Baudot Code and Digital Telegraphy | Generated by AI
Question: Who was Émile Baudot, and what was his contribution to telecommunications?
Answer: Jean-Maurice-Émile Baudot (1845–1903) was a French telegraph engineer and inventor who revolutionized digital communication. He is best known for inventing the Baudot code, the first truly digital character code, and for developing a multiplexed telegraph system that allowed multiple messages to be sent over a single wire simultaneously.
1. The Baudot Code (Digital Foundation)
Before Baudot, telegraphy relied largely on Morse code, which used variable-length signals (dots and dashes). Baudot’s breakthrough was the creation of a 5-bit binary code.
- Fixed Length: Every character was exactly five bits long.
- Binary Nature: Each bit was either “on” or “off” (current or no current).
- Capacity: $2^5 = 32$ possible combinations. To handle the full alphabet plus numbers and symbols, he introduced “Letter” and “Figure” shift keys—a concept still used in modern keyboards.
2. The Multiplex System
Baudot’s system was designed for efficiency. Using a synchronized distributor (a rotating mechanical switch), he enabled up to six operators to share a single telegraph line.
- Synchronous Timing: The sending and receiving machines had to spin at the exact same speed.
- Time-Division Multiplexing (TDM): This was a primitive version of TDM, a cornerstone of modern fiber-optic and cellular communications.
3. The Baudot Keyboard
Unlike the Morse key, Baudot’s interface looked like a piano with five keys.
- Operators pressed combinations of keys with their left and right hands.
- The operator had to maintain a steady rhythm to stay in sync with the rotating distributor, often cued by a “click” sound from the machine.
4. Legacy and the “Baud” Unit
Baudot’s influence is so fundamental that his name was immortalized in the SI unit for communication speed:
- The Baud (Bd): This unit measures the number of symbol changes (events) per second in a communication channel. While often confused with “bits per second,” the Baud specifically honors his work in pulse-based signaling.
Summary Table: Morse vs. Baudot
| Feature | Morse Code | Baudot Code |
|---|---|---|
| Length | Variable (dots/dashes) | Fixed (5-bit) |
| Timing | Asynchronous | Synchronous |
| Automation | Difficult to automate | Ideal for machine printing |
| Usage | Human-to-human | Machine-to-machine (Telex) |
Would you like me to explain how the “shift” characters allowed Baudot to squeeze more than 32 characters out of a 5-bit system?