Scott-tee transformer to develop the 3-phase stator
voltage outputs (S1, S2, and S3) of the single-speed
D/S converters are designed with holding circuits
that retain the contents of the BAM words between
computer updates of BAM data. The synchro output of
the D/S converter is continuous in nature, indicating a
new rotor angle only when a BAM word received from
the controlling computer contains anew angular value.
This section covers those forms of digital data
handled by various shipboard data conversion devices.
These devices are used to convert digital data from
shipboard weapon, radar, and other subsystems to the
voltage levels and formats acceptable to the CDS
The types of data converted include control and
status signals, ready digital (RD) data, demand digital
(DD) data, demand digital interrupt (DDI) data, and
digital input channel/digital output channel (DIC/DOC)
Control and Status Signals
Control and status signals are discrete ac or dc
signals that indicate or control a single function (on/off,
true/false, and so forth) or condition in a subsystem.
Signals transmitted by CDS equipment to another
subsystem are referred to as control signals because
they generally initiate an action in the receiving system.
Discrete signals received by CDS equipment are
referred to as status signals because they generally
indicate the status of a condition or function in another
CONTROL SIGNALS. Control signals are
generated from individual bit positions in a control
word. Each bit position of the control word represents
one control signal. The individual bits from the control
word are fed to relay circuits. A binary ONE will cause
a relay closure to take place and an ac or dc signal to be
generated from the appropriate supply voltage. A
binary ZERO will cause the relay to de-energize, open
its contacts, and prevent the voltage transmission.
STATUS SIGNALS. Statis signals are ac or dc
voltages received from external subsystems. Each
status signal is assigned to an individual bit position in
a status word. The status bit becomes a binary ONE
when a status voltage is sensed. Lack of a status voltage
signal causes the status bit to remain a binary ZERO.
Status words are sampled periodically by the
controlling computer to determine the current condition
of the individual status signal bits.
Ready Digital (RD) Data
Ready digital (RD) data is 12-bit parallel digital
data generated by the CDS radar azimuth converters
(RACs). The data indicates the antenna or sweep
position of each individual ships radar. This data is
transmitted to the CDS computer as requested by the
computer for program processing and tracking of radar
Demand Digital (DD) Data
Demand digital (DD) data is parallel digital data
input from manual entry devices. Two input channels
are normally used. Each channel may be used by up to
eight daisy-chained devices. Each device is identified
by an address in the input word. DD data is sampled
periodically by the computer to test for operator entries.
Demand Digital Interrupt (DDI) Data
Demand digital interrupt (DDI) data is parallel
digital data similar to DD data. The major difference is
in the method of data entry. DDI devices cause an
interrupt to be generated to the controlling computer
when an entry is made from the applicable device.
Digital Input Channel/Digital Output Channel
Digital input channel/digital output channel
(DIC/DOC) channels are multiplexed parallel digital
computer channels used to increase the input/output
capabilities of the controlling computer. Up to four
DICs and four DOCs are provided. The channels may
be used for input only, output only, or input/output (I/O)
with external peripheral devices or computers
depending on the mode or format selected.
In this topic, you will learn about specific
equipments and groupings of equipments involved in
the data conversion and interfacing process aboard ship.
These equipments permit nominally independent