AmateurRadio.com

Everyone wants to know how their signal sounds on the air and often the best way to find out is a signal report from other ham radio operators. The standard signal reporting method for amateur radio is the RST (Readability-Signal Strength-Tone) system. See Practical Signal Reports on HamRadioSchool.com.

When using 2m FM on Summits On The Air (SOTA), we can simplify the signal report. Because it is a voice mode, we drop the reading for Tone and just give RS reports, so a perfect signal on voice is RS 59 or simply “five nine.”  The Readability report is a number between 1 and 5, while the Signal Strength report goes from 1 to 9. (See the listing at the bottom of this article.) The signal strength generally corresponds to the S meter reading on your radio but most FM rigs have very basic meters. Some don’t provide a meter reading at all. The photo to the left shows a typical bar graph on a Yaesu FT-60. Don’t expect high accuracy, so if the meter reads full scale, give an S9 report. If it reads half-scale, that’s probably S5, etc.

On VHF FM, signal reports may also be given in terms of FM quieting. A strong FM signal is said to “quiet the receiver” since there is virtually no noise present in the received audio. As the signal strength is decreased, noise starts to appear on the received signal. At lower signals levels, the noise increases dramatically and the signal becomes unreadable. This dramatic increase is called the threshold effect, meaning that FM signals do not gradually fade out, they tend to fade quickly into the noise. The key idea here is that you want your signal to be strong enough to be above this noise threshold. In terms of a signal report, a strong signal may result in a “full quieting” report. If the signal is less than full quieting, you may hear a report like “90 percent quieting” or “you have about 10% noise”, which both describe the amount of noise present in the signal. If the signal is really noisy, the report might be “50% quieting.”

Keep It Simple

For practical 2m FM operating, don’t overthink these signal reports. If the signal is easy to hear and is full-scale, give a 59 report. If it is easy to hear but the meter reading is less than full scale, reduce the signal level report to something like 56 or 57. If there is some noise present, you might want to reduce the readability to 4, so maybe give a 44 or 45 report. (Usually, if there is a readability issue, the signal strength will also be lower.) If you are having a difficult time hearing the signal, it’s probably a 33 or less. Readability of 1 or 2 is rarely used because it indicates you are not actually hearing the other station.

One final note is that sometimes the operator on the other end is looking for a more critical evaluation of his signal quality. If he says something about “checking out this new microphone” or “have been working on solving an audio problem”, that may be the clue to spend a little extra time really listening to the signal and providing more comments on how it sounds. For most of us, we don’t actually get to hear our own signal on the air, so it’s very helpful to get quality feedback from other radio amateurs.

73 Bob KØNR

The RST system as listed on the ARRL web site, Quick Reference Operating Aids:

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.