Y Measurements; Using The Delayed Time Base - Philips PM 3214 Anleitung

24
2.3.9
XY Measurements
XY measurements are made with the TIME/DIV switch at X DEFL, the source of horizontal deflection being
selected by the EXT X DEFL or TRIG pushbutton switch (A, B, EXT or LINE►.
XY measurements provide a useful means of making frequency or phase shift comparisons by displaying
Lissajous patterns.
Measurements can be made up to 100 kHz with less than 3° phase error between oscilloscope channels.
The sensitivity for the different XY modes is shown in the following table:
X DEFL.
SENSITIVITY
A
AMPL/DIVA ± 10%
B
AMPL/DIV B ± 10%
EXT 0.5 V/div ± 10%
LINE 8 divisions at nominal line voltage
2.3.10
Using the Delayed time base
The delayed time base can be used for the accurate study of complex signals. The delayed time base generator
starts (TIME/DIV switch not at OFF► after the selected delay time and the delayed signal is intensified when
the MTB pushbutton of the horizontal deflection controls has been selected.
The DELAY TIME potentiometer control enables to intensified portion to be shifted along the time axis. The
duration of the intensified portion, its length, can be controlled in steps and continuously by means of the
TIME/DIV controls of the delayed time base generator. When pushbutton DTB of the horizontal deflection
controls is depressed, the intensified portion occupies the full width of the screen.
In the DTB position, the delay time (i.e, the interval between the starting points of the main time base and
that of the delayed time base) is determined by the setting of the main time base TIME/DIV controls and the
DELAY TIME control. The PM 3214 is equipped with display switching. This offers the instrument user a
simultaneous display of the signal on the two time scales provided by the main time base and by the delayed
time base.
By selecting ALT TB, detailed examination of a certain portion of the main time base display is enabled by
expanding the time interval of interest, using the delayed time base.
Expansion is achieved by selecting a correspondingly faster sweep for the delayed time base TIME/DIV control
and positioning the time interval by the DELAY TIME potentiometer.
The part of the signal under detailed observation by the delayed time base also remains as an intensified portion
of the main time base display. This not only facilitates the location of the required detail during dialling, but
also serves as a visual indication of the portion of the overall trace being examined. Selection of ALT TB thus
enables immediate correlation of the detail with the overall signal, which may be extremely complex, without
the need to switch between MTB and DTB.