Service manual

Simrad EK 500 / EY 500
P2260/E 15
- transmitter pulse
- upper layer limit (red line)
- sphere echo
- lower layer limit (red line)
- echo from the additional weight (if used)
- bottom echo
all well separated, and no other echoes within the layer limits.
TS-measurement
Select the TS-Detection Menu to get the horizontal projection window. With the
sphere in the center of the beam, the TS compensated and the TS uncom-
pensated should be identical. These values are read on the screen underneath
the horizontal projection window. If there is a small difference use the TS
compensated value as the measured TS value. It is recommended that the
measured TS value is logged together with other important information. A
recommended form is attached at the end of this document.
If the measured TS value differs from the known TS value of the sphere, then
calculate a new TS transducer gain:
TS measured - TS sphere
New transd. gain = Old transd. gain +
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2
Select the new TS Transducer Gain in the Transceiver Menu and check that the
measured target strength is correct.
In software version 5.20 and higher, TS values have been corrected for TVG
inaccuracies because of the sample intervals and the pulse rise time.
s
A
- measurement
The calibration of the TS-measurement described in the previous paragraph is
the primary calibration and it will in many cases be a sufficient calibration. The
TS-measurement, however, is based on the peak value of the echo samples in
the sphere echo, whereas the s
A
-measurement is based on integration
(averaging) of the echo samples. The received echo may have a smoothed rise
and decay. Therefore the algorithm for calculation of s
A
in the sounder uses an
effective pulse length rather than the nominal pulse length. A test, and if
necessary, a calibration of the s
A
calculation may be carried out according to the
following procedure.