Operating Instructions—Type 324
Period = 50 ys X 1.37 X 7 = 480 ]is
This answer can be converted to frequency by taking the
reciprocal of the period (see applications on Frequency
Measurements).
Lissajous Figures. An unlimited number of trace
patterns (Lissajous figures) can be obtained by simultan
eously applying signals of different frequencies or phase
angles to the two input connectors. If the frequencies are
different and do not have a common divisor, the pattern
will change continuously. If the frequencies are the same,
or have a common divisor, the pattern will be stationary,
permitting phase, amplitude and frequency comparison.
(The ease of comparison varies inversely with the ratio of
frequency to common divisor.) One of the most practical
uses of these patterns is in making extremely accurate
adjustments of one frequency in respect to another.
An analysis of these patterns is a science in itself, and
beyond the scope of this manual. However, a few patterns
and their interpretations are contained in Fig. 2-15 and
2-16.
phase shift each one will introduce. For example, the hori
zontal circuit will introduce less than 5° phase shift at 200
kHz (its high-frequency half-power point).
The amount of difference in phase shift between the
vertical and horizontal circuits will increase as frequency
increases. This amount can be determined at any specific
frequency. Couple the same signal into both the vertical
and horizontal input connectors and calculate the differ
ence in phase which appears in the presentation, using the
method explained in Fig. 2-16.
GLOSSARY OF TERMS
The terms and definitions contained herein are limited
to information required to understand the material in this
manual. If a term is synonymous with a preferred term, its
definition is restricted to the name of the preferred term.
—3 dB Point—Half-Power Point
AC Coupling—The condition existing when a capacitor is in-
The characteristics of the oscilloscope s vertical and hori-
serted between the signal pickoff point and the circuit to
zontal amplifier circuits must be considered in X Y opera-
which the signal is applied,
tion. Their bandwidth capabilities determine how much
1. Center the display horizontally.
2. Measure total vertical amplitude ( V t ) .
3. Measure amount of center vertical line which is enclosed
by ellipse (V c) .
4. Divide Vc by V t to obtain sine of phase angle.
5. Determine phase angle from table of trigonometric values.
6. Angle is > 2 7 0 ° and < 0 9 0 ° if ellipse rises from left
to right.
7. Angle is >
0 9 0 ° and < 2 7 0 ° if ellipse falls from left
to right.
Fig. 2 -1 6 . D eterm in ing phase angle.
Accelerating Voltage—A voltage applied to components
within a cathode-ray tube to accelerate beam electrons
during their passage from cathode to phosphor screen.
Astigmatism—Any deviation from a circular appearance of
the electron beam spot. Also the control which corrects
for the deviation.
Attenuator—Normally, any device used to intentionally
decrease the amplitude of a signal prior to its application
to the oscilloscope's amplifier circuitry. Any device
which decreases a signal's amplitude.
Automatic Triggering—Applies to the trigger circuit. A
triggering mode in which triggers to the Type 324 sweep
circuit will initiate triggered sweeps in response to a
broad range of internal or external signals without
adjustment of the triggering level control. It will also
provide a free-running sweep for reference in the absence
of triggers.
Balanced Circuit—Tw o symmetrical (electrically identical)
branches or nodes of a circuit which carry equal but
opposite polarity signals. Also called Push-Pull circuit.
2-24
