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The R-S-T system

The R-S-T 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.

For non-CW (non Morse code) signals, the Tone (i.e. last) digit is normally omitted.



R1 - Unreadable

R2 - Barely readable, occasional words distinguishable

R3 - Readable with considerable difficulty

R4 - Readable with practically no difficulty

R5 - Perfectly readable



S1 - Faint—signals barely perceptible

S2 - Very weak signals

S3 - Weak signals

S4 - Fair signals

S5 - Fairly good signals

S6 - Good signals

S7 - Moderately strong signals

S8 - Strong signals

S9 - Extremely strong signals



T1 - Extremely rough hissing note

T2 - Very rough AC note, no trace of musicality

T3 - Rough, low-pitched AC note, slightly musical

T4 - Rather rough AC note, moderately musical

T5 - Musically modulated note

T6 - Modulated note, slight trace of whistle

T7 - Near DC note, smooth ripple

T8 - Good DC note, just a trace of ripple

T9 - Purest DC note

Informal use of the most common Q-codes

QRG - Frequency

QRM - Interference from other stations

QRN - Interference from atmospheric noise or from nearby electrical apparatus

QRO - High-power

QRP - Low-power

QRT - Close(d) down

QRV - Ready

QRX - Stand by

QSB - Fading

QSL - Verification card; confirm contact

QSY - Change frequency

QTC - Message

QTH - Location

QTR - Time


Note also: QTHR means: Address is correct in the current RSGB yearbook

International Morse Code

1. The length of a dot is one unit.

2. A dash is three units.

3. The space between parts of the same letter is one unit.

4. The space between letters is three units.

5. The space between words is seven units.