SUBSIM Radio Room Forums - View Single Post - Why is there a sonar blind spot at 0d relative?

Pisces · 02-16-08, 08:31 AM

This link should explain the theory behind how the GHG work. But I must warn you it's is quite technical/scientific:

http://www.xs4all.nl/~aobauer/sonar-ghg.htm

Basically a number of microphones (24) were built into each side of the hull, with certain distances between them. If the sound came directly from the side of the uboot the sound would reach all microphones (on one side) at the same time. But if the sound came from a bearing forward or aft of the beam then each microphone would hear the sound a little bit sooner or later than the others. This difference in time, or rather 'phase' for each frequency as electrical technicians would call it, can be reconstructed electronically to provide a bearing. But because of the orientation of the microphones they hardly can hear sounds on bearings near the bow and stern, because that is 'not in their face' for them. It doesn't make them vibrate as much, or at least relative to the unwanted noise. Also bearing uncertainty was becoming a problem in those directions.

02-16-08, 08:31 AM	#4
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	This link should explain the theory behind how the GHG work. But I must warn you it's is quite technical/scientific: http://www.xs4all.nl/~aobauer/sonar-ghg.htm Basically a number of microphones (24) were built into each side of the hull, with certain distances between them. If the sound came directly from the side of the uboot the sound would reach all microphones (on one side) at the same time. But if the sound came from a bearing forward or aft of the beam then each microphone would hear the sound a little bit sooner or later than the others. This difference in time, or rather 'phase' for each frequency as electrical technicians would call it, can be reconstructed electronically to provide a bearing. But because of the orientation of the microphones they hardly can hear sounds on bearings near the bow and stern, because that is 'not in their face' for them. It doesn't make them vibrate as much, or at least relative to the unwanted noise. Also bearing uncertainty was becoming a problem in those directions.