Block Diagram of Wireless Telegraph System

Block Diagram of Wireless Telegraph System Points : block diagram of wireless telegraph system The block diagram of wireless telegraph system is shown.
At the transmitter side, when the key is pressed, the telegraph signal current passes through the modulator, where high frequency signal from the oscillator is also received. The two are mixed and jhen after passing through amplifier, the antenna radiates power in the air and is received by the distant receiving antenna.

Applications of Teleprinter

Applications of Teleprinter Points : applications of teleprinter The following is the applications of the teleprinter machine:
(i). The teleprinter is basically used for sending and receiving of telegraph signals.
(ii). Teleprinter switching system is used in Telex (teleprinter exchange) which is a convenient method of sending printed messages. An auto-telex service has the advantage of communication as in telephone system and transfer of written record as in telegraph system.

Salient Features of Teleprinter

Salient Features of Teleprinter Points : salient features of teleprinter The salient features of teleprinter are listed below:
(a). A teleprinter is a telegraph transmitting-receiving machine.
(b). It resembles a typewriter because it has a typewriter like keyboard.
(C). A teleprinter is a mechanical device driven by electric motor. However, recently electronic machines have been introduced, controlled by microprocessor.
(d). Code used by teleprinter machine is the 5-unit code, operating on double current basis.

Merits and Demerits of Machine Telegraphy

Merits and Demerits of Machine Telegraphy Points : Merits and Demerits of Machine Telegraphy, advantages and disadvantages of Machine Telegraphy Merits 1. The machine telegraph uses the equal length code.
2. The synchronization of the sending and receiving mechanism is made with the help of start-stop signals.
3. The machine telegraphy is speedier and efficient.

Working Principle of Machine Telegraphy

Working Principle of Machine Telegraphy Points : working principle of machine telegraphy Machine telegraphy started with the 5-unit code system and worked very well. However, the matching of the sending and receiving mechanism was very critical. ‘To overcome this difficulty the start-stop principle was introduced in machine telegraphy.

In the start-stop principle, for each character the transmitter automatically prefixes the group of code elements with a start signal and terminates with a stop signal. Before any character is sent, a start (space) signal of 20 ms duration is transmitted which shows the start of a character.

Single and Double Current Morse Code System

Single and Double Current Morse Code System Points : single and double current morse code system The Morse code system may be either single current or double current. In the single current system single battery is used. The current on the line flows only in one direction. There is current on the line when dot or dash is transmitted and no current when neither dot nor dash is transmitted. The advantage of single current system is low power consumption. However, the flow of current is slower and thus is a disadvantage.

Morse Telegraph System

Morse Telegraph System Points : Morse Telegraph System The Morse telegraph system is a simple electric circuit consisting of the following components:
i. A battery: which acts as a source of electrical energy in the circuit.
ii. Morse key: It is a manual key and acts as a switch to open and close the circuit. Thus causing pulses of current to flow on the line. When the operator starts opening and closing of the key, the transmission of information and encoding starts at the same time.

Necessity of Telegraph Code and Their Types

Necessity of Telegraph Code and Their Types Points : Necessity of Telegraph Code and Their Types, Telegraph Code Types Necessity of Telegraph Code In sending the information from the source to the destination, it is first converted into codes by the encoder. The received information at the destination is interpreted or decoded for understanding the meaning of the message. This process of encoding and decoding information is two fold: (i) efficient transmission and (ii) secrecy. Telegraphy is the method of transmitting messages by means of signalling codes. Hence telegraph alphabet is made from the set of possible code combinations in a unique pattern for representing each character. The most important features in any code are: