MATLAB Simulation of BPSK Modulation for GPS Signals and Power Spectrum Analysis of BOC Signals

This technical documentation presents a MATLAB-based simulation framework for generating and analyzing BPSK (Binary Phase Shift Keying) modulated GPS signals alongside BOC (Binary Offset Carrier) signal power spectral density. The implementation involves creating custom MATLAB functions to generate pseudo-random noise (PRN) codes, apply BPSK modulation using carrier wave multiplication, and compute BOC signals through subcarrier modulation techniques. Key algorithmic components include: - PRN sequence generation using Gold codes for satellite identification - BPSK modulation implementation via carrier phase inversion (0° and 180°) - BOC signal generation using square wave subcarrier modulation - Power spectral density calculation employing FFT-based periodogram methods The simulation enables parameter adjustment for code length, carrier frequency, subcarrier frequency, and sampling rates to study signal characteristics under different configurations. Comparative analysis features include overlay plots of both spectra, measurement of main lobe widths, side lobe attenuation levels, and spectral separation coefficients. This hands-on approach provides deep insights into GPS signal structure, interference resistance, and spectral efficiency properties of both modulation schemes. Through systematic parameter variation and real-time visualization, users can experimentally verify theoretical concepts like spectral nulls, bandwidth requirements, and multi-access interference performance. The modular code structure allows easy extension to advanced GPS signal formats including MBOC and AltBOC implementations.