TM 11-6625-1668-12
(8) Typical EXT message operation. The following is a typical example of an external (free run)
message operation. For the purpose of this procedure 25% switching bias distortion is introduced to the
message. The output signal applied to the equipment under test is low level 6 volts polar (fig. 3-8).
Set the generator controls as follows:
Control
Position
Control
Position
P-N switch ...............................................
P (Polar)
CODE LEVEL switch.................................
5
DISTORTION SELECT switch .................
BIAS switch
CHARACTER LENGTH switch ..................
8
PERCENT DISTORTION switches ...........
25
CHARACTER RELEASE switch ................
FREE RUN
SELECTED CHARACTER BITS
M (all switches)
Single switch.............................................
INT
switches............................................
Alarm switch .............................................
DISABLE
MESSAGE SELECT switch.......................
Ext
BAUD RATE switch...................................
1200
NOTE
During external message operation the SELECTED CHARACTER BITS, CODE LEVEL,
and CHARACTER LENGTH switches have no effect on the generator output.
(a) Connect the external message data signal from the analyzer at 2A3J2 pin 1 and 2A3J2 pin 15
(ground) to the generator rear panel connector 1A3J2 pin 1 and at 1A3J2 pin 3 (ground).
(b) Connect a patch cord from the DATA 6/12V generator OUTPUT jack to the equipment under
test.
(c) Set the POWER switch to ON.
(d) The regenerated and distorted external message is applied to the equipment under test. (The
signal indicator lamp does not illuminate for low level output keying.)
c. Character Release Operation.
(1) EXT (stepped). For stepped operation the CHARACTER RELEASE switch must be set to the EXT
position. This enables externally applied step pulses to release each character. Each time a suitable step
pulse occurs a character is released. After a particular character is released it remains in its stop pulse period
until a new character is released. Thus a stop pulse period is a function of the step pulse. The amplitude of the
external step pulse must be -60 volts dc at 2 ma and is applied to connector 1A3J3 at pin 6.
(2) FREE RUN. The generator operates in the free run mode when CHARACTER RELEASE switch is
set to FREE RUN. During this mode of operation, the output signal from the generator is determined by the
MESSAGE SELECT switch and can be either a selected character, 1:1 reversals, test message, steady mark,
steady space, or EXT (an externally applied pseudo-random test pattern).
(3) MANUAL. For manual character release set the CHARACTER RELEASE switch to MANUAL. The
SINGLE switch is of the spring return type, a character is released by depressing and releasing the SINGLE
switch. With the MESSAGE SELECT switch in SELECTED CHARACTER the generator will release one
character with each depression and release of the switch. With the SELECTED CHARACTER switch in the
MSG position, operation of the SINGLE switch will generate one character (one letter) from the 80-character
message.
d. Outputs
(1) Low level DATA 6/12. The low level output circuit is a solid-state polar output which provides
signals with amplitudes of 6 or 12 volts. The voltages for the low level output are furnished internally from
the generator power supply. The low level output is available from the front panel only, from the rear panel
only, or combined front and rear. The front panel low level output is designated DATA 6/12 volts.
(2) Low level CLOCK 6/12V. A clock out-put signal is provided as a timing source for external
synchronous data systems. The clock is a polar signal with an amplitude of 6 or 12 volts. Clocking signals
occur at twice the baud rate and are available for speeds up to 9600 baud. Normal factory strapping is 6
volts.
(3) High level, DRY CONTACTS. The high level output circuit is a solid-state output available from the
front and rear panel only. When shipped from the factory, the generator is strapped for combined front and
rear access. The front pane) output for high level signal is designated DRY CONTACTS. An external power
supply is required to furnish the battery for the high level loops. The external high level output will key with any
battery from .5 volt to 150 volts with a maximum current of 100 ma. The P-N switch will provide a high level
polar output when in the P position and a high level neutral output when in the N position.
e. Generator Strap Options. Strapping options are available in the generator to accomplish addi-
3-13
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