The R-S-T System

	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 ac or less, very rough and broad.
2	Very rough ac, very harsh and broad.
3	Rough ac tone, rectified but not filtered.
4	Rough note, some trace of filtering.
5	Filtered rectified ac 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.