Intro to Communications

When looking at communication systems for overland adventure travel there are a wide range of options. The goal of this article is to cover the basics and introduce the various systems, how they work, how they are similar, how they are different, and what their advantages and disadvantages are. In later articles we will expand on this foundation to look at the particulars of each system and how to maximize them.

Whether it’s a walkie-talkie, a cell phone, or a CB radio the basic principles by which they operate is all the same. You have a device capable of transmitting and receiving a signal, and you have a tower (of some kind) that can relay that signal over long distances. Aside from subtle differences in size, shape, frequency, and range they all work over radio waves.

The Electromagnetic Spectrum

The most common point on the EM spectrum is visible light. Each color of light has its own frequency. Shift too far right and you get into the infrared spectrum. Too far to the left and you’re into the ultra-violet spectrum. The human eye cannot see either IR or UV light, or other forms of radiation on the EM spectrum, but we can sometimes see the effects of them. Blacklights are an example of UV light.

Past UV is X-ray. If you’ve ever broken a bone or been to the dentist you’re probably familiar with X-rays. X-rays are super powerful and will go through solid matter. Another powerful part of the EM spectrum are microwaves. I’m sure you’ve all cooked something in a microwave. The high energy put out by a microwave cooks food by heating up the water in the food.

On the left end of the spectrum, beyond x-rays, are gamma rays. They aren’t worth mentioning too much for the purpose of this article, but they supposedly did give Bruce Banner the ability to turn into the Hulk (Disclaimer: do not expose yourself to gamma radiation; it will not give you super powers, it will give you cancer). On the far right end of the spectrum passed microwaves are radio waves. This is the spectrum of the EM spectrum that we as humans have harnessed for our various forms of communication.

Radio Frequency Spectrum

There’s a rather wide range of the EM spectrum that we can communicate on known as “Radio Frequency Spectrum” or simply RF. The RF spectrum includes all kinds of hand held radios, marine band, business radios, and even cellphones and satellites. Regardless of their type, the basic principles by which they operate is the same.

When talking about EM and RF waves, size is always relative.
A short radio wave is still a long EM wave by comparison.

First, let’s go over a little bit of terminology. A radio wave has two components: frequency and amplitude. Frequency is the number of waves that pass within a second of time, it’s also an indication of wavelength which is meastured from one wave peak to the next peak. This is measured in hertz (Hz) (not the car company). So 60 Hz means sixty waves per second (for reference the wavelength is 3000 miles). Did I mention radio waves are fast? Like near the speed of light fast (remember, light is on the EM spectrum). Amplitude is the strength of the wave which is the height of the peaks of each wave.

Please note, this chart is reverse compared to the one above.
To the right (as frequency goes up and wavelength goes down) you move toward visible light.

Sorry for the confusion.

When we focus in on the RF portion of the EM spectrum we see a lot of familiar forms of communication. The two things to take note of are the relationship between wave length and frequecy. A lot of times people will use them interchangably. So when someone talks about “two meter” band, they are talking about frequencies near the 400 MHz range. Each of these ranges also has a name. So the Ultra High Frequency Range (UHF) corisponsds to the 70cm wavelength which is somewhere around the high 300 MHz frequency range.

Another important thing worth mentioning is that each of these bands has some limitations to it imposed by the Federal Communication Commission (aka the FCC or “the feds“). For instance, within the Very High Frequency range (VHF) lies the FM radio band. This is a range of radio frequencies we can listen to, but cannot talk on. Similar restrictions apply to portions of the radio spectrum like business band, frequencies associated with aviation, television, emergency services, etc.

The most common frequencies we as overland adventure enthusiasts will communicate on are CB (Citizens Band), Family Band (FRS), GMRS (General Mobile Radio Service), HAM (Amature Radio), cellphones, and lastly satalite. There are other subsets like marine band and business band that some people might be familiar with, but they aren’t commonly used by off-road enthusiasts.

Licensed vs Unlicensed

The first thing to discuss when it comes to radios is which ones require a license and which ones do not. CB and FRS do not require licenses. GMRS, HAM, and Business Band do. HAM also has three teirs of licenses each with progressively more difficult tests and progressively more privileges. Althought it’s worth mentioning knowing Morse Code is no longer a requirement (sorry all you grumpy old HAM’s from the mezioic era).

The biggest thing about the varios radio types and their corisponding licenses is how it impacts broadcast wattage (ie the amplitude of the signal). This impacts both the range and quality of the signal. CB and FRS which do not require a license have the lowest wattages, and consequently the worst range (relatively speaking). In the off-road world CB’s are pretty ubiquitous amonst trailrides groups and Jeep clubs. The problem is the range is of a CB is limited to not much more than line of sight. CB’s are also negatively affected by terrain. While CB’s work great for truckers on long flat highways, they don’t work so well when it comes to off-road terrain where there are a lot of elevation changes. You could be less than a mile away from someone on opposite sides of a hill and not be able to talk to each other. Same goes for FRS. Although they share the same frequencies as the lower GMRS channels (yes, there is some overlap) the wattage of a FRS radio is a fraction of a GMRS radio. For reference FRS is limited to a between a half watt and two watts (depending on exact channel). GMRS can go as high as 50 watts now.

When you transition to GMRS and HAM radios you can make use of repeater sations. Think of these like cellphone towers for radios. Even though the two vehiles cannot communicate directly (which would be a problem for CB and FRS radios) a GMRS or HAM radio can bounce a signal through a repater.

Does more wattage mean more range? The simple answer is yes, well more of a maybe. There are a lot of things that can affect range like terrain, atmostpheric conditions, and even the type of antenna. All of these things will get covered in greater detail in a standalone article. However, like most things, is “you get what you pay for.” A better quality more powerful radio will give you much better signal quality and range than cheaper less powerful ones.

Cellphones & Satalites

If you go back to the RF spectrum graphic up above you’ll notice that cellphones and satalites are on the far edge under the UHF (Ultra High Frequency) and SHF (Super High Frequency) ranges respectively. This means they have a very very very high frequency with a very very very short wavelength. This means they can have small short antennas. Think of your cellphone, you can’t even see the antenna on most modern cellphones because they are small and hidden inside. Most GPS devices have a small stubby antenna not much larger than a thumb.

I have an iPhone XR on the Verizon Network
I have traveled up and down the eastern US and out to mid-west (AZ and UT).
Of all the carriers I think Verizon has the best coverage, but there are limitations.

One of the biggest advantages of cellphones and satalite communication devices (whether it is a sat-phone or a sat-data device) is that they are a simulatious two-way communication device. Radios, like a tin can on a string, is only one-way. Meaning although the device can transmit and recieve a signal, it cannot do both at the same time. Cellphones on the otherhand can transmit and recieve at the same time.

Newer cellphones even have a technology called MIMO (multiple-in/multiple-out) meaning not only can it transmit and recieve at the same time, it can transmit and recieve multiple signals at the same time. My current phone, an iPhone XR has 2×2 MIMO. The iPhone XS has 4×4 MIMO. This means better signal quality and better bandwidth in areas where cell reception isn’t that great. Reason being is each of these signals is cumulative. Four weak signals is better than a single weak signal. This is something to remember when we look into things like cellphone boosters like the weBoost. Stay tuned for an install writeup and indepth look at a weBoost.

The biggest advantage of satalite communcations is coverage.
The biggest disadvantages are cost and latency (delay).

When it comes to satalite communications, the two most common ones used by overland adventure enthusiasts are Iridium (used by the Garmin inReach) and Globalstar (used by SPOT). While there are other networks out there, these are the two most common. As far as satalite communication devices, the three most common ones are doing to be a passive tracker (like a basic SPOT), a data device (like a mobile hotspot), and a satatlite phone (for strictly voice communication).

Trackers are great, but they are limited in use. It’s great for telling someone where you are, but not why you are there. There are some trackers that have an SOS feature which can signal for help, but again, they tell the rescues where you are but not what’s wrong.

Data communication devices (like an inReach or advanced SPOT) are great because they allow two-way communication. So if I press the SOS button on my inReach I can actually communicate with rescues on the other side. Devices like the inReach can also do things like access the internet (for email and social media), access weather data, and communicate with friends and family via text messaging.

Satalite phones work just like a normal cellulare phone, only in most places normal cellphones don’t work. However the cost for a satalite phone (both the hardware and network subscritpion) usally makes them cost prohibative for the average overland adventure enthusiast. In constrsast, something like an inReach is more affordable both for the hardware and the network subscription. It also offeres more flexibility in use than just voice communication.


I know I just shotguned a ton of information at you. And to be honest, we’re barely scratching the surface so far. However this is, as a reminder, an introduction level article. We’re just laying a foundation for future articles (as well as videos – spoiler alert) that will go more indepth into each form of communication.

Don’t worry, there will be more.

You can’t stop the signal…