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Manually Operated JR Switch Panel Assembly | Up
Fire Controlman Volume 03-Digital Data Systems | Next
ANALOG AND DIGITAL QUANTITIES |
Figure 13-38.—JR switch (type 4).
Each panel contains a REMOTE-MANUAL
toggle switch. The servo system controls the position
of the AJR switch when the toggle switch is in the
REMOTE position. The toggle switch must be placed
in MANUAL to allow personnel to rotate the switch.
Linear Movement Switches
In newer switchboards and upgrades to older
switchboards, the rotary-type JR and AJR switches
have been replaced by linear movement switches with
the same electrical configurations as the JR switches.
We covered linear movement switch panel assemblies
in the Mk 70 DFCS.
Figure 13-39.—Remotely operated JR switch panel
assembly.
END-AROUND-TEST (EAT)
One of the functions provided by both analog and
digital switchboards is the end-around-test (EAT).
When switches are in the EAT position, switchboards
take the output of a device and feed it back to the same
or similar device as input data. For instance, a control
signal generated by a device such as the KCMX can be
routed end-around as a status signal input. The output
of a digital-to-synchro (D/S) converter can be fed end-
around to a synchro-to-digital (S/D) converter or the
output channel of a computer can be end-around as an
input channel for the same computer. EAT allows for
offline testing and verification of the operability of
digital and analog interfaces, both within the CDS and
external to the CDS.
SUMMARY-DATA CONVERSION
DEVICES AND SWITCHBOARDS
This chapter has introduced you to analog-to-
digital (A/D), digital-to-analog (D/A), and digital-to-
digital (D/D) conversion methods and some typical
conversion devices. You were also introduced to data
switchboards used in system configuration. The
following information summarizes important points
you should have learned.
FUNDAMENTALS OF DATA CONVER-
SION— The digital equipment that composes the
combat direction system (CDS) uses information in
analog form. To use this information, the analog signals
must first be converted to digital signals. The
amplitude, frequency, or phase of an analog signal may
represent a value within a given set of limits (minimum
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