6.8.2 The table and master compass shall be turned at a rate not greater than 20°/s, to read data both of THD output and angle of the table at least 5°intervals during this test.
The maximum follow-up errors shall conform to the requirements specified in 5.3.4.
6.9 speed error correction test
With the master compass mounted on a level and stationary base and the fore and aft mark of the compass aligned to North, the master compass shall be settled and the settled point heading recorded.
A speed signal of 20 knots shall be applied to the Gyro-compass and allowed to resettle.
The difference between the settle point heading so obtained and that recorded initially shall agree with the value computed theoretically for the latitude of the test to within 0,35°× secant latitude.
6.10 General requirement test
For these tests, the datum from which settle point variations shall be measured is the settle point heading obtained in the absence of the particular environmental condition to be applied.
6.10.1 Voltage variation test
The supply voltage shall be set to 10 % above the nominal value for 3 h, during which time the THD heading shall be recorded at 20 min intervals. The supply voltage shall then be set to a value 10 % below nominal for 3 h, and the THD heading again recorded at 20 min intervals. None of the recorded headings shall depart from the original datum by more than 1,5°× secant latitude.
6.10.2 Frequency variation test
In case of AC supply the frequency shall be set to 5 % above the nominal value for 3 h, during which time the THD heading shall be recorded at 20 min intervals. The supply frequency shall then be set to a value 5 % below nominal for 3 h and the THD heading again recorded at 20 min intervals. None of the recorded headings shall depart from the original datum by more than 1,5°× secant latitude.
6.10.3 Vibration test
6.10.3.1 Vibration test of master compass
In all these tests, the direction of the master compass fore and aft mark shall be +30°±1°to the meridian. The master compass shall be subjected to the vibration described below. Three separate tests shall be carried out, the direction of vibration being:
a) +30°±1°to the meridian and horizontal;
b) -60°±1°to the meridian and horizontal;
c) vertical.
In each case the compass shall be settled initially and then the vibration shall be applied at the lowest frequency, holding the appropriate vibration amplitude for a period of 25 min. At the end of that period, the frequency and amplitude shall be changed to the next value tabulated below and held for a further 25 min. This process shall continue until the entire frequency range has been covered.
