| 摘要 |
1,129,961. Voltage ratio measurement. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Dec.15, 1965 [Dec.29, 1964], No.52686/64 Heading G1U. Apparatus for indicating the ratio of the amplitudes in two different parts of the cycle of a repetitive signal comprises an amplifier 19-25 having a. g. c. to hold constant its output during the portion of the cycle having the larger amplitude, and a circuit to derive the difference between the amplifier output during the portion of the cycle having the lower amplitude, and half the peak-to-peak output. The signal is derived from an infrared pyrometer and produces at the output of amplifier 19 a two level step waveform Fig. 2 (not shown) having a peak-to-peak amplitude V1, and a lower amplitude V2. This signal is fed to positive and negative D.C. restorers C2, D1 and C1, D1 the outputs from which are fed to two resistors R1, R2. If the values of these resistors are suitably chosen, the current in meter M is proportional to V 1 /2 - V2 which, if V 1 is maintained constant by the a. g. c. action, is proportional to the required ratio. Modified D.C. restoring circuits giving difference signals which swing above and below zero are given in Figs. 4, 5 (not shown) and further circuits in which the signals swing about a mean D.C. level are given in Figs. 6, 7 (not shown). In order to compensate for variations in the peak-to-peak output from the amplifier the backing off circuit of Fig. 3 (not shown) may be employed in which a capacitor (C3) is charged to the voltage V 1 , and a portion of this is applied from a potential divider (R3, R4) to the meter. |
