Before I take my leave from EmComm and revert to FunComm, I thought I would share some of my meditations on digital modes.
My use of digital modes goes back to the mid-2,000’s. I was an early adopter of Winlink and ran a regional digital PSK31 net. I have had the pleasure of working with many fine amateur radio operators with many different skill sets. Recently, I have had the opportunity to run a national digital PSK31 net for a few months. Again, the experience of working with amateur radio operators was a fun and fulfilling endeavor. I have used most of the modes for Winlink with VARA being the current favorite. Other modes I have used include PSK31, PSK125, QPSK125, Contestia, MT63, and Olivia. They all work as intended, however, when it comes to the less experienced digital operators, PSK31 is the easiest to master. I have run nets where we started on PSK31 and then moved to another mode and then back to PSK31. Many ops do fine on PSK31; however, once we move to a different mode, they get lost. When considering EmComm we should always play to the least common denominator.
My favorite modes for EmComm are:
1) Winkink/Vara. If I had to choose one, this would be it. With nodes all over the world, the probability of getting into a node is greater than if you had to depend on a single point. Because messages are stored until they are retrieved, Radios do not have to be left on to forward and retrieve messages. This can be done at any time and there is no need for a schedule. An operator can wait until favorable propagation exists. I have not tried VARAC yet, but it is on my to-do list.
2) PSK 31 and 125. I like PSK31. I have run a national net using it. Typically, I take check-ins on 31, send a message using FLMsg on 125, and then go back to 31. I have a much higher percentage of people getting the message using PSK31 than with other modes. On most modern radios, PSK31 can be decoded and sent without the use of a computer. While those at home with mains power see that as frivolous, a computer or laptop can be a serious drain on a battery when mains power is not available when operating under potable/emergency conditions. Because PSK31 has a narrow bandwidth (60 Hz) compared to MT63-1000s (1000 HZ), it enjoys a 2 S-unit advantage. Roughly that means a PSK31 message transmitting at 5 watts is equivalent to an MT63-1000s message transmitting at 100 watts (5 watts to 100 is about 2.2 S-unit gain and PKS 31 to MT63-100 is about 2.03). My point of view here is someone operating in the field, using portable equipment. In addition, we do not always get to choose who is in the field and who is at home. Throughput on PSK31 is about 50 wpm and MT63-1000 is about 100 wpm. If we bump up to PSK125 (which is about 1 S-unit better than MT63-1000) we get about 200 wpm.
3) My third mode would be CW and this would be used when nothing else is working. It requires the least amount of equipment and what can be used is not complicated. This would be an emergency mode. Any communications plan should include CW and any EmComm group should try to maintain a few CW ops on their rosters.
What would I do if I was in charge? I would try to keep the communications plan as simple as possible and play to the least common denominator. I would use the U.S. Army acronym PACE which stands for Primary, Alternate, Contingency, and Emergency. My plan would look something like:
a) Primary – normal infrastructure/internet-based communication. When it’s working, it’s the best. I have seen operators try to use their radios when there is a working FAX machine next to them.
b) Alternate – This could be a combination of Voice/SSB and Winlink. Establish a voice net because that is where most of the operators operate and provide an email address where to send Winlink Messages.
c) Contingency – This could be a Peer-to-Peer digital mode such as MT63-1000, or VARAC. I like the idea of VARAC because VARA is used by Winlink but I have to try it out before I can recommend it. Down at this level, the more experienced ops may not be prevalent, and it might be the less informed ops on the scene.
d) Emergency – This is no man's land in the EmComm community. The probability of us getting to Emergency is quite low, maybe 1%. Here you might find an operator with a radio and antenna while a geomagnetic storm is raging overhead. I have been deployed to a disaster area while a storm was raging, and we have had a couple of SETs with poor band conditions. Here might be the realm of PSK31 and/or CW.
What I am saying is to keep your comm plan simple. You don’t have a legion of professional-level operators on hand that can tackle all the modes available. What you do have are operators with widely varied skill levels, with amateur radio either a secondary or tertiary interest. Pick the fewest modes that use the fewest different types of software and stick with them. Don’t forget to train, train, train. Additionally, have exercises that get operators out in the field. Field ops are hugely different than operating from home. Try to get them at least 20 miles from their home, this reduces the run home for something I forgot. Many times, during a deployment/exercise there were ops who could not complete the tasking. I like to go camping at least once a month and bring my radios with me. I usually do a POTA activation; it gives my radio system a good shakedown and helps me understand its performance. Get out, get on, and go do! 73 de Scott
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