Emerson Rosemount 3408 Reference Manual page 102

Service and troubleshooting
September 2022
5. Select Save.
7.5.4 Handling strong double bounce echoes
Double bounces are most commonly present in spherical or horizontal cylinder tanks, and
usually appear when the tank is about 60-70 percent filled. In these cases, the amplitude
may be strong enough for the transmitter to interpret the double bounce as the surface
echo. The Double Bounce Handling function is used for managing such problems.
A double bounce echo occurs when a radar signal bounces back and forth between the
product surface and tank roof (or other object within the tank) before it is detected by the
transmitter. Normally, these signals have a low amplitude and are ignored by the
transmitter.
Figure 7-25: Double Bounce Echoes
A
B
A. Distance to surface
B. Distance to first double bounce
C. Actual level
D. Virtual level (first double bounce)
E. Signal amplitude
F. Distance
Prerequisites
Note
The Double Bounce Handling function should only be used if the problem of double
bounces cannot be solved by changing the mounting position.
102
E
C
D
F
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