Pulse rate techniques are well suited to electronic instrumentation. Conversion of analogue signals is simple, and computations on measured variables are accurate and economical. The Digital Transfer Function Analyser discussed in this paper is an example of a complex instrument designed on the basis of these techniques. It consists of an oscillator to excite the system under test and a correlator to measure the response. Binary rate multipliers and counters are used to generate sine waves, to multiply the return signal by sine and cosine functions, and to change frequencies and integrator scalings. An extension of the method permits conversion from cartesian to polar co-ordinates, and a further conversion gives the modulus in logarithmic form. Accuracies of a half per cent and a tenth of a degree are readily obtained, the results being presented on a digital display. © 1969.
