Emergency radio
A two-way radio is a radio that can both transmit and receive (a transceiver), unlike a broadcast receiver which only receives content. A two-way radio (transceiver) allows the operator to have a conversation with other similar radios operating on the same radio frequency (channel). Two-way radios are available in mobile, stationary base and hand-held portable configurations. Hand-held radios are often called walkie-talkies, handie-talkies, or just hand-helds.
Two-way radio systems usually operate in a half-duplex mode; that is, the operator can talk, or he can listen, but not at the same time. A push-to-talk or Press To Transmit button activates the transmitter; when it is released the receiver is active. A mobile phone or cellular telephone is an example of a two-way radio that both transmits and receives at the same time, ie in full-duplex mode. Full-duplex is generally achieved by the use of two different frequencies or by frequency-sharing methods to carry the two directions of the conversation simultaneously. Methods for mitigating the self interference caused by simultaneous same-frequency transmission and reception include using two antennas, or dynamic solid-state filters.
Emergency Communication
So how would you communicate with your family or get help if communications go down? If you found yourself in the middle of a wide-scale disaster such as a hurricane or other catastrophe and you had no government coming to help for a while, how would you communicate with your family or others? What if the power grid went down?
You won’t be able to rely on your cell phone. There are alternatives, however. This is a pretty long article that goes into some good detail, but if you want the short answer, this is what you need.
I’ll go over the basics of some emergency communication methods but if you want more detail, check out Personal Emergency Communications: Staying in Touch Post-Disaster: Technology, Gear and Planning.
Short-term emergencies have shown the limitations of using cell phones to coordinate with each other. Even if the towers are operational, they can’t handle the added traffic of millions of people trying to get a hold of loved ones – or help. Ever had trouble calling your mother on the morning of Mother’s Day?
During many recent events, cell phone service wasn’t an option for many for days. The system became seriously overloaded on 9/11 so calls wouldn’t go through, 70% of the towers went down during Katrina and were down for days, and most areas haven’t been adequately improved across the US.
These won’t be isolated events. Don’t think that because you live in a large metropolitan area that you’re safer. A quick look at some of the things that went on during Hurricane Sandy in NY will show that the government has a lot to deal with in addition to just trying to get your cell phone service back up so even though that was a pretty short-term event, it caused a lot of problems.
Here are just a few issues that would affect you being able to pull out your iPhone to call up people:
Cell phone communication has a lot of vulnerabilities that make it a poor solution for widespread or long-term emergencies.
Heavy winds or flooding can disrupt the cables between towers such as during Hurricane Sandy.
Cell towers require AC power to operate so if they don’t have an automatic backup system, they stop. Keep in mind that a lot of towers are just glorified antennas on the tops of buildings or mountains and backup power, such as an emergency generator, is a very short-term solution. Generators require fuel and that fuel has to be replenished quite often. In a lot of cases, the only backup power available is a bank of batteries that stop charging when the main power system stops.
Backhaul systems (essentially the system that connects and/or allows overflow from outer systems to the core, often including other carriers) aren’t always reliable. A lot of this system is wired but has been expanded to microwave and other systems.
Most cell phones will only stay charged for a day or three. If you don’t have local power to keep it up, when the system does come back up, you won’t be able to talk to it.
Cell phones require satellites, which are vulnerable to hackers, physical attack, or solar storms.
Now don’t get me wrong, for day-to-day emergencies, such as getting a flat tire, a cell phone usually works pretty well. It’s just a crappy solution for big emergencies. They’ll be pretty useless if the national grid goes down due to a cyber attack, EMP or CME, which is actually a lot more likely than you might think.
One cool idea that’s coming out is the go Tenna cell phone radio antenna system. Your cell phone connects to it via Bluetooth and an app, and the signal is sent and received through an encrypted radio signal. How awesome is that? It won’t be able to reach to the other side of a city but you should be able to locate your family if they’re in the area and maybe even communicate with others if they have the system.
So if you can’t rely on cell phone service, what other options do you have?
Emergency Communication Gear
During a disaster, it’s very likely that most communication channels will go down. Hopefully this will only be temporary, but either way, you need to plan for the worst case scenario and have multiple options available.
CELL PHONES
We will start with cell phones, because almost everyone has one. While cell networks are often overwhelmed during a disaster, they still might help you make contact.
If your initial attempts to make a call fail, try texting or using your phone’s data plan to make contact.
As we’ve seen in past disasters, texting and even social media apps can sometimes work, even when voice doesn’t. A text message takes a lot less bandwidth than a phone call, so during a disaster, this might be your best bet for making contact.
SOCIAL NETWORKS
While you’ll still need some way to access them, social networks can be a great way to communicate during a disaster. If you can make your way to an emergency crisis center, or access them on your cell phone, you may be able to post a status update to your social networks.
While I wouldn’t rely on this as my primary means of communication, it can be a great way to let friends and family know you’re ok, or let them know what you’re planning to do next.
SATELLITE PHONES
While on the expensive side, during a natural disaster or crisis, having a satellite phone just might save your life.
Satellite phones offer a couple of advantages during a disaster. First, they don’t rely on local cell networks, so they’re less likely to be affected by an increase in call volume. Second, even if the entire local cell network goes down, your satellite phone is still going to be operational.
Recently I’ve been testing the SPOT Global Sat Phone , and I’ve been really impressed with its ability to call from even the remotest areas of the backcountry. In areas where my cell phone has zero reception, my SPOT phone is able to call out to anywhere in the world.
CB RADIO
I know, you’re probably picturing big rig trucks or bad movies from the 1980’s; but the fact is, the C.B. Radio can be an important part of your emergency communications arsenal. I recommend having one in your vehicle, having a handheld one in your bugout bag, and having a base station at home.
During a localized disaster, you should be able to make contact within a 20 – 30-mile radius. This makes the CB Radio a great way to coordinate with friends and family during localized disasters.
FRS/GMRS, PMR/KDR Two Way Radios
The Family Radio Service (FRS) and The General Mobile Radio Service (GMRS) are both designed for short-distance two-way communication. They’re generally used with small walkie-talkie devices and have a range of somewhere between 5 to 35 miles (line of sight) and about 1 mile in an urban setting.
I personally use the Motorola MS350R Talkabout and recommend them for caravanning or when hiking in groups.
HAM RADIO
Having and knowing how to use a Ham Radio is probably one of the most important things you can do to ensure your ability to communicate during a disaster. For over a hundred years, the Ham Radio has played a vital role in almost every major disaster this country has faced.
When the grid goes down, the cell networks stop working, and every other line of communication fails, there’s a pretty good chance the Ham Bands will be alive and operating. Just remember to have a set list of frequencies where you and your group will try to make contact.
Radio range
The useful direct range of a two-way radio system depends on radio propagation conditions, which are a function of frequency, antenna height and characteristics, atmospheric noise, reflection and refraction within the atmosphere, transmitter power and receiver sensitivity, and required signal-to-noise ratio for the chosen modulation method. An engineered two-way radio system will calculate the coverage of any given base station with an estimate of the reliability of the communication at that range. Two-way systems operating in the VHF and UHF bands, where many land mobile systems operate, rely on line-of-sight propagation for the reliable coverage area. The "shadowing" effect of tall buildings may block reception in areas within the line-of-sight range which can be achieved in open countryside free of obstructions. The approximate line-of-sight distance to the radio horizon can be estimated from : horizon in kilometres = 3.569 times the square root of the antenna height in meters.
Hand-held UHF sets can be used both in and out of a vehicle, so they are useful for groups travelling together; particularly those planning on participating in activities that require additional communication tools, such as rock climbing! The range can be anywhere from 1 to 10 km. If you are in deep forest or mountainous terrain, the range is obviously less than on flat terrain.
We will under here give you a little info about the frequency the radio is using and if you choose to use sub tones or not.
More info on PMR446
PMR 446 is a handportable, short-range, voice-only communication system. It provides a basic but effective radio service for both business and non-business users, and is ideal for providing communication over short distances (e.g. within office buildings, factories and building sites). Please note that it is for speech transmissions only.
No need for a licence.
The PMR 446 service is licence-exempt; you do not require a licence to use PMR 446, as long as they comply with the requirements.
PMR Because the frequencies are shared, you may experience interference and channel-sharing problems if there are many other PMR 446 users locally. You may be able to reduce these problems by changing your frequency, CTCSS tone and/or DCS code. PMR 446 is not suitable for safety-of-life use, or for users who need access to frequencies at particular locations and times.
FRS 2-way radios are simply dual-service, or "hybrid," radios that provide access to both the FRS and GMRS bands, utilizing FRS channels (1-14) and GMRS channels (15-22). Use of a dual-service radio's GMRS bands requires an FCC operator's license. Dual-service radios may be used without an operator’s license, if only the FRS channels are used.
Advantages of FRS and PMR 446 radios over CB radios or cell phones:
- No charge for airtime
- No monthly contracts
- No per-call charges
- Less static and interference than CB radios
- Lighter and more compact than CB radios
- Easy to operate.
The range of the PMR446, just like any VHF or UHF radio, is dependent on many factors like environment (in city range is far less than in open field), your height above surrounding obstructions and to a very much lesser extent weather conditions. The antenna type and location, transmit power and receive sensitivity also affect range. However with PMR446 most of these variables are fixed at manufacturing to comply with the PMR446 specifications.
Range may be many kilometres e.g from hilltop to hilltop, or only a few hundred meters if for example a hilltop or large metal construction is in the transmission path i.e. between radios.
The best known long distance record is 535.8 km (333 mi) from the town of Blyth in United Kingdom to the city of Almere in The Netherlands.
