3-System Setup Parameters
pulseEKKO PRO
60
3.5.2.2
SEC Gain
The SEC (Spreading & Exponential Compensation)
gain is a composite of a linear time gain and an
exponential time gain. This gain compensates for the spherical spreading losses and the exponential
dissipation of energy in the data being collected. Since radar data is attenuated exponentially and the SEC
is an exponential gain (Figure 3-18), it tends to be the gain closest to physical reality. Therefore, unlike the
AGC gain, reflections can be compared for relative signal strength (Figure 3-19 and Figure 3-20).
This gain is essentially an exponential function. This exponential function could, in fact, go to infinity.
Therefore, as with the AGC gain some gain limiting factor must be applied. This gain limiting factor is
identical to the one used in the AGC gain (see AGC above).
Figure 3-18: The SEC function has one parameters that must be specified. GMAX is a limiting value on the function. The Atten-
uation (alpha) value determines the steepness of the ramp. When data are collected in areas with high attenuation, a higher Atten-
uation (alpha) value may be necessary to reveal weaker signals.
Figure 3-19: Shows the exponential nature of the SEC function (middle). The SEC gained trace (bottom) is a result of multiplying
each point in the raw trace (top) with the equivalent point in the SEC function.
