TM 11-6625-1668-12
triggered and synchronized by the analyzer. The synchronizing signal is supplied one-half bit into the start
pulse when the analyzer TRANSITION switch is set to ALL or 1. The point of synchronization can be varied by
the analyzer TRANSITION switch. When the switch is advanced to 2, the synchronizing signal occurs half- way
into first bit time interval, rather than the start bit. As the TRANSITION switch on the analyzer is advanced to
the succeeding positions, the synchronizing signal from the analyzer to the oscilloscope advances halfway into
the next bit time.
NOTE
The last or highest numbered effective setting of the TRANSITION switch is one position
higher than the position of the CODE LEVEL switch.
(6) Typical Operation, INT (EXT TRIG). For the purpose of this procedure assume that the analyzer is
measuring distortion on a 60-volt 20-ma input at 150 bauds. The initial control settings are listed below.
Control
Position
Control
Position
PWR ....................................................
OFF
Z MARKERS.........................................
OFF
DISPLAY RELEASE RATE switch.........
NORMAL
VERTICAL VOLTS (MA)/CM switch ......
20
TRIGGER & SWEEP SELECT switch. ..
INT (EXT TRIG)
TIME MILLISEC switch .........................
5.0 to 0.5
(a) Set the PWR switch to ON.
(b) Adjust the FOCUS, ASTIG, INTENSITY CRT, VERT POS and HORIZONTAL POSITION
controls for the best display.
(c) The oscilloscope displays the data signal measured by the analyzer at 60 volts. Note that the
horizontal sweep is synchronized and that sweep range is adjusted by the TIME MILLISEC controls.
(d) Set the DISPLAY RELEASE RATE switch to MAN and note that the horizontal sweep is
disabled.
(e) Press the SINGLE release toggle switch and note that the horizontal sweep is released.
c. Vertical Input Control. For the purpose of calibrating the vertical input to the oscilloscope, the analyzer
is provided with a VCAL position for the INPUT switch. When the analyzer INPUT switch is set to this position
a calibrated 10-volt 60-hz signal is applied to the oscilloscope. The signal viewed on the CRT is adjusted for
the proper deflection as designated by the position of the VERTICAL VOLTS (MA)/CM control. The VERTICAL
VOLTS (MA)/CM controls are used to measure input signal current in the 2 through 50 positions and input
signal voltage levels in the 2 through 200 positions.
d. Display Release Operation. The display of each triggered sweep may be controlled by the DISPLAY
RELEASE RATE switch when operating the TRIGGER & SWEEP SELECT switch in the INT positions, to
effectively blank an integral number of characters. In the NORMAL position of the DISPLAY RELEASE RATE
switch, the sweep triggers once per character, as determined by the analyzer. Thus every character is dis-
played. In the VARIABLE position, the time between sweeps is controlled by the variable DISPLAY RELEASE
RATE control. The sweep although still triggered by the analyzer is not generated for a period of 1/2 to 2
seconds as determined by the setting of the variable DISPLAY RELEASE RATE control. The setting of this
control therefore limits character-viewing rate. This feature is especially useful when the character rate is high
and the operator is viewing random characters or traffic. Waveshapes would otherwise be indistinguishable.
Only full characters will be viewed since the synchronizing signal from the analyzer occurs at the beginning of
the character one-half bit after the start pulse. In the MAN position of the DISPLAY RELEASE RATE switch
the sweep is effectively blanked until the SINGLE release toggle switch is pressed and released. The next
sweep to be triggered will then be displayed. The sweep is still synchronized to begin at the same point in a
character that would occur if the DISPLAY RELEASE RATE switch were in the NORMAL position.
3-10. Stopping and Shutdown Procedures
Shutdown each major component of the test set as follows:
a. Disconnect all external equipment connections.
b. Set all POWER switches to OFF.
c. Return all front panel operating controls to the starting positions listed in paragraph 3-7.
Section III. OPERATION UNDER UNUSUAL CONDITIONS
3-11. General
The operation of the test set may be ;difficult in regions where extreme cold, heat humidity, or other moisture
and sand conditions prevail. Paragraphs 3-12, 3-13, and 3-14 provide procedures that minimize the effects of
these unusual climatic conditions.
3-21
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