The indicated heading shall be recorded at the end of each period; any difference between these recorded heading and the datum settle point heading shall be not more than 1,5°× secant latitude during the test.
NOTE Provision may be made to reduce or nullify any adverse effect on the equipment performance caused by the presence of any electromagnetic field due to the vibration unit.
6.10.3.2 Vibration test of compass equipment other than master compass
This equipment, complete with any shock absorbers which are part of it, shall be secured by its normal means of support to the vibration table. It shall then be connected in its normal electrical configuration to the master compass. The master compass shall then be switched on in accordance with the manufacturer's instructions and its settle point heading ascertained and recorded.
The equipment on the vibration table shall then be vibrated vertically at all frequencies between
a) 5 Hz and 13,2 Hz with an amplitude of 1,0 mm;
b) 13,2 Hz and 40 Hz with a maximum acceleration of 0,7 × 9,8 m/s2; taking at least 25 min to cover each frequency range.
This whole procedure shall be repeated when the equipment is vibrated in two mutually perpendicular directions in the horizontal plane. There shall be no electrical or mechanical failure during any part of this series of tests.
The indicated heading shall be recorded at the end of each period any difference between these recorded heading and the datum settle point heading shall be not more than 1,5°× secant latitude during the test.
6.10.4 Temperature test
The equipment shall be placed in a chamber at normal room temperature, switched on and allowed to settle. The settle point heading shall be obtained and recorded. The temperature of the chamber shall then be raised to 45℃±2℃ and maintained for a period of 3 h. At the end of this period, the THD heading indication shall again be recorded The temperature of the chamber shall then be reduced to O℃±2℃ and maintained at this temperature for 3 h. At the end of this period, the THD heading indication shall be recorded once more. Neither of the recorded heading indications shall differ from the datum settle point heading by more than 1,5°× secant latitude.
NOTE When the temperature of the chamber is being changed it should not alter by a rate which exceeds 45℃ per hour.
6.10.5 Damp heat test
The equipment shall be placed in a chamber at normal room temperature and humidity and then be switched on and allowed to settle. The settle point heading shall be obtained and recorded. The temperature and relative humidity of the chamber shall then be raised steadily over a period. of 3 h ±O,5 h to 40℃±2℃ and a relative humidity of 93 % ±3 %. These conditions shall be maintained for a further period of 3 h ±0,5 h.
The THD indication at the end of this test shall not differ from the datum settle point heading by more than 1,5°× secant latitude
