Power Source Considerations
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A recent round-table discussion on portable operation with limited power and its application in EMCOMM resulted in a question about solar power as a sole power source for Summit or Parks on the air operation. The question prompted a whole line of reasoning about not just alternative power, but the many factors involved in selecting and utilizing a variety of power sources.
Volts & Amps & Watts (Oh, my!)
The first thing to determine is the voltage and current demands you have to operate as planned, or the voltage and current limitations you face and must operate your equipment within. In an ideal situation you control the former, in some situations, such as EMCOMM, you may need to operate at the limits of the latter.
Since most amateur radio systems can operate off 12 volts (or something around 12 volts, usually ranging from 12-15V), you will normally be working with voltage in that range. If not, then you'll have to ensure voltage is somewhere within the range your equipment will handle. Handhelds, for instance, will often operate at lower power with as little as 7.2 volts input.
Automated Packet Reporting System (APRS)
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APRS is packet-based digital tracking and communication system. It's best known for allowing operators to report their position or weather station data by internet or radio and be tracked using APRS clients and websites like aprs.fi, but APRS is useful for more than that. APRS also allows simple short messages between operators, sort of a radio-based text-messaging system. As a matter of fact, there is a text-message gateway available, allowing an operator to use their APRS setup to send text messages to cell phones and receive responses!
Since APRS allows for position reporting it has applications in search and rescue, damage assessment situations, and public service events like running and bike races. By embedding amateur radio operators into the field teams their progress can be monitored via APRS utilizing both online and offline mapping systems.
Although this makes APRS a potentially robust tool for public service, it's also useful for other activities, such as our summer balloon launches, where the balloon carries an APRS transmitter we then track to recover the balloon payload, which usually includes cameras and other electronics.
Tabletop Exercises
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Tabletop exercises are a useful tool for developing the skills to operate in a real-world situation, with the opportunity to identify many challenges and pitfalls before ever going through the effort of staging an actual exercise or deploy to an actual disaster.
Why tabletop versus a Simulated Emergency Test type exercise? Well, they are easier to plan and execute, all you need is a meeting place, and even the table is optional! Trying to coordinate an actual drill may require coordination with served agencies and place demand on physical resources like repeaters, radio equipment, or even served agency locations; all of this takes time and often places demands on other organizations.
Tabletop exercises can often be executed in an hour or two, where actual drills typically run much longer, placing more demands on the time of volunteers.
Tabletop exercises provide an opportunity to develop a plan or just work the bugs out of existing plans by playing "What if" games and talking through option when dealing with mission critical information such as knowing primary and backup repeaters, what to do when repeaters are down, frequencies and timetables for simplex communication, etc.
Why Digital Communications?
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We've been covering various digital modes over the past few months, particularly PSK, APRS & Winlink.
While digital voice modes like D-Star, Fusion, and others offer some other EMCOMM related enhancements to our conventional analog modes, the real improvement in our ability to communicate comes from our ability to automate various functions and communicate complex data more efficiently, digital modes that allow us to harness the power of computers.
While operators tended to deploy more as "shadows" of key personnel like ambulance drivers, police, fire, or shelter employees in decades gone by, the growing ability of local, state, and federal agencies to interoperate has virtually eliminated the need for such services.
As a result, our mission required change, and are still changing. Communities with active Community Emergency Response Teams (CERT) often embed amateur radio operators as members, serving as a CERT member, enhancing their team with additional communication capabilities. Amateur Radio operators have been included in Search and Rescue (SAR) and Damage Assessment teams during disasters as well.
Linked Repeater Networks
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Many National Weather Service offices in the U.S. include Amateur Radio as a part of their operations plan, and most of those utilize a linked repeater network of some sort. We’re going to cover the general concept of a linked repeater network as well as how they work, and why local weather nets are often held on non-network repeaters.
A linked repeater network is a coordinated group of repeaters that rebroadcast radio transmissions picked up by other repeaters on the network, allowing ham radio operators hundreds of miles apart to communicate using a simple handheld, mobile, or fixed base radio. As a result, the NWS can keep up with weather conditions over a broad area, and operators can be forewarned of incoming weather conditions that may require local monitoring.
So, how do linked repeaters actually link? Linked repeaters have a 2nd radio interfaced with the repeater’s main radio, often called a “remote base”. This allows a signal coming in from the Remote Base to be transmitted by the repeater’s main radio and a signal coming in on the repeater’s main radio to be rebroadcast on the Remote Base.
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