Clarity Should Be Goal of Radio Codes
Almost all fire departments use a set of signals or codes in their radio communications. Most do so without a clear idea of why they do.
When queried, they generally say something about keeping the general public from understanding their transmissions. But in truth, any serious emergency band listener knows the local signals or code. In some cases, he can get them just by asking for them and seldom is security very tight. Once out, they pass from one person to another with astonishing efficiency. Changing the code often is no solution, because it confuses the firemen.
Actually there is a good, sound reason for using codes that has nothing to do with secrecy. It is the very opposite, in fact. It is to make the message clear.
Experts in information transfer systems have come up with a general principle: the smaller the selection of possible messages, the higher the probability of the receipt of the intended message by a given means in a given time or, with the same probability of receipt, the fewer the possible messages, the shorter the time to get the message through.
In a simple example, if only two messages are permitted—yes or no— versus a system of five possible messages—yes, no, probably, maybe and improbably—then the number of times the listener will ask for a repeat will be greater in the second system.
In the real world using radio voice, the number of possible messages is almost infinite. We ar£ helped somewhat because we expect the text on the fire frequency to pertain to fires or the fire service. The word “booster” conjures up an image of a hose, not a club supporter or a high chair. This is a message limiting of a sort. But even the English of the fire service has a number of words at its disposal.
We can greatly improve our transmissions by doing nothing more than limiting the words and phrases permitted in the most used messages. Instead of letting the man at the mike choose whether to say, “on the scene,” “We’re here,” “At the site,” “Have arrived,” etc., we tell him always to say, “We’ve arrived,” for example. The dispatcher is expected to hear arrived, so if only “_____ved” is received, he still understands.
While the electronics industry has worked miracles in giving us reliable, clear communications systems, it cannot control the fireground or other conditions. The noise of a siren, a pumper pumping, people shouting all tend to interfere with communications. It is precisely under such circumstances that the utility of the expected message comes forth. At least when something unusual is transmitted, the different words alert the receiver to this.
The technique of limiting the message pool is carried to a practical limit on the numerical code system. It forces a limit on the normal vocabulary without totally restricting possible messages because one can always revert to using words to say anything. Furthermore, it is clear when the speaker is stating a message from the limited pool (using numerals) or is stating something out of the ordinary (using words).
The most effective codes seldom use more than 40 to 60 signals. When fewer signals are available, the resort to words becomes too frequent.
For years each department has devised its own code. Some use “signal XX,” others use the “10-XX” codes. The purpose of the word, “signal” or “10-” preceding the significant numeral is to be sure the squelch has opened the receiver so the main messages gets through. It also alerts the receiver that a code rather than words will follow. Mutual assistance agreements and common dispatching have forced a certain standardization in limited areas, but there is still no standard fire service code for the United States.
Urges 10-code for standard
I would propose the ubiquitous 10-code as the base for a standard. Many use it already. Unfortunately, there is no real standard 10-code upon which to draw. Solely by popular usage, there has jelled a more or less standard meaning for many of the “10” signals in most areas of communications. Many fire departments have used this list, changing those not applicable to their use and adding others.
I think we all consider “10-4” as “acknowledge,” but only locally does “10-13” mean “false alarm” (to the majority, it means “weather and road report). Obviously the most used signals for a rural department will be different from those of an airport crash truck company. Hopefully, however, the proposed standard will contain enough signals to fill the needs of both. Each could then choose those that would make up its local set. At least the same numerals would not mean different things to different departments!
I would like to challenge some central body, the International Association of Fire Chiefs, for example, to set up a recommended standard set of codes for the fire service.