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Specification for HK-91M anti-noise transmitter
1 Scope
1.1 Subject content
This specification specifies the technical requirements and the acceptance rules of HK-91M anti-noise transmitter used for aviation communication system (hereinafter referred as to transmitter).
1.2 Application scope
It is applicable to HK-91M anti-noise transmitter.
2 Normative references
GJB 179-86 Sampling procedures and tables for inspection by attributes
GJB 367.2-87 General specification for military communication equipments - Environmental test methods
GJB 457-88 General specification for airborne equipment
SJ 1735-81 Generic specification for communication receiver
SJ 1736-81 Acoustic test method for communication transmitter
3 Requirements
3.1 General requirements
3.1.1 Appearance
The overall dimension of transmitter is as shown in the Figure 1 and the surface of the shell shall be free from cracks, obvious scratches and other damages.
Figure 1 Outline drawing of the transmitter
3.1.2 Weight
The transmitter weighs no more than 8g.
3.1.3 Components, spare parts and materials
The selected materials for transmitter shall meet the relevant requirements of GJB 457, 5.20, 5.21, 5.22 and 5.23.
3.1.4 Structure and technology
The design of those including structure, technology and surface treatment of transmitter shall meet the relevant requirements of GJB 457, 6.1 and 6.16.
3.1.5 Environmental adaptability
3.1.5.1 Low pressure
After transmitter is subjected to low pressure test, its sensitivity shall meet the requirements of 3.2.1. The air pressure for the low pressure test is:
a. 57kPa, the test temperature is 15~35℃ and the test time is 30min (working);
b. 18.8kPa, the test temperature is 15~35℃ and the test time is 30min (not working).
3.1.5.2 Temperature shock
After transmitter is subjected to temperature shock test, its sensitivity shall meet the requirements of 3.2.1. The temperature of temperature shock test is -55 to 70℃, and the number of shocks is 5.
3.1.5.3 Shock
After transmitter is subjected to shock test, its sensitivity shall meet the requirements of 3.2.1. The acceleration of the shock test is 15g, the pulse length is 16ms, the total number of shock is 18, and the shock waveform is half-sine wave.
3.1.5.4 Drop
After transmitter is subjected to drop test, it shall be free from cracks, deformation and looseness causing fault and its sensitivity shall meet the requirements of 3.2.1. The height of drop test is 1m and the number of drops is 3.
3.1.5.5 Vibration
After transmitter is subjected vibration test, its sensitivity shall meet the requirements of 3.2.1. Frequency range of the vibration test is 10~55~10Hz; one cyclic scanning time is 6min; amplitude is 0.2mm; test time is 3h.
3.1.5.6 Damp heat
After transmitter is subjected damp heat test, its sensitivity shall meet the requirements of 3.2.1. The temperature of damp heat test is 30 to 60℃. The relative humidity is 95%, and test lasts for 5 cycles (24h per cycle).
3.1.5.7 Salt spray
After transmitter is subjected to salt spray test, its sensitivity shall meet the requirements of 3.2.1. The salt concentration is 5%; salt spray sedimentation rate is 1.0~2.0ml/80cm·h; continuous spray is adopted for salt spray treatment; and the test time is 24h.
3.1.5.8 Mold
After transmitter is subjected to mold test, the mold-growth grade shall not be greater than Grade 2.
3.2 Electrical performance requirements
3.2.1 Sensitivity
Under normal test conditions, when the transmitter is 6mm away from the sound source,
1 000Hz audio signal is added and the sound pressure is 1Pa; the open circuit output voltage of transmitter shall not be less than 0.4mV; under specified environmental conditions, the sensitivity shall not be changed by more than ±3dB.
3.2.3 Frequency response
Under normal test conditions, the frequency response curve of 200~5 000Hz shall be in the block as shown in Figure 2.
3.2.3 Impedance
The impedance of the transmitter at 1 000Hz audio signal is 150Ω±15%.
3.2.4 Distortion
When the transmitter is 6mm away from the sound source and the sound pressure level is 114dB (1 000Hz), the distortion shall not exceed 5%.
3.2.5 Anti-noise ability
The axial discrimination rate between the front near-field and the back far-field is not less than 8dB (1 000Hz) and that between the front near-field and the front far-field is not less than 4dB (1 000Hz).
Figure 2 Frequency response
3.2.6 Linear
When the frequency is 1 000Hz and the sound pressure level applied to the transmitter is 74dB, 94dB and 114dB respectively, the output voltage of the transmitter shall be the linear function of the input sound pressure (at deviation of ±1dB).
3.2.7 Voltage withstand performance
When the transmitter is subjected to the AC voltage withstand test of 50Hz and 500V for 1min, there shall be no arc discharge or breakdown.
3.2.8 Magnetic leakage field
The leakage magnetic field of transmitter shall not cause an offset of more than 5° for the magnetic compass pointer at 30cm away from the transmitter.
3.2.9 Influence of external magnetic field on the transmitter
The sensitivity of the transmitter in 400Hz-external magnetic field shall be no more than 25% of that of the calibration coil placed in the same magnetic field.
4 Quality assurance provisions
4.1 Inspection responsibility
Unless otherwise specified in the contract or the order, the contractor shall be responsible for completing all inspections specified in this specification. If necessary, the ordering party or superior appraisal organization has the right to inspect any of the inspection items described in the specification.
4.2 Acceptable responsibility
Products must meet all requirements given in clauses 3 and 5. The inspections specified in this specification shall be an integral part of the entire inspection system or quality program of the contractor. If the contract includes inspection requirements not specified in this specification, the contractor shall also ensure that the products submitted for acceptance meet the contract requirements. It is neither allowed to submit products that are known to be defective in quality consistency sampling, nor requires the ordering party to receive defective products.
4.3 Test equipment and apparatus
In order to complete the required inspection items, the contractor shall set up and maintain the test equipment and inspection device sufficient in accuracy, quality and quantity. The performance of electroacoustic test apparatus shall meet the requirements of SJ 1736-81.
The artificial mouth shall meet the following requirements: the sound radiation port is φ10mm, which can produce sound pressure with distortion less than 2% and 1Pa (1000Hz) at 6mm and sound pressure with distortion less than 5% and 1Pa (1 000Hz) at 9cm; in case of compression, and in the frequency range of 200 to 5 000Hz, the unevenness is ≤±1dB at 6mm and ≤±2dB at 9cm.
