Readability Basics

Everyone wants to know how their signal sounds on the air and often the best way to find out is a signal report from other ham radio operators. The standard signal reporting method for amateur radio is the RST (Readability-Signal Strength-Tone) system (see below).

The RST system as listed on the ARRL web site, Quick Reference Operating Aids:

Readability
1 – Unreadable
2 – Barely readable, occasional words distinguishable.
3 – Readable with considerable difficulty.
4 – Readable with practically no difficulty.
5 – Perfectly readable.

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

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