MORE thoughts on mobile radios

[The War Wagon]

GREAT stuff the last couple of days on Survivalblog - pt.I

Radios for Emergency and SHTF Use – Part 1

by Rufus King

SurvivalBlog Contributor September 7, 2021

I have been interested in radios since I was about 12 years old. Long before cell phones were ubiquitous, the adult leaders in my Boy Scout Troop all had CB radios installed in their vehicles on road trips, and I witnessed them being used to good effect for communication between vehicles. I know now that the 11 meter band and the AM operating mode of those radios is a suboptimal choice for that kind of short-range voice communication, but it was the practical choice when CB was about the only unlicensed radio service available.

A couple of the scout leaders I knew also had amateur (ham) radio licenses, and I once watched one of them produce a handheld radio from his belt and make a phone call via a telephone patch system operated by the local ham club. Needless to say, he had my interest. That was long before I ever saw my first cell phone. Ham radio was out of my financial reach at the time, but I never forgot it.

When I got a little older, I had a few mobile CB radios, which I installed in various vehicles I owned. At the time I knew nothing about standing wave ratios or antenna tuning but got them to work. Later, I was briefly involved as a volunteer first responder in New York City around the time of the 9/11 attack. I bought a used Motorola Saber radio off eBay and learned how to program it with an old computer and some even older software.

My interest continued to grow, and I continued to tinker with radios. The 9/11 attacks, or more specifically the way the city government reacted to them, caused me to end my sojourn in NYC and return to Virginia. After more public safety work and more tinkering with radios, I eventually revived my interest in amateur radio. I took and passed the Technician exam (which by that point no longer required Morse code), and I bought both a 50 watt VHF (very high frequency) radio for my truck and a small VHF/UHF (very high frequency/ultra high frequency—capable of operating on both bands) handheld (called an HT for handie-talkie by amateur radio folks). I learned more by doing and by making mistakes.

I also quickly realized that through my ham endeavors, I knew more about radios and how they worked than anybody in the county emergency communications center or in the administration of the sheriff’s department I was working for. I am not an engineer by training, but I could read and tinker, and I have always been reasonably handy with computers. Over time, I upgraded my ham license to General Class and then finally to Amateur Extra—the top-level license in the US.

As I have learned more about radio, I have tried to share my knowledge with others—with mixed results. I frequently find myself in a conversation with someone either in person or online, who wants to buy a radio or two for emergency communications, and often we both end up frustrated. Most people have unreasonable expectations, both in terms of what a radio can allow them to do and how simple it will be set up and use. I’ve also found that I have unreasonable expectations as to how much effort my interlocutor is willing to expend in order to have emergency communications.

One of the other sequelae I experienced from the 9/11 attacks was that I started to get serious about emergency preparedness. I have been making provision for hard times ever since as resources have allowed. Everyone has different ideas about what sort of social, political, economic, and political events might require them to rely on their preparations and plans. I have been able to put my emergency communication skills to use on a number of occasions where there was an emergency short of a long-term societal collapse. These have included severe weather events, riots, and providing communications support for a large gun rights demonstration. This has led to a cycle of thinking through and evaluating my equipment and preparations.

What follows is my attempt at providing a primer on radio communication for preppers. It is not intended to be an exhaustive treatment or any kind of technical treatise; rather, I am trying to boil it down to the essentials to help you make some good decisions. I am not anything close to an expert on radios: I am at best an advanced novice. As a lawyer by profession, I have included a number of citations to the applicable FCC rules as published in the Code of Federal Regulations (CFR) in case anyone wants to look up the sources for the information on the law.

Expectations
Before I go further, it is important to set expectations. I have fielded a number of questions online from people who seem to think they can buy a $25 Chinese radio and use it to talk to their friends all over the country with no license and no training. This is no doubt because folks are used to having a similarly-sized device that does exactly that—a cell phone. That is not realistic. Cell phones allow you to do all of that because of a very expensive and complex infrastructure. Take that away and they are useless. A handheld radio will allow you to talk to people in your immediate area, say a few miles at best. Add a repeater up on a tower, such as those used by public safety agencies or amateur radio clubs, and you can use it to talk to people in a metro area. Sometimes repeaters can be linked to extend coverage across a broad geographic area, but that is done using a hard-wired telephone or Internet connection that is not likely to last long once the grid goes down.

Lower frequency amateur equipment (“high frequency” or HF in ham speak) will allow you to talk to people all over the world if conditions are right by bouncing signals off the ionosphere (referring to these frequencies as “high” is an artifact of the early days of radio when the technology was focused on even lower frequencies). This is potentially very useful for gathering information, but it is not terribly reliable when you want to talk to one particular person at one particular time. I have had reasonably good success making contacts domestically at pre-scheduled times using digital modes where a laptop is connected to my HF radio. This type of communication works with lower quality signals than voice communication, so it can be useful. But any kind of radio communication beyond your immediate area takes expensive equipment, training, skills, and licensing. That is just how it is.

The RF Spectrum
Radio communication relies on modulating electromagnetic waves to carry information and then decoding them on the other end. The radio spectrum is a scarce resource. There is not really a lot of it compared to the number of possible users. Radio frequencies are most often measured in megahertz and less often in gigahertz (GHz). A hertz is a unit that measures the number of cycles per second. A megahertz, abbreviated MHz, is equal to 1,000,0000 (1 million) Hertz or 1,000,000 cycles per second. Killohertz (KHz) is equal to 1,000 cycles per second. Thus 1 MHz is equal to 1,000 kHz. GHz is billions of cycles per second. Think of it as 1,000 times more than mega, or 1,000,000,000 cycles per second.

Radio waves have the familiar sine wave shape of alternating current, and the number of waves per second is what determines frequency. A frequency of 150 MHz means the wave has 150 million cycles per second. Sometimes we also talk about frequency in terms of wavelength. This is usually measured in meters and is related to frequency. Often the two ways of referring to a given piece of spectrum will be used interchangeably in the same conversation. To convert frequency to wavelength you just divide 300 by the frequency. So, a signal with a frequency of 150 MHz has a wavelength of 2 meters. A signal with a frequency of 15 MHz has a wavelength of 20 meters. Ham operators often speak in terms of “the 20 Meter Band’ or “The 40 Meter Band.”

Another thing to know about radio spectrum is that signals at different frequencies have different properties. Lower frequency signals tend to propagate over much longer distances and penetrate walls better. High frequency signals tend to be highly directional and work better for line of sight (LOS) applications.

These two statements are oversimplifications, but they will serve for present purposes. Your cell phone uses frequencies in the gigahertz range. It is extremely directional and actually very short range. It must have line of sight to a tower, or it is useless. This is convenient because there are millions of such devices a trying to use the same portion of the radio spectrum, so it is a feature, not a flaw, that they are short-range and don’t interfere with one another. A 28 MHz signal can allow you to communicate around the world with the right conditions and the right antenna. Meanwhile, a 2.8 GHz signal will let you hit the cell tower up on the hill, but that is about it.

As an aside, while mobile phones are extraordinarily convenient (so convenient, in fact, that we voluntarily carry surveillance devices around with us at all times), they are highly dependent on a very sophisticated infrastructure. In any kind of grid-down situation that lasts for more than a few days, mobile phones will not be useful for communication.