What is Telegraph? | What is its History and Evolution?

The telegraph laid the groundwork for the telecommunications revolution. It served as the initial means of instant communication over long distances.

The Invention of the Telegraph

The telegraph works with two electrical signals: a point and a line. Morse code uses varying combinations of dots and dashes. Electrical impulses send messages along a single wire.

Like an electric switch, Morse structure requires finger pressure. The original Morse receiving device utilizes an electromagnetically controlled gauge. This gauge draws lines on a rotating paper belt. A cylinder places the paper belt. Also, the length of the lines depends on the duration of the electric current passing through the electromagnet wires.

Telegraph History

The American Samuel F. B. Morse invented the first telegraph transmission device in 1837. The same year, the English physicist Sir Charles Wheatstone and engineer Sir William F. Cooke developed Morse code. This code served as the entire communication system. Samuel Morse first publicly published the Morse device in 1844.

During experiments using the Morse device, an important finding emerged. Researchers discovered that signals could be sent within approximately 20 miles. Beyond this distance, communication became challenging due to weakened signals.

Morse and her friends later built the telegraph device. They connected it to a line that was 20 miles away from the signal station. This device could repeat signals automatically. By doing this, they could send communications over longer distances.

They created a relay system using an electromagnet switch that, when turned, closed a circuit. A separate battery powered this circuit, and it worked by exciting the magnet’s coil. This initiates a powerful current pulse, which activates other relays until it reaches the receiver.

After a few years, they needed to update Morse’s receiver equipment. Operators found a new way to understand points and lines using only sound. However, they continued to use the remaining parts of Morse’s system in wire telegraph circuits.

Due to the high cost of the telegraph device, people developed methods to send many messages on the same line. They used a bidirectional system as one of these methods. This enabled the transmission of messages between two stations in both directions.

Evolution of History

In 1874, Thomas Edison created the quadruple system. This invention allowed for the simultaneous transmission of two messages in all directions. Later, in 1915, researchers began many methods to send eight or more letters.

The introduction of teletype machines in the 1920s caused a decline in the popularity of Morse’s manual-coded system. As a result, wired and wireless communication methods became more common.

In 1844, they opened the first telegraph line connecting Baltimore to New York. This achievement facilitated the spread of communication worldwide. Later, in 1850, they devised a plan to join Britain and France with a submarine cable. But, laying the line across the Atlantic proved challenging. After many failed attempts, they finally united the two sides of the ocean in 1866.

Development of Telegraph

They used the point-and-line coding system to send and decode telegraph messages. This system led to the creation of other devices that could perform these tasks. One such device is the Hughes device, which uses rotating wheels to represent symbols and characters. These wheels turn and synchronize at the same speed for transmission.

The Hughes device works like this: the radio operator presses a key, and the device sends a pulse when the character wheel is in the correct position. In the receiver, an electromagnet strikes a wheel with paper band types. These wheels move using weight or a hydraulic motorized clock system.

Later, they introduced a synchronization protocol to send a specially designed message. It depended on the radio operator, although the transmission rate was lower than the Morse system. It is because an experienced person could send several characters in one turn of the wheel.

The Baudot telegraph device was an improved version of the Hughes system. This encodes characters differently. It sends a pulse through five-time intervals, not just one location. So, they used a unique code called a five-bit binary code. This code allowed them to send 31 characters and an empty state. Furthermore, they possessed two characters, and certain letters and numbers remained blank.

The Baudot code is different because it uses only five slots. It is better than one slot per character. It also improves the magnetic circuits of electromagnets. By doing this, it reduces inductions as much as possible. As a result, telegraphy allows communication to use shorter pulses.