HAM Radio 101

Signal Reporting | Ham Radio 101

This weekend I was on SSB for a few activities. While scrolling through the frequencies, I heard this conversation after a CQ. I am going to call Ham 1 AB8XXX and Ham 2 AB8YYY to protect those who don’t know better.

            Ham 1: AB8XXX

            Ham 2: No copy. Please come again.

            Ham 1: AB8XXX. Alpha Bravo 8 X-Ray X-Ray X-Ray

            Ham 2: I think that was an “A.” Is someone starting with an “A?”

            Ham 1: Alpha Bravo 8 X-Ray X-Ray X-Ray (louder)

            Ham 2: I got Alpha Bravo 8. I still need the suffix. We’re almost there!

Ham 1: Alpha Bravo 8 X-Ray X-Ray X-Ray. That’s three X-Rays (even louder this time)

Ham 2: Ah! Got you that time, finally. Alpha Bravo 8 X-Ray X-Ray X-Ray, you’re 5 9 into [wherever he was]

Ladies and gentlemen, I can fully assure you that if it takes even more than one time to fully comprehend a call sign, you do NOT have a 5 9 signal.

So, in honor of Ham 1 and Ham 2, and with May finally here, I wish you all a…


The day that everyone is truly 5 9.

So what do these numbers REALLY mean?

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 three-digit number conveys an assessment of the signal’s readability, strength, and tone. The code was developed in 1934 by Arthur W. Braaten, W2BSR, and was similar to that codified in the ITU Radio Regulations, Cairo, 1938, as noted by online sources.

The R stands for “Readability,” which is a qualitative assessment of how easy or difficult it is to correctly copy the information being sent during the transmission. In a Morse code transmission, readability (measured on a scale from 1 to 5) refers to how easy or difficult it is to distinguish each of the characters in the text of the message being sent; in a voice transmission, this refers to how easy or difficult it is for each spoken word to be understood correctly.

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

Measured on a scale of 1 to 9, “Strength” (S) is an assessment of how powerful the received signal is at the receiving location. Although an accurate signal strength meter can determine a quantitative value, in practice this portion of the RST code is a qualitative assessment, often made based on the S meter of the radio receiver at the location of signal reception.

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

Also measured from 1 to 9, “Tone” (T) only applies to Morse code and other digital transmission modes. With modern technology, imperfections in the quality of digital modulation able to be detected by human ears are rare and therefore not focused on in this article. Just be aware that the system exists.

Questions? Share them in the comments below or email me at KE8FMJ@gmail.com.

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