Example 16: Distance from echo timing

An RBRconcerto³ Alti has a RBRalti sensor which outputs distance and echo timing. Only distance is reported by the RBRconcerto³. 

Full, in-situ derivation of distance from echo timing requires an average speed of sound over the path used by the sound.

Distance is a 'pure' derived parameter which has its own channel assigned to it, but there is no underlying measurement hardware for distance itself; it simply uses the outputs of the echo timing channel and the average speed of sound setting. This makes its specification rather sparse: there are no coefficients in either of the c or x groups; all that is needed is to specify the indices in the n group.

In our example:

• n0 is the index of the echo timing channel, 2 in this example,
• n1 is the index of the average speed of sound channel, value in this example, ie the default setting.

The distance is calculated as follows:

where

• Te is the echo timing (round trip) in milliseconds, value(n0).
• ASS is the average sound of speed, value(n1) (refer to "settings avgsoundspeed").

Examples

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