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Baudot Code

Tool to decode/encode with Baudot. Baudot code is one of the first telecommunication code in binary from a machine (telegraph), it uses 5 bits per character and 2 character sets.


Baudot Code -

Tag(s) : Telecom, Character Encoding

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Baudot Code

Baudot Decoder


Baudot Encoder


See also: Chappe Code

Answers to Questions (FAQ)

What is the Baudot code? (Definition)

The Baudot code is an ancient coding system implemented to communicate with the telegraph.

Its alphabet allows alphanumeric characters to be represented using a sequence of 5 binary elements.

Baudot has had several variations to adapt to different users and languages and has even been standardized under the name ITA2 (International Telegraph Alphabet No. 2).

How to encrypt using Baudot cipher?

Encryption with the Baudot code uses a substitution/coding alphabet on 5 bits and 2 sets of characters (usually one for letters and the other for numbers and punctuation).

Each character is encoded sequentially (one after the other) to form a complete message.

The coding alphabet depend on the machine (Baudot type) used:

BaudotOriginal Alphabet (French)
Baudot UKAlphabet modified by the British
ITA2International Telegraph Alphabet No. 2 (most common)
ITA1International Telegraph Alphabet No. 1
MurrayBaudot Alphabet Modified by Murray (CCITT2)
Murray(Météo)Baudot-Murray Alphabet for Meteorologists
US-TTYITA2 Alphabet Modified for the American Teletypewriter
MTK2ITA2 Alphabet Modified for Russian
ATU80ITA2 alphabet modified for Arabic languages

The encoding binary alphabet can be used in both directions: MSB (most significant bit) or LSB (least significant bit) first.

Encryption consists in transcribing the characters of the message by their code. To switch between character sets, there are two keys: (switch to letters) and (switch to digits).

Example: Encode the message IA2 BAUDOT with a machine using the international telegraphic alphabet no. 2 (the most widespread). The coded message is 00110 00011 11011 10011 11111 11001 01001, explanations in detail:

I00110By default the letter character set is used
11011The next character (2) is a number (therefore absent from the letters' character set), type ⇧ (switch to digits)
(space)00100The space code is the same for each character sets (numbers and letters) in the international alphabet 2
11111The next character (B) is a letter (thus absent from the digits' character set), type ⇩ (switch to letters)

The letters are generally in capitals, the Baudot code does not allow a change of case.

How to decrypt Baudot cipher?

Decryption with the Baudot code requires knowing the machine and / or the alphabet used. The decoding consists of replacing the 5-bit groups (0 and 1) by their corresponding character in the alphabet.

When the code corresponds to (digits to letters) or (letters to numbers), the character set must be changed.

Example: The encrypted message is 01001 01110 11011 10110 11111 01001 11011 00001


Example: The plain message is DC0D3.

How to recognize a Baudot ciphertext?

The message is a binary code, usually 0 and 1 grouped by 5.

The code consists of a number of bits multiple of 5.

Why was Baudot Code developed?

Baudot Code was created to improve telegraph communication by encoding characters in a more efficient manner, allowing faster transmission of messages.

Baudot Code marked a transition from manual telegraphy to automated teleprinters, revolutionizing long-distance communication in the late 19th and early 20th centuries.

Early teleprinters utilized Baudot Code for text transmission. Each key press generated a unique five-bit code, facilitating telecommunication.

What is the Least/Most significant bit first/last?

For 5-bit binary coding, usually the most significant bit is on the left (least on the right)

Example: The value 3 is written 00011 (5bit, least significant bit on the right).

But it is possible to write with the least significant bit to the left

Example: The value 3 is written 11000 (5bit, least significant bit on the left).

What is the International Alphabet n°2?

IA2 is the Baudot variant the most used, here are the codes and their characters:

01000Carriage Return CRCarriage Return CR
00010Line Feed LFLine Feed LF
11011Switch to Digits

What is the WRU code?

On some machines, there was a WRU key (for who are you) which allowed you to request the identification of people before initiating a telecommunication. dCode displays .

How to understand the Coldplay album X&Y?

The cover drawing of the album represents colored boxes or blank ones, either in binary 1 or 0, the translation in Baudot code for each line gives X & Y the title of the album.

When was Baudot Code invented?

Émile Baudot described it at the end of the 19th century (patents from 1874 and 1878). The electric telegraph had already been invented since 1838.

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