Modelling of a Data Transmission System over an HF Channel

Abstract

The paper deals with the modelling of a data transmission system over an HF radio link. In particular, the system is modelled for the transmission of digital data at 4800 bit/s employing a serial quaternary phase shift keyed (QPSK) signal with a carrier frequency of 1800 Hz and an element rate of 2400 bauds. A brief description is given of the characteristics of the HF channel and the type of distortion introduced on the data transmitted over such a channel. The simulated HF radio link is modelled as having three different Rayleigh fading paths (sky waves), and the modulation and demodulation processes are both assumed to be linear. The simulation is based on the model recommended by the CCIR. Finally the results of the computer-simulation of the channel model are presented.

Indexing terms:

• Rayleigh fading
• Channel model
• Multipath fading
• Sky wave channel