The DAC is mounted on an Electronic Equipment
Mounting Base MT-3574B/USQ-20(V), referred to as
a BASE. The BASE can accommodate two DACs, as
shown in figure 13-5.
It provides all electrical
interfaces,
selects DAC operating modes
(TRIGONOMETRIC or LINEAR), and provides
simulated digital data for test purposes.
There is an accessory to the DAC called the
Analog-to-Analog Converter (AAC) CV-2518/UYK.
The AAC provides signal conversion from linear ac to
linear dc or linear dc to linear ac.
Each DAC is divided into two identical channels,
designated channels A and B. Each channel can output
two linear voltages, a sine/cosine resolver (scalar), or a
single-speed synchro, depending on the operational
mode selected. For simplicity, only one base with one
channel of a DAC connected in the converter 1 position
is covered here. The base and converter operate as one
unit and are discussed as one.
The DAC normally receives computer output from
digital output channel (DOC). Both the KCMX and
DOC functions are covered in this chapter. The output
passes through the mounting base, which is transparent
for normal computer operations. The output buffer
consists of an external function (EF) word, a control
address word, and up to eight data words. The EF word
master clears the DAC and initiates the receive data
from unit computer (RDUC) operations. The control
address word defines the control address of the DAC to
receive the data words. The individual DAC’s control
address is set using the eight-position CONTROL
ADDRESS switch on the DAC front panel (figure
13-6). If the data is properly addressed to the DAC, the
DAC initiates RDUC operations to process the data
words coming from the computer.
Each data word contains a data address code (0-7)
to define the DAC channel (A or B) that is to process
the data. Both DAC channels receive the data;
however, only the channel with the CHANNEL DATA
ADDRESS switch in the position to match the data
a 30-bit parallel keyset central multiplexer (KCMX)
address will process the data.
Figure 13-6.—DAC front panel.
13-9
