Triggering On Complex Or Non-Repetitive Signals; Triggering On Line Frequency; Figure 3-26: Channel 1 Signal Triggered With Channel 2 - Tektronix 2221A User Manual

2221A User Manual

Triggering on Complex or Non-Repetitive Signals

Some signals are too complex or irregular to provide a usable trigger of
there own. Circuits that carry digital information are a good example. Often,
however, a signal from another part of the circuit, such as a more widely
spaced clocking signal, will provide a meaningful trigger event. You can
even view the trigger signal at the same time as the other signal with a
two-channel display:
□ Step 1: Connect one signal to Channel 1 and the trigger signal to
Channel 2. Move the CHI BOTH CH2 switch to CH 2.
□
Step 2: Set the trigger mode to NORM and the SOURCE to CH 2.
Step 3: Adjust the TRIGGER LEVEL to trigger on the signal.
□
Step 4: Set the oscilloscope in STORE.
□
Step 5: Move the CHI BOTH CH2 switch to BOTH.
Step 6: Move the ADD ALT CHOP switch to ALT or CHOP. {In general,
it is better to use CHOP when the SEC/DIV control is set in the millisec­
ond {ms) range, and ALT when the SEC/DIV is in the microsecond (ps)
range.)
□ Step 7: Position both signals on screen and adjust the vertical and
horizontal scales.
aU 1= 0 . 0 0 V i TRIG 2=i£ ,5U
.aU2 = 8 , 8 8 U I 1 . ........L
!
_ _
I
i
a------ —
IV
n
I
W
3T,T ''M r .... T "
2U P E fiK D E T
2U

Figure 3-26: Channel 1 Signal Triggered with Channel 2

The STORE mode is ideally suited for viewing extended {4K) acquisitions
and events that occur before during or after a trigger. Refer to Selecting the
Acquisition Record Length (1KI4K), page 3-15.

Triggering on Line Frequency

To trigger on power line signals, apply the signal to an input and move the
COUPL switch to LINE SOURCE.
a T = 0 | 0 0 u &
i _ L
Channel 2 (Trigger) Signal
i !
; | !
m
:
\
j |
Channel 1 Signal
S u s
Displaying Signals
3-27