Tektronix 2205, Operator'S Manual

Page: 54 / 91

Applications
Phase Difference
In a similar manner to the preceding measurement, you can
make a phase comparison between two signals of the same fre­
quency using the dual-trace feature of the 2205. This method
of phase-difference measurement can be used for signals with
frequencies up to the limit of the vertical deflection system. To
make a phase comparison, use the following procedure:
1. Set the TRIGGER SOURCE selector to C H I.
2. Set both input coupling controls to the same position, de­
pending on the type of input coupling desired.
3. Using probes or cables with equal time delays, apply a
known reference signal to the CHI input connector and ap­
ply the unknown signal to the CH2 input.
4. Set VERTICAL MODE to BOTH; then select either ALT or
CHOP, depending on the frequency of the input signals. The
reference signal should precede the comparison signal in
time.
5. If the two signals are opposite in polarity, set the middle
VERTICAL MODE switch to CH2 INVERT to invert the Channel
2 display.
6. Set both VOLTS/DIV and VOLTS/DIV Variable (CAL) controls
to display equal-amplitude waveforms.
7. Adjust the TRIGGER LEVEL control for a stable display and
center the display vertically.
8. Set the SEC/DIV control to a sweep speed that displays
about one full cycle of the waveforms.
9. Position the displays and adjust the SEC/DIV Variable (CAL)
control so that one cycle of the reference signal occupies
exactly eight horizontal graticule divisions at the 50% rise­
time points (see Figure 3 -8 ). Each horizontal division of the
graticule now represents 45° of the cycle (360° divided by 8
divisions), and the horizontal graticule calibration can be
stated as 4 5 ° per division.
3-14 2205 Operator's