Project Experience

MK71 Mod 1 Programmable Target Detecting Device (TDD)

A mine Target Detection Device is the electronic fuse that observes changes in the environment in order to detect ships and submarines and decide whether the target is close enough to damage.  Current bottom mines (Quickstrike and Submarine Launched Mobile Mine [SLMM]) use a TDD MK57, which is a magnetic/seismic device designed specifically for Cold Water targets, such as large combatants and submarines on or near the surface.  The Quickstrike MK65 can also use the TDD MK58 which is a magnetic/seismic/pressure device.  The TDD MK71 is a programmable device capable of responding to emerging threats - such as quiet diesel-electric submarines, mini-submarines, fast patrol boats, and air cushioned vehicles - through a software modification.  It adds an enhanced pressure sensor and has the capability to respond to remote control signals.  The TDD71 has completed development and is approved for production.  The TDD71 is designed for use in all Quickstrike-series mines, SLMM, or Improved SLMM.

The Quickstrike Mine MK62 and MK63 are air-delivered bottom mines that use General Purpose Low Drag Bombs MK82 and MK83 (500 and 1,000 pounds, respectively) as the explosive payload.  The Quickstrike Mine MK65 is a thin-wall, 2,000 pound air-delivered bottom mine.  Because a specialized kit is used to convert bombs into mines, demand for magazine space on aircraft carriers is dramatically reduced.  These mines use either the TDD MK57 or, when available, the TDD MK71.  Arming takes place at a preset time after the mine enters the water.

The Quickstrike (including the MOD 3) system is a family of bottom mines developed to provide special high-density explosive capability for shallow water transit areas.  In addition there are test sets used to test the TDDs, Batteries, and S&A Devices.  To allow aircraft deployment, there are fins, tail section and parachute packs.  The specific MKs and MODs of the Quickstrike are governed by the warhead case and TDD chosen.

The TDD MK71 is the central component of the Quickstrike Mine MK62 & MK63 MOD 3 systems.  This TDD employs a combination 3-Axis magnetometer, pressure and seismic target sensing systems coupled with a microprocessor and algorithm to determine the presence of a valid target and to generate a firing signal.

The TDD MK71 algorithm consists of three separate programs.  Two of these, the default algorithm and the TDD control program, reside in the TDD’s read only memory (ROM).  The third program, the target detection algorithm, is loaded into the TDD’s random access memory (RAM).Prior to deployment, the algorithm is loaded into the battery powered TDD MK71 via a standard serial port.  The TDD is then ready to be loaded into the selected case to create the required Quickstrike configuration.

A Class B Test Set, the EX 650 is used at Intermediate Maintenance Activities (IMA) for testing the TDD MK71 and its batteries.  This test set is also a microprocessor controlled, self-contained, portable unit that operates from standard 120V wall power.  This unit automatically conducts its tests and provides a GO/NO GO indication for the device being tested.  It also has a self-test feature that is capable of isolating faults to the replaceable electronic module unit.  This Test set can conduct further fault isolation using a computer attached to the test set through their RS 232 interfaces.

The Battery EX 143 will be used in the TDD MK71.  This crescent shaped battery consists of 70 button cells configured in 14 parallel strings.  Each string consists of 5 cells connected in series.  The cells use mercuric oxide as the cathode and zinc as the anode.  The entire battery produces about 6.75 volts dc for operating the TDD MK71.

The adapter MK157 is an electromechanical device of cast aluminum that adapts the TDD MK71 to the MK65 mine case and provides the mechanical mounting to the batteries MK131 and MK132.

Two items of Interface Equipment, the Test and Interface Module (TIM) and the Cable-to-Shore Interface Module (CSIM), permit monitoring and evaluation of the real-time performance of an operating TDD MK71.  The TIM provides the required interface with the CLASS A test equipment and the CSIM allows In-Water Equipment (IWE) to interact with the TDD MK71 in an ocean environment.

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Sechan Electronics, Inc. :: 525 Furnace Hills Pike, Lititz, PA 17543-8954
Phone: 717.627.4141 :: Fax: 717.627.4144 ::

Sechan is a leading Department of Defense contractor and electronics manufacturer, specializing in military electronics, electronic contract manufacturing services, and defense electronics.