Secured HF image transmission system

Abstract

The HF (3 to 30 MHz) spectrum is utilized for long distance communications by the military, amateur radio, shipping and diplomatic services. Communications is no longer limited to voice and telegraphy, but now include applications such as email, text messaging, image, and telemetry. This project looks into the design and development of an image transmission system that for use in the HF radio frequency spectrum. Additional features of the system include short messaging, text file transfer, and electronic security such as authentication and confidentiality. An AES (Advanced Encryption Standard) block is cipher is used for both authentication and key distribution with key length 256 bits and 128 bits respectively. For confidentiality, stream cipher algorithm used is based on the linear feedback register (LFSR) and a nonlinear combining function. To meet the requirements of the maritime industry, further research were done to include light house telemetry and automatic vessel tracking system. The system is built around an HF data communication system: HF transceiver, modem, controller and computer. Experiments were performed for data transmission over the HF spectrum at lower power of 5 to 25 watts on the 40 meter band (7.0 to 7.1 MHz) and marine band (8.0 to 8.8 MHz) for selected links within the Peninsular Malaysia. At low power, the advantage is in increasing equipment life, minimize power supply requirements, and minimize interference to other users.