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All Journal bit-Tech Journal of Innovation Information Technology and Application (JINITA)
Devi Wahyuni
Politeknik Negeri Sriwijaya
Computer Science & IT Decision Sciences, Operations Research & Management Engineering

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Analysis of Frequency Spectrum in Digital Image Transmission Using Orthogonal Frequency Multiplexing Sarjana Sarjana; Ade Silvia Handayani; Devi Wahyuni
bit-Tech Vol. 8 No. 1 (2025): bit-Tech
Publisher : Komunitas Dosen Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32877/bt.v8i1.2749

Abstract

Accurate and efficient data transmission is increasingly essential due to the growing reliance on digital communication, particularly for multimedia content such as images. Orthogonal Frequency Division Multiplexing (OFDM) provides high bandwidth efficiency and strong noise resilience by transmitting data over multiple orthogonal subcarriers. Despite its advantages, limited studies have explored how modulation schemes influence frequency-domain characteristics during image transmission under different noise conditions. This study addresses that gap by evaluating digital image transmission through OFDM using Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation. The objective is to compare spectral performance across various signal-to-noise ratio (SNR) levels. A grayscale image is converted into a binary stream, modulated using BPSK and QPSK, and processed through an OFDM system with 512 subcarriers and a 25% cyclic prefix. The signals are transmitted through an Additive White Gaussian Noise (AWGN) channel at SNR values of 0 dB, 5 dB, and 10 dB. Power Spectral Density (PSD) is measured using the Welch method with a Hamming window, 50% overlap, and 1024-point Fast Fourier Transform (FFT). The results show that increasing SNR improves spectral sharpness, reduces the noise floor, and enhances symmetry. BPSK offers better performance in noisy conditions, while QPSK is more efficient in high-SNR environments. These findings provide practical insight for optimizing modulation choices in OFDM-based image transmission systems where spectral efficiency and noise robustness must be balanced.
Performance Evaluation of a Standalone OFDM System for Digital Image Transmission over AWGN Channels Ade silvia handayani; Sarjana; Aryanti; Nurhajar Anugraha; Muhammad Hanif Fatin; Devi Wahyuni; Muhammad Rafly Wijaya; Dely Andini
Journal of Innovation Information Technology and Application (JINITA) Vol 8 No 1 (2026): JINITA, June 2026
Publisher : Politeknik Negeri Cilacap

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35970/jinita.v8i1.2991

Abstract

This study investigates the performance of a standalone digital communication system based on Orthogonal Frequency Division Multiplexing (OFDM) for digital image transmission over Additive White Gaussian Noise (AWGN) channels. The system was tested using two digital modulation techniques: Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK). Unlike previous studies that focused on OFDM implementation in large-scale communication systems such as cellular networks, this research explores a simplified standalone scenario without any supporting network infrastructure. Simulations were carried out in the MATLAB environment using grayscale image inputs ranging from 1 MB to 10 MB, with signal-to-noise ratio (SNR) levels varying from 0 to 30 dB. The results show that BPSK modulation maintains a low Bit Error Rate (BER) of approximately 0.077 even under low SNR conditions (as low as 0 dB). In contrast, QPSK modulation achieves optimal performance when the SNR reaches at least 15 dB, where the BER drops to 0.00000. The image size did not significantly affect system performance, indicating robustness across varying data loads. Overall, the findings suggest that BPSK provides higher reliability in noisy channels, whereas QPSK offers better spectral efficiency under cleaner conditions. Therefore, the proposed standalone OFDM system demonstrates strong potential for lightweight data communication applications such as sensor networks and remote monitoring systems operating in limited network environments.
Co-Authors Ade Silvia Handayani Aryanti Dely Andini Muhammad Hanif Fatin Muhammad Rafly Wijaya Nurhajar Anugraha Sarjana Sarjana, Sarjana