Complex sentence: A more accurate system was developed using signalling in the 1.6MHz range, named Hi-Fix, was used for specialised applications such as precision measurements involved with oil-drilling, etc. Other systems were used in the Middle East.
Split into simpler sentences: A more accurate system named Hi-Fix was developed using signalling in the 1.6MHz range. It was used for specialised applications such as precision measurements involved with oil-drilling, etc. Other systems were used in the Middle East.