Linear Movement Switches

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Movement Switches In newer switchboards and upgrades to older switchboards, the rotary-type JR and AJR switches have been replaced by linear movement switches with the same electrical configurations as the JR switches.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 13-39