What it means on the air: QSB is the Q signal for fading—variation in received signal strength caused by changing propagation, multipath, polarization, movement, or other channel effects.
Why operators use it
Fading may be slow or rapid and can selectively affect tones or parts of a wide signal. It is a path behavior, not automatically a transmitter fault.
Where the contact goes wrong
Increasing power during every fade may add interference without fixing deep multipath cancellation.
A cleaner operating method
Wait through the fade, use concise repeats, diversity or a different antenna when available, adjust band or timing, and distinguish recurring equipment intermittency from propagation by comparing other signals.
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.
