Dual Safety Satcom (Warm Standby); Aircraft Directed Dual Safety Satcom (Warm Standby) - Honeywell ASPIRE-400 System Description, Installation And Maintenance Manual

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
NOTE:
(2) The SDU enters Standalone Configuration if the ORT is configured for Standalone
(3) When in Standalone Configuration, the ACD asserts its Dual System Select (DSS)
discrete.
C.

Dual Safety SATCOM (Warm Standby)

(1) When the ORT is configured for Dual Safety SATCOM, the SDU can be in an Active state
or a Standby state. The SDU is only allowed to transmit when in the Active state. When in
the Standby state, the SDU is not allowed to transmit over the RF interface.
(2) In Dual Safety SATCOM configuration, both SATCOM can provide safety voice and data
services. Both have independent RF chains and antennas but only one can be active and
logged onto safety services at any one time.
(3) The SDU considers itself "SDU in coverage" when:
(a)
(b)
(4) When the SDU does not have a valid spot beam map, the SDU considers itself as "SDU
in coverage" when:
(a)
(5) When ORT configured for Dual Safety SATCOM, on entering the Active state, the SDU:
(a)
(b)
(c)
(d)
(6) When ORT configured for Dual Safety SATCOM, on entering the Standby state, the SDU:
(a)
(b)
(c)
(d)
(e)
D.

Aircraft Directed Dual Safety SATCOM (Warm Standby)

(1) In Aircraft Directed Dual Safety SATCOM configuration, the SDU powers up in Standby
state and waits until it receives directions to go to Active state. Switching decisions are
aircraft directed and not determined by the SATCOM systems using the crosstalk bus.
(2) Communication and control of the SDU in an Aircraft Directed Dual Safety SATCOM
Configuration are via:
(a)
(b)
EFFECTIVITY
ALL
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ASPIRE-400
The SDU can be strapped as SDU1 or SDU2.
The SDU has a valid spot beam map from the spot beams listed on the global
beam common channel.
And is in coverage for its current location.
SDU can see a satellite that has elevation angle > - 4 degrees.
Asserts its DSS discrete before enabling RF transmission (this will assert the
companion SDU DSD discrete).
Enables its RF transmission.
Sets Bit 18 of Label 270 SDU "ACARS" MU/CMU Status Word to "0".
Continues to assert its DSS discrete as long as it is in the Active state.
Terminates all user services (if any).
Logs off (if logged on).
Disables its RF transmission.
De-asserts its DSS discrete (this will release the other SDU DSD discrete).
Sets Bit 18 of Label 270 SDU "ACARS" MU/CMU Status Word to "1", and
continues to de-assert its DSS discrete as long as it is in Standby state.
Dual System Disable (DSD)
Dual System Select (DSS)
23-15-49
3rd rvw Draft as of:
29 January, 2020
Page 2-22
22 Apr 2019