| 摘要 |
1283705 Measuring time intervals SPERRY RAND CANADA Ltd 25 Aug 1969 [29 Aug 1968] 42219/69 Heading G4H Clock pulses are accumulated in a counter 21 (Fig. 1) at a full repetition rate between a reference pulse (27, Fig. 2, F, not shown) on lead 2 and the next positive zero crossing (9, Fig. 2 B, not shown) of a sine wave signal from generator 5 and then at half the repetition rate until the next negative zero crossing (14, Fig. 2 D, not shown) of the sine wave signal so that the count represents the time between the reference signal and the peak value of the sine wave signal. As described the reference pulse occurs at half the frequency of the sine wave signal. Errors due to a D.C. component in the sine wave signal are avoided since the time for which pulses are accumulated at the full repetition rate is either increased or decreased by an amount t, the time for which pulses are counted at half the repetition rate being correspindingly decreased or increased by a time 2t. By making the capacity of the counter equal to the number of pulses from generator 20 in one cycle of the sine waveform, if the sine signal lags the reference by less than 90 degrees the counter overflows the final count representing the required time interval. Reference has been directed by the Comptroller to Specification 1,145,842. |
