R.S.T In Amateur Radio

 R.S.T In Amateur Radio

Amateur radio enthusiasts and operators use the readability-strength-tone system (R-S-T) to share information about the quality of signals on the receiving end of the communication.

Each of the three digits (R-S-T) shows the values of a signal’s readability, strength, and tone.

History Of The R-S-T System

The first instance of recognized use of the R-S-T system in amateur radio communications dates back to 1934. Before this, Receiver Meters (R-Meters) and Signal Meters (S-Meters) were proposed for amateur radio use.

In the early 1940s, a proposition to standardize the manufacture of S-Meters was shot down by manufacturers because of the variation of the receiver gain distribution between bands.

One of the earliest instances of R-S-T use originated from the Q-Signal system, where the code QSA was used to enquire about signal strength.

In 1925, during the initial stages of using the R-S-T system, the R system was used to indicate audibility. It used:

R1- Indicated that the audio signals were faint.

R2- Indicated that the signals were weak and almost unreadable.

R3- Indicated that the signals were weak but a little readable.

R4- Indicated that the signals were fair and easy to read.

R5- This code indicated that the signals were strong but moderately so.

R6- Indicated that the signals were strong.

R7- Indicated that the signals were strong enough to be read through heavy static noise and signal interference.

R8- Indicated that the signals were very strong.

R9- Indicated that the signals were extremely strong.

This system gave birth to the R-S-T system as it is today.

In 1934, Arthur M. Braaten (W2SR) proposed a new standard of reporting signal information. This new way turned out to be the R-S-T system.

W2SR’s method of reporting signals was simple. It comprised a scale describing the strength of the signal;

1 for faint signals,

2 for weak signals,

3 for fairly strong signals,

4 for good signals,

And 5 for excellent signals.

Later, the scale was expanded to a 9-number scale.

The T (Tone) is also measured on a 1 to 9 scale. It is used in morse code and digital transmission modes to monitor imperfections that would not otherwise be detectable by the human ear. It is, however, omitted in amateur radio communications.

In 1936, the American Radio Relay League Handbook contained the basic version of the modern-day R-S-T system.