Last week I spent most of the article discussing listening options. Well, surprise, We’re not done with that topic quite yet, after all we do have two ears and only one mouth right?
Amateur radio operators are often called upon to establish communications during and after disasters. This kind of voluntary works puts them right in the action as they pass messages from one point to another. These various points of communication are often operational centers for disaster management organizations, so listening in on them would give you first hand knowledge about what exactly is going on. The following is a table of pre determined frequencies that emergency operators will use…plus or minus a few khz if they need to move around a bit due to interference or poor conditions.
|80 M||3.675 MHz LSB||Alfa||3.535 MHz||Golf||3.596 MHz||Mike|
|40 M||7.135 MHz LSB||Bravo||7.035 MHz||Hotel||7.096 MHz||November|
|20 M||14.135 MHz USB|
|17 M||18.135 MHz USB||Delta||18.075 MHz|
21.235 MHz USB
|Echo||21.035 MHz||Kilo||21.096 MHz|
|10 M||28.235 MHz USB||Foxtrot||28.035 MHz||Lima||28.096 MHz||Romeo|
Of course it goes without saying that you should NEVER interfere with emergency frequencies as lives are often on the line. Notice that every band has three modes and each band/mode combination has it’s own tactical designation. This allows for quick and easy changes in communication methods. Of course, this is an open source and publicly available plan, but you can easily create your own, keeping frequencies and modes private, while instructing your peeps on how to communicate. It should be noted, if you are unfamiliar with terms such as “band” or “mode”, you really need to take an amateur radio course.
Now, gathering information is handy, but what if you want to actually exchange information with other preppers or groups? The UHF and VHF bands are handy for local comms, such as on a homestead, prepper retreat, or around the neighborhood, but they won’t get you much past that range wise without repeaters. HF is the way to go for any communications over distance. The HF (high frequency) bands are what hams use to communicate across oceans. Unfortunately, if a ham operator in Canada is rag chewing with another operator in say Europe, most likely other Canadian operators will not hear him. Here’s why. With HF bands, radio signals are bounced off of the ionosphere (actually the radio waves are bent, but you’ll learn about that by taking a course). The transmitting station sends a signal up to the ionosphere and that signal returns to earth a great distance away. The space between the signal being generated and the signal being received is called a skip zone, where no signals are being returned to earth. There is a bit of ground wave propagation, but not much.
These long distance (DX) transmissions are neat, and in the event of a global scenario, might get you some interesting information, but more than likely you will benefit the most from regional communications. Introducing the NVIS (Near Vertical Incidence Skywave). As the name suggests, instead of sending a signal to the ionosphere as far away as possible to get the greatest distance, instead we send the signal almost straight up. This the “near vertical” part. In the image below, you can see how that signal is returned in a very (relatively) tight area near the transmitter. Another bonus to this type of communications is the difficulty for people to use direction finding techniques to locate you, as the signal will appear to be coming from straight up.