The many changes to this radar set have improved its minimum range capability, as well as made it more reliable and easier to maintain. General  Theory  of  Operation The  AN/SPS-40  radar  set,  with  the  automation module, is better able to detect targets over land and water and to generate clutter-free target data. It has a two-speed drive motor, which increases the antenna rate to 15 rpm for high-data rate capabilities and operates at a normal 7.5 rpm speed in the long-range mode (LRM). Some   special   operating   features   of   the AN/SPS-40B/C/D/E include the following: DMTI Long-range, long-range/chaff, and short-range modes Automatic target detection (ATD) Built-in-test (BIT) equipment Analog/digital   conversion Four-pulse  staggered  pulse  repetition  frequency (prf) Operator selectable antenna scan rate Sensitivity  time  control  (STC) Configuration Figure   2-6   illustrates   the   AN/SPS-40B/C/D DMTI/RVC  radar  system.  The  DMTI  field  change replaces the analog moving target indicator with more reliable and more easily maintained digital circuitry. It also provides a new radar set control (RSC) and replaces the duplexer with a solid-state unit. The RVC field change allows the radar to interface with the AN/SYS-1 IADT  system. Installation  of  the  solid-state  transmitter,  field change (FC-11 ), replaces 11 shipboard units (units 2, 3, 4, 6, 16, 17, 18, 19, 21, 23, and 25) with five units (units 28 through 32) as shown in figure 2-7. SIGNIFICANT   FIELD   CHANGES.—   As we mentioned before, this radar set has had many changes. Some  of  the  more  significant  field  changes  are: Digital moving target indicator (DMTI)—solid-state   upgrade Radar video converter (RVC)—interface with AN/SYS-1 Solid-state  transmitter  (SSTX)—changes  the number of units in the configuration and the nomenclature  of  the  system AN/SPS-40E   Field   Change   2—changes   the two-cabinet PA configuration to a single cabinet PA AN/SPS-40E  Field  Change  3—replaces  the DMTI with a new coherent receiver processor SIGNIFICANT INTERFACES.— The An/SPS- 40B/C/D/E  interfaces  with  shipboard  display  systems via   conventional   radar   switchboards   and   NTDS switchboards.   The   AN/SPS-40B/C/D/E   radar   with DMTI/RVC  interfaces  with  the  AN/SYS-1  Integrated Automatic Detection and Tracking System (IADT). FOR THE MAINTAINER.—  The increased use of solid-state  design  and  modular  construction  in  the AN/SPS-40 radar results in a longer mean time between failures (MTBF) and a shorter mean time to repair (MTTR).  The  new  receiver  and  mti  both  use built-in-test  equipment  to  help  in  alignment  and troubleshooting. Maintenance The  AN/SPS-40B/C/D/E  radar  is  designed  for continuous  operation  during  deployment.  The maintenance responsibilities are assigned to the ET rating  (NEC  ET-1516,  ET-1508  (with  DMTI),  and ET-1511  (with  FC-11)).  The  SPS-40’s  modular  design minimizes  maintenance  actions  at  the  organizational level. Organizational   maintenance   includes   preventive and   corrective   maintenance. PM  is  performed according  to  technical  manuals  and  maintenance requirement cards (MRCs). CM  is  performed  according  to  the  corrective maintenance section of the technical manuals and by the Source Maintainability and Recovery (SM&R) code assigned in the APL. You may be required to perform any of the following actions: Remove  and  replace  cabinet-mounted  piece parts,  modules,  assemblies  or  sub-assemblies. Repair  modules,  assemblies,  or  sub-assemblies designated  as  shipboard  repairable. Turn in depot repairable items using prescribed supply   procedures. 2-11