Figure 3-5.—Control monitor front panel.

Figure 3-5.—Control monitor front panel. radar, it can accommodate rotation rates from 2 to 30 rpm, receiving radar synchro information via the radar switchboard. In the manual mode, it can position the antenna to any azimuth directed from a remote position. The antenna pedestal assembly can mount the AS-2188( )/UPX or any other 10-foot antenna designed to mount on the same platform. The pedestal disconnect mast switch, located above decks, removes all power from the pedestal assembly. The selection of system antenna equipment depends on which radar is using the Mark XII system. For installations where the rotary joint will not pass the switching bias, the AS-2188( )/UPX will transmit a sum pattern only, with a separate AS-177( )/UPX omnidirectional antenna transmitting the difference rf. Some installations use an integral antenna to transmit and receive both radar and IFF signals, with difference rf transmitted on a separate AS-177( )/UPX antenna. TRANSPONDER SECTION.—The transponder receives interrogation pulses and, in turn, generates the proper reply pulses. A simplified block diagram of a typical shipboard transponder section is shown in figure 3-6. As we discussed before, desired reply codes are set by thumbwheel switches for modes 1, 2, and 3/A; ships are wired for code 0000 mode C replies. Mode 4 replies are coded automatically according to the crypto key installed in the TSEC/KIT-1A. The organizational-level maintenance of the Mark XII IFF system is performed by ETs (NEC ET- 1572). You must have formal training or written permission from your commanding officer to work on the TSEC/KIR-1, TSEC/KIT-1, or TSEC/KIK-18 crypto units. The AIMS Newsletter, published by Naval Electronic Systems Engineering Activity (NESEA) St. Inigoes, Maryland, provides information to shipboard technicians and operators on AIMS systems, primarily Mk XII IFF and its related subsystems. It keeps you up to date on any equipment modifications, PMS changes, and significant interface problems. It also gives you an AIMS hotline number to use if you have any questions or problems concerning maintenance or operation of Mk XII IFF equipment. You can find more information on this publication in ET, Volume 2, Administration. Agreements between the Navy, Air Force, and FAA, under the AIMS program, required the development of a system to present ATCRBS data instantly, in symbolic and numeric form, directly on the indicator, and superimposed over live radar video. The AIMS Mark XII IFF system does this for ships. Under the AIMS 3-6