Continuous wave burst set, c 1980.
© Science Museum / Science & Society Picture Library
Racal-Decca commercial CW Burst test set for testing coaxial telephone cables. Because of the wide bandwidth needed, the use of coaxial telephone cables for digital transmission has led to the need for more stringent testing techniques. It is important to measure a condition known as impedance regularity when cables are put to such use. Continuous wave (CW) burst is an improvement over earlier testing techniques as echoes from unwanted components can be rejected by selecting a suitable time delay and duration of the burst of CW. This Racal-Decca test set represents an important stage in the transition from analogue to digital signals.