subTRAX

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006699" TEXT="#080000" bgproperties="fixed" background="04e285a1erlcgo.png"> <div> <FONT SIZE="5" COLOR="#FFCC66" FACE="Arial" ><B>Chaplin Marine Instruments</B></FONT><B>    </B><B> |     </B><A HREF="index.htm" TARGET="_top" TITLE="Chaplin Marine Instruments"><U><B>home</B></U></A></div> <div> <A HREF="id2.htm" TARGET="_top" TITLE="About Us"><U>About Us</U></A>   |   <A HREF="id8.htm" TARGET="_top" TITLE="Design Services"><U>Design Services</U></A>   |   <B>subTRAX</B>   |   <A HREF="id16.htm" TARGET="_top" TITLE="Popeye Data Shuttle"><U>Popeye Data Shuttle</U></A>   |   <A HREF="id6.htm" TARGET="_top" TITLE="Contact Us"><U>Contact Us</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000" background="04dd2c00dkelyh.png"> <bR> </td> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <I>subTRAX</I></div> <div> <B>A GPS-Enhanced Passive Sonar System</B></div> <bR> <div>   I<B>nnovative features of the subTRAX system:</B></div> <bR> <div> inexpensive</div> <div> small</div> <div> lightweight</div> <div> low-power</div> <div> easy to deploy, move & recover</div> <div> interchangable buoys</div> <div> applications in shallow or deep water</div> <div> GPS synchronous operations</div> <div> simple & inexpensive target signal generator</div> <div> simple acoustics - no transponders, non-synchronous target signal</div> <bR> <bR> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">The basic subTRAX system has three parts:</div> <div> > an array of four navigational reference nodes deployed on the sea surface.</div> <div>             > an ashore or shipboard base station within 20 miles of the array.</div> <div>             > a small module to attach to the underwater target to generate an acoustic signature</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Each node in the subTRAX array is a small, lightweight (<30kgs) spar buoy hereafter referred to as a GEB (GPS Enhanced Buoy).</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Each GEB is equipped with an underwater acoustic receiver, a GPS receiver, and a 1Watt, 900MHz RF transceiver to continuously report the GEB location and target data to the base station.</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">The GEBs can be moored to the sea floor or allowed to drift during tracking operations.</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Each GEB is equipped with a precision clock, disciplined by its GPS receiver's atomic clock signal (PPS = 5Hz).  This results in all detection counters in the array running in-phase and "locked" to universal time (UTC).  Each GEB clock phase is disciplined to  +/- 1 count of a 16-bit, 10KHz counter... the equivalent of 15 cm a underwater distance.</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Each GEB is equipped with an underwater, omnidirectional, narrowband (150Hz) acoustic receiver with acoustic edge-detection capability.  The receiver can determine the arrival time of the target signal to within +/- 0.1millisec... again, the equivalent of 15 cm of underwater distance.</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Acoustically, each GEB is a listen-only module.  The base station determines target position by the differences in time-of-arrival reported by the GEBs in the array.  Note that it is not a GEB requirement to initiate a range measurement with the target.  This is not a transponder system... the GEB does not need an acoustic transmitter.</div> <div> <IMG BORDER="0" SRC="Wing0a73007700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">The target (diver, AUV, etc.) will be equipped with a tiny hemispherical pinger, capable of emitting a specific frequency CW pulse, e.g., 12.00kHz for 10millisec.</div> </td> </tr></table></body>