Foundations Of Amateur Radio

Foundations of Amateur Radio The continued discussion in our community about Digital Modes got me thinking about what a Digital Mode actually is. At the most fundamental level, it's about encoding information into discrete chunks to exchange information. Morse Code is an example of a Digital Mode, made up from combinations of dits and dahs. If you change frequency whilst sending dits and dah's you invented RTTY or Radio-teletype. There are two frequencies involved, 170 Hz apart, where the lower frequency is the SPACE frequency and the upper frequency is the MARK frequency. If someone gives you a RTTY frequency, they're talking about the upper frequency. Instead of using Morse Code to send messages, RTTY uses 32 different codes, 5 bits, to exchange information. This isn't enough for the entire alphabet, with digits and punctuation, so two of the codes are used to swap between Letters and Numbers. Some radios can change frequency between the lower SPACE and upper MARK frequencies in a single transmission. T