How far will this radio go?


How far can a radio transmit?  There are many factors that go into the answer.  The advertised distance of a radio is usually theoretical distances; a distance achieved in optimal conditions.  Very similar to the miles per gallon ratings of new cars.  How much do you believe in those?

The distance a radio wave can travel depends highly on the frequency being used, the water vapor in the air, ionization in the upper atmosphere, and interference from other sources.

Propagation: VHF and higher frequencies

Light of sight is a common term used with VHF and higher frequency radios.  This means that radio waves are not bent by the atmosphere.  The radio waves cannot follow the curvature of the Earth.  If the Earth’s surface was perfectly smooth (like if you were on water) and you were not standing on anything, you could see about 3 miles.  Moving up to a height of 500 feet and you’ll see 27 miles.  Granted, this is assuming perfect atmospheric conditions.  If the thing you are looking for is elevated, then factor in their height too.  Theoretically, a 6-foot person (with binoculars) should be able to see the head of another 6-foot tall person six miles away.

A handheld radio would follow this same theory.  The good news is that most public safety antenna towers are tall.  If the radio was held at 6 feet and was transmitting to a 500-foot high tower, then the maximum range would be about 30 miles.  27 miles for the tower + 3 miles for the person = maximum possible range.

Cell phones operate at frequencies higher then VHF, so they are all line of sight.

Propagation: Below VHF frequencies

These radio frequencies bounce off the upper atmosphere and are directed back to Earth.  For most users, this is enough of a description to get a visual of what’s occurring.  The actual process is that the ionosphere is refracting the radio waves similar to how a glass of water makes a straw look bent.  When the sun is shining on the atmosphere, it changes the characteristics of the ionosphere to increase the radio wave’s signal loss.  At night, the characteristics of the atmosphere become more favorable for radio waves.  This is why you can hear more distance radio stations at night, and pick up shortwave (HF) radio stations from other countries more at night.

A radio wave that is bouncing off the atmosphere creates skip zones.  A radio transmitting from Washington, DC to San Diego, CA successfully doesn’t mean that the radio waves will be heard in Kansas City, MO.  The radio waves may be refracting in the upper atmosphere over Kansas and not near the ground where they can be received.

A lot of very smart people have posted other information about calculating exact radio distance based on power, antenna height, frequency, time of day, weather and so on.  Here is just enough information to get your feet wet.

Additional readings:

Understanding propagation:

US Navy propagation explanation:

If radio waves were visible light

There is a lot more in common between radios and cell phones then most people expect.  It can be hard to see similarities when the user interfaces are designed so differently.  Fundamentally, they both have a power source that drives the device to generate a signal across an antenna.  In turn, the antenna generates radio waves that run through the atmosphere until they hit another antenna attached to a receiver.

If you could see radio waves, they’d appear as if we had hundreds of lights turned on all around us.  We’d see the waves coming off our cell phones, wifi-enabled devices, blue-tooth devices, wireless phones, cellular-enabled tablets and hot spots.  Also visible is the radio waves from your neighbors’ equipment coming right through your walls as if the walls weren’t even there.  The wireless baby monitor would probably appear just as annoying as the tantruming child.  Larger sources of radio waves would emanate from cell towers.  Way off in the distance, AM and FM towers would glow like a sun.  Even the fast food drive through isn’t immune due to the wireless headsets and speakers.  Look to the sky and you’ll see the satellites sending their signal to the earth.  Right above the equator, the concentration of transmitting satellites would resemble the Milky Way.    Add in all the natural sources and unintended sources from poorly designed electrical systems to really complete the image.  No lie.  Radio waves are everywhere.

In the US, the National Telecommunications and Information Administration will set the broad allocation of the spectrum and how it can be used.  They publish the US Frequency Allocations: The Radio Spectrum chart.  It is very finely divided down, yet you’ll still see major sections allocated to broadcasting.  Spectrum is a finite resource.  We cannot create any more and all of it is allocated to something.  That is why spectrum management is so important.  Broadcasting has had to make better and more efficient use of the spectrum to keep it.  Hence the evolution of HD radio; which by the way is hybrid digital not high definition.  It also led to the use of Digital TV to include more information and resolution in the TV station’s broadcast.

At the bottom of this chart is the full spectrum.  Near the left end is the audible wave lengths; the middle contains a very narrow band of the visible spectrum; and the far right is cosmic rays.  The continuous range of frequencies (and then some) is called “DC to daylight”.  DC refers to direct current or 0 Hertz.  Daylight refers to the band of visible light, starting about 405 THz.  Thz is Terahertz or 1012 Hertz.  If you’re used to the metric system, Tera comes after Giga.  Looking for a radio that does “DC to daylight” isn’t a literal radio.  It is referring to a radio that will continuously cover all possible radio bands.  Keep in mind that the more bands (frequency ranges) a radio will cover; the less impressively it can master a single band.  Think of it this way: a Swiss army knife provides a lot of tools which are better than nothing, but far less handy then having the actual tool needed.


Additional reading

National Telecommications and Information Administration. (2003). U.S. Frequency Allocation Chart.  Retrieved from



PACE and Interoperable Communications

Primary, Alternate, Contingency, Emergency

PACE is a structure to build a communications plan.  The key to a good communications plan is that everyone has a basic idea of what will be attempted and when.  It makes no sense to be standing by a fax machine while someone is trying to call you on the radio.

Primary is the day-to-day communication system used.  This could be desk phone or cell phone for most businesses.  It can be the two-way radio system used in public safety.  Primary is the first way that you attempt to reach someone during routine times.

Alternate is the next-used system.  If you normally call a person at their desk and they are not there, the next step might be to call their cell, use a radio, page them, or call their home.  It could even be email, text messaging, whatever; there is no single right answer.  It will all depend on what systems your organization uses.  The right answer will be the consistent one that everyone knows.  This avoids the “Oh, I was listening for you on the radio; I didn’t think to check email” confusion.

Contingency is the system that you fall back to when the main methods of communicating are not working or not able to reach the person.  Normally, when this point is reached, it is obvious that something not routine is going on.  When including radios in your plan, make certain that predefined frequencies and modes have been agreed on and shared.  Saying generically that you’ll use amateur band or business band two-way radio is like telling someone that you’ll meet in Virginia and not be any more specific to the address.

Emergency is the system of last resort.  When nothing else is working, expect to pull this out.  There are two important things to note here.  Anything kept behind glass that says “break in case of emergency” will not work.  The equipment will not be tested and the users not trained.  Make certain that your emergency communications systems are regularly tested and used for highest impact during a disaster.  Second, sneaker-net is a valid communication system.  Setting up runners, shuttles or other ways to manually carry messages is fine.  Sometimes the best technology to use is none at all.

Interoperable Communications

Interoperable communications is not a technical problem; it is a political problem.  The technology exists today (and is widely used) to interconnect any number of systems to each other.  The political problem comes in when teams from different organizations are in direct contact in a way that bypasses the “normal” chain of command.  Regardless of how much interoperability exists, the Police Chief wants authority over all the police units and the Fire Chief wants authority over all the fire units.

Everyone wants interoperable communications but who do they really want to talk with?  Do they want the ability to do broadcast information that cross many channels, or is it for two-way exchanges between anyone?

Interoperability requires pre-disaster decisions to be made.  Who is authorized to activate or start using the interoperability channels?  Who has the authority to control radio traffic on the shared channel?  When units are engaged on the interoperability channels, do they have an expectation to monitor or check in on their normal primary channel?  The Incident Command Systems appears to resolve these problems but only within the scope of the incident itself.  These political pitfalls exist outside ICS.  Major incidents can be divides across a number of channels so interoperability isn’t just one channel but a whole suite depending on local plans.

Ten-digit interoperability: The phone system is a communication system, and totally interoperable.  You give me your phone number and I’ll give you mine.  It is simple and works everywhere in the US.  The basic telephone number is still the foundation of voice communication regardless if it is land-line, cellular, or satellite.

I like to tell people that I do INTRA-operable communication.  If I can get my organization to talk to itself, then most of my work is done.


Another tool in the tool box

The AIDF 2012 panel I was on generated the report: “Another tool in the toolbox.”  The report shares a series of outcomes.

  • Approach new technologies with cautious enthusiasm.
  • Partnerships involve giving too, not just taking.
  • If we agree to share, we can achieve more and save money.
  • Social media is a valuable source of information. Let’s take advantage of it.
  • Let’s innovate together.
  • Education trumps limitation.
  • Always be in preparedness mode.

The panel provided different view points because we were all at different points in technology with unique perspectives.  It was a pleasure to be on this panel and I look forward to next year at AIDF.

Introduction to Communications

Communications Introduction

Communication is vital.  It is the passing of information from one person to another.  This information can be a thought, a request, a need … anything at all.

An interesting thought was put forth about communications in a historical show about the Dark Ages in Europe: after the plague and the Viking hordes, there were not enough people left living in Europe near each other to share ideas and spark creativity.  The Renaissance had to wait until the population rebounded to create a density of shared ideas.  Hence, the lack of communication held back the advancement of European civilization after the fall of Rome until the Renaissance.

If there was an after-action report on Europe in the Dark Ages, the blame would have been placed on poor communications.  I wonder when we’ll stop using this centuries old excuse for problems that occur during disasters.

Communicating ideas can take place in many ways.  It can be voice, data, images, sounds, video and any other form of medium that you can image.  Using all these methods can still be challenging when all infrastructure is at its best.  Think of all the people who everyday complain about dropped cellular calls, emails not getting  through, files too large to upload, and so on.

Disasters have a way of magnifying all cracks in technology, as well as socially, culturally, and economically.  Expecting the same level of pre-disaster services during the disaster or after is just not realistic.  The infrastructure is weakened, and the users’ demands are increasing.

When you are asked to provide communications during a disaster, you will not have the assets to bring everything back online at once.  Each communication medium will need to be prioritized and rank ordered.  There is one place where the PACE acronym will come in.  Using PACE while writing your preparedness plans will also help set expectations across all the users.  Solid expectation setting is key to being successful during a disaster as everyone will be on the same thought process in evaluating your work.


Keep it simple.  People will use what they use every day to make communications occur.  Training is critical.  Ask a law-enforcement officer how much weapons training they have, and how much radio training they have.  Then ask which one they use more.  A common response that I hear is no radio training but it is used every day.  That’s a problem.

Locations and Connection Methods

There are many different types of sites that will need connectivity.  Fundamentally, they are all going to be the same.  Each site will need connectivity external to the site, such as to the Internet.  Each site will need some way for users to use the technology inside the site, such as a computer or phone.  Then these need to be connected together; a network or antenna wire.

All these systems will require a few basics to get started: space and power.  Do you have the space to bring these systems into the site, set them up and operate?  Do you have the power to bring the equipment online?  Secondarily, is there infrastructure to support the people: food, water, sleep, toilets, etc.

The “last mile” connections are going to be the hardest to finish in a disaster.  The core of the major utilities may be functioning fine.  The power station is generating electricity and it is getting to the sub stations.  The natural gas lines are charged.  The telecommunications network is active.  Except for where you are.  Include in your plans how you will overcome these challenges.  It will likely be a combination of direct work with the utility companies to be on the priority restoration list, and rental companies that can provide the service on an emergency temporary basis.

Wired communications

A single voice line is the basic unit of the phone system.  To you, this is both a pair of wires coming into your home plus a phone number.  These are really two separate things.  The voice line is the dial tone to your home.  The phone number is how the phone company identifies your line.  Business lines commonly have different numbers of voice lines and phone numbers.

I have a phone system with just under 2,000 direct dial phone numbers but only capable of just under 200 concurrent external phone calls.  Why?  Because all 2,000 phone numbers won’t be in use at the same time.  It is a lot like a gym membership.  They don’t expect everyone to show up on the same day to use the same treadmill.  Some use it in the morning, some in the evenings, and some never.  Some of my users will only be calling others in the same phone system.  These never use an external voice line and stay completely within the system.

Data lines are all based on the simple single voice line.  A single voice line can carry 64 kbit/sec, although the 8 kbit/s overhead make the practical maximum only 56 kbit/s.  A T1 circuit is also called a DS-1 or PRI.  The name varies depending on the specific use and those in the industry will be very specific.  For our purposes here, they are lumped together.  A T1 circuit is a bundle of 24 voice lines.  The math is simply 64 kbit/sec x 24 lines = 1.5 Mbit/sec.  A T3 circuit is a larger bundle and has 672 lines, therefore 43 Mbit/sec.  It used to be that a T1 was the gold standard for a circuit into a facility.  In my experience, a T1 can support 100 active users at best.  We’re now planning in the direction to pull T3s into large sites.  The sad part is that my home broadband runs faster than 4 Mbit/sec – almost three times the speed of a T1.


Additional resources

A Primer: Planning for a hurricane strike

At the bottom of this post is a link to a PowerPoint file that has the storm tracks to accompany this reading.

Hurricanes are a common occurrence in the Gulf and Atlantic basins.  Hurricane forecasts can provide a many day warning.  This is both a blessing and a curse.  Emergency managers face a challenge.  They need to meet the unforgiving expectations of the public they serve, and the news media that wants to sensationalize failures.  A local emergency manager who doesn’t take enough action ahead of a storm that hits the community will be tagged as incompetent; yet the same EM who mobilizes resources ahead of a storm that misses the community will be tagged as wasteful.

A good example of this is Hurricane Ike.  The forecasted track showed many possible scenarios five days out from the current day.  It started as Tropical Depression Nine on Monday, September 1, 2008.  The first few forecasts tracked the storm nearly due West toward Cuba and possibly into the Gulf of Mexico.

Wednesday, the forecast track started to swerve and it looked like it could track more North into Florida or even up the East Coast.  It is always best for a storm to make landfall late in the week when planning the mobilization of resources and public notifications.  However, this storm was different.  The timing was the worst in the week as the critical 3 days prior to landfall were over a weekend.  It is harder to contact government, non-governmental organizations, and private industry over the weekend, and even more difficult to get action taken.

Thursday evenings forecast provided some grim news.  Hurricane Ike appears that it will make landfall directly into Miami as a strong hurricane Tuesday evening.  The EM in Miami would need to start making arrangements on Friday expecting to work through the weekend.  The storm is so large that the outer rain bands would arrive Tuesday morning making travel more difficult.  Anything not in place by Monday would need to wait until after the storm passed.

Luckily for the EM in Miami, the storm’s turn to the North is shift farther West.  This means that Miami will get a glancing pass instead of a direct hit.  Imagine if the Miami EM started to mobilize expensive resources, and was calling for an evacuation of tourists.  There would be some unhappy politicians at the expenses, and businesses calling the politicians due to lost revenue.  Now the EM in Key West faces a similar problem.

Over the weekend, the track of Hurricane Ike keeps changing with a turn to the North shifting more and more West.  Alabama has a turn as the landfall location.  As does Mississippi and Louisiana.  The news on Monday morning reveals a straight shot to Galveston, TX with landfall the following weekend.  By Monday evening, the track shows landfall in Corpus Christi.

Consider that along the way, every EM of a coastal community has gone through a similar process of the Miami EM.  They had to weigh decisions on actions to take for what might occur four to five days away.  No EM wants to replay some of the catastrophes that occurred during prior seasons as the main character … or worse yet, the public scapegoat.

The track seems to be mostly consistent during Tuesday and Wednesday with a mid-Texas coast landfall on Saturday.  The storm will also speed up and move quickly across the Gulf.  It will cross the Western side of the Gulf in half the time of the Eastern side.  Note that the speed of the storm’s movement and the wind speed in the storm are two different things.  The wind speeds of the storm Tuesday evening were 80 mph, but the storm was only moving at 9 mph.  Just after landfall, the wind speed was 100 mph and the storm moved at 15 mph.

During this entire time, technology was used in many different ways.  The Weather Service was using computers to create forecast models, and then disseminate the information.  Both traditional media and social networking was pushing the information out to inform the public.  Emergency managers were using technology to plan for their response.

In this course, technology is used in the broad sense of the term.  It is any technology that is used to help make decisions, capture action, and connect.  It can be voice or data systems.  It can be stand-alone or networked.  It can be established or ad-hoc.  The key to successful integration of technology in disasters, emergencies and crisis is to think broadly and creatively on primary and alternate ways it can be used.

The needs around technology change from general hurricane planning, to the immediate planning in the days before the landfall, during the landfall when conditions are at the worst, and into the response and recover where the infrastructure may be damaged.

Hurricane Ike Track

FedEx and Red Cross shoot done by Good.

Here is a video about how the Red Cross and FedEx work together to respond to help those in need.  It was produced by a crew from Good that was a lot of fun to work with. It is always enjoyable to share how we are driven by our passion to help. It is a common trait with all the Red Cross people I have worked along side.

The original video is posted at  Click on FedEx at the bottom, then on the 2nd truck.

Preparedness: Science + Outreach + Splash + Social + Mobile

Preparedness is the tough nut to crack because it requires the public to take on personal responsibility for their own safety during and recovery following a disaster.  If they don’t accept that a disaster will happen to them, they’ll never buy the concept of preparedness.

Peel readiness separate from preparedness for the rest of this.  Readiness is the internal actions that a response agency takes to be ready to response that I’m not touching on here.

The preparedness phase is characterized as the long period of quiet between disasters.  Preparedness missionaries around the country advocate for individuals to take action to prepare for the disaster.  Many forests gave their lives for the quantity of printed materials that have been distributed over the decades.  “Prolific” described the disaster education unit that I was in; meaning we wrote lots of content to be used by preparedness missionaries.  It remains tough to quantify the effectiveness of putting a brochure in hand.  Long ago, I was told that the non-impact of a non-disaster couldn’t be measured.

The public health education model was merged with disaster preparedness.  It shifted the model in two ways.  First, the concept of reaching people where they are, how they wanted to be reached, in a culturally sensitive manner became a mantra.  Public health educators know that there is a specific process (or steps) to reach people to create intent to change.  Measuring the intent to change was key to determining the success of disaster preparedness education.

Still, getting the information to individuals is a time consuming process.  Education is an individual or small group process; mass education is hard to do.  Mass media selling a concept is different though.  Marketing and advertising companies have millions (billions?) of dollars invested to generate highly effective programs that for-profit companies use to get people to believe in something and pay for it (think retail establishments).  Non-profit organizations and emergency management lack the funding and skills to launch a big enough program to compete with major advertisers.  There is a lot of noise yelling for individual’s attention.  Competing messaging is everywhere with advertisements being the most obvious.

Getting acceptance in someone’s mind and heart is all about repeated impressions; no silver bullet works.  If I was in advertising, there would be plan to always spread preparedness messages around to create regular impressions.  When the person was ready to buy my product, the action would shift to overdrive to surround the person with messages to influence the decision.  Disaster preparedness is really good at the general spreading of preparedness messages yet seems to be lacking in targeting the people most ready to take preparedness actions.  I believe that people are most ready to become prepared right before a disaster and right after a disaster.

“Selling” preparedness as an idea to the public has always been an uphill challenge.  Preparedness has never been as sexy a sale as response.  The cost and effort of response was easy to see.  Money spent nationally on preparedness versus response is probably preparedness pennies to the response dollar (although I don’t have specific data to support this).  Some days, I feel as if those valuable pennies for preparedness were not being effective, but there were no solid tools to reach people any other way.  That has changed with the emergence of social media, followed by social networking, and now social engagement.  Social tools now exist to reach people in new and effective ways.

Disaster preparedness needs a shift from only steady state of messaging with urgency all the time.  The new model is a relaxed steady state that shifts to overdrive immediately before and after a disaster.  The relaxed steady state should still be enough to catch those people who are ready to make the change and seeking information, plus those people who were on the fence and just needed a little nudge.

The overdrive mode would use social tools to reach people just in time.  More specifically, reaching the right people on the right medium at the right time with the right information to bump their preparedness better.  We are not talking about a silver bullet at the right time to sky rocket their state of preparedness, but instead just bumping them along the continuum of preparedness when they are motivated to make a change.

The future of disaster preparedness will be a blending of disaster science, public health outreach experience, advertising splash and social mediums with an eye to making it all mobile.

Disaster Life Cycle: Too Elementary for Reality

The disaster life cycle: Preparedness, Response, Recovery, Mitigation, Repeat.

That’s my growing issue with the disaster life cycle when applied to the public.  The cycle is flat and prescriptive implying that disaster will occur again the same way.  Life is a spiral.  Some days, the spiral the goes up and some days the spiral goes down.  But the spiral never puts you back to last week because your experiences have changed you.  We needs to reflect that life is constantly moving and doesn’t cleanly split into four buckets.

The right information at the right time will help people make better and more informed decisions on what immediate actions to take to be safer.  Just after a disaster, the right information at the right time will help people build back better.  If they take the wrong (or none) actions, the survivors will build back the same or at a lower state of resilience.  Either way, disaster survivors don’t return to a pre-disaster state; they move to a new normalcy.

People and communities are more than physical.  Disaster impacts people socially, politically, economically, emotionally and spiritually too.  These are not in lock-step together and do not move through the traditional disaster life-cycle together.  That’s another issue I have.  A house can be rebuilt quickly, but the emotion trauma can slow the house becoming a home again.  An injury or death may be physically handled, but the spiritual trauma to the survivors may be long lasting.

We need a way to explain pre-disaster, during disaster, and post-disaster on a continuum to reflect that every disaster is a major disaster to an individual, and that each survivor is on a unique recovery path of thing we can see and things we can’t see.

White Rabbit teaching method

The White Rabbit from Alice in WonderlandThere are instructors that want to have the course lesson completely planned out so they know exactly what to say at what time.  I’m not really one of those instructors.  There are definite objectives that need to be reached during a class session but the path doesn’t need to be that prescribed.  I’d rather let the class be a discussion with the students and let them help drive the direction of some the class.  If there is students’ desire to slow down to really explore a topic in depth, then by all means the instructor needs to do it.  The instructor is there to teach the student.  Interest by the students needs to be taken hold by the instructor and promoted.  Ignoring students’ interest is a great way to spend two hours hearing your voice bounce off the back wall uninterrupted.

I describe my teaching style as following the White Rabbit.  Chase the White Rabbit to see where the path leads.  When I’m on my game, we can chase the White Rabbit yet still direct that character to get us to the royal Hearts in the end.  Is there any other way to explain how I can be teaching a lesson on GIS, but split off and explore sexagesimal numeric systems?

Here’s a rabbit hole that we’ll “randomly” fall into during my GIS lesson…

I’m sure that all this talk about degrees, minutes and seconds has made you wonder why there are 60 seconds in a minute, 60 minutes in an degree and 360 degrees in a circle.  We have the Babylonians to thank for that.  They used a base-60 numeric system (sexagesimal) that is used in both time measurements and angles.  You are familiar with a based-10 numeric system (denary), and maybe a base-16 (hexadecimal) if you program computers.  Latitude and longitude are minutes of an arc that originates in the middle of the Earth.

Sexagesimal numbers would name each place past the point in Latin: primus, seconde, tierce, etc.  Minutes are the first position.  Second position is 1/60th of a minute, or seconds as we call them.

While we are off topic, there are 24 hours in a day because the ancient Egyptians used sundials that showed 10 parts day, 10 parts night, 1 part morning twilight, and 1 part evening twilight.

Has anyone ever come up to me in a disaster and asked why our time is a base-60 numbering sequence?  Well, no.  But it is handy knowledge where you’re at a cocktail party, the conversation is in an uncomfortable silence, and you have nothing else to say.

Back to the class.

And here we are.  The students have another peice of trivia stuck in their head.  Some will never think of it again.  Some will keep it as curious trivia to help understand.  A few will think it is the best thing shared all night.