Handling Strong Double Bounce Echoes - Emerson Rosemount 5408 Reference Manual

Service and Troubleshooting
5.
7.5.4

Handling strong double bounce echoes

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.
Double bounces are most commonly present in spherical or horizontal cylinder tanks, and
usually appear when the tank is about 60-70% 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.
Note
The Double Bounce Handling function should only be used if the problem of double bounces cannot
be solved by changing the mounting position.
Note
The surface echo is required to suppress the double bounce. If the surface echo enters the Upper Null
Zone, there is no product surface reference and the double bounce might be interpreted as the
surface echo.
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