The author labled this mode as a 4-FSK modulation so this is why it is under FSK
This mode is intended to use as a network of beacons to report across the internet for real time propagation conditions, it also has the abilitiy to band hop.
Standard message: callsign + 4-digit locator + dBm (e.g., K1ABC FN20 37)
Messages with a compound callsign and/or 6-digit locator use a two-transmission sequence. The first transmission carries compound callsign and power level, or standard callsign, 4-digit locator, and power level; the second transmission carries a hashed callsign, 6-digit locator, and power level. Add-on prefixes can be up to three alphanumeric characters; add-on suffixes can be a single letter or one or two digits.
Standard message components after lossless compression: 28 bits for callsign, 15 for locator, 7 for power level, 50 bits total.
Forward error correction (FEC): non-recursive convolutional code with constraint length K=32, rate r=1/2.
Number of binary channel symbols: nsym = (50+K-1) * 2 = 162.
Keying rate: 12000/8192 = 1.4648 baud.
Modulation: continuous phase 4-FSK, tone separation 1.4648 Hz.
Occupied bandwidth: about 6Hz
Synchronization: 162-bit pseudo-random sync vector.
Data structure: each channel symbol conveys one sync bit (LSB) and one data bit (MSB).
Duration of transmission: 162 * 8192/12000 = 110.6 s.
Transmissions nominally start one second into an even UTC minute: e.g., at hh:00:01, hh:02:01, etc.
Minimum S/N for reception: around -28 dB on the WSJT scale (2500Hz reference bandwidth).
If you ran across this on the radio you might think it is a birdie in your radio due to the small bandwith.