Radio Propagation Measurement and Channel Modelling

Chapter 4

Radio Channel Sounders

In this chapter we review the history of radar and show the similarity between radars and sounders. We then discuss the different modes of operations and suitable waveforms including continuous wave, narrow pulse and pulse compression waveforms. We then outline architectures suitable to implement single input–single output to multiple input–multiple output sounders for different applications. We investigate the range Doppler ambiguity that might arise in certain applications and present advanced waveforms that can resolve this ambiguity. Finally, we discuss typical calibration procedures.

4.1 Echoes of Sound and Radio

The use of the word ‘sounder’ for determining distance goes back to the early seventeenth century where sounding was used to determine the depth of water in rivers and lakes by means of a line and plummet. Early usage of sounders was mainly for the determination of any physical property at a depth in the sea or at a height in the atmosphere, such as the temperature soundings made in 1875.

After the disaster of the Titanic in 1912, the German physicist Alexander Behm conducted research to find a way to detect icebergs. He discovered echo sounding, which he patented in 1913. However, echo sounding turned out to be inefficient in spotting icebergs, but a great tool to measure the depth of the sea. Thus echo sounding is defined as the technique of using sound pulses directed from the surface or from a submarine vertically down to measure ...