Two-way radio range:  VHF and UHF walkie talkies

Two-way radio range: VHF and UHF walkie talkies

VHF, UHF, PMR, Watts, Privacy, Licenses, channels,  miles or km – It’s all too confusing!


“Hey Bruce!  which walkie talkies should I buy for my work / holiday /  kids?   Do these look good ? – it says they go 25Km “

I’m asked these sorts of questions from time to time and despite 40 years experience with two-way radio I still find it tricky to come up with a short answer.  There’s a lot of vagueness, exaggeration  and contradiction on the web so I thought I’d take the time to document and share my own view :

I will cover the basics:   VHF vs UHF, Power levels & equipment, licences, tips and radio-range information.  There is a lot of information but at the end I hope you’ll understand enough to know what you are doing and what to watch out for !

Firstly let me say a couple of (maybe shocking) things.

  • The ‘up-to’ ranges on radio boxes are not real-life  (unless you live on a mountain)
  • The power quoted is the highest they ever saw  (and can be much lower)
  • The ‘maximum’ range isn’t what you should be really be worrying about anyway!

So let’s deal with the facts :

When should I look at two way radios ? 

  1. For frequent rapid communication between a predefined group of people
  2. Communications when out of reliable mobile phone coverage
  3. Management of large events where mobile network capacity gets overloaded
  4. Local community support, floods/disasters, power cuts or mobile/internet failures
  5. Where very rugged communication equipment is needed

When are they not the right answer  ?

X  Safety at sea – Get a marine-band two way radio radio and ship radio licence
X  Very long distance ‘off-grid’ communication – You’ll need HF or satellite radio
X  Children’s safety  –  A radio isn’t enough to assure safety

For groups walking in the countryside or hills, ski safety etc . –
Walkie Talkies are invaluable  for organisation and rendezvous within groups
but The group also needs other ways (Beacons, radio etc) to get emergency assistance

 

For business, community, farms, camping, family and event management etc. . .
Read on:

Do I want VHF or UHF  radios ?

Most ‘walkie talkies’ you will see are classed as Private Mobile Radio (PMR) equipment and use either VHF or UHF frequencies.  You’ll find there’s a choice/debate over whether VHF or UHF is best.   A few professional radios do both but this is rare.

Lets deal with VHF vs UHF  first;  There are two main issues to consider.

VHF radios ideally need slightly larger aerials than UHF radios if they are to work well over long distances.

With a direct ‘Line of Sight’ between, say,  2 radios on two mountain-tops either VHF or UHF signals will go a very long distance…. the kind of long distance manufacturers love to put in adverts and on boxes..
Once something is ‘getting in the way’ the situation changes very significantly and it’s different for VHF vs UHF.

VHF radios.

⇒  Most operate on frequencies around 160 -175 MHz    (but some are 40-86MHz).

If a hill or the horizon (curve of the earth) gets in the way of UHF and VHF radio signals both will be much reduced;  but generally VHF comes out a bit stronger on the other side of the obstacle  ..  it has a slightly better ability to  ‘follow the terrain’.

This advantage in ‘just over the hill’ communication can be particularly valuable to large farms, country estates, hill-walkers, campers, activity centres and parks.

VHF radio waves are reluctant to get into buildings or into bouncing around and off small things.  Due to the the lower frequencies it is a ‘big-picture radio wave’ that will usually carry further in the great outdoors.

UHF radios.

⇒  Most operate on frequencies around 430 – 470MHz,

As I’ve said the UHF radio wave can go for quite long ‘Line of Sight’ distances in the open but its special skill is getting in-to and out-of even small sized windows, offices, cars etc. It can also ricochet off metalwork, pipes, steel, trees, buildings etc. to reach almost every floor or corner of a building.
So it will work well if your short-range communication needs include concrete /steel buildings, car to car, dense woodland, city streets etc.  After a few hundred metres of bouncing around like crazy the signal will, however, have become too weak to use.

The choices:

If your world is hills and farms or flat lands over long distances go for VHF.Quarter wave whip for 169MHz with magnetic base. Mounted on roof of 4x4 vehicle

And if maximum mobile range is key you have the option to connect the walkie talkie to a ‘full size’ external VHF ‘wire whip’ aerial (antenna) on a vehicle roof.  The range improvement over the shortened ‘rubber’ aerials on radio handsets can be really impressive.  A ‘full size’ VHF ‘whip’ for 169MHz will be about 420mm long (standing above a magnetic base that adds another 20mm).

 

If you will mostly use the radios inside buildings, cars, shops, clubs, dense town streets, city or low-rise office locations please be aware that your signal probably won’t get very far  – but UHF is almost always the best choice here.

UHF vehicle whip’s are smaller (about 150mm)  but are more rarely seen as the extra range achieved is somewhat less impressive.

If it helps to decide I’d guess that 90%+ of the licensed walkie talkies in the UK are using the UHF frequencies.

Frequencies and Channels

Within the VHF or UHF band you’ve chosen, a radio works on one particular frequency at a time.  So within ‘UHF’ a radio might be set to work on exactly 446.00625 MHz

Channel programming on UHF PMR radioMost ‘off the shelf’ radios will come programmed with several approved VHF or UHF radio frequencies and also their manufacturer’s favourite selection from the many different Privacy codes or modes that avoid you hearing other people’s conversations.
Each programmed combination of a frequency and a privacy code is given a Channel number so that you can quickly alter your ‘frequency and privacy’ choice using a knob or button if required.
1, 8 , 16 or even 100’s of channel choices are common.
Often the rather limited number of actual radio frequencies are each given 2 or more privacy options by the manufacturer to create a larger range of channel choices.
Where all the radios are bought from a specialist dealer they can sometimes be re-programmed to match other radios or to use your own codes and set of frequencies.

⇒ Privacy or private channel codes in more detail: 
Privacy codes (called QT, DCS, CTCSS , digital ID’s etc.) are a popular feature intended to avoid you having to hear bursts of noise, digital buzzing and unintelligible weak signals from other groups of users  . . .  Sounds perfect . .  in theory.   It may be mentioned that with ‘Privacy’ or Digital transmission ‘on’ you may notice a further increase in the usual short delay before the radio starts to receive another radio’s transmission on the loudspeaker.

What is often not explained in the user guide is that the privacy system may also stop you becoming aware of any very strong signals from other user-groups that could be, or already are, blocking your group from sending or hearing your own messages on ‘your’ chosen frequency.

So, most radios with these privacy features on will have a Green ‘receive’ LED or another display to indicate a busy frequency – It lights up when the frequency is in use even if privacy codes mean your loudspeaker stays silent.
You’ll soon learn that the LED or indicator will come on with any signal on the frequency – from the slightest distant signal which poses no problem up to a huge local signal that blocks all other signals out.  This uncertainty isn’t ideal as in some cases important messages can get blocked and missed.

This risk gets very significant on mountains or other locations where the ‘radio-using population’ of the area you can receive strong signals from expands and the signals from other members of your group may be at the same time be getting quite weak.

On balance I still think privacy codes /ID’s are a good thing as they make it more certain that any noises or calls you do hear are actually from your group.
I would suggest you find out if your radios have a ‘monitor’ button that lets you listen on the frequency without the ‘filter’ of a privacy code or noise reducer (squelch).  If so, then ‘monitor’ the frequency regularly to check if it is still clear enough and/or to choose another frequency that’s better.

Digital ?

Some two-way radios now use ‘Digital’ rather than ‘Analogue FM’.  Digital has some advantages and some disadvantages over FM so it is hard even for the manufacturers to declare a winner – unless only Digital has a particular feature you really need.

The Digital signal is normally very clear (if a little robotic sounding) and appears to be interference-free in almost all conditions.    At longer distances both Digital and Analogue FM signals get too weak, usually at around the same distance.    At that point digital signals can be totally silent or a complete mess.  Some users therefore find recognising this situation and moving around searching for a location with a better signal is more intuitive on Analogue.

Digital is still a bit more expensive and running a mixture of Analogue and Digital radio is a bit more complicated.  Things work in different ways and functions like a monitor button and easily chatting to users outside your group are often missing on Digital.
As the various digital systems (dPMR, IDAS, Tetra, DMR/MOTOTRBO etc) are not compatible with each other most digital radios also support the analogue FM system!

Yet another variety of Digital radios are the so-called ‘Network Walkie Talkies‘. These use a paid SIM / Subscription to a 3G/4G/5G mobile phone data network to provide a walkie-talkie type experience anywhere there is a mobile network data signal – across the country or even internationally if needed.   I can see good uses for this system in transport companies etc. this but as many of the best two-way radio applications I mentioned at the start of this page need them to work when or where there isn’t a mobile signal I’m not sure you’d want to rely on one of these in an emergency . . .


Power Levels:

⇒  Most radios have a maximum RF Power output of  0.5 Watt or 5 Watts.

RF Power output defines the level of signal that will be available at the aerial connection on transmit.  More power out broadly means more distance can be covered.

0.5Watt out is about as low as you would sensibly go.  It is cheap to produce and gives good battery life.  Some radios can even be run using disposable AAA batteries.

5 Watt  radios are significantly better for maximising range.  Transmitting at 5 Watts they use quite a lot of power from a matching rechargeable battery pack.  Some 5W radios can be switched to a lower power to increase their battery life when in local use.

The quality of the radio receiver circuit is another factor affecting range.

An excellent receiver is sensitive to distant / weak signals on frequency while ignoring any strong interference and other signals on nearby frequencies that might stop a poorer receiver from receiving properly or at all!

Cheaper radios tend to have a poorer receiver and lower transmitter power while more expensive radios are generally of the 5 Watt variety and include a high quality  receiver – so they work better ‘at both ends’.

A 5 Watt radio will not transmit 10 times further than a 0.5W radio.  However, if we allow for it also having a better receiver and better aerial,  I would expect a 2- 3 x range improvement and a noticeable increase in communication reliability.

In the UK all 5 Watt radios need a licence, while some 0.5 Watt one’s do not . .

Licencing

If you really don’t want a licence you can buy quite cheap ‘Licence Free’ radios in many shops.  They transmit 0.5W power on UHF and meet European specification  ‘License Exempt PMR446’ which allows them to be used in most places in Europe.
Everyone from children playing to shops and businesses share the same UHF frequencies though, so you’ll find some of these get fairly busy at holiday times and at recreation, school, shopping, festival and sports venues.   At times it became nearly impossible to get a message through so a few more frequencies were added recently.

Getting a license

Yes, we all hate spending money but getting a business-type  Private Mobile Radio (PMR) Licence (like the ‘Simple Light’ licence from Ofcom in the UK)  is sensible and surprisingly affordable.  It currently costs £75 for 5 years and you don’t actually have to be a business.

As the named Licensee you are responsible for the (sensible) use of any radios you choose to buy and give out.  You are not required to be a technical expert though!

This ‘Simple Light’ license gives you access to 5 Watt power levels, better radios, more/ different choice of radio frequencies  (7 on VHF and 7 on UHF) with fewer users and generally more ability to get your message through.    It is a UK-wide licence so you can travel the UK with your radios but you can’t use the UK frequencies in other countries.

It’s worth pointing out that the amazingly cheap ‘5 – 10 Watt’  ‘long range’ walkie talkies you might see on Amazon, ebay etc. may not even be legal to use in the UK on the licence free or the ‘business’ bands.  They often come randomly or wrongly programmed with non-UK frequencies and some just don’t work very well.
Well established brand names with more ‘foolproof’ and ‘still affordable’  5 Watt ‘off the shelf ‘ radios include Mitex and Tritan .  At a higher price still the makers of really ‘heavy duty’ professional radios include MotorolaKenwoodIcomHytera etc.

10 key tips

1)  Teach all users to operate the radio and recognise /check /change volume and channel settings and to know their battery status.  Include charging or changing batteries.

2)  Learn the microphone’s location on the radio  and talk clearly into it.  Many users talk too quietly – experiment with how loud you can talk before distortion is heard on another nearby radio.
Practice ‘Press to Talk’,  ‘Wait a second’  then ‘Talking clearly’ with each user in turn before using the radios ‘in action’.

3)  If each radio you buy will be Military-spec shock, crush, dust and waterproof and float when dropped in the water that’s great (but very very expensive) .  Many ‘more affordable’ radios are not ‘Military spec’ though, and for office / car/ sunny day use they may not actually need to be.   (A large Zip-seal sandwich bag works well for emergency waterproofing of smaller radios as does a wrapping of cling-film)
Whatever you choose, brief the users on the level of radio care required !!

4)  Many radio batteries have metal contacts on the top or back that can deliver a nasty burn or short circuit if metal keys or tools etc. touch across them.
A bit of black tape or a carrying case may help users avoid these problems.

5)  Many radios have lovely illuminated LCD displays, lots of buttons, bleeps, symbols, torches, keyboards, whistles, mp3 players, cameras, FM radio receivers, multiple channels and privacy options that users can select.  The downside of these is the much increased possibility of losing contact due to just one knock, battery change or experimental button turn or press.
I think the more of these ‘handy features’ you can turn off or ‘lock’ for typical users the better are your chances of staying in touch all day!   For the most foolproof use get a radio without any keypad or display at all – although users might then need to think harder about how much battery they have used.
Professional radios often have every frequency and feature you could ever want built in too but they are carefully and identically programmed into each radio using a dealer’s PC-link cable and the users have no way to tweak, change or mess with them!
Battery life and channel changes for example can be announced by ‘voice prompts’ rather than needing to be displayed on a fragile screen.

6)  While 5 Watt transmissions will drain a battery in under an hour many radios can listen for and receive messages for 20 – 30 hours on one charge.    As most walkie-talkie usage is a mixture of both it usually works out that most user’s radios will last an 8 hour day on one battery.   Carrying and then changing to a spare battery only takes 30 seconds and is advisable after 8 – 10 hours even if the radio hasn’t actually ‘died’ yet.

7)  Reliable range is a lot less than maximum range.
⇒  This is a very, very, important concept to understand.

Maximum range is standing up, as high as possible, holding the radio, listening carefully, aerial held up high, moving to a window, tilting the radio aerial around for the best sounding signal . . .

Reliable range means still getting heard when the other user has put their radio on the floor, in a drawer, on their lap or in a car pocket, or in a backpack or inside coat pocket.   (VHF radios in particular only receive best when either body-worn, hand-held all the time or left standing in the clear on top of a metal sheet, cabinet or surface)

Reliable range means also being the strongest signal compared to the signals from other people on or around ‘your’ selected frequency/channel.

Reliable range can be therefore be disappointingly short,  especially in urban areas and steel warehouses/boats/buildings etc where there can be quite large and frequent radio ‘shadow’ areas or sources of local radio interference.  Some buildings, ships and other vehicles with metal layers in the walls and windows may even stop a radio signal entirely after just a few metres.

I would say the ‘reliable range’ is unlikely to be more than a third of the maximum range achievable in a particular location / situation.  And that’s all going to be waaaaaay less than ‘it said on the advert or box’!

The following chart draws on my own personal experience for establishing Reliable communication .  Your experience may of course be very different . .

The power and ranges of distance for VHF and UHF walkie talkie radios
The ranges of VHF and UHF walkie talkie radios

So I’m not saying the 25Km ranges some manufacturers claim is a lie.  I’m saying it requires very specific circumstances and is therefore very hard to achieve, let alone guarantee.

8)  The ‘big 5’ things that go wrong with walkie-talkie radio schemes are:

*  Not enough range, battery life or speaker volume for the job..
*  Untrained users, and old/flat batteries..
*  Radios in drawers, pockets, cars etc. that don’t get a signal..
*  Strong local signals on a frequency that blocks out yours..
*  ‘Lost’ or damaged radios or incorrect radio settings..

9)  Practice makes perfect.  Rent or borrow some radios before spending a lot of money.
Test the system before relying on it.  Understand channels, battery warnings / level signals etc.

10)  Take it to the next level :

Most professional retail and rental PMR providers will be happy to advise you on the best solution to a specific need as part of a ‘sale’ or ‘rental’.

They may also mention that the ‘professional solution’ to range and reliability issues is a ‘relay station’, called a radio repeater.  This unit is usually installed on a tall building or mast.  For short term events it can be in a vehicle parked on the nearest hill.  Because of its elevated height and bigger / better aerials the ‘repeater’ should be able to clearly see / reliably connect to all the radios in the area all the time and vice-versa.

What then distinguishes a repeater from a ‘normal walkie talkie on a hill’ is that it can both receive and transmit at the same time.  That means it can hear a signal from any one walkie talkie and immediately re-broadcast it so all the other walkie talkies hear it too.

Repeater6

So radios that might have a poor, or no, signal path directly between them can instead take turns to use the strong clear radio paths that go up to, and back from, the repeater. .

Just one repeater in an area can therefore give a large number of  walkie talkies a reliable range of 5 -30 Kilometers when talking to every radio in the group.   A very neat trick!

 

Thank you for reading, I hope this helped.

Please feel free to comment, correct or discuss via twitter using  @Bruce_Ak

© Bruce Akhurst 2018

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