Design of low-cost, long range radio communication systems

The technology applied in long-range, beyond line-of-sight (BLOS) radio system implementation has generally advanced less rapidly. However, low-cost transceivers and powerful digital signal processing (DSP) devices are now available for incorporation into long-range systems operating in the HF/VHF frequency range. Such radio systems should be available at a cost affordable by developing nations. The primary interest of the Hull-Warwick Communications Research Group (HWCRG) is in the design and implementation of BLOS radio systems operating at the lower end of the radio spectrum up to about 100 MHz. This part of the spectrum is a valuable natural resource but, in many respects, is still used inefficiently and ineffectively. The authors outline a range of propagation media and transmission techniques which can form the basis of economic and efficient BLOS communication systems. The techniques discussed are compatible with DSP implementation and systems with mobile terminals