What it means on the air: MFSK is multiple-frequency-shift keying, a modulation family that encodes information by selecting among more than two discrete tones.
Why operators use it
Interleaving and error correction can make MFSK variants resilient to fading and impulse noise, but tone count, spacing, baud rate, and bandwidth must match.
Where the contact goes wrong
MFSK is a family, not one interoperable mode; choosing the wrong variant can produce a visible signal with no readable text.
A cleaner operating method
Name the exact mode, set the software and filters to its occupied bandwidth, center the tones, avoid audio clipping, and use appropriate power for its duty cycle.
Operating boundary
Use current software and radio documentation, published band plans, applicable licensing rules, and the lowest power that closes the path. A decode, map position, or automated exchange does not by itself prove end-to-end communication.
