RST – Readability Reports

The RST system is used by amateur radio operators, shortwave listeners, and other radio hobbyists to exchange information about the quality of a radio signal being received. The code is a three digit number, with one digit each for conveying an assessment of the signal’s readability, strength, and tone. The code was developed in the 1934 by Amateur radio operator Arthur W. Braaten, W2BSR

NOTE: Tone is only used for CW (Morse Code)

Readability – R

2Barely readable, occasional words distinguishable
3Readable with considerable difficulty
4Readable with practically no difficulty
5Perfectly readable

Signal Strength – S

1Faint signals, barely perceptible
2Very weak signals
3Weak signals
4Fair signals
5Fairly good signals
6Good signals
7Moderately strong signals
8Strong signals
9Extremely strong signals

Tone – T

1Sixty cycle a.c. or less, very rough and broad
2Very rough a.c. , very harsh and broad
3Rough a.c. tone, rectified but not filtered
4Rough note, some trace of filtering
5Filtered rectified a.c. but strongly ripple-modulated
6Filtered tone, definite trace of ripple modulation
7Near pure tone, trace of ripple modulation
8Near perfect tone, slight trace of modulation
9Perfect tone, no trace of ripple or modulation of any kind