CommoFreq
Member
Hello everyone,
I'm brand new to the board, and right off the bat, I'm seeing some advanced communications discussions taking place here. I've decided to take what we already know, and simplify it for those who know absolutely zilch about radio communications, and are interested in learning more.
Let's begin!
1. I'm sure that most of you, after thinking about Doomsday, instantly thought of CB radio or FRS walkee-talkees. Here's a few reasons why you don't want to rely on that:
a) "CB" stands for "Citizens' Band" - that is, a radio for "citizens", i.e., every swinging d--- on the planet. When everything goes to Hell, you can rest assured that everyone else will have the same idea. Imagine walking into an auditorium packed full of crowded people. That's what CB radio will sound like during an apocalypse. And no, that's not a theory - that is a fact. This is what truck drivers use.
b) Fresh out of the box, a CB radio will put out a maximum of 4 watts (thanks to federal law). This will get you about a mile of range on average.
c) If you don't want to be "found" and would rather be incognito (which is intelligent), using a radio that millions of others will be using is not a great idea.
d) Yes, have one to listen into what's going on around you, and play with it now so that you can learn more about how radios work. No, don't use it for communications unless you absolutely must in the event of mass chaos. The same applies to FRS walkee-talkees.
2. Ham radio is a dying hobby. You can't just run to your local Wal-Mart or Radioshack and buy one. These radios are now a very exclusive item to have. Some (but not all) places that DO sell them, will ask to see your ham license before they'll even sell you one. They are becoming few and far between, and this means guaranteed communications away from interference caused by a panicked populace.
a) Yes, right now, you must have a license to use one. No, in the event of the apocalypse, that requirement goes right out the window, along with everything else in life.
b) If CB and ham radio were both telephones, a CB radio would be more like a rotary phone from the '60s, and a ham radio would be like an Apple iPhone 4.
c) Ham radio can therefore be as simple or as complex as you need it to be. You can hook one up to a computer and send text, or, you can have one in your vehicle and use it like a truck driver uses a CB radio. You can talk locally, or, you can communicate over distances of thousands of miles. They even come in walkee-talkees, which, when accessing a repeater, is just like using a base station.
d) A tri-band radio (like an IC-7000) will suit any and every possible need, guaranteed.
3. Think always of radio communications in terms of "frequencies". A frequency is simply a number. Radio stations have them. My favorite is 101.5 FM, which is a classic rock station. Other radios are no different than the one in your car, except for the fact that you can send information out as well.
a) CB radios have 40 "channels". Without getting too in-depth, you could consider this to be like having 6 "favorite radio stations" saved on those 6 buttons on your car radio, that jumps straight to the station. These 40 frequencies are spaced out between 29.965 AM and 27.405 AM., but unlike your car radio, you can't change them - they are permanently programmed.
Such a range of frequencies is called a "band". And that particular range is called, "Citizens' Band". The radio in your car has a range of 87.5FM to 108.0FM. This is also another "band", called the "FM Band" or "FM Broadcast Band". If you live near a large body of water, then you probably have heard of "Marine Band" radios, or, radios for boats. Those are from 165.0 FM to 162.025 FM.
b) In the above examples, one radio seems to cover one band. Ham radio, however, includes many different bands. And while in the above examples, each band has some kind of a "name", ham radio bands are named by meters (i.e., the 10 meter band 28.0-30.0, 2 meter band 144.0-148.0, and the 70cm band 430.0-440.0). This is because if you could physically see the radio waves coming out of the antenna, this is roughly how long they would be (not very creative, I know - I would have named them names like "the long-distance band", and the "super duper band", etc.). And like the above examples, there are ham radios which only handle one band. But, there are others that will handle multiple bands.
Confused yet?
c) As a general rule for frequencies: "30.0 is the boundary between two worlds".
0 - 30.0 is used for long distance communications on AM. This is because these waves like to bounce around. We don't understand exactly why this is so, but this is just part of their physical properties. The more they bounce, the farther they travel. They even bounce off of the atmosphere and back down to the ground, multiple times, if you can imagine how many thousands of miles that would include.
30.0 and up is used for local communications on FM. These waves tend to be absorbed by other objects more than they bounce. Of course, they are more "bouncy" at 30.0 than they are at, say, 440.0. But you get the point. Under 30.0, use AM. Over 30.0, use FM. There's much more to that story, but for beginners, this is what you need to know.
So, if you buy a ham radio that only covers 2 meters (144.0-148.0), then no, you are not going to be using it to talk to someone hundreds or thousands of miles away. For that, you will need a radio that covers o - 30.0, which is also known as HF.
4. Your success depends more on the antenna than on the radio.
Here's how this works, in a nut-shell:
a) Your radio will send a signal through a coax cable to the antenna, and that signal has a certain amount of power. It's the antenna's job to radiate that signal out. The more efficiently it does this, the stronger your radio signal will be, going out. In other words, if two radios - one with the right antenna and one with the wrong antenna - both sent out a signal with the same amount of power, one may have the same amount of power coming out of the antenna, and the other would have significantly less power coming out of the antenna than what the radio is generating.
So how does one make an antenna more "efficient"?
b) What this means is, your antenna has to be around the same length (or a perfect fraction of) the actual physical radio sine wave. It also means that you want that coax cable to be as short as possible, because the more cable it has to travel through, the more metal it has to travel through to get to the antenna (we call this "resistance").
c) This is why some antennas are longer than others. It has nothing to do with one being "better" than the other. The physical radio wave length has to somehow have something in common with the length of the antenna, or the antenna simply won't work.
d) As an example, we look at the 70cm band, which is 430.0-440.0 FM. How long is the antenna? You guessed it! It's 70cm long. This is called a "full wave" antenna (experienced ham operators, please shut up - I know, I know), because its length is exactly the same length of the radio frequency going out of it, that being, 70cm.
For this band, we *could* also use an antenna that is exactly half as long, (a half-wave antenna), or 1/4 as long (a quarter-wave antenna). We do that because sometimes, a true full-wave antenna would simply be too long to put on a car, for example. Imagine if you wanted a full-wave antenna for the 10-meter band! No car is going to have an antenna on it that is 10-meters long. Oh, and FYI, the "Citizens' Band" that you find truck drivers using, is also known by hams as the "11-meter" band.
e) What happens when the antenna length isn't "related" to the frequency you're using? If that radio wave can't smoothly exit the antenna, then only part of it will, and part of it won't. If part of it. . . "won't". . . then what happens to it then?
It gets reflected back down the antenna, back down the coax cable, and back into your radio. This is not good for your radio. It could handle it for a little while, depending on how often you use it, but eventually, this will burn up your radio.
This is where we get into what is called "SWR", or "Standing Wave Ratio". You can get a meter that you can connect between the radio and the antenna, that will tell you how much signal is going out of the antenna and how much is going back into your radio. We use them to adjust antennas to the correct length. And yes, truck stops have them.
5. Yes, you can be tracked down.
This applies to any radio - CB, ham, walkee-talkees, etc. And it's extremely easy to do. If someone was looking for you, they would use a process called "triangulation", which involves a directional antenna, a ruler, and a map. They measure your signal while you are transmitting, find the azimuth where it is strongest on their directional antenna, and draw a line on a map. They change locations, and repeat. After 3 times, wherever the lines intersect on the map, is where you are sitting.
This is why it's important to limit your communications as much as possible. It's also important to use different frequencies for your needs as often as possible. And lastly, use only the amount of power that you need to. If you think that someone is trying to track you down, it would be wise to cease communications completely, or if you have a ham radio, switch to a radically different band entirely.
If you have any questions, or would like more in-depth information, don't hesitate to ask. From what I've seen, the Communications Forum has a lot more detailed info that you will hopefully be able to better understand.
I'm brand new to the board, and right off the bat, I'm seeing some advanced communications discussions taking place here. I've decided to take what we already know, and simplify it for those who know absolutely zilch about radio communications, and are interested in learning more.
Let's begin!
1. I'm sure that most of you, after thinking about Doomsday, instantly thought of CB radio or FRS walkee-talkees. Here's a few reasons why you don't want to rely on that:
a) "CB" stands for "Citizens' Band" - that is, a radio for "citizens", i.e., every swinging d--- on the planet. When everything goes to Hell, you can rest assured that everyone else will have the same idea. Imagine walking into an auditorium packed full of crowded people. That's what CB radio will sound like during an apocalypse. And no, that's not a theory - that is a fact. This is what truck drivers use.
b) Fresh out of the box, a CB radio will put out a maximum of 4 watts (thanks to federal law). This will get you about a mile of range on average.
c) If you don't want to be "found" and would rather be incognito (which is intelligent), using a radio that millions of others will be using is not a great idea.
d) Yes, have one to listen into what's going on around you, and play with it now so that you can learn more about how radios work. No, don't use it for communications unless you absolutely must in the event of mass chaos. The same applies to FRS walkee-talkees.
2. Ham radio is a dying hobby. You can't just run to your local Wal-Mart or Radioshack and buy one. These radios are now a very exclusive item to have. Some (but not all) places that DO sell them, will ask to see your ham license before they'll even sell you one. They are becoming few and far between, and this means guaranteed communications away from interference caused by a panicked populace.
a) Yes, right now, you must have a license to use one. No, in the event of the apocalypse, that requirement goes right out the window, along with everything else in life.
b) If CB and ham radio were both telephones, a CB radio would be more like a rotary phone from the '60s, and a ham radio would be like an Apple iPhone 4.
c) Ham radio can therefore be as simple or as complex as you need it to be. You can hook one up to a computer and send text, or, you can have one in your vehicle and use it like a truck driver uses a CB radio. You can talk locally, or, you can communicate over distances of thousands of miles. They even come in walkee-talkees, which, when accessing a repeater, is just like using a base station.
d) A tri-band radio (like an IC-7000) will suit any and every possible need, guaranteed.
3. Think always of radio communications in terms of "frequencies". A frequency is simply a number. Radio stations have them. My favorite is 101.5 FM, which is a classic rock station. Other radios are no different than the one in your car, except for the fact that you can send information out as well.
a) CB radios have 40 "channels". Without getting too in-depth, you could consider this to be like having 6 "favorite radio stations" saved on those 6 buttons on your car radio, that jumps straight to the station. These 40 frequencies are spaced out between 29.965 AM and 27.405 AM., but unlike your car radio, you can't change them - they are permanently programmed.
Such a range of frequencies is called a "band". And that particular range is called, "Citizens' Band". The radio in your car has a range of 87.5FM to 108.0FM. This is also another "band", called the "FM Band" or "FM Broadcast Band". If you live near a large body of water, then you probably have heard of "Marine Band" radios, or, radios for boats. Those are from 165.0 FM to 162.025 FM.
b) In the above examples, one radio seems to cover one band. Ham radio, however, includes many different bands. And while in the above examples, each band has some kind of a "name", ham radio bands are named by meters (i.e., the 10 meter band 28.0-30.0, 2 meter band 144.0-148.0, and the 70cm band 430.0-440.0). This is because if you could physically see the radio waves coming out of the antenna, this is roughly how long they would be (not very creative, I know - I would have named them names like "the long-distance band", and the "super duper band", etc.). And like the above examples, there are ham radios which only handle one band. But, there are others that will handle multiple bands.
Confused yet?
c) As a general rule for frequencies: "30.0 is the boundary between two worlds".
0 - 30.0 is used for long distance communications on AM. This is because these waves like to bounce around. We don't understand exactly why this is so, but this is just part of their physical properties. The more they bounce, the farther they travel. They even bounce off of the atmosphere and back down to the ground, multiple times, if you can imagine how many thousands of miles that would include.
30.0 and up is used for local communications on FM. These waves tend to be absorbed by other objects more than they bounce. Of course, they are more "bouncy" at 30.0 than they are at, say, 440.0. But you get the point. Under 30.0, use AM. Over 30.0, use FM. There's much more to that story, but for beginners, this is what you need to know.
So, if you buy a ham radio that only covers 2 meters (144.0-148.0), then no, you are not going to be using it to talk to someone hundreds or thousands of miles away. For that, you will need a radio that covers o - 30.0, which is also known as HF.
4. Your success depends more on the antenna than on the radio.
Here's how this works, in a nut-shell:
a) Your radio will send a signal through a coax cable to the antenna, and that signal has a certain amount of power. It's the antenna's job to radiate that signal out. The more efficiently it does this, the stronger your radio signal will be, going out. In other words, if two radios - one with the right antenna and one with the wrong antenna - both sent out a signal with the same amount of power, one may have the same amount of power coming out of the antenna, and the other would have significantly less power coming out of the antenna than what the radio is generating.
So how does one make an antenna more "efficient"?
b) What this means is, your antenna has to be around the same length (or a perfect fraction of) the actual physical radio sine wave. It also means that you want that coax cable to be as short as possible, because the more cable it has to travel through, the more metal it has to travel through to get to the antenna (we call this "resistance").
c) This is why some antennas are longer than others. It has nothing to do with one being "better" than the other. The physical radio wave length has to somehow have something in common with the length of the antenna, or the antenna simply won't work.
d) As an example, we look at the 70cm band, which is 430.0-440.0 FM. How long is the antenna? You guessed it! It's 70cm long. This is called a "full wave" antenna (experienced ham operators, please shut up - I know, I know), because its length is exactly the same length of the radio frequency going out of it, that being, 70cm.
For this band, we *could* also use an antenna that is exactly half as long, (a half-wave antenna), or 1/4 as long (a quarter-wave antenna). We do that because sometimes, a true full-wave antenna would simply be too long to put on a car, for example. Imagine if you wanted a full-wave antenna for the 10-meter band! No car is going to have an antenna on it that is 10-meters long. Oh, and FYI, the "Citizens' Band" that you find truck drivers using, is also known by hams as the "11-meter" band.
e) What happens when the antenna length isn't "related" to the frequency you're using? If that radio wave can't smoothly exit the antenna, then only part of it will, and part of it won't. If part of it. . . "won't". . . then what happens to it then?
It gets reflected back down the antenna, back down the coax cable, and back into your radio. This is not good for your radio. It could handle it for a little while, depending on how often you use it, but eventually, this will burn up your radio.
This is where we get into what is called "SWR", or "Standing Wave Ratio". You can get a meter that you can connect between the radio and the antenna, that will tell you how much signal is going out of the antenna and how much is going back into your radio. We use them to adjust antennas to the correct length. And yes, truck stops have them.
5. Yes, you can be tracked down.
This applies to any radio - CB, ham, walkee-talkees, etc. And it's extremely easy to do. If someone was looking for you, they would use a process called "triangulation", which involves a directional antenna, a ruler, and a map. They measure your signal while you are transmitting, find the azimuth where it is strongest on their directional antenna, and draw a line on a map. They change locations, and repeat. After 3 times, wherever the lines intersect on the map, is where you are sitting.
This is why it's important to limit your communications as much as possible. It's also important to use different frequencies for your needs as often as possible. And lastly, use only the amount of power that you need to. If you think that someone is trying to track you down, it would be wise to cease communications completely, or if you have a ham radio, switch to a radically different band entirely.
If you have any questions, or would like more in-depth information, don't hesitate to ask. From what I've seen, the Communications Forum has a lot more detailed info that you will hopefully be able to better understand.
