| 摘要 |
1,186,690. Phase detectors. INTERNATIONAL STANDARD ELECTRIC CORP. 28 July, 1967 [19 Aug., 1966], No. 34810/67. Heading G4H. In apparatus for measuring the phase between two frequency signals n 1 F, n 2 F having a common harmonic frequency nF, the first signal n 1 F is fed to an AND-gate 14 so-that the first positive-going edge of the signal after a start pulse sets a bi-stable 16 to its one stable state to enable an AND-gate 17 to pass clock pulses -at frequency NF, (N # n 1 n 2 ) to a counter 2 which counts from 0 to N/n -1 and then recycles. The first positive-going edge of the second signal n 2 F resets the bi-stable device 16 to stop the count, which then represents the phase difference measured in degrees with respect to the common harmonic frequency nF of the two signals n 1 F, n 2 F. To derive the average phase difference from e.g. 5 phase difference samples taken at intervals of K/F seconds, where K is an integer, a divider (21, Fig. 3, not shown) dividing the output of AND-gate 17 may precede the counter. |
