GB1507323A - Arrangement for and method of determining the phase shift angle between two electrical alternating signals of the same frequency - Google Patents

Abstract

1507323 Measuring phase difference LICENTIA PATENT VERWALTUNGS GmbH 7 July 1975 [6 July 1974] 28546/75 Heading G1U In phase difference measurement, the reference signal phase is displaced by a predetermined amount if the difference falls within a predetermined range around zero, to avoid 180 degrees ambiguity in an averaged measurement, owing to the discontinuity at 360 degrees. In a direction finding system the reference signal is derived from an oscillator 4 via divider 5, and change-over switch 7. The pulse generator 3 provides pulses whose width indicates the phase difference. These pulses open gate 8 and counter 10 counts clock pulses from the generator 4. The system is controlled by unit 9 comprising a four stage counter incremental at every cycle of the input signal 1. At state "8", output 12 enables gate 8 to start measurement. At the end of state "8" output 13 goes high, enabling gate 15. If the measured phase difference lies in the range Œ45 degrees trigger 16 resets the counter 9 to "8", operates switch 7 to supply the second input of generator 3 with a 180 degree shifted reference signal and passes a signal to counter 10 to adjust the measured values accordingly. If no output is provided by gate 15, the measurement proceeds and eight values are stored in counter 10 (up to state "15"). During the other states of counter 9, gate 8 is blocked, and at state "4", the counter 10 has its oldest eight values cleared. After sixteen measurements, the counter stored values are averaged and output at 19.