Five by five
Encyclopedia
Five by five is the best of 25 possible subjective responses used to describe the quality of communications, specifically the signal-to-noise ratio
. As receiving stations move away from an analog radio transmitting site, the signal strength decreases gradually while noise levels increase. The signal becomes increasingly difficult to understand until it can no longer be heard as anything other than static.
In voice procedure
(the techniques used to facilitate spoken communication over two-way radios) a transmitting station may request a report on the subjective quality of signal they are broadcasting. In the military of the North Atlantic Treaty Organization (NATO) countries, and other organizations, the signal quality is reported on two scales; the first is for signal strength, and the second for signal clarity. Both these scales range from one to five, where one is the worst and five is the best. The listening station reports these numbers separated with the word "by". "Five by five" therefore means a signal that has excellent strength and perfect clarity — the most understandable signal possible.
"Five by five" (occasionally written "'5 by 5", "five-by-five", "5 x 5", or "5-by-5"), by extension, has come to mean "I understand you perfectly" in situations other than radio communication. A further shortened form is "five by". Post-World War II
, the phrase "Loud and Clear" entered common usage with a similar meaning.
The term is arguably derived from the signal quality rating systems such as shortwave's SINPO
code or amateur radio's RST
. Given that this slang spans not only generations but also a spectrum of communications technologies (spark-gap transmitters, shortwave, radio telephone, Citizen's Band (CB) radio, cellular among others) and organizations (hobbyist, commercial, many military branches in different countries), there are many interpretations in popular misuse.
This reporting system is not appropriate for rating digital signal quality. This is because digital signals have fairly consistent quality as the receiver moves away from the transmitter until reaching a threshold distance. At this threshold point, sometimes called the "digital cliff
," the signal quality takes a severe drop and is lost. This difference in reception reduces attempts to ascertain subjective signal quality to simply asking "Can you hear me now?" or similar. (The only possible response is "Yes;" otherwise, there is just dead air.) This sudden signal drop was also one of the primary arguments of analog proponents against moving to digital systems. However, the "five bars" displayed on many cell phones does directly correlate to the signal strength rating.
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
. As receiving stations move away from an analog radio transmitting site, the signal strength decreases gradually while noise levels increase. The signal becomes increasingly difficult to understand until it can no longer be heard as anything other than static.
In voice procedure
Voice procedure
Voice procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the military, in civil aviation, police and fire dispatching systems, citizens' band radio , etc....
(the techniques used to facilitate spoken communication over two-way radios) a transmitting station may request a report on the subjective quality of signal they are broadcasting. In the military of the North Atlantic Treaty Organization (NATO) countries, and other organizations, the signal quality is reported on two scales; the first is for signal strength, and the second for signal clarity. Both these scales range from one to five, where one is the worst and five is the best. The listening station reports these numbers separated with the word "by". "Five by five" therefore means a signal that has excellent strength and perfect clarity — the most understandable signal possible.
"Five by five" (occasionally written "'5 by 5", "five-by-five", "5 x 5", or "5-by-5"), by extension, has come to mean "I understand you perfectly" in situations other than radio communication. A further shortened form is "five by". Post-World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, the phrase "Loud and Clear" entered common usage with a similar meaning.
The term is arguably derived from the signal quality rating systems such as shortwave's SINPO
SINPO
SINPO, acronym for signal, interference, noise, propagation, and overall, is a code used to describe the quality of radio transmissions, especially in reception reports written by shortwave listeners...
code or amateur radio's RST
RST code
The RST code 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 code is a three digit number, with one digit each for conveying an assessment of the signal's readability, strength, and...
. Given that this slang spans not only generations but also a spectrum of communications technologies (spark-gap transmitters, shortwave, radio telephone, Citizen's Band (CB) radio, cellular among others) and organizations (hobbyist, commercial, many military branches in different countries), there are many interpretations in popular misuse.
This reporting system is not appropriate for rating digital signal quality. This is because digital signals have fairly consistent quality as the receiver moves away from the transmitter until reaching a threshold distance. At this threshold point, sometimes called the "digital cliff
Cliff effect
In telecommunications, the cliff effect or brickwall effect describes the sudden loss of digital signal reception. Unlike analog signals, which gradually fade when signal strength decreases or electromagnetic interference or multipath increases, a digital signal provides data which is either...
," the signal quality takes a severe drop and is lost. This difference in reception reduces attempts to ascertain subjective signal quality to simply asking "Can you hear me now?" or similar. (The only possible response is "Yes;" otherwise, there is just dead air.) This sudden signal drop was also one of the primary arguments of analog proponents against moving to digital systems. However, the "five bars" displayed on many cell phones does directly correlate to the signal strength rating.
External links
- Ham Radio RST Signal Reporting System for CW Operation, by Charlie Bautsch, W5AM