6A001      Acoustics

(a)   Marine acoustic systems, equipment and specially designed components therefor, as follows:

(1)    Active (transmitting or transmitting-and-receiving) systems, equipment and specially designed components therefor, as follows:

Note:

6A001(a)(1) does not control:

(a)    Depth sounders operating vertically below the apparatus, not including a scanning function exceeding +20⁰, and limited to measuring the depth of water, the distance of submerged or buried objects or fish finding;

(b)    Acoustic beacons, as follows:

(1)     Acoustic emergency beacons;

(2)     Pingers specially designed for relocating or returning to an underwater position.

(a)    Wide-swath bathymetric survey systems designed for sea bed topographic mapping, having all of the following:  (L.N. 132 of 2001)

(1)    Being designed to take measurements at an angle exceeding 20⁰ from the vertical;

(2)    Being designed to measure depths exceeding 600 m below the water surface; and

(3)    Being designed to provide any of the following:

(a)     Incorporation of multiple beams any of which is less than 1.9⁰; or

(b)     Data accuracies of better than 0.3% of water depth across the swath averaged over the individual measurements within the swath;

(b)    Object detection or location systems having any of the following:

(1)    A transmitting frequency below 10 kHz;

(2)    Sound pressure level exceeding 224 dB (reference 1 μPa at 1m) for equipment with an operating frequency in the band from 10 kHz to 24 kHz inclusive;

(3)    Sound pressure level exceeding 235 dB (reference 1 μPa at 1m) for equipment with an operating frequency in the band between 24 kHz and 30 kHz;

(4)    Forming beams of less than 1⁰ on any axis and having an operating frequency of less than 100 kHz;

(5)    Designed to operate with an unambiguous display range exceeding 5120 m; or

(6)    Designed to withstand pressure during normal operation at depths exceeding 1000 m and having transducers with any of the following:

(a)     Dynamic compensation for pressure; or

(b)     Incorporating other than lead zirconate titanate as the transduction element;

(c)    Acoustic projectors, including transducers, incorporating piezoelectric, magnetostrictive, electrostrictive, electrodynamic or hydraulic elements operating individually or in a designed combination, having any of the following:

Notes:

1.      The control status of acoustic projectors, including transducers, specially designed for other equipment is determined by the control status of the other equipment.

2.      6A001(a)(1)(c) does not control electronic sources which direct the sound vertically only, or mechanical (e.g., air gun or vapour-shock gun) or chemical (e.g., explosive) sources;

(1)    An instantaneous radiated acoustic power density exceeding 0.01 mW/mm²/Hz for devices operating at frequencies below 10 kHz;

(2)    A continuously radiated acoustic power density exceeding 0.001 mW/mm2/Hz for devices operating at frequencies below 10 kHz; or  (L.N. 132 of 2001)

Technical Note:

        Acoustic power density is obtained by dividing the output acoustic power by the product of the area of the radiating surface and the frequency of operation.

(3)    Side-lobe suppression exceeding 22 dB;  (L.N. 132 of 2001)

(d)    Acoustic systems, equipment and specially designed components for determining the position of surface vessels or underwater vehicles designed to operate at a range exceeding 1000 m with a positioning accuracy of less than 10 m rms (root mean square) when measured at a range of 1000 m;

Note:

6A001(a)(1)(d) includes:

(a)    Equipment using coherent "signal processing" between two or more beacons and the hydrophone unit carried by the surface vessel or underwater vehicle;

(b)    Equipment capable of automatically correcting speed-of-sound propagation errors for calculation of a point.  (L.N. 132 of 2001)

(2)    Passive (receiving, whether or not related in normal application to separate active equipment) systems, equipment and specially designed components therefor, as follows:

(a)    Hydrophones having any of the following characteristics:  (L.N. 132 of 2001)

Note:

The control status of hydrophones specially designed for other equipment is determined by the control status of the other equipment.  (L.N. 132 of 2001)

(1)    Incorporating continuous flexible sensing elements;

(2)    Incorporating flexible assemblies of discrete sensing elements with either a diameter or length less than 20 mm and with a separation between elements of less than 20 mm;

(3)    Having any of the following sensing elements:

(a)   Optical fibres;

(b)   'Piezoelectric polymer films' other than polyvinylidene fluoride (PVDF) and its copolymers {P(VDF-TrFE) and P(VDF-TFE)}; or

(c)   'Flexible piezoelectric composites';

(4)    A hydrophone sensitivity better than -180 dB at any depth with no acceleration compensation;

(5)    When designed to operate at depths exceeding 35 m with acceleration compensation; or

(6)    Designed for operation at depths exceeding 1000 m;

Technical Notes:

1.      'Piezoelectric polymer film' sensing elements consist of polarized polymer film that is stretched over and attached to a supporting frame or spool (mandrel).

2.      'Flexible piezoelectric composite' sensing elements consist of piezoelectric ceramic particles or fibres combined with an electrically insulating, acoustically transparent rubber, polymer or epoxy compound, where the compound is an integral part of the sensing elements.

3.      Hydrophone sensitivity is defined as twenty times the logarithm to the base 10 of the ratio of rms output voltage to a 1 V rms reference, when the hydrophone sensor, without a pre-amplifier, is placed in a plane wave acoustic field with an rms pressure of 1 μPa. For example, a hydrophone of -160 dB (reference 1 V per μPa) would yield an output voltage of 10^-8 V in such a field, while one of -180 dB sensitivity would yield only 10^-9 V output. Thus, -160 dB is better than -180 dB.  (L.N. 95 of 2006)

(b)    Towed acoustic hydrophone arrays having any of the following:

(1)    Hydrophone group spacing of less than 12.5 m or able to be modified to have hydrophone group spacing of less than 12.5 m;  (L.N. 65 of 2004)

(2)    Designed or able to be modified to operate at depths exceeding 35 m;  (L.N. 132 of 2001)

Technical Note:

'Able to be modified' in 6A001(a)(2)(b) means having provisions to allow a change of the wiring or interconnections to alter hydrophone group spacing or operating depth limits. These provisions are: spare wiring exceeding 10% of the number of wires, hydrophone group spacing adjustment blocks or internal depth limiting devices that are adjustable or that control more than one hydrophone group.  (L.N. 65 of 2004)

(3)    Heading sensors controlled by 6A001(a)(2)(d);

(4)    Longitudinally reinforced array hoses;

(5)    An assembled array of less than 40 mm in diameter;

(6)    (Repealed L.N. 254 of 2008)

(7)    Hydrophone characteristics specified in 6A001(a)(2)(a);  (L.N. 132 of 2001)

(c)    Processing equipment, specially designed for towed acoustic hydrophone arrays, having "user accessible programmability" and time or frequency domain processing and correlation, including spectral analysis, digital filtering and beamforming using Fast Fourier or other transforms or processes;

(d)    Heading sensors having all of the following:

(1)    Any accuracy of better than +0.5⁰; and

(2)    Designed to operate at depths exceeding 35 m or having an adjustable or removable depth sensing device in order to operate at depths exceeding 35 m;  (L.N. 132 of 2001)

(e)    Bottom or bay cable systems having any of the following:

(1)    Incorporating hydrophones specified in 6A001(a)(2)(a); or

(2)    Incorporating multiplexed hydrophone group signal modules having all of the following characteristics:

(a)   Designed to operate at depths exceeding 35 m or having an adjustable or removable depth sensing device in order to operate at depths exceeding 35 m; and

(b)   Capable of being operationally interchanged with towed acoustic hydrophone array modules;  (L.N. 132 of 2001)

(f)     Processing equipment, specially designed for bottom or bay cable systems, having "user accessible programmability" and time or frequency domain processing and correlation, including spectral analysis, digital filtering and beamforming using Fast Fourier or other transforms or processes;  (L.N. 183 of 1999)

(b)   Correlation-velocity and Doppler-velocity sonar log equipment, designed to measure the horizontal speed of the equipment carrier relative to the sea bed, as follows:

(1)    Correlation-velocity sonar log equipment having any of the following characteristics:

(a)    Designed to operate at distances between the carrier and the sea bed exceeding 500 m;

(b)    Having speed accuracy better than 1% of speed; and

(2)    Doppler-velocity sonar log equipment having speed accuracy better than 1% of speed;

Notes:

1.      6A001(b) does not include depth sounders the function of which is limited to:

(a)    Measuring the depth of water;

(b)    Measuring the distance of submerged or buried objects; or

(c)    Fish finding.

2.      6A001(b) does not include equipment specially designed for installation on surface vessels.  (L.N. 254 of 2008)