Archive for the ‘What is Ham radio?’ Category

Amateur Radio Activities – What is it? Hows it Work?

Saturday, September 22nd, 2007

Amateur Radio: What is it?

The Federal Communications Commission (F.C.C.) defines the Amateur Radio service as: “A radiocommunication service for the purpose of self training, intercommunication, and technical investigations carried out by amateurs, that is, duly othorized persons interested in radio technique soley with a personal aim and without a pecuniary interest”. Part 97.1(4)

So, what the heck does that mean? Well, Amateur Radio, as a service, is all volunteers. We provide our skills and equipment for use in public service, emergencies, and when any backup communication is needed by any other service. We can provide communications for such events as marathons, bike races, football games, search and rescue missions. We can relieve strain on current communications systems already in use, as well as bring up systems where there aren’t any or they have been rendered useless due to a catastrophic event. Two prime examples are the aftermath of Hurricane Katrina and the Wold Trade Center tragedy. Amateur radio played a vital role in linking emergency operations, hospitals, law enforcement, and public agencies. Amateur radio got through when current systems were down or over-crowded. The National Weather service also utilizes Amateur radio operators to get vital weather reports from on the ground – severe weather that is currently happening (tornadoes, large hail, strong winds) as well as report damage after a weather event.

OK, enough of the “practical” stuff.. lets cut to the FUN!

Amateur radio operators can talk to people anywhere – across town, across the state, across the country, even around the world. Yep, I just said around the country and around the world. Well, in actuality we can communicate OUTSIDE of this world. The Space Shuttle has a VHF Amateur radio station on board and most astronauts are licensed operators. We can also use a variety of satellites orbiting the Earth to communicate to one another. You know the big, round, white ball in the night sky? Yeah, the Moon. We can use that too! EME , or “Earth-Moon-Earth”, is the ultimate long-distance, weak signal mode of communications. You can literally bounce your radio signals off of the Moon. Pretty cool, huh?

Another activity is Amateur Television. This is sending live video and audio across the radio waves to other stations. This is similar to watching TV, only it is two-way. Amateur television systems can be used at home, in your car, remote monitoring sites, and even on remote controlled devices. Yep, you can put an Amateur Television system in a radio controlled airplane and fly it like you do playing a computer game. You can make your radio controlled car drive all around the house chasing your dog and not be in the same room.

Talking to other people on the radio waves is where 90% of all amateur radio operation takes place. We do this in a variety of ways. We can pick up a microphone and talk, this is called “phone” (SSB, AM, FM, Digital Voice). We can send Morse code with a “key”. Yep, Morse code is still used – its one of the BEST modes for cutting through weak signal and/or poor band conditions. Computers have been used in Amateur radio for many years now. We can type to other people over the radio as well as send and receive pictures and data.

DX’ing is a term we use for contacting people all over the world. Every country has it’s own unique letters and numbers in operators’ call signs. In the U.S., the prefixes can be one or two letters beginning with W, N, A, or K followed by any number 0-9 (there are 10 call districts). In Mexico the prefix begins with one or two letters beginning with X and has any number 0-9 following. The islands of Curacao and Bonaire begin with PJ2, PJ4, and PJ9. Every country/island/entity on the planet has its own designators.

QSL cards are exchanged between operators who wish to confirm their contacts. It’s one thing to write the information about the contact in a log, but you have to officially confirm that contact with a QSL card to show proof of that contact. These QSL cards can be used towards many different awards – Worked All States, DXCC (worked 100 or more DX entities), Worked All Continents, etc. Many operators like to display these as “wall paper” in their stations for visitors to look at.


Some of my “wallpaper” at my previous location. The left 3 are from Meteor Scatter contacts on the 2-meter band, the big cluster to the right (and they go lots further down) is my collection of cards from Top Band – 160-meters. I was working on the Worked All States award – Top Band only, all Morse code (separate endorsements). I got 30-some in a couple years of being on the band, the latter year being the most serious I was ever in to it.

Amateur radio is the ultimate “nerd” hobby. You can think and analyze Amateur radio for an eternity and never feel like you have done it all. You can get as deep in to it as you want or as shallow as you want.

To get a little deeper into the subject – Amateur radio is “radio communications”. We send out signals in electromagnetic energy to other radio operators – as close as a couple feet to as far as you can imagine, and then some.

How do radio signals get from one place to another? Well, we call this “propagation”. Throw a rock in a calm pond. See the ripples spreading out from where the rock went in to the water? These are waves. The same principle applies to radio waves, only you can’t see them, you can’t hear them, and you can’t feel them. They are all around us. They go everywhere. They come from just about everywhere. We, as radio operators, can make use of this propagation to
communicate.

There are a couple modes of propagation that are important, for starters.

1. Line of Sight
This is the propagation of radio waves in a straight line from one point to another. As long as the two antennas on the stations in communication can “see” each other (not literally) you can get a signal through. The density and material, as well as the distance between the station and radiated power all affect the strength of the signal at the other end. The higher the antennas of the stations communicating the further apart they can be. That is why cell towers are tall and antennas are mounted on tall buildings. This mode of propagation works best on frequencies in the VHF spectrum and above. However, the Shortwave bands also operate line of sight for
a little bit.

2. Sky Wave, or, for the geeks – Ionospheric Skip This is what makes the Shortwave bands (all those below 30mHz) work so well. These are the waves that can go all over the world. There are many things that affect how these waves propagate. The main factor is the ionization in the atmosphere. Basically, the sun charges up particles in the atmosphere (the F layers to be specific) and the radio waves bounce off this ionization. The take off angle of the signal, or the angle at which the signal propagates from the antenna, also affects how Sky Wave propagation works. The lower the angle (the closer to the horizon) the shallower the skip angle is of the atmosphere. The shallower the skip angle and the softer the reflection the further the radio signals go. The frequency of operation determines how soft the angle of reflection is. The higher the frequency the softer the reflection, the lower the frequency the harder the reflection. The frequency at which the signals no longer are reflected, but instead break through the atmosphere, is called the Maximum Usable Frequency. Depending on what this value is, the skip zone between the reflections changes. With the HF bands we can pretty much pick a frequency for wherever we are trying to get to. Now, I say that loosely. We try to contact different general areas – such as Africa, Europe, Australia,etc. The signals don’t go to one specific town. If you are operating an emergency or public service station and have a need to communicate with a specific station you can choose a specific frequency band to talk to where you need to talk to. Typically, if you are communicating within about 500-800 miles 40 meters is a good band. Further than that and 20 meters is preferable. However, with the current condition of the solar cycle these bands have degraded performance.

To make propagation easier to think about Ill use this analogy: a radio signal is like light. A regular light bulb, open, with no shield/cone (for directivity, like a headlight on a car), spreads light out equally well in all directions. Place it in the center of a room and it illuminates the whole thing well. The light emitting from the bulb is going to everywhere in the room by line of sight. The light “sees” everything. Now, put a big mirror on the ceiling near the doorway and in-line with the light bulb. Now look down the hall. See the patch of light? That is sky wave propagation. The light is reflecting off of the mirror on the ceiling to the floor of the hall, some several feet away.

If you have any interest in radio communications, Amateur radio is the ULTIMATE!!! Even though it is called “Amateur” the skill and usefulness are anything but “Amateur”. You can get as deep in to the subject as you wish. I can guarantee one thing – you will learn a lot with radios!