JNTU B.Tech IV TELEMETRY AND TELECONTROL Previous Question Paper (September - 2020 - R16)

A Telemetry system is essential for monitoring, measuring, and transmitting data from remote or inaccessible locations to a central control station. It enables real-time decision-making, process automation, and safety management in hazardous environments such as power grids, aerospace, and industrial pipelines where manual data collection is impractical or dangerous.

An Electrical Telemetry System converts physical variables (like pressure, temperature, or flow) into electrical signals for transmission. The system typically consists of:

1. Transducer: Converts the physical parameter into an electrical quantity (voltage, current, or resistance).
2. Signal Conditioning: Amplifies, filters, or linearizes the signal to ensure it is suitable for transmission.
3. Transmission Link: The physical medium (copper wires, fiber optics, or wireless links) that carries the signal to the receiver.
4. Receiving/Display Unit: Processes the incoming signal and displays or records the data for analysis.

Line Coding involves mapping binary data into digital signals (voltage levels) for transmission over a physical medium. It focuses on the physical layer, ensuring synchronization, minimizing DC components, and reducing bandwidth. Common techniques include:

• Unipolar NRZ: Uses a positive voltage for 1 and zero for 0.
• Polar NRZ: Uses positive voltage for 1 and negative for 0.
• Manchester Coding: Represents bits by transitions (e.g., low-to-high for 1, high-to-low for 0), providing self-clocking capabilities.

Channel Coding (or Forward Error Correction) adds redundant bits to the data stream to detect and correct errors introduced by noise or interference in the channel. By increasing the Hamming distance between codewords, the receiver can reconstruct the original data without retransmission. Examples include:

• Block Codes: Data is divided into fixed-size blocks (e.g., Hamming codes).
• Convolutional Codes: Data is processed as a continuous stream, where output depends on current and previous bits, suitable for real-time telemetry links.