RST Signal Reports

The RST code is used by amateur radio operators, shortwave listeners, and other radio hobbyists to grade the quality of a radio signal being received. The code is a three digit number, with one digit each for the signal's READABILITY, STRENGTH and TONE.

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R-S-T Characteristics	Readability R	Strength S	Tone (CW only) T
1	Unreadable	Faint signals, barely perceptible	Sixty cycle a.c or less, very rough and broad
2	Barely readable, occasional words distinguishable	Very weak signals	Very rough a.c., very harsh and broad
3	Readable with considerable difficulty	Weak signals	Rough a.c. tone, rectified but not filtered
4	Readable with practically no difficulty	Fair signals	Rough note, some trace of filtering
5	Perfectly readable	Fairly good signals	Filtered rectified a.c. but strongly ripple-modulated
6	N/A	Good signals	Filtered tone, definite trace of ripple modulation
7	N/A	Moderately strong signals	Near pure tone, trace of ripple modulation
8	N/A	Strong signals	Near perfect tone, slight trace of modulation
9	N/A	Extremely strong signals	Perfect tone, no trace of ripple or modulation of any kind