Design Concepts for Transportable Ionoscatter Systems and Experimental Results

An experimental ionoscatter system carrying four 50-baud telegraph circuits has been designed and tested at 36 MHz over a distance of 1000 km between the Netherlands and Southern France. The object was to demonstrate the possibility of designing a system sufficiently compact to be made transportable. By using multiple-diversity reception and automatic request (ARQ) equipment, it has been possible to achieve a reliability of 99.9 percent with simple Yagi antennas and a transmitter power of 5 kW. The performance limits were an error rate of 1 to 3000 characters and a speed reduction of 10 percent. Frequency, horizontalspace, and vertical-space diversity reception have been tried. Signal strength measurements have also been made over paths shorter than 1000 km. It is shown that for a system with low-gain antennas the propagation loss at 400 km is 6 dB greater than at 1000 km. The use of error-correction codes is suggested for one-way connections where the ARQ technique is not applicable. It is shown that it is possible to obtain the same performance as with ARQ.