GB1378197A - Frequency response analyser - Google Patents

Abstract

1378197 Measuring transfer characteristics SOLARTRON ELECTRONIC GROUP Ltd 12 June 1973 [12 June 1972] 27409/72 Heading G1U The transfer characteristic of a system 10 under test, is determined by applying a cyclic test signal, digitally synthesized, to it, and by multiplying, integrating, and displaying, the resulting output signal from the system under test by sine and cosine signals of the same frequency as the cyclic test signal, the multiplication and integration being performed digitally. As described a 1Mc/s clock 12 drives known devices 13, 14, 16, 18, 24, which produce a sinusoidal test signal of a discretely selectable frequency is converted by a further known arrangement 34, 34a into a pulse train, on a lead 34b, having an instantaneous frequency linearly proportional to the modulus of the instantaneous amplitude of the output signal from the system under test, together with a signal on one of leads 34c, 34d, indicating the sign of the output signal. These pulses, 34b, algebraically gate sine and cosine values, in digital form from read only memories (ROM) 42, 44, into accumulators 47, 48, each comprising an adder and a circulating shift register, and ten second running averages of the resulting totals are displayed 50.