Home' RTCA Documents for Review : DO-204B, MOPS Aircraft ELT 406MHZ Contents © EUROCAE, 2018
The ELT battery source shall provide sufficient capacity for a self-test to be conducted
at least every 6 months and tested in accordance with C/S T.007 or C/S T.021
Operating Lifetime at Minimum Temperature as applicable.
3.4 EXTERNAL ANTENNA CABLE
Materials and methods used in the manufacture of antenna cable systems shall meet
or exceed the specifications of MIL-DTL-17 or equivalent.
MIL-DTL-17 invokes MIL-PRF-39012, which includes the vibration
performance specification for the cable connectors
3.5 MINIMUM OPERATING LIFE TIME
The ELT system shall be capable of continuous operation over the temperature range
for the class of the unit as defined in § 4.2.1 for a period of time defined in Cospas-
Sarsat document C/S T.001 for first generation ELT or C/S T.018 for second
generation ELT, in addition the homing transmitters, if applicable, shall function within
specification for the periods of time defined in § 3.8.6 and/or § 3.9 as applicable.
Apply the test in § 5.4.1.
3.6 POSITION DATA (OPTIONAL EXCEPT FOR ELT(DT))
If an ELT provides position data then it shall meet all the encoded position data
requirements specified in the Cospas-Sarsat document C/S T.001 for first generation
ELT or C/S T.018 for second generation ELT.
If the cabling used to connect the position source to the ELT(DT) is provided as part of
the ELT System components it shall meet the fire resistance specifications detailed in
3.7 MINIMUM PERFORMANCE SPECIFICATION COSPAS-SARSAT 406 MHZ ELT
To ensure ELT compatibility with Cospas-Sarsat receiving and processing equipment,
ELTs shall meet all the requirements specified in the Cospas-Sarsat document C/S
T.001 for first generation ELT or C/S T.018 for second generation ELT and shall be
tested according to C/S T.007 or C/S T.021 as applicable.
ITU emission type
The emission designator shall be ITU-16K0G1D for C/S T.001 ELT and ITU-80KGXW
for C/S T.018 ELT.
3.8 MINIMUM PERFORMANCE SPECIFICATION - 121.5 MHZ (243 MHZ OPTIONAL) HOMING
A 121.5 MHz homing transmitter is mandatory for all ELT types, except for ELT(DT)s.
If fitted, an ELT(DT) shall inhibit the 121.5, 243 and 406 MHz homing transmitters in
flight (see § 184.108.40.206).
When a homing capability is declared, the following corresponding paragraphs apply
including for ELT(DT)s.
If the ELT includes an optional 243 MHz homing transmitter then the requirements in
this section that apply to the 121.5 MHz homing transmitter shall also apply to the 243
MHz homing transmitter unless stated otherwise.
The transmitter shall operate on 121.5 MHz and optionally on 243.0 MHz. The carrier
frequencies shall remain within ±0.005% under all environmental operating conditions.
The RF carriers shall be amplitude modulated. The modulation factor shall be at least
0.85 but shall not exceed 1.0. (see FIGURE 3-1) The figure specified for modulation
factor assumes a sinusoidal modulating signal. If the waveform of the modulating
signal is other than sinusoidal, the modulation factor due to the fundamental
component of the modulating signal shall be at least 0.85.
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