MATLAB Source Code Example for Unipolar Return-to-Zero Line Coding

Unipolar Return-to-Zero (RZ) coding is a commonly used digital signal encoding method primarily employed in baseband transmission systems. Its key characteristic is that the signal amplitude returns to zero during part of the bit period, making it particularly useful for clock synchronization scenarios. The core implementation logic for unipolar RZ coding in MATLAB can be divided into three main steps: 1. Data Generation: Generate binary bit streams using random functions (like randi() or rand()) to create the original signal for encoding. 2. Waveform Mapping: Map each binary "1" to a high-level pulse (returning to zero in the latter half of the bit period), while binary "0" maintains low level throughout the entire bit duration. This can be implemented using logical indexing and pulse shaping functions. 3. Time Axis Alignment: Ensure continuous concatenation of each bit's waveform along the time axis using proper sampling rate calculation and vector concatenation to form a complete encoded signal. Extended Considerations: The pulse width ratio (e.g., 50% or 25%) can be adjusted to observe waveform variations, which has practical significance for studying interference resistance. Key MATLAB functions like pulsewidth() or custom duty cycle parameters can facilitate this analysis. Compared to non-return-to-zero (NRZ) coding, RZ coding offers superior synchronization capabilities but requires higher bandwidth. Implementation differences between RZ and NRZ can be demonstrated through comparative plotting using subplot() and stem() functions.