Kenwood CS-3025 Instruction Manual

APPLICATION. OF X-Y OPERATION* Phase Shift MeasurementA method of phase measurement requires calculations based on the Lissajous patternsobtained using X - Y operations.Distortion due to non-linear amplification also can be displayed.A sine w a v e input is applied to the audio circuit being tested. T h e same sine w a v e inputis applied to the vertical input of the oscilloscope, and the output of the tested circuit isapplied to the horizontal input of the oscilloscope. T h e amount of phase difference be-t w e e n the t w o signals can be calculated from the resulting w a v e f o r m .T o make phase measurements, use the following procedure.1 . Using an audio signal generator with a pure sinusoidal signal, apply a sine w a v e testsignal at the desired test frequency to the audio network being tested.2 . S e t the signal generator output for the normal operating level of the circuit being test-ed. If desired, the circuit's output may be observed on the oscilloscope. If the test cir-cuit is overdriven, the sine w a v e display on the oscilloscope is clipped and the signallevel must be reduced.3 . Connect the channel 2 probe to the output of the test circuit.4 . Select X - Y operation by rotating the S W E E P T I M E / D I V control clockwise to the X - Yposition.5 . Connect the channel 1 probe to the input of the test circuit.(The input and output test connections to the vertical and horizontal oscilloscope in-puts may be reserved.)6. Adjust the channel 1 and 2 gain controls for a suitable viewing size.7. S o m e typical results are s h o w n in Fig. 1 6 .If the t w o signals are in phase, the oscilloscope trace is a straight diagonal line. If thevertical and horizontal gain are properly adjusted, this line is at a 4 5 ° angle. A 9 0 °phase sift produces a circular oscilloscope pattern.Phase shift of less (or more) than 9 0 ° produces an elliptical oscilloscope pattern. T h eamount of phase shift can be calculated from the oscilloscope trace as shown in Fig. 1 5 .Where 0 = phase angleF i g . 1 5 Phase shift calculation F i g . 1 6 Typical phase measurementoscilloscope displays28SINE 4>= —B No amplitude distor-tion, no out of phaseNo amplitude distor-tion, out of phaseAmplitude distortion,no out of phaseAmplitude distortion,out of phase1 8 0 ° out of phase 9 0 ° out of phase