One of the most basic features of an amateur radio contact (ham-speak=QSO) is an exchange of signal reports so each participant knows how well they are coming through. If either end has a poor signal then usually the exchange is minimized to avoid the frustration of trying to copy the other ham. Conversely, a good signal report means you are likely to have a good QSO and can exchange a lot of information if you want to.
Signal reports vary with operating mode and other factors. We will look at three basic types: CW (Morse code), general phone (voice), and repeater use (very different here).
The complete standard ham radio signal report is a three number code representing Readability, Strength and Tone, or RST. The RST system is defined as follows:
R = Readability
1 – Unreadable
2 – Barely readable, occasional words distinguishable
3 – Readable with considerable difficulty
4 – Readable with practically no difficulty
5 – Perfectly readable
S = 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
T = 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
The first RST number represents Readability and is self-explanatory from the chart above; it needs no elaboration.
The second RST number, Strength, is usually derived from the S-meter reading on the listener’s receiver when the sender is transmitting. S-meters are normally graduated 1-9, corresponding to the RST S-scale, and many receivers also add a level or two above 9 (+10 and +20dB).
Even FM handhelds and VHF/UHF mobile rigs usually have an S-meter built in. In some cases it is a bar graph on the display where you may have to count the bars to get a real number from this but be aware that FM signal meters are not typically calibrated the way normal SSB and CW receivers do it so with FM the S meters are really a relative indicator.
The third RST number refers to Tone and applies only to the CW operating mode. It indicates the quality of the Morse code tone, from 1-9. Unless you’re operating CW, you will not have to worry about this third number as it is not used for phone (voice) signal reports. There are additional suffixes that can be added to CW reports to indicate crystal stability, chirping or key clicks but these are uncommon with modern transceivers.
When operating on AM, SSB or FM voice modes the third number is meaningless so it becomes simply a two-digit RS report scheme. A voice signal report will be something like, “I have you 3 8 in Austin Texas” where it would indicate readable with some difficulty and with a fairly strong signal. Or you might hear “Copy you 5 by 9” which means perfectly readable with full signal strength. Readability and strength often go together and increase the chances of a good contact. However (a big but here), you can have good readability with a weak signal and you will also experience strong signals with interference or fading resulting in poor readability, so be aware that RS signal reports can vary significantly.
During contests and with rare or popular contacts, “rubber stamp” signal reports of 59 (phone) or 599 (CW) are often given regardless of actual conditions. Those stations are typically trying to work as many contacts as possible in a short time so they don’t trouble themselves to assess actual signal quality. At other times, however, you should be honest with the ham on the other end and give him an accurate or appropriate report. It helps them know how well they are coming through.
If you’d like more detail on the RST system for signal reports, an excellent reference is located here from HamUniverse. It is also found on the Links page.
OK, so that’s how basic signal reports work for HF and simplex VHF/UHF. Now let’s talk about signal reports on a repeater. Of course, readability is readability regardless of mode or signal processing or any other way of messing with a radio signal. But with a repeater, you are not hearing the transmitting station directly; the repeater is re-transmitting what it picks up. Repeaters typically have high antennas for good coverage and they have a lot more power than the typical ham transmits with. So readability from a repeater is likely to be better than what you might hear from the transmitting ham directly. The received signal strength will almost certainly be much higher as well. Remember, you’re really hearing the repeater’s strength and possibly its readability so a RS signal report is mostly meaningless to the transmitting ham.
For these reasons, a different scheme is more commonly used for FM repeater signal reports. Actual signal strength is rarely used; the most important thing is signal quality. There are some common terms that describe FM signal quality:
- First up and most common is Full-Quieting. This means that the signal is strong enough that it overcomes any noise like hissing or buzzing. This is the strongest signal you can report.
- The term Scratchy is also heard. That means that there is some noise may sound like crackling that blanks out parts of words but the transmission can mostly be heard.
- Flutter or Picket Fencing describes a signal that alternates between strong and weak levels. This is most often due to a moving transmitter (mobile operation), and is likely because the signal propagates via more than one geometry (multi-path).
- In and Out means the listener can sometimes copy but not enough to be useful.
These are four common repeater signal reports. There may be others commonly used that the reader can share with us in the comments.
You may also hear questions on how someone sounds, which becomes a subjective opinion about audio quality (typically microphones or background noise.)
If you’re working with a fellow ham to test an antenna or microphone or some other piece of gear and want to give him a true signal report, try using simplex mode instead of the repeater. That will give a more accurate relative indication of any changes in signal strength or quality.
Also if you want to hear a transmitter signal coming into the repeater, hit the reverse button on your rig to switch transmit and receive frequencies. Then you’ll be listening in to the same signal the repeater is hearing. Sometimes this is helpful to give a fellow ham some feedback on his equipment.