6A001 Category 6A

Acoustic systems, equipment and “components,” as follows (see List of Items Controlled).

Category 6: Sensors and Lasers

Reasons for control

• NS: National security
• AT: Anti-terrorism

Country chart

List-based license exceptions

Items

1. a. Marine acoustic systems, equipment and “specially designed” “components” therefor, as follows:
2. a.1. Active (transmitting or transmitting-and-receiving) systems, equipment and “specially designed” “components” therefor, as follows:
3. a.1.a. Acoustic seabed survey equipment as follows:
4. a.1.a.1. Surface vessel survey equipment designed for sea bed topographic mapping and having all of the following:
5. a.1.a.1.a. Designed to take measurements at an angle exceeding 20° from the vertical;
6. a.1.a.1.b. Designed to measure seabed topography at seabed depths exceeding 600 m;
7. a.1.a.1.c.'Sounding resolution' less than 2; and
8. a.1.a.1.d. 'Enhancement' of the depth “accuracy” through compensation for all the following:
9. a.1.a.1.d.1. Motion of the acoustic sensor;
10. a.1.a.1.d.2. In-water propagation from sensor to the seabed and back; and
11. a.1.a.1.d.3. Sound speed at the sensor;
12. a.1.a.2. Underwater survey equipment designed for seabed topographic mapping and having any of the following:
13. a.1.a.2.a. Having all of the following:
14. a.1.a.2.a.1. Designed or modified to operate at depths exceeding 300 m; and
15. a.1.a.2.a.2. 'Sounding rate' greater than 3,800 m/s; or
16. a.1.a.2.b. Survey equipment, not specified by 6A001.a.1.a.2.a, having all of the following:
17. a.1.a.2.b.1. Designed or modified to operate at depths exceeding 100 m;
18. a.1.a.2.b.2. Designed to take measurements at an angle exceeding 20° from the vertical;
19. a.1.a.2.b.3. Having any of the following:
20. a.1.a.2.b.3.a. Operating frequency below 350 kHz; or
21. a.1.a.2.b.3.b. Designed to measure seabed topography at a range exceeding 200 m from the acoustic sensor; and
22. a.1.a.2.b.4. 'Enhancement' of the depth “accuracy” through compensation of all of the following:
23. a.1.a.2.b.4.a. Motion of the acoustic sensor;
24. a.1.a.2.b.4.b. In-water propagation from sensor to the seabed and back; and
25. a.1.a.2.b.4.c. Sound speed at the sensor.
26. a.1.a.3. Side Scan Sonar (SSS) or Synthetic Aperture Sonar (SAS), designed for seabed imaging and having all of the following, and “specially designed” transmitting and receiving acoustic arrays therefor:
27. a.1.a.3.a. Designed or modified to operate at depths exceeding 500 m; and
28. a.1.a.3.b. An 'area coverage rate' of greater than 570 m 2/s while operating at the maximum range that it can operate with an 'along track resolution' of less than 15 cm; and
29. a.1.a.3.c. An 'across track resolution' of less than 15 cm;
30. a.1.b Systems or transmitting and receiving arrays, designed for object detection or location, having any of the following:
31. a.1.b.1. A transmitting frequency below 10 kHz;
32. a.1.b.2. Sound pressure level exceeding 224dB (reference 1 µPa at 1 m) for equipment with an operating frequency in the band from 10 kHz to 24 kHz inclusive;
33. a.1.b.3. Sound pressure level exceeding 235 dB (reference 1 µPa at 1 m) for equipment with an operating frequency in the band between 24 kHz and 30 kHz;
34. a.1.b.4. Forming beams of less than 1° on any axis and having an operating frequency of less than 100 kHz;
35. a.1.b.5. Designed to operate with an unambiguous display range exceeding 5,120 m; or
36. a.1.b.6. Designed to withstand pressure during normal operation at depths exceeding 1,000 m and having transducers with any of the following:
37. a.1.b.6.a. Dynamic compensation for pressure; or
38. a.1.b.6.b. Incorporating other than lead zirconate titanate as the transduction element;
39. a.1.c. Acoustic projectors, including transducers, incorporating piezoelectric, magnetostrictive, electrostrictive, electrodynamic or hydraulic elements operating individually or in a designed combination and having any of the following:
40. a.1.c.1. Operating at frequencies below 10 kHz and having any of the following:
41. a.1.c.1.a. Not designed for continuous operation at 100% duty cycle and having a radiated 'free-field Source Level (SLRMS)' exceeding (10log(f) + 169.77)dB (reference 1 µPa at 1 m) where f is the frequency in Hertz of maximum Transmitting Voltage Response (TVR) below 10 kHz; or
42. a.1.c.1.b. Designed for continuous operation at 100% duty cycle and having a continuously radiated 'free-field Source Level (SLRMS)' at 100% duty cycle exceeding (10log(f) + 159.77)dB (reference 1 µPa at 1 m) where f is the frequency in Hertz of maximum Transmitting Voltage Response (TVR) below 10 kHz; or
43. a.1.c.2. [Reserved]
44. a.1.c.3. Side-lobe suppression exceeding 22 dB;
45. a.1.d. Acoustic systems and equipment, designed to determine the position of surface vessels or underwater vehicles and having all of the following, and “specially designed” “components” therefor:
46. a.1.d.1. Detection range exceeding 1,000 m; and
47. a.1.d.2. Determined position error of less than 10 m rms (root mean square) when measured at a range of 1,000 m;
48. a.1.e. Active individual sonars, “specially designed” or modified to detect, locate and automatically classify swimmers or divers, having all of the following, and “specially designed” transmitting and receiving acoustic arrays therefor:
49. a.1.e.1. Detection range exceeding 530 m;
50. a.1.e.2. Determined position error of less than 15 m rms (root mean square) when measured at a range of 530 m; and
51. a.1.e.3. Transmitted pulse signal bandwidth exceeding 3 kHz;
52. a.2. Passive systems, equipment and “specially designed” “components” therefor, as follows:
53. a.2.a. Hydrophones having any of the following:
54. a.2.a.1. Incorporating continuous flexible sensing elements;
55. a.2.a.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;
56. a.2.a.3. Having any of the following sensing elements:
57. a.2.a.3.a. Optical fibers;
58. a.2.a.3.b. 'Piezoelectric polymer films' other than polyvinylidene-fluoride (PVDF) and its co-polymers {P(VDF-TrFE) and P(VDF-TFE)};
59. a.2.a.3.c. 'Flexible piezoelectric composites';
60. a.2.a.3.d. Lead-magnesium- niobate/lead-titanate (i.e., Pb(Mg1/3Nb2/3)O3-PbTiO3, or PMN-PT) piezoelectric single crystals grown from solid solution; or

Related controls

See also 6A991.

Notes

Note: 6A001.a.1 does not control equipment as follows: a. Depth sounders operating vertically below the apparatus, not including a scanning function exceeding ± 20°, 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.

Technical Notes: 1. For the purposes of 6A001.a.1.a.1.c, 'sounding resolution' is the swath width (degrees) divided by the maximum number of soundings per swath. 2. For the purposes of 6A001.a.1.a, 'enhancement' includes the ability to compensate by external means.

Technical Note: For the purposes of 6A001.a.1.a.2, the acoustic sensor pressure rating determines the depth rating.

Technical Note: For the purposes of 6A001.a.1.a.2.a.2, 'sounding rate' is the product of the maximum speed (m/s) at which the sensor can operate and the maximum number of soundings per swath assuming 100% coverage. For systems that produce soundings in two directions (3D sonars), the maximum of the 'sounding rate' in either direction should be used.

Technical Notes: For the purposes of 6A001.a.1.a.3: 1. 'Area coverage rate' (m2/s) is twice the product of the sonar range (m) and the maximum speed (m/s) at which the sensor can operate at that range. 2. 'Along track resolution' (cm), for SSS only, is the product of azimuth (horizontal) beamwidth (degrees) and sonar range (m) and 0.873. 3. 'Across track resolution' (cm) is 75 divided by the signal bandwidth (kHz).

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 that direct the sound vertically only, or mechanical (e.g., air gun or vapor-shock gun) or chemical (e.g., explosive) sources. 3. Piezoelectric elements specified in 6A001.a.1.c include those made from lead-magnesium-niobate/lead-titanate (Pb(Mg1/3Nb2/3)O3-PbTiO3, or PMN-PT) single crystals grown from solid solution or lead-indium-niobate/lead-magnesium niobate/lead-titanate (Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3, or PIN-PMN-PT) single crystals grown from solid solution.

Technical Note: For the purposes of 6A001.a.1.c.1, the 'free-field Source Level (SLRMS)' is defined along the maximum response axis and in the far field of the acoustic projector. It can be obtained from the Transmitting Voltage Response using the following equation: SLRMS = (TVR + 20log VRMS) dB (ref 1µPa at 1 m), where SLRMS is the source level, TVR is the Transmitting Voltage Response and VRMS is the Driving Voltage of the Projector.

N.B. See 6A001.a.1.c.1 for items previously specified in 6A001.a.1.c.2.

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.

N.B.: For diver detection systems “specially designed” or modified for military use, see the U.S. Munitions List in the International Traffic in Arms Regulations (ITAR) (22 CFR part 121).

Note: For 6A001.a.1.e, where multiple detection ranges are specified for various environments, the greatest detection range is used.

Note: 6A001.a.2 also applies to receiving equipment, whether or not related in normal application to separate active equipment, and “specially designed” components therefor.

Note: The control status of hydrophones “specially designed” for other equipment is determined by the control status of the other equipment.

Technical Notes: For the purposes of 6A001.a.2.a: 1. Hydrophones consist of one or more sensing elements producing a single acoustic output channel. Those that contain multiple elements can be referred to as a hydrophone group. 2. Underwater acoustic transducers designed to operate as passive receivers are hydrophones.

Technical Notes: 1. For the purposes of 6A001.a.2.a.3.b, 'piezoelectric polymer film' sensing elements consist of polarized polymer film that is stretched over and attached to a supporting frame or spool (mandrel). 2. For the purposes of 6A001.a.2.a.3.c, 'flexible piezoelectric composite' sensing elements consist of piezoelectric ceramic particles or fibers combined with an electrically insulating, acoustically transparent rubber, polymer or epoxy compound, where the compound is an integral part of the sensing elements. 3. For the purposes of 6A001.a.2.a, '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.

Technical Note: For the purposes of 6A001.a.2.b, hydrophones arrays consist of a number of hydrophones providing multiple acoustic output channels.

Technical Note: For the purposes of 6A001.a.2.b.2, '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.

N.B.: For inertial heading systems, see 7A003.c.

Note: 6A001.a.2.g does not apply to particle velocity sensors or geophones.

Technical Notes: 1. For the purposes of 6A001.a.2.g, accelerometer-based hydro-acoustic sensors are also known as vector sensors. 2. For the purposes of 6A001.a.2.g.2, 'acceleration 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 hydro-acoustic sensor, without a preamplifier, is placed in a plane wave acoustic field with an rms acceleration of 1 g (i.e., 9.81 m/s2).

Note 1: 6A001.b does not apply to depth sounders limited to any of the following: a. Measuring the depth of water; b. Measuring the distance of submerged or buried objects; or c. Fish finding.

Note 2: 6A001.b does not apply to equipment “specially designed” for installation on surface vessels.

N.B.: For diver deterrent acoustic systems, see 8A002.r.

Source: eCFR, version 2026-08-01, retrieved 2026-08-20T04:04:59+00:00.