Editing Morse code (section)

===Speed in words per minute===
All Morse code elements depend on the dot / ''dit'' length. A ''dah'' is the length of 3&nbsp;dits (with no gaps between), and spacings are specified in number of ''dit'' lengths. An unambiguous method of specifying the transmission speed is to specify the ''dit'' duration as, for example, {{val|50|ul=milliseconds}}.

Specifying the ''dit'' duration is, however, not the common practice. Usually, speeds are stated in words per minute. That introduces ambiguity because words have different numbers of characters, and characters have different ''dit'' lengths. It is not immediately clear how a specific word rate determines the ''dit'' duration in milliseconds.

Some method to standardize the transformation of a word rate to a ''dit'' duration is useful. A simple way to do this is to choose a ''dit'' duration that would send a typical word the desired number of times in one minute. If, for example, the operator wanted a character speed of 13&nbsp;words per minute, the operator would choose a ''dit'' rate that would send the typical word 13&nbsp;times in exactly one minute.

The typical word thus determines the ''dit'' length. It is common to assume that a word is 5&nbsp;characters long. There are two common typical words: '''{{sc|PARIS}}''' and '''{{sc|CODEX}}'''. '''{{sc|PARIS}}''' mimics a word rate that is typical of natural language words and reflects the benefits of Morse code's shorter code durations for common characters such as '''{{sc|e}}''' and '''{{sc|t}}'''. '''{{sc|CODEX}}''' offers a word rate that is typical of 5&nbsp;letter code groups (sequences of random letters). Using the word '''{{sc|PARIS}}''' as a standard, the number of ''dit'' units is 50 and a simple calculation shows that the ''dit'' length at 20&nbsp;words per minute is {{val|60|u=milliseconds}}. Using the word '''{{sc|CODEX}}''' with 60&nbsp;dit units, the ''dit'' length at 20&nbsp;words per minute is {{val|50|u=milliseconds}}.

Because Morse code is usually sent by hand, it is unlikely that an operator could be that precise with the ''dit'' length, and the individual characteristics and preferences of the operators usually override the standards.

For commercial radiotelegraph licenses in the United States, the Federal Communications Commission specifies tests for Morse code proficiency in words per minute and in code groups per minute.<ref name=US-CFR-Title-47/>{{rp|at=§13.207(c), §13.209(d)}} The [[FCC]] specifies that a "word" is 5&nbsp;characters long. The Commission specifies Morse code test elements at 16&nbsp;code groups per minute, 20&nbsp;words per minute, 20&nbsp;code groups per minute, and 25&nbsp;words per minute.<ref name=US-CFR-Title-47/>{{rp|at=§13.203(b)}} The word per minute rate would be close to the '''{{sc|PARIS}}''' standard, and the code groups per minute would be close to the '''{{sc|CODEX}}''' standard.

While the Federal Communications Commission no longer requires Morse code for amateur radio licenses, the old requirements were similar to the requirements for commercial radiotelegraph licenses.<ref name=US-CFR-Title-47/>{{rp|at=§97.503, 1996}}

A difference between amateur radio licenses and commercial radiotelegraph licenses is that commercial operators must be able to receive code groups of random characters along with plain language text. For each class of license, the code group speed requirement is slower than the plain language text requirement. For example, for the Radiotelegraph Operator License, the examinee must pass a 20&nbsp;word per minute plain text test and a 16&nbsp;word per minute code group test.<ref name=FCC-radiotelegraph/>

Based upon a 50&nbsp;dit duration standard word such as '''{{sc|PARIS}}''', the time for one ''dit'' duration or one unit can be computed by the formula:

:{{math|''T'' {{=}} {{sfrac|{{val|1200|fmt=commas}}|''W''}}}}

where: {{mvar|T}} is the unit time, or ''dit'' duration in milliseconds, and {{mvar|W}} is the speed in [[words per minute|{{sc|wpm}}]].

[[High-speed telegraphy]] contests are held; according to the ''[[Guinness Book of Records]]'' in June&nbsp;2005 at the [[International Amateur Radio Union]]'s 6th&nbsp;World Championship in High Speed Telegraphy in [[Primorsko]], Bulgaria, Andrei Bindasov of [[Belarus]] transmitted 230&nbsp;Morse code marks of mixed text in one minute.<ref name=Guinness-records-Morse/>