Signal Strength & Reports

Terms

The term “full quieting” in ham radio usually signifies a good quality signal on a repeater or FM transmission – it means that your signal is clear, free of static, and easily readable by others.

The phrase Picket Fencing is used to describe the way an FM transmitter will cut in and out as it nears the capture threshold of a moving receiver or transmitter as it passes through fresnel zones, thus chopping the speech of the transmitting operator. It refers to the way portions of speech are stripped from the conversation, as if the listener was walking by a picket fence, and hearing a conversation on the other side that changes audibly depending on the position of the pickets relative to the listener.

This phrase is also used to describe the same audio phenomenon in digital voice modes which is caused by various methods including being on the fringe of a coverage range. In some digital modes this is caused by “packet loss”

Another term which isn’t as much about a signal report but rather why a signal could be bad is multipath. Multipath is the propagation phenomenon that results n radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from water bodies and terrestrial objects such as mountains and buildings. Just as it sounds the signal is taking multiple paths and can result in the same signal being received at the receiver at multiple time delays. Digital modes tend to be more susceptible to multipath.

Analog

RST

Amateur radio users in the U.S. and Canada have used the R-S-T system since 1934. This system was developed by amateur radio operator Arthur W. Braaten, W2BSR. It reports the readability on a scale of 1 to 5, the signal strength on a scale of 1 to 9, and the tone of the Morse code continuous wave signal on a scale of 1 to 9. During amateur radio contests, where the rate of new contacts is paramount, contest participants often give a perfect signal report of 599 even when the signal is lower quality, because always providing the same signal format enables them to send Morse code with less thought and thus increased speed.

Obviously in phone or “voice” modes only the first R and S are used and often stated in the “5 by 9” fashion.

Readability Signal Strength
   
R1 Unreadable S1 Faint signals, barely perceptible
R2 Barely readable S2 Very weak signals
R3 Readable with difficulty S3 Weak Signals
R4 Readable with no difficulty S4 Fair signals
R5 Perfectly readable S5 Fairly good signals
  S6 Good signals
  S7 Moderately good signals
  S8 Strong signals
  S9 Extremely strong signals
Tone
 
T1 Extremely rough hissing note
T2 Very rough AC note, no trace of musicality
T3 Rough, low pitched AC note, slightly musical
T4 Rough AC note, moderately musical
T5 Musically modulated note
T6 Modulated note, slight trace of whistle
T7 Near DC note, smooth ripple
T8 Good DC note, just a trace of ripple
T9 Purest DC note

Plain-language radio checks

The move to plain-language radio communications means that number-based formats are now considered obsolete, and are replaced by plain language radio checks. These avoid the ambiguity of which number stands for which type of report and whether a 1 is considered good or bad. This format originated with the U.S. military in World War II, and is currently defined by ACP 125 (G), published by the Combined Communications Electronics Board.

The prowords listed below are for use when initiating and answering queries concerning signal strength and readability.

Proword Meaning
RADIO CHECK What is my signal strength and readability; how do you hear me?
ROGER I have received your last transmission satisfactorily.
NOTHING HEARD To be used when no reply is received from a called station.
Proword Meaning   Proword Meaning
LOUD Your signal is very strong. AND or BUT, depending on which prowords are combined CLEAR The quality of your transmission is excellent.
GOOD Your signal strength is good.   READABLE The quality of your transmission is satisfactory.
WEAK Your signal strength is weak.   UNREADABLE The quality of your transmission is so bad that I cannot read you.
VERY WEAK Your signal strength is very weak.   DISTORTED Having trouble reading you due to interference.
FADING At times your signal strength fades to such an extent that continuous reception cannot be relied upon.   WITH INTERFERENCE Having trouble reading you due to interference.
INTERMITTENT Having trouble reading you because your signal is intermittent.  

Digital

In the digital realm signal strength is irrelevant as it isn’t something that can be distinguished via the human ear. What can be reported upon is audio level which can be adjusted in a radio by the mic gain. Another item which can be reported on in some digital systems with forward error correction is packet loss. Basically the error correction isn’t able to piece the message together at 100% accuracy and therefore it results in choppy transmissions. We have all experienced this phenomenon with cellular telephones. This can be caused by many things, including weak signal, intermittent signal, multi-path and interference.