

Range issue? Did I miss this. Hand-held to hand-held in a relatively uncluttered environment, when people have the radio in their pockets? Maybe half a mile reliably. Power is rarely an issue really - PMR446 is low - half a Watt-ish, and other than that, 3-5W is typical. Are you having problems with range on things you’ve tried? I’m not really trying to convince you of anything, other than PMR446 is a band shared with kids given radios as toys and people trying to use them for more serious stuff. Idiots exist at all levels, but are much, much rarer if you go for the OFCOM lite licences. To be fair there are plenty of budget radios that will do the job for you. What you want is waterproof, tough, drop in chargers and decent battery life. VHF or UHF would work for you. This is a link to the OFCOM site OFCOM business simple 5yr

Yes, sorry, up to my neck in 50 different things at the moment (grandson, radio comms, RFID/keypad access control with Wiegand 26, automated people counter, RFID bracelets for unaccompanied swimmers. 20+ emails per day and I code and support the website booking system). We have over 1000 people signed-up for a 15m x 8m lido.

Full requirements:
On-site walkie-talkies with 50m range (easy).
Waterproof(required), robust (required), floating(desirable), emergency button(desirable), vox(desirable), hi-vis (desirable), licence-free (desirable, but looking less likely)
Radio-based PTT public call box (desirable)

As I worked in IT my entire career I’ve always attempted to solve 5 problems when I’m required to solve one, by simply future proofing and thinking a little bigger.

So, an out-of-hours PTT public call box integrated into the radio solution would be perfect. The out-of-hours team and in-hours support team(same thing) all live within 750m of the pool.

Costs are an issue, we are a volunteer-based community charity (we cannot incur debts of any size) and only open Apr - Sep (for the 1st time). Ongoing-costs are always an issue, single capital outlays are not. I suggested radios, so I got the task of finding a solution. PMR446 seemed like a no-brainer when it was just on-site(and I believed the sales literature) and I was unaware of the privacy issues, but I would like to solve the support/PTT call-box issue at the same time(if possible) - if not significantly more expensive.

I can probably swing extra funds for a licence for more power, privacy or exclusivity. It would be a decision for the Trustees.

I think that’s everything. Any more questions - fire away.
Thanks for your help.

If you could put a small power supply in a box to power a radio (plastic box for RF to escape) you could leave a gap for a speaker mic? That would work fine - if you label it as press to talk, release to listen?
Range fine for virtually all radios. If you are IT skilled - I’d personally look for a business style radio - that’s just not expensive, has few features and away you go. The non PMR446 Retevis version of what you looked at, USB programming cable, software and job done - ebay or aliexpress really. OFCOM licence and you are away. If you find an advert - happy to advise. Paul

Yes. Interesting idea. I looked at the Midland GB1 with the same thought.

HI again,
Purchased a pair of Retevis RT648s and did some testing - looks like we are going to need 5w/10w radios and a licence.
Looking at the RT81 DMR - it’s a bit more expensive, but gives us options.
Just need some advice on licencing. Does the £100/5yr lite licence give us a dedicated exclusive frequency to use?
Also, any reason not to go for the RT81?

£75 for 5 years You can choose from these frequencies, but they are not allocated as dedicated. For your own channel - look for a technically assigned licence - same price, but annual, and they pick the frequency. You could still be sharing, but sharing with somebody less likely to interfere, if you are in a busy area. The number of wider range systems are reducing so technically assigned is becoming easier.
You pick one channel based on occupancy usually - so listen in your area, pick the quietest, and then apply tones for analogue. Digital systems are not specified by Ofcom, but just the DMR association guidelines - so a few handhelds working single frequency can be set up pretty much how you want. From the Retevis business style radios I have sold - they’re decent products and well built.

This is the current list of available frequencies for the UK, excluding NI where the rules are a bit different. The licence actually gives these frequencies in an annex, and there’s no need as far as I’m aware to actually tell them which one you pick!

169.0875 MHz 169.3125 MHz 173.0500 MHz 173.0625 MHz 173.0875 MHz

164.0500 MHz 164.0625 MHz

449.3125 MHz 449.4000 MHz 449.4750 MHz 458.7875 MHz 458.8 MHz 458.8125 MHz 458.825 MHz

You sell Retevis products?

Yep = but it’s a bit bad form to talk about that here.

Oh ok, not really a forum person. I will email you…