STANDOFF MINEFIELD MARKING FOR VERY SHALLOW WATER

A NEED EXISTS FOR MARKING CLEARED LANES THROUGH MINEFIELDS. TWO PROPOSED LANE MARKING SYSTEMS WILL PERMIT THE BEST SELECTION FOR THE PREVAILING CONDITIONS. PHASE I WILL BUILD BREADBOARD TO DEMONSTRATE EACH SYSTEM. ONE SYSTEM USES CODED TRANSPONDERS APPROXIMATELY 1" DIAMETER MOUNTED ON TOP OF A TUBULAR EXTENSION FROM A TRIANGULAR 3-PRONG BASE THAT SERVES AS AN ANCHOR TO POSITION THE TRANSPONDERS ON THE BOTTON WHEN THEY ARE DROPPED IN LEFT AND RIGHT-HAND CODED PAIRS FROM THE SIDES OF THE MINEFIELD BREACHING VESSEL AS IT CLEARS A LANE FOR THE PASSAGE OF THE ASSAULT FORCES. THE LANDING CRAFT USES A PORTABLE RECEIVER THAT PERIODICALLY TRANSMITS A SONAR PULSE AS IT PROCEEDS ALONG THE CLEARED LANE. WHEN THE NEXT BOTTOM-MOUNTED TRANSPONDER PAIR RECEIVES THE SONAR PULSE THEY EACH INSTANTLY TRANSMIT A CODED SIGNAL. THE DIFFERENCE IN ARRIVAL TIME OF THE CODED SIGNALS, INDICATED ON A METER ON THE LANDING CRAFT, SHOWS THE OFFCENTER CORRECTION REQUIRED TO KEEP THE VESSEL MOVING ALONG THE CENTER OF THE CLEARED LANE. A SECOND BREADBOARD SYSTEM WILL BE BUILT IN PHASE I WHICH WILL INCLUDE A NUMBER OF TRANSPARENT PLASTIC SPHERES (50% RED AND 50% GREEN). EACH SPHERE IS ATTACHED TO THE END OF A NYLON CORD WHICH IS CONTTAINED ON A SMALL SPOOL MOUNTED INSIDE A WEIGHT MEMBER WHICH SERVES AS AN ANCHOR FOR THE ASSEMBLY. INSIDE EACH SPHERE IS A FLASHLIGHT BULB AND BATTERY SUFFICIENT FOR A 2-HOUR LIFE AS SPECIFIED. AT THE END OF TWO HOURS, A SOLUBLE PLUG ON THE SPHERE ADMITS WATER TO SINK THE LANE MARKERS.