Tektronix 1S1 Instruction Manual page 25

Operating Instructions – Type 1S1
of the signal is displayed on the crt screen, the proper
amount of delay to be added or subtracted can be deter-
mined from the sweep rate of the display and the amount
of displacement that the signal must be moved.
Advancing the trigger signal with respect to the vertical
input signal may be accomplished either by using a pre-
trigger pulse generated before the vertical signal pulse, or
by delaying the vertical signal with high-quality coax cable.
If signal delay in excess of 60 nsec is required, the use of a
Tektronix Type 113 Delay Cable is recommended.
Delaying the triggering signal may be done by inserting
delay cables between the signal source and the EXT TRIG
connector or by removing some delay cable from the vertical
signal path. Connecting cables for the triggering signal
may be RG-58A/U or RG-8A/U.
Pretriggering
If a test device has a significant amount of signal delay,
a pretrigger pulse may be used to advance the triggering
signal to the Type 1S1. The time relationship between the
pretrigger and the test pulse should be such that the pre-
trigger precedes the test pulse by less than one half the
reading of the TIME POSITION RANGE scale to be used,
minus the delay time of the test device. This positions the
response signal on the crt when the TIME POSITION control
is centered, and allows the display to be examined in detail.
Table 2-3
Type of
Triggering
Normal
Operation
COVERY TIME not
at SYNC)
Sync Triggering
(RECOVERY TIME
control switched to
SYNC)
2-16
Triggering Sig-
nal Frequency or
Repetition Rate
triggered Below 80 kc
(RE-
80 kc to 20 Mc
20 Mc to 1 Gc
If a pretrigger pulse generator is to be used for trigger-
ing when the response signal is being observed from a
test device without significant delay, the pretrigger may
have to be delayed up to 40 nsec in order to use the 50 nS
time position range. Otherwise the triggering may occur
before the response signal has reached the sampling gate.
(All other time position ranges have enough positioning
capability to overcome the time shift produced by the delay
line.)
Triggering Controls
Operation of the triggering controls depends on the
frequency or repetition rate and the waveshape of the input
triggering signal. Table 2-3 outlines the use of the TRIGGER
SENSITIVITY and RECOVERY TIME controls with the TRIG-
GER SOURCE switch set to INT ± or EXT ± and an appro-
priate triggering signal applied.
For triggering signals from approximately 100kc to 1 Gc,
the trigger circuit recognizes either positive-going or nega-
tive-going excursions of the input triggering signal. The setting
of the
TRIGGER SOURCE
tive-going (+) or negative-going (-) excursion of the signal
causes a trigger recognition to be made, and the TRIGGER
SENSITIVITY control determines the level of the triggering
signal that causes the recognition. The RECOVERY TIME
control adjusts the rate at which the trigger circuit is allowed
to recover and be rearmed.
Use of Triggering Controls
Waveshape
Sine wave
± Pulse 1. Set RECOVERY TIME to any
position, preferable counterclockwise
but not to SYNC
2. Adjust TRIGGER SENSITIVITY
to trigger display at desired level.
Sine wave Either A or B.
Or
A. 1. Set RECOVERY TIME to any
± Pulse
B. 1. Set TRIGGER SENSITIVITY to
Sine wave 1. Set RECOVERY TIME to SYNC
position.
Or
2. Adjust TRIGGER SENSITIVITY
±Pulse
to synchronize circuit with triggering
signal.
switch determines whether the posi-
Operation of Controls
position, preferably counter-
clockwise but not to SYNC.
2. Adjust TRIGGER
SENSITIVITY to trigger display at
desired level.
free run region (45° or more
clockwise from midrange).
2. Adjust RECOVERY TIME to
count down smoothly
triggering signal frequency.
from