This design has realized a low-frequency phase measuring system, including three parts: phase measuring apparatus, digital phase excursion signal generator and phase excursion network.
Phase-shifting network mainly by the RC phase shifter circuit and LM324 op amp circuit, will the measured signal into the phase-shifting network, by the RC phase shifter, LM324 enlarge isolation, resulting in two signals, all the way through wave-based signal conversion, another way for the phase-shifted signal. Waveform, respectively, after conversion, shaping ,second sub-frequency to the phase measurement and frequency measurement module.
Phase difference measurement is the main phase-locked loop PLL (Phase Lock Loop) frequency reference signal 360 generated and phase-shifting network of reference signal varies with the test signal or after the display of the signal as the gate circuit and control signals.
Frequency measurement module is measured by counting the frequency, which is a known time interval Ts, the measured signal to detect the number of repeated N, and then calculated the frequency of f = N / Ts.
Display circuit modules mainly by the counter, latch, decoder and digital tubes.
For low-frequency phase measurements, using traditional analog pointer instrument is clearly not able to meet the required accuracy, with the electronic technology and computer technology, digital high-precision measurement instrumentation for its resolution and a high degree of intelligence, visual characteristics of a wide range of applications has been increasing. Sinusoidal signal with frequency between the phase difference measurement in electrical technology, industrial automation, intelligent control and communications, electronics and many other fields have a wide range of applications, such as electricians in the field of electric power angle test, dielectric materials, such as the determination of loss angle. Therefore, the phase measurement techniques have a wide range of practical value.
Keywords:Phase Measurement;Frequency Measurement;Low- Frequency ;PLL