POWER SUPPLY SECTION. —The power
supply section provides five regulated dc voltages (-4.8,
-15, +15, -26.65, and +26.65 vdc) that support the
operation of the digital and analog sections of the DAC.
The power supply section receives primary ac power
from the mounting base.
Base Controls and Indicators
The mounting base (figure 13-8) provides controls
and indicators for the operation of the mounting base
and the two associated converters (CONVERTER 1 and
CONVERTER 2).
MODE CONTROL LOCAL/REMOTE. —This
rotary switch selects either REMOTE control of
converter operating modes or LOCAL control via the
BASE switches.
DIGITAL INPUT NORMAL/TEST. —This
rotary switch selects either NORMAL digital inputs
from the computer or TEST digital inputs simulated by
switches on the BASE.
OA/EF. —The OA (output acknowledge) and EF
(external function) pushbuttons are used to simulate
their respective control signals to the converters in
TEST mode.
CONVERTER 1 POWER ON/OFF. —This
switch applies ac power to converter 1 and the right half
of the BASE indicator lights. (Because both converter
switches and indicators are identical, we will only cover
converter 1.)
CONVERTER 1 CHANNEL A. —This group of
switches and indicators is used to select and monitor the
channel mode (TRIG/LINEAR toggle switch) and the
subchannel linear voltage type (CHANNEL A1 AC/DC
and CHANNEL A2 AC/DC toggle switches) when the
BASE is in LOCAL or REMOTE. (Because both
channel A and channel B switches and indicators are
identical, we only cover channel A.)
THIRTY TOGGLE SWITCHES. —A row of 30
toggle switches is used to simulate EF and data word
binary data bits when in the TEST mode.
DAC Controls and Indicators
The DAC provides controls for addressing channels
A and B, selecting the TRIG mode (synchro or
resolver), and test points for verifying individual
channel functions.
CHANNEL A MODE SYN/RSVR. —When the
TRIG mode is selected at the BASE, this switch selects
synchro or resolver output.
CHANNEL A DATA ADDRESS. —This
7-position switch is used to select the address for
channel A. (Because both charnel A and channel B
controls are identical, we only cover channel A.)
Digital-to-Synchro (D/S) Conversion
A digital-to-synchro (D/S) converter converts
BAM data words to single-speed synchro output
signals. The D/S converter requires a reference voltage
input (115 volt, 60/400 Hz). The D/S conversion is
effectively a reverse of the S/D conversion process.
The BAM word is used to generate two analog
voltages representing the sine and cosine of the synchro
rotor angle to be transmitted (figure 13-9). These two
voltages are developed by modulating the stepped down
reference voltage in phase and amplitude. The phase
relationship and amplitude of the sine and cosine signals
are based on the data contained in the BAM word. The
sine and cosine signals are then stepped up and fed to a
Figure 13-9.—Digital-to-synchro (D/S) conversion.
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