Improvements in or relating to electrical measuring systems and apparatus therefor

Abstract

Abstract 355,705. Frequency measurements. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.- (Reeves, A. H.; 46, Avenue de Breteuil, Paris.) May 23, 1930, No. 15894. [Class 37.] Apparatus for measuring alternating-current frequency, the duration of a current impulse, or a small interval of time comprises a number of thermionic tube relays interconnected so that the system contains a predetermined number of different states of stable equilibrium, the system being changed from one state to the next in order by a current impulse and the particular state of equilibrium at any moment determining the number of impulses received. The relays are arranged in n pairs, so that the total number of impulses that may be counted is 2n. The apparatus comprises cascaded pairs of thermionic tubes 1, 2, Fig. 1, arranged so that two states of stable equilibrium occur when their respective impedances are a maximum and minimum. The tubes may be resistance coupled as described in Specification 344,936, [Group XL]. Fig. 3 shows a system for measuring an unknown frequency applied at I, N. FD comprises a frequency divider of the type described in Specification 296,827, [Class 37, Electricity, Measuring &c.], and is connected to the frequency counter system OC through a clock-controlled switch ES which may be of the type described in Specification 356,111, [Group XL]. The clock C may be an astronomical one. Small time intervals, or current impulse durations, can be measured by interconnecting a switch ES between a stable oscillator and the frequency counter system, the applied current impulse opening and closing the switch ES and the counter OC recording the number of oscillations during this time. The time interval is calculated from the known frequency. Fig. 5 shows a further arrangement for measuring or obtaining a small time interval, an auxiliary thermionic tube S being connected to the frequency counter elements A, C, E and to a switch W. When the key K is closed an impulse is transmitted to the terminals O, T and the frequency counter A .. E is connected. After a time depending upon the setting of the frequency counter, a further impulse is received at the terminals O, T, and this interval between the two impulses can be adjusted to any value of time in terms of one counter period.

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