I’m someone who is involved with the ARES group of the Peel Amateur Radio Club. I am an Assistant Emergency Co-ordinator that handles documentation for the group – which consists mostly of maintaining a MediaWiki instance. This site holds articles and educational material for our ARES group.
At one of our simulated emergency tests last year, one of the problems we ran into was traffic congestion. Packet communication was not possible with the endpoints, thus most traffic passing had to go through traffic nets. The lack of packet was unfortunate, as packet can speed up message passing, but at the same time, you could not guarantee that your communication partners have packet available. With this in mind, I started to wonder if there was a digital mode that could be used that could be easier to deploy than packet in a pinch, and it would work well on VHF/UHF. With a little bit of digging, I came across an incredible digital mode – MT63.
MT63 is a digital mode that uses multiple audio frequencies within the voice band for the particular band you are operating. For example, MT63-2K uses a 2.4 kHz wide band to transmit over VHF and UHF. If you are operating on HF, you can use MT63-500 for a 500 Hz wide band. The most important thing about MT63 is that it has very good noise tolerance. The multi-frequency transmission has data redundancy and code-correction which allows users to permit loose audio coupling of a radio to a computer. Basically, that means that you can type up your message, transmit the message via your computer speakers, hold your radio mic with the PTT depressed for transmission, and the receiving party simply can hold their radio next to the computer mic and decode the transmission. The data rate is much faster that trying to spell out the message verbally. An added bonus, MT63 does not need a TNC, interface cables, or other extraneous items save a radio itself. This kind of simple flexibility can be done ad-hoc through simplex communications, or even through a repeater. If your immediate environment can be noisy, MT63 can cope with background noise which allows for the loose audio coupling.
MT63 is supported by Ham Radio Deluxe, but it really shines when you use MT63 with FL-DIGI and the NBEMS collection of software. FL-DIGI is open source software. It runs on Windows, Mac, and Linux, and it has support for ICS/IMS forms through the use of FL-MSG software. FL-DIGI has no need of external modems, as it can process digital transmissions via the sound card. FL-DIGI can do a whole plethora of digital modes, but MT63 is a great mode to use for your emergency communications.
Joe de VA3POR