LINE CODES IN DIGITAL TRANSMISSION SYSTEMS
Keywords:
Digital transmission, Line codes, NRZ, RZ, AMI, HDB-3, Bipolar coding, Synchronization, Scrambling, Error detection, Spectrum efficiency.Abstract
This paper discusses line codes in digital transmission systems, focusing on the conversion of binary signals into different coding schemes such as NRZ (Non-Return-to-Zero), RZ (Return-to-Zero), AMI, and HDB-3 (High Density Bipolar of order 3). The principles of coding, spectrum characteristics, error detection, and synchronization issues are analyzed. Special attention is given to HDB-3 coding, which solves the problem of long sequences of zeros in AMI by replacing them with specific bipolar patterns. The paper also examines scrambler techniques for improving statistical signal properties, ensuring reliable transmission, and compatibility with regenerators. The advantages, disadvantages, and application areas of unipolar and bipolar line codes in communication systems are presented.
References
1. Digital and Analog Transmission Systems. Edited by V. I. Ivanov. Moscow: Goryachaya Liniya–Telecom, 2003.
2. Multichannel Transmission Systems. Edited by N. N. Baeva and V. V. Gordienko. Moscow: Radio i Svyaz, 1997.
3. Yu. A. Gromakov. Standards and Systems of Mobile Radio Communication. Moscow: Radio Svyaz Publishing, 1998.
