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TRACKPOINT 3
OPERATION
3-77
2.
If a slower repetition rate does not solve the problem (or if the repetition rate is already
slower than two or three seconds), the operator should try to isolate the sources of multi-path and
resolve the independent factors using the above guidelines.
F.
Transponder responds correctly and hydrophone receives correctly giving accurate slant
ranges but erratic bearings.
This is usually a sign of low signal to noise ratio at the hydrophone. The hydrophone receives the
signal and causes a valid detection but the data processing performed on the wideband signal is
not consistent enough for a bearing calculation. In this case the detected signal is usually flagged
with a low quality factor. To improve Signal to Noise ratio at the hydrophone:
1.
Use a “louder” sound source. If the configuration is fixed can a directional beacon with
higher source level be used?
2.
Lower the hydrophone to reduce ship radiated noise.
3.
Check that hydrophone shaft is not strumming or vibrating excessively. This causes excess
noise at hydrophone. If hydrophone pole is vibrating but not strumming try shock mounting
hydrophone. (rubber bushings between top of Hydrophone Model 4610B and shaft). If pole
is strumming, change configuration (shorten the shaft, but watch out for reflections) or add
fairing to shaft.
3.6.2
ACOUSTIC PROBLEMS IN RESPONDER MODE
A responder replies acoustically to an electrical interrogation pulse from the TrackPoint II transmit-
ter. Like a transponder, a responder provides the timing information needed to measure horizontal
range directly, but the interrogation pulse is not subject to the acoustic interference associated
with a transponder. However, because a responder must be electrically connected to the tracking
system, it may not be a feasible option for some operations.
When operating in the responder mode, multi-path interference is limited to cases where the direct
arrival of the acoustic reply is blocked or reflected.
If this occurs, it may be necessary to reconfigure the system so that the C/DM hydrophone is in a
position to receive the direct signal. For example, the hydrophone may not be mounted far enough
below the ship's keel to receive a direct signal from a responder on the other side of the ship.
Avoid an operation where a towfish is tracked behind the vessel near the water surface, so that the
direct signal from the beacon is reflected or attenuated by the ship's wake. Either tow the fish off-
center, out of the ship's wake, or sink the responder below the wake.
When operating in and around subsea structures, there is always a number of locations where
there is no direct path between the responder and the hydrophone, and the operator should expect
occasional multi-path interference in these situations. A lower filter setting may help somewhat
under these conditions by detecting earlier.
Содержание TRACKPOINT 3 4211A
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Страница 13: ...PRECAUTIONS viii ...
Страница 14: ...SECTION ONE GENERAL INFORMATION ...
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Страница 18: ...TRACKPOINT 3 GENERAL INFORMATION 1 3 TRACKPOINT 3 CONSOLE FRONT VIEW FIGURE 1 1 ...
Страница 20: ...TRACKPOINT 3 GENERAL INFORMATION 1 5 TRACKPOINT 3 SYSTEM COMPONENTS FIGURE 1 3 ...
Страница 21: ...TRACKPOINT 3 GENERAL INFORMATION 1 6 FIGURE 1 4 ...
Страница 27: ...TRACKPOINT 3 GENERAL INFORMATION 1 12 ...
Страница 28: ...SECTION TWO INSTALLATION ...
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Страница 34: ...TRACKPOINT 3 INSTALLATION 2 5 FIGURE 2 2 ...
Страница 35: ...TRACKPOINT 3 INSTALLATION 2 6 FIGURE 2 3 ...
Страница 38: ...TRACKPOINT 3 INSTALLATION 2 9 MODEL 4740A INSTALLATION FIGURE 2 5 ...
Страница 39: ...TRACKPOINT 3 INSTALLATION 2 10 FIGURE 2 6 C A U T I O N ...
Страница 52: ...TRACKPOINT 3 INSTALLATION 2 23 FIGURE 2 15 ...
Страница 53: ...TRACKPOINT 3 INSTALLATION 2 24 FIGURE 2 16 ...
Страница 56: ...TRACKPOINT 3 INSTALLATION 2 27 FIGURE 2 17 ...
Страница 62: ...SECTION THREE OPERATION ...
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Страница 177: ...SECTION FOUR PRINCIPLES OF OPERATION ...
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Страница 185: ...TRACKPOINT 3 PRINCIPLES OF OPERATION 4 7 TRACKPOINT BLOCK DIAGRAM FIGURE 4 3A ...
Страница 186: ...TRACKPOINT 3 PRINCIPLES OF OPERATION 4 8 TRACKPOINT BLOCK DIAGRAM FIGURE 4 3B ...
Страница 189: ...SECTION FIVE MAINTENANCE ...
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Страница 193: ...TRACKPOINT 3 MAINTENANCE 5 1 DSP CARD PROGRAMMING MODE JUMPER FIGURE 5 1 ...
Страница 201: ...APPENDIX A CARE OF CABLES ...
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Страница 205: ...APPENDIX B STATIC DISCHARGE ...
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Страница 209: ...APPENDIX C WARRANTY ...
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Страница 213: ...APPENDIX D DRAWINGS ...
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Страница 216: ...TRACKPOINT 3 APPENDIX D D 2 ...
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