wip/ft8-lib 0.1 NetBSD

A C++ implementation of FT8 protocol, mostly intended for experimental use on microcontrollers. The intent of this library is to foster experimentation with e.g. automated beacons. For example, FT8 supports free-text messages and raw telemetry data (71 bits). The encoding process is relatively light on resources, and an Arduino should be perfectly capable of running this code. Decoding is is still work in progress. So far a 15-second WAV file can be decoded on a desktop machine or SBC, and the routines are somewhat ready for a fast microcontroller, perhaps with some tradeoffs. One definite limitation is the necessity to store the whole 15-second window in some representation (either waveform or DFT spectrum) for decoding at the end of the time slot. The current implementation uses about 200 KB of RAM for that purpose. # --- What works --- Currently the basic message set of the revised FT8 protocol with 77-bit payload (introduced since WSJT-X version 2.0) is supported: * CQ {call} {grid}, e.g. CQ CA0LL GG77 * CQ {xy} {call} {grid}, e.g. CQ JA CA0LL GG77 * {call} {call} {report}, e.g. CA0LL OT7ER R-07 * {call} {call} 73/RRR/RR73, e.g. OT7ER CA0LL 73 * Free-text messages (up to 13 characters from a limited alphabet) (decoding only, untested) * Telemetry data (71 bits as 18 hex symbols)