معايره اجهزه المساحه البحريه

[Mohamed Hashem]

Verification and calibration shall be performed on the following system:

-DGPS verification
-Gyrocompass calibration at mobilization·
-Navigation Software data entry verification at mobilization
-Echo sounder calibration infield

DGPS Verification (healthy check)

The differential GPS shall be verified by comparison of the corrected DGPS with independently observed positions on the working datum. The verification shall be done as following:

-DGPS Verification in port: Done by placing the GPS antenna over a coordinated point, Control points that are located in the port of mobilization shall be adopted for this Purpose. 30 min of observation and logging at this Known position to test and assure the integrity of the receiver and antenna.

Gyrocompass calibration
سبق للزميل محمد جابر تناولها

Echo sounder calibration

The echo sounder transducer shall be deployed from a pole with swivel connection to assist in its recovery and deployment. Wire restraining lines shall be led from the base of the pole to the bow and stern and a safety strop shall be run from an eye on the pole, above the flange, to the transducer shoe.

It will be necessary to calibrate the echo sounder before commencing survey work.

The calibration shall be undertaken in two stages:

1.Setting the echo sounder motor speed for the acoustic velocity of propagation at location. The velocity of propagation shall be determined by deploying a temperature, salinity depth sensor or the calibration transducer and recording readings at 2 m intervals through the water column. The mean temperature / salinity /depth values shall then be entered into the chen millero formula to compute velocity.

2.Setting the transmission line for the depth of the transducer below water line. This shall be achieved by deployment of calibration plate at two meters intervals below sea level, with the plate positioned directly below the transducer. The transmission line shall then be adjusted so that the depth to the plate is recorded at its true depth below sea level. The plate shall then be lowered to the greatest depth possible to confirm that the velocity setting made in that echo sounder is correct.

ودمتم سالمين