What do "QRM" and "QSB" refer to?

Question

An answer on Basic QSO format? mentions things like "QRM" and "QSB". What do those terms mean?

Answer 1

"QRM" is one of many Q-codes used as abbreviations in radio communication. "QRM" in particular refers to human-generated interference (as opposed to "QRN" which is used to refer to atmospheric noise). "QSB" refers to fading (variation in signal strength over time).

The codes originated from the desire to keep CW (morse code) transmissions as brief as possible due to the format's inherent bandwidth limits, but have stuck around and now often show up as abbreviations in regular conversation as well.

Answer 2

I keep these "Q" signals in line with this :

• QRN is "N"atural band noise ( lightning )
• QRM is "M"an-made band noise ( crowded signals )
• QSB is "B"utterfly effect from Ionosphere in-stability.

Answer 3

QRM is interference in general, regardless of the source, mostly because it's rarely obvious what the source is. QRN is static, like with wall switches and atmospheric noise. Not sure where / when the "man-made" and "nature-made" thing came about, but I don't believe they are generally understood meanings of those Q-codes.

Answer 4

To clarify some of the definitions of QRM here:

QRM is a signal from another radio station, that is interfering with you hearing the station that you are in QSO with (or you want to receive).

• It can be any mode: CW, SSB, AM, digital, etc.
• It can be another amateur station
• It can be a shortwave broadcast station.
• It can be a jamming station run by a country.

QRN is lightning, power line arcs, or similar RFI.

Answer 5

I may have introduced a new Q code, it is used locally and often. QRM - (Man) made, such as electrical, cross talk, etc QRN - (natural), lighting QRW - (wife) occurs when husband spends excessive time on the air