Long-range paths can occur with water depths greater than 1,000 fathoms, depending on bottom slope. At shallower depths high intensity loss is produced from multiple-reflected bottom bounce paths that develop between the source and receiver. Since 85 percent of the ocean is deeper than 1,000 fathoms and bottom slopes are generally less than or equal to 1, relatively steep angles can be used for single bottom reflection. With steeply inclined rays, transmission is relatively free from thermal effects at the surface, and the major part of the sound path is in nearly stable water.

Inactive detection, bottom bounce transmission can produce extended ranges with fewer shadow zones because more than one single-reflected bottom path exists between the sonar and the target. These paths combine to produce an increase in the received signal and reduce the extent of the shadow zone. The major factors affecting bottom bounce transmission include the angle at which the sound ray strikes the bottom (grazing angle), the sound frequency, the bottom composition, and the bottom roughness.

There are two graphic outputs available with the BBR product. 

1. A shaded bottom bounce range display. The amount of shading indicates the range in nmi. See figure 9-3.

2. A shaded bottom bounce probability display. This product provides estimates of the existence of low-loss bottom bounce paths between a sonar (source) and the target (receiver) based on the environmental and geoacoustic parameters. See figure 9-4. The amount of shading indicates the probability conditions as follows:

Figure 9-3.-A shaded bottom bounce range display.

This information is now available on CD in Adobe PDF Printable Format

Privacy Statement - Press Release - Copyright Information. - Contact Us - Support Integrated Publishing