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It can be very confusing to get two different makes/models of walkie-talkies to be able to communicate with each other.

The different channels are not always numbered the same, and other features can also interfere with simple easy communication.

 
 
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FRS/GMRS Frequencies Explained

How to get two different Walkie-Talkies to communicate with each other
 

There are many different makes and models of FRS and GMRS radios.

And - alas - many different ways of numbering the different communication channels they use, too.

Part 5 of a 5 part series - click for Parts  One  Two  Three  Four  Five

 

 

A combination of confusing FCC frequency allocations, different types of radio service, nonstandard channel numbering, deceptive advertising by radio manufacturers, and confusing features has made it extremely difficult to get different makes and models of walkie-talkies to work with each other.

Although these devil's brew of different challenges would seem to make for a very daunting task, if you separate out the nonsense from the relevant reality, and do just a few simple things, you should have no problems.

In other words, please read on.

A Modern Day Electronic Tower of Babel

With the proliferation of remarkably inexpensive walkie-talkie radios, it is entirely likely that you will find yourself with a Brand X Model 100 type radio transceiver (walkie-talkie) and trying to communicate with your friend who has a Brand Y Model 200 type unit.

You both turn to the same channel number, but when you try and send him a message, nothing happens.  And when he sends back to you, again nothing happens.

Or, even more confusing, one of you can receive signals from the other, but not vice versa.

You know it isn't an underlying problem with the radios, because you can talk just fine to the other radio you have when you bought a pair of them, but somehow, there is a problem when going from your radio to your friend's different make/model radio.

There are four possible issues interfering with your ability to send and receive messages.

CTCSS Blocking

CTCSS stands for Continuous Tone Coded Squelch System, but for most non-technical people, knowing the full glorious name of this system doesn't really aid much in the understanding of it.

Many people completely misunderstand what this is and does - including, unfortunately, many people who describe and review these radios.

So let's first understand what they don't do.

CTCSS does NOT give you privacy

Using a CTCSS code on your radio does not mean that other people can't hear what you are saying.  It means you can't hear what they are saying, but it does not mean they can't hear what you are saying.

CTCSS does NOT give you more channels

We've seen people who multiple the channels by the CTCSS codes (eg 22 x 38 = 836) and marvel at the number of different 'channels' to choose from, saying words to the effect 'With 836 different channels to choose from, you don't need to worry about congestion or other users'.

This is nonsense.  All the other users are still sharing the same channel - just because you can't hear them doesn't mean they're not there, and your signals have no priority over theirs when you come to transmit.

So, having hopefully debunked these two myths, let's now see what CTCSS does do.

What CTCSS does

When activated, CTCSS sends a tone along with your voice whenever you send a transmissions.  This tone is not normally audible, but it is detected by the receiving radio.

If the receiving CTCSS is switched on, it listens for the tone.  If it is the tone that it has been told to accept, it will then play the broadcast over its speaker.  But if the tone is a different frequency, it will ignore the message.

This means that the person listening to their receiver is not bothered by people who are not intending to communicate with him, because they are either using no tone at all (with CTCSS switched off) or a different tone.

However, there is still only one channel, and only one person can broadcast on it at any one time.  The different tones don't enable multiple transmissions to occur simultaneously, and if that should happen, they will still interfere with each other, no matter if they are using tones or not.

And if a person switches off the CTCSS on their receiver, they can hear all transmissions, no matter what the tone that might be used, on a given channel.

The problem with CTCSS

Different systems use different sets of tone frequencies.  The most common system uses 38 tones, but there are a number of other 'standards' out there too.

So there is the problem.  If your radio uses one set of tones, and the other radio you are trying to communicate with uses a different set of tones, they are probably not going to be able to talk to each other unless you both switch off your CTCSS function.

DCS Blocking

DCS stands for Digital Coded Squelch, and it can be thought of as being identical in function to CTCSS, but using a slightly different method of signalling.  Instead of adding a tone to the transmission, DCS sends a digital code.

DCS blocking has exactly the same limitations and challenges as CTCSS, and can be available in over 100 different codings.

Making things even more complex are some radios that have both CTCSS and DCS on them!  That starts to really make for complexities upon complexities.  Multiple perhaps 40 CTCSS codes with perhaps 100 DCS codes, and that gives you 4,000 different ways to limit what you can hear on each channel (but remember, although it limits what you hear, it doesn't limit what other people can hear if they have turned off their CTCSS and DCS controls).  Multiply that by perhaps 22 channels at you are at almost 100,000 different combinations of channel, CTCSS and DCS code.

The best thing to do with CTCSS, DCS, and any other similar features is to turn them off.  Maybe, once you've verified you can at least get to the same channel, then you might experiment with one of these extra features, but until you have regular communication going conveniently, you shouldn't add extra wild cards to the mix.

Channel Selection and Numbering

This too is a bit confusing.  There are historical reasons for how things evolved, but to cut to the chase, the reality is that there are 14 different frequencies for the FRS radio service, and 23 different GMRS frequencies.

Sounds simple, right?  Well, sort of, yes.

But then it gets a bit more complicated.  The first complication is that seven of the 14 FRS frequencies are the same as seven of the GMRS frequencies.

So the 14 + 23 don't total 37.  They actually come to 30 different channels.

The second complication is that few GMRS radios - and almost no consumer grade ones - use all 23 GMRS frequencies (most use only 15).

The third complication is that there is a sort of crazy order to the frequencies and how they are assigned, and no manufacturer provides a sensible sequential series of channel numbers to the frequencies.

So what might appear to be Channel 1 on one radio might be Channel 8 on another.

And, one of the channels on one of your radios might not even be in use at all with the other of your radios.

FRS and GMRS Issues

The fourth issue is whether both radios are able to send/receive the same bands.  Some radios are only FRS.  Some are only GMRS.  Some are both FRS and GMRS.  In other words, even with the best will in the world, maybe your radios don't have all the same frequencies in them (but, don't despair - the chances are that they at least have some overlap in frequencies, even if not all the same ones shared identically).

Some explanation and clarification may be in order!  The FCC has allowed GMRS (General Mobile Radio Service) type radio service to operate since the 1940s.

In 1988, the FCC slightly changed the purpose of the GMRS service, allowing it to be used by individuals for personal use, while still requiring people using GMRS radios to buy a license from the FCC to be allowed to operate the radios.  Licenses are good for an entire family, and are valid for five years.  The current cost of a license is $85.

In 1996 the FCC came out with a new type of radio service, FRS (Family Radio Service).  This used frequencies in the same area as the GMRS frequencies (indeed, it shares seven frequencies and also uses another seven frequencies in the same range).

The new FRS service had slightly different rules.  It was not as powerful as GMRS service, but it was open to anyone, without the need to buy a license or to register at all with the FCC.

There were presumably obscure reasons that probably make sense to the FCC, but not to us, as to why the FCC had FRS radios share some but not all frequencies with GMRS.

This inevitably lead to radio manufacturers selling combined FRS/GMRS radios on the 'honor' system.  You had to promise to not use the GMRS part of the walkie-talkie unless you had a GMRS license.

Well, with these radios being sold to anyone and everyone - children, adults, whoever, and with few people bothering to read much more in the instructions than how to turn the radio on, the GMRS frequencies were rapidly filled with non-licensed users.  This so overwhelmed the FCC enforcement division that in 2010 the FCC sort of gave up enforcing the need for licenses with GMRS radios.

Radios are sold with a strange mix of 'on these frequencies you can only transmit on low power, on these frequencies you can only transmit on high power if you promise you have a GMRS license, and on these frequencies, you can only use them if you have a GMRS license.

Some radios have some GMRS frequencies, some have all of them.

This is very confusing for users, who largely completely ignore such requirements.

Midland Invents New 'Channels'

But wait - there's more.  Alas.  And it isn't good.  It is bad.

Midland - a one time fine company with excellent products has clearly let its marketeers run amok.

They now offer radios that claim to have 50 different channels.  As you know from reading above, there are, in total, only 30 channels permitted by the FCC.  What are the other 20 channels that Midland offers?

This is a mystery.  Amazingly, when one visits their website and looks at the specifications for these radios, there is a partial list showing frequencies for the first 22 channels (a standard set of FRS and GMRS frequencies) and then no details at all for the other 28 channels.

What are these channels?  We sent emails to two different parts of Midland, and got no reply from either.  Are they truly secret channels?

We did some more research, and as best we can tell (and we invite Midland to break their embarrassed silence and correct us) these new channels are total marketing fictions.  They are just repeating the earlier 22 channels in their radios (so that some frequencies end up being called three different channel numbers!) but with hard-coded CTCSS and DCS settings.

This does not do anything of any benefit to users at all, and we repeat our earlier recommendation that the best use of these radios is usually with no DCS and CTCSS enabled at all (see below for a discussion on when and how to use DCS/CTCSS).

The only beneficiary of this 50 channel claim is Midland, enabling them to sell walkie-talkies claiming to have more channels than their competitors.

Shame on Midland for inventing the 50 channel nonsense.  Let's hope the other manufacturers don't respond, by offering radios with 100 'channels' and so on, without limit.

How to Match Channel Numbers and Frequencies

Okay, after all that preamble, now for the meaty part.

The following table can be used to help you understand the different frequencies and also to match the channel numbers on one walkie-talkie with the channel numbers on another walkie-talkie.

To match channel numbers, simply look up the frequencies of the channels for the first radio, and write the channel numbers alongside the frequencies in the Radio 1 column.  Next, do the same for the second radio in its column.

Every walkie-talkie we've found (apart from the Midland '50 channel' monstrosities) have a chart listing the frequencies and assigned channel numbers in their documentation.  Use that to fill out the form below.

If you've lost the manual, the chances are you can download a copy from the manufacturer's website.

After having done this exercise for both radios, you have an easy conversion chart, showing the channel numbers on the first radio and the corresponding channel numbers on the second radio.

 

Table of Frequencies and Typical Uses
Frequency in MHz Use Radio 1 Radio 2
462.5500 GMRS-O1    
462.5625 GMRS-S & FRS    
462.5750 GMRS-O2    
462.5875 GMRS-S & FRS    
462.6000 GMRS-O3    
462.6125 GMRS-S & FRS    
462.6250 GMRS-O4    
462.6375 GMRS-S & FRS    
462.6500 GMRS-O5    
462.6625 GMRS-S & FRS    
462.6750 GMRS-O6    
462.6875 GMRS-S & FRS    
462.7000 GMRS-O7    
462.7125 GMRS-S & FRS    
462.7250 GMRS-O8    
467.5500 GMRS-I1    
467.5625 FRS    
467.5750 GMRS-I2    
467.5875 FRS    
467.6000 GMRS-I3    
467.6125 FRS    
467.6250 GMRS-I4    
467.6375 FRS    
467.6500 GMRS-I5    
467.6625 FRS    
467.6750 GMRS-I6    
467.6875 FRS    
467.7000 GMRS-I7    
467.7125 FRS    
467.7250 GMRS-I8    

 

Note on Table Data

For the GMRS frequencies, we specify them as either output from repeater frequencies (with the letter 'O'), or input to repeater frequencies (with the letter 'I'), and we number them to show which input frequencies are matched by which output frequencies.

GMRS frequencies not intended to be used with repeaters are marked with the letter 'S' (for simplex).

You don't really need to understand what these mean, the main thing to do is simply to match the frequencies to your channel numbers on your radios.

The One Time it Makes Sense to Use CTCSS or DCS

If you find that all the channels on your radios are being used by many other people at the same time, and if that means you are being plagued by lots of annoying radio transmissions, none of which are intended for you, then you can buy yourself some peace and quiet by activating a CTCSS or DCS blocking tone so that only transmissions from the other people in your group (who will be using the identical tone of course) will cause your radio to actually broadcast the received message over its speaker.

If you do this, there is a very important thing you must do.

Any time you want to send a message yourself, you should turn off the blocking first to check that no-one else is currently transmitting.  All walkie-talkies are required to have a button, usually right next to the push-to-talk button, that will 'open' the squelch (ie turn off the CTCSS/DCS blocking) and enable you to hear if anyone else is transmitting at all on the channel, but without your specific CTCSS/DCS code.

If you don't do this check, then when you do transmit, two things might happen.

The first is that your transmission would scramble the transmission of any other person who is currently in the middle of their transmission.

The second is that your transmission would also be scrambled by the other person's transmission.

But you won't know this, and you'll be wondering why the message you just transmitted hasn't been responded to by the person in your group you were sending the message to.

The person you were hoping to send a message to might send a message saying 'Did you just try to say something, please repeat it'.  The person the other person was sending to will do the same.  Other people on the channel might also say 'Was that a message for me?'.  You'll end up retransmitting.  The other person who had been sending at the same time will end up retransmitting.  The net result - massive more congestion, confusion, and traffic than if you just pause and check before then transmitting.

So, please, if using these tone controls, be sure to check that no-one else is using the channel before you start your own transmission.

Of course, if you have your CTCSS/DCS switched off, there is not so much need to open the squelch before sending your message.

Summary

Sometimes more is less, and in the case of walkie-talkie radios, more options for limiting the transmissions you here, and more channels to choose from, can sometimes result in less readily understood radios and much more confusion.

Use the conversion table above to enable you to equate the different channel numbers in different radios, and in general, avoid using the CTCSS and/or DCS functions, which most of the time make things more complicated rather than more convenient. 

See also Parts 1, 2, 3 & 4

In Part 1 we explain the different types of personal radio services available to you, and what they variously mean.

In Part 2 we discuss how it is that manufacturers can claim ranges of 'up to seven miles' when the effective range - as tested by us - is sometimes as little as one twentieth the claimed range. Many factors influence maximum range - some we can influence, most we can not. In particular, read the startling truth about the importance of transmitter power to give you more range.

In Part 3 we give you real world test results of 'consumer grade' radios and help you choose which is the best system for your needs.

In Part 4 we do a second round of testing, comparing professional grade GMRS radios and antennas to consumer grade radios.


 

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Originally published 1 June 2012, last update 02 Jul 2017

You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me (David Rowell - KF7VVM) as original writer.

 
 
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