When a contact is made using amateur radio, both stations usually want to know how well their signal is heard by the receiving station. The system they use is called RST.
Why is it called RST?
RST is actually an acronym. This stands for R – readability, S – strength and T – tone.
Signal reports are always given as numbers, e.g. 599. The exception to the rule is when 5NN is used in CW (Morse code). Why is CW the exception? Simply because it is quicker and easier to send the letter “N” rather than the number 9.
The next question has to be, what do the numbers mean?
Taking each part of the RST in turn, the numbers have the following standardised meanings.
Value from 1 to 5.
1 – Unreadable
2 – Barely readable, occasional words distinguishable
3 – Readable with considerable difficulty
4 – Readable with practically no difficulty
5 – Perfectly readable
Value from 1 to 9.
1 – Faint signal, barely perceptible
2 – Very weak signal
3 – Weak signal
4 – Fair signal
5 – Fairly good signal
6 – Good signal
7 – Moderately strong signal
8 – Strong signal
9 – Extremely strong signal
(CW and digi-modes only): Value 1 to 9.
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
In the case of SSB, there is no tone consideration so the signal reports are given in a slightly different format.
The Strength is commonly replaced by the radio signal meter reading.
Most transceiver signal meters display the signal strength using the dB (deciBel) scale.
Therefore operators will be heard giving reports similar to “you’re 5 by 9” or “5 by 9 plus 10”.
The use of macros in digi-mode software has now turned the use of RST signal reports into a mockery.
Some stations will now simply send you a report of 599 regardless of the actual signal you are producing. This is especially true during contests where the station can hardly hear you, yet they will give a 599 report just to get you in their log, scoring points in the contest.
I have lost count of the number of times I have heard a station asking for details again, again, again, only to reply “You’re 5 by 9”
Is it better to know if the signal sounds terrible? I certainly think so!
In conclusion, I guess there’s a fear of upsetting someone these days, rather than give an honest and helpful report!