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21 March 2023

Network Radio - Radio for the 21st Century?


In this thought-provoking new feature, Chris Rolinson offers us an introduction to the idea of network radios


In this thought-provoking new feature, Chris Rolinson offers us an introduction to the idea of network radios, looking at internet propagation, technical aspects and potential uses for this new form of communication.


Radio User - the title pretty much encompasses anyone who ‘uses’ radio, doesn’t it? It might seem obvious to you as a reader of this magazine, but I hope you will understand why I make this point at the start of this article. It is because the new batch of network radios are, for some people, not real radio, however that may be defined.

In this article, I hope to show you that they arebut maybe not in the way you might expect.

Join me on a journey of exploration into an aspect of 21st-Century radio many enthusiasts are only just now beginning to discover and explore more fully.


Commercial Origins

Businesses have made use of two-way radios for many years. However, they have been restricted by coverage issues. PMR and LMR ultimately have a limited range, however many repeaters one uses.

In the wider context of the global economy, the needs of businesses have changed dramatically. Your local services could well – and often are these days – administered and directed from another part of the UK, sometimes from another country altogether. PTT communications would be a boon in this instance if they were possible worldwide. Against this background, manufacturers started experimenting, drawing on mobile phone networks. These were used as a multi-connected repeater system for PTT communications, making use of voice-over-data technologies for just this kind of scenario.

Imagine having operatives on five continents – all using PTT together as a group!


Mass Market Devices

Following these early experiments, the Chinese have recently produced affordable network radios using the Android OS in a form factor that closely resembles HT’s and mobile phones (Fig. 1). No surprises then that equally enterprising radio users have been experimenting to see what can be done with these ‘PTT over Cellular’ (PoC) devices.


What is a Network Radio?  

Put simply, network radios are radios that require some kind of network in order to work. They are very low power microwave RF devices which, interestingly, do not communicate directly to each other. They only ‘talk’ to a network (Cellular or Wi-Fi) in order to access the internet. The RF here is, therefore, either 2.4GHz/5GHz Wi-Fi or 800-2100 MHz Cellular.

Therefore, network radios are RF-generating radio devices.


Matters of Propagation

Radio signals of all frequencies, in theory, only propagate via line-of-sight. None go much further than the horizon unless, of course, they are enhanced in some way. To do that operators need a little assistance.

Generally speaking, short wave signals bounce off one of the atmosphere’s layers (the ionosphere) while VHF/UHF signals are extended via tropospheric ducting; microwave signals might be enhanced by rain scatter and so on. There are other methods of propagation too, of course but, simply put, Mother Nature frequently assists us to achieve longer distances than would normally be possible.


The Internet as Propagation?

Now, this is where it gets interesting. You see, the internet fulfils the criterion of actually being a mode of propagation in itself! If the Earth’s atmosphere provides us with natural ways of extending the range of radio signals, in exactly the same manner, the internet can be seen as a man-made form of extending the range of low-power devices.

Those signals will not be analogue radio signals as we have previously understood them in the 20th Century. The Internet deals exclusively with digital signals and yes, they might have a yet further ‘helping hand’ along the route, applied in the form of, for example, fibre-optic networks.

However, the point remains: The Internet is a way of extending the range of a variety of signals.

Furthermore, it is the 21st Century’s favoured means of propagation.

More than this even, it is open to everyone to use and requires no transmitting license.

Thus, no exam has to be taken to use it!

Can you begin to understand the controversy surrounding these devices a little better now, perhaps? There is an inclusivity to this, versus the exclusivity of having a transmitting licence.


Complementary, not in Competition

I would argue, however, that network radios simply represent a 21st Century form of communicating and are not ‘in competition’ with more ‘traditional’ radio as we have known it to date. Network radios use internet propagation, rather than natural propagation. Consequently, they are just different, that’s all!

Here are three questions for you to think about:

1. How much does it matter that propagation can be man-made or natural?

2. Is one mode ‘better’ (whatever that means) than the other?

3. Is only one of these worthy of our attention or can we use both?


An Example from Tennis

Take a look at Figs. 2 to 4: Fig. 2 shows a game of tennis, played in the great outdoors!

But what are the people in Figs. 3 and 4 doing? I would argue that they are playing tennis too. OK, it could be indoors, it might not be on grass, but it is still tennis, is it not?

Do you see my point? I liken tennis outdoors to using ‘natural’ propagation and tennis indoors to using ‘man-made’ propagation. The people in the photographs are all playing Tennis, just in different ways.

Here is another question for you: Do you think the growth of indoor tennis centres has given a boost to tennis as a participation sport or not?


Because most hobby network radios are, in essence, Android computers, this leads many to dismiss them disparagingly as ‘just phones’. However, the form-factor plays a greater role than you might imagine; until you try one, you probably won’t quite ‘get’ it.

You can actually use them as phones by the way. However, they are not quite as easy to use for calls or texts as a device specifically made for those purposes – in the same way, perhaps, that your mobile phone is not the best way to get the optimal network radio experience.

The PTT button makes a discernible difference in use. Moreover, the presence of a powerful loudspeaker differentiates the genre. In addition to this, the weight and feel in the hand lend themselves much more to PTT communications.

Unlike most smart devices, network radios have removable, replaceable, high-capacity batteries; sporting smaller screens also means battery life is much extended over a typical smartphone; network radio handheld transmitters can also stand up on a flat surface unaided (Fig. 5).

You can use your existing smartphone device; this is, in fact, a great way to try out the system for starters. But it is not dissimilar to comparing apples to oranges; they are both fruit but differ in taste.



Clearly, a 2018 pocket computer is a very powerful device. It is more powerful than a desktop of a few years ago. However, any computer is only as good as its software. Luckily there are lots of radio-related programs (apps) available for the Android platform. For example, Broadcastify allows you to listen in to public service streams from around the world. If the likes of the Chicago Police Department are your bag, you will love this.

There are many similar apps; if there is an internet stream of something, you can probably listen to it on a network radio.

Moreover, WebSDRs are plentiful these days – just navigate to them via the built-in browser and listen around the ‘traditional’ bands. Use them as propagation aids or monitor your favourite nets.

What is more, APRSDroid allows access to the APRS system and you can send a record of your travels to a map while walking, driving or cycling.

Last but certainly not least, some amateurs have been playing with RemoteHams software - the Android client is called RCForb. One of my top band friends uses his network radio to control his remote station in Scotland. Because network radios have a dedicated PTT button, he can map this in software to the PTT of the remote transceiver. It works very well! 1.8MHz from anywhere in the world? What fun!


International Radio Network

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The International Radio Network (IRN) is a fascinating concept too. IRN is a group of servers on a piece of software called Teamspeak 3. It allows various amateur radio streams to link to each other.

Here, you will find audio from analogue, DMR, D-STAR & Fusion stations crossing over to each other as well as onto the internet. The brainchild of a Manchester-based radio amateur Gareth M6IGJ, the IRN platform is growing very fast; by the time you read this, it will have developed even further (Fig. 6).



Many of you will know of the Echolink system – there is an Android app for this. And recently, reflecting the growth of network radio devices, it has gained an option to map the PTT switching to a hardware button. Now you can transmit into the Echolink network directly from a Network Radio’s PTT.

While you can access these networks freely via the internet, your voice could conceivably exit them on an Amateur RF band - therefore for many uses, an Amateur transmitting license will be necessary.

Safeguards are applied by the network administrators to ensure compliance with the regulations.


Regular Communications

Network radios can also communicate to each other – not directly but via the network. This is, arguably, the one aspect that upsets people. Many have difficulty accepting it as ‘radio’, although, in its strictest sense, it clearly is.

What I suspect many mean, is that network radios are not ‘traditional’ radios and do not use an ‘acceptable’ band, whatever is meant by that.

Nonetheless, does that make it less valid?


Radio in 2018

The nature of radio is very different today to how it was just 30 years ago; take broadcast radio as one pertinent example. If you go to purchase a radio in your local store, chances are it will be a push-button device with a screen.

If it is a DAB radio, it will self-tune and the display will tell you what station you are listening to. There is no tuning dial.

Another way in which many now experience radio is via internet or satellite streaming. Again, there is no tuning dial! In fact, if you ask anyone under the age of around 40 what a tuning dial is or does, you will likely get a blank look!

Broadcast radio has adapted and the advent of digital technology and internet propagation has changed it almost beyond recognition.

When I holidayed in Europe years ago, I took my Sony ICF-7600SW to listen to short wave broadcasts, exploiting the vagaries of ionospheric propagation. By contrast, today I use my smartphone with a Bluetooth speaker (internet propagation) and the quality is first rate! No fading, no static, no noise.

You might reply by shouting at me “no magic either”. However, do you not think there is a lot of magic in a device that is a handheld computer, picking up any world broadcast station that I choose, when I want it?

In my view, this is still magical - it is just a different kind of magic!


PTT Has Changed

It is no surprise then that two-way radio is changing as well. Network radios are but one manifestation of this.

Recently, we have seen the growth of new digital HF modes like FT8 on the one hand and of digital voice modes like D-STAR & DMR on the other hand.

In spite of this, it appears that we are still finding our way in the new digital world.

One of the more ‘philosophical’ problems has been that we, as radio users, have been more accustomed to an analogue world; and there is nothing wrong with that. In fact, let’s rejoice about it.

Nevertheless, we do now have a new digital playground to play in too.


The Zello App

In the Autumn of 2017, two ferocious hurricanes hit the Florida coast. Yet only 3% of the mobile phone infrastructure went down. This meant that Zello (a PTT application for mobile platforms) became one of the most used apps for search and rescue following those cataclysmic events.

This might surprise you, as we are used to hearing that ‘traditional’ radio is of most use in natural disasters.

This remains true to some extent, but one thing it does show is that the resilience of mobile networks is increasing.

In the UK, the emergency services have a privileged, ‘top-tier’, access to the cell network and it is gradually being used more and more for emergency services’ and SAR communications. I feel that, for this reason, we can expect the network to become even more resilient.


What Can You Do with Zello?

Zello is a kind of PTT enthusiast’s ‘alternate universe’. You can set it up to PTT one-to-one privately; you can PTT one-to-many; you can create ‘channels’ of your own, based on any criteria you wish, for instance, a family group, a special interest group or a wide-interest group. You can ‘restrict’ or ‘open’ the membership of those groups and moderate them (lightly or heavily) in a ‘social media’ fashion.

Is someone using foul language or misbehaving? Just block them or kick them out for good!

Zello, in many respects, is a little like ‘PTT meets social media on steroids’.


Something for Everyone

Search the list of Zello channels online and there’s something for everyone. However, what is really interesting is the way radio users are adapting, developing and expanding this new technology.

Earlier this year, Karl Hobson G1YPQ created a set of Zello channels called Network Radios (Fig. 7).

This is a meeting place for radio amateurs in a similar format to the traditional top band chats or 2m repeater nets from years ago.

It uses radio amateur protocols and is a very friendly place in which to meet new folk. However, there is one big difference - there are also unlicensed stations on the air.

Pick your own callsign or name and you can join in the fun.

You might bump into Felip from Belgium - an Android expert who might help you set up your new device. Maybe, you will chat with Hairy Paul from Scotland - an electronics professional who takes his network radios mobile on his mountain bike (Fig. 8).

Neither have an Amateur license but – dare I say – are often more knowledgeable than many who have.

Because license restrictions do not apply, you can also transmit from some unusual places; for example, from 40,000 feet over the Atlantic, if your airline provides Wi-Fi.

Tim G4VXE has used the London Underground Wi-Fi and found that it worked well; you could even transmit on a cross-channel ferry; indeed, you can do so from anywhere you can connect to the Internet.


An exciting hobby

I hope this short article has given you a taste for what network radios are all about and that you can see that this corner of the hobby is very inclusive in its outlook.

Why not download a few apps and try them out on your smartphone for starters? Remember though, the experience is surprisingly handicapped by the form factor. Try a network radio device and you will feel the difference!

Why not enjoy the delights of internet propagation and its ‘crossing-over’ into natural propagation? Why not try some of the delights of being a 21st Century radio user?

A whole new branch of the hobby has come into existence and you might find it exciting to be part of it.


This article was featured in the August 2018 issue of Radio User