NEW ZEALAND GAZETTE

No. 190

(2) The equipment shall comply with the following minimum performance requirements.

9. Range of Depths—Under normal propagation conditions the equipment shall be capable of measuring any clearance under the transducer between 2 metres and 400 metres.

10. Range Scales—(1) The equipment shall provide a minimum of two range scales one of which, the deep range, shall cover the whole range of depth, and the other, the shallow range, one tenth thereof.

(2) The scale of display shall not be smaller than 2.5mm per metre depth on the shallow range scale and 0.25mm per metre depth on the deep range scale.

11. Method of Presentation—(1) The primary presentation shall be a graphical display which provides the immediate depth and a visible record of soundings. Other forms of display may be added but these shall not affect the normal operation of the main display.

(2) The visible record shall, on the deep range scale, show at least 15 minutes of soundings.

(3) A clear indication shall be given when the paper remaining is approximately 10 per cent of the length of the roll.

12. Pulse repetition rate—The pulse repetition rate shall not be slower than 12 pulses per minute.

13. Accuracy of measurement—Based on a sound speed in water of 1500 metres per second, the allowable tolerance on the indicated depth shall be: either

(a) ±1 metre on the shallow range scale
±5 metres on the deep range scale

or

(b) ±5 per cent of the indicated depth, whichever is the greater.

14. Roll and pitch—The performance of the equipment shall be such that it will meet the requirements of this performance standard when the ship is rolling ±10° and/or pitching ±5°.

Part III

Performance Standards for Radio Direction-finding Systems

15. Introduction—(1) The direction-finding equipment shall indicate both bearing and sense of radio transmissions in the frequency bands specified in paragraph 16 of this Recommendation.

(2) In addition, the equipment shall comply with the following minimum performance requirements.

16. Frequency ranges and classes of emission—The equipment shall be capable of receiving signals of classes of emission A1A, A2A, and H2A in the frequency range 255 to 525 kHz and A1A, A2A, H2A, A3E and H3E in the frequency range 2167 to 2197 kHz.

17. Selectivity—The selectivity shall be such as to allow a bearing to be taken readily without interference from other radio transmissions on frequencies more than 2 kHz from the desired signal.

18. Signal Identification—(1) Means of audio-monitoring shall be provided regardless of the method used for direction-finding.

(2) The equipment shall be operated with headphones. A loudspeaker, if provided, shall be capable of being rendered inoperative by simple means.

19. Bearing indication—Means shall be provided to indicate the bearing of the desired transmission. Such indication shall be capable of being easily, rapidly and precisely resolved within 0.25 degrees.

20. Bearing accuracy—(1) The instrumental accuracy in taking relative bearings shall be within ±1°. This requirement shall be met at all frequencies in the frequency bands specified in clause 16 of this performance standard and throughout the whole 360 degrees of azimuth at field strength values between 50 μV/m and 50 mV/m. The instrumental accuracy referred to above does not include the operational accuracy attainable in service, which shall be determined for each installation. In particular the operational accuracies in the 2 MHz band shall be sufficient for homing purposes.

(2) Pre-set facilities to correct the quadrantal error shall normally be provided for the frequency band 255–525 kHz.

21. Manual controls and their operation—(1) A tuning scale or indicator shall be provided, calibrated to indicate directly the carrier frequency of the signal to which the equipment is intended to be tuned.

(2) (a) If a tuning scale is provided, at all points in its range, 1mm shall correspond to not more than 2.5 kHz in the frequency range 255–525 kHz.

(b) The maritime distress frequencies shall be prominently marked.

(c) Where other means of frequency indication are provided, the resolution shall be at least 1 kHz.

(3) All controls shall be of such size and location as to permit normal adjustments to be easily performed, and shall be easy to identify and use.

(4) The sense switch, if fitted, shall be of a non-locking type.

22. Operational availability—The equipment shall be ready for operation within 60 seconds of switching on.

23. Special requirements for different methods of direction-finding—(1) Aural minimum method

(a) With a field strength sufficient to ensure a signal/noise ratio of at least 50 dB, a change in the setting of the bearing indicator of 5° in either direction from the position of minimum output shall cause the audio-frequency output to increase by not less than 18 dB. Similarly, a change of 90° in either direction shall cause an increase of not less than 35 dB.

(b) The equipment shall be provided with a minimum-clearing control giving a noticeable minimum of the output at all settings.

(c) The sense shall be determined with reference to the lower output.

(d) The sense ratio in the frequency ranges 255–525 kHz and 2167–2197 kHz shall be 15 dB and 10 dB, respectively.

(e) The automatic gain control, if provided, shall be rendered inoperative automatically when the equipment is used for bearing determination.

(2) Other methods

(a) There shall be means of indicating that the receiver gain and signal strength are sufficient to enable a correct bearing to be taken.

(b) With a field strength of 1mV/m the indicated bearing shall not change by more than 1° when the receiver is detuned to a point where the indication referred to in sub-paragraph (a) above shows that the signal strength is just sufficient to take a bearing.

(c) For any signal of strength sufficient to give a bearing indication, there shall be no observable change of indicated bearing when the beat frequency oscillator is switched on.

(d) Fluctuations of the indicated bearing caused by any servo mechanism shall not exceed ±0.5° from the mean value.

(e) If, after identifying a station the bearing of which is required, it is necessary to check or alter the adjustment of any control as part of the process of direction-finding, this check and adjustment shall be capable of being made within 10 seconds.

24. Miscellaneous—The equipment shall be protected from excessive voltages induced in the aerials.