Fluke CombiScope PM3370B User Manual page 103

4 - 58
The signal on channel 1 is a square wave. Consequently,
there will be only two vertical levels to display.
The signal on channel 2 is a sine wave, which is now
displayed as a function of the square wave on channel 1.
- Press the X SOURCE softkey so that 'line' is intensified.
- Turn off channel 1.
Horizontal deflection is now obtained from the line voltage. On the screen channel
2 (sine-wave) is displayed against the line voltage. The signals on the horizontal
deflection (line) and the vertical deflection (ch2) have different frequency.
- Vary the frequency of the generator to get an almost stable picture.
The displayed figure is called a Lissajous figure. This lissajous figure has 5 (60 Hz
line) or 6 (50 Hz line) tops depending on the line frequency. The number tops
multiplied by the horizontal (line) frequency results in the frequency of the vertical
signal.
2
CH2 1V
If the generator is equal or close to the line frequency, the Lissajous figure is an
ellips whose shape depends on the phase difference. Measuring phase difference
using the X Deflection mode is one of the typical applications for this mode.
50Hz
X=lne
HOW TO USE THE INSTRUMENT
ch1
ch2
ch3
2
ch4
line
60Hz
CH2 1V
2
1
CH1 200mV
CH2 1.00V X=ch1
X=lne
ST6006
ST6739