Aerospace and Electronic Systems Magazine May 2018 - 63

Jayousi et al.

Figure 6.

M2M communication system: Web service interfaces.

Time validity and priority checks. Upon reception of a new
MAMES Message from the Satellite MCC, the SAE parses
the received message to compare priority and validity of the
new uploaded message with the previously stored message
(Case 2).

The check results make the SAE decide for a message broadcasting or queue cancellation (Case 1 options) and for a message
replacement or discarding (Case 2 options). The ISAE, which
guarantees the SatAlert experiment independence from the rest
of the mission by managing the software-hardware interaction between the transceiver and the on-board computer, is then informed
about the SAE performed action.
In particular, the MAMES message upload by the Satellite MCC, the consecutive D-SAT on board processing and the
storage (if required) in the On-Board Computer memory and the
broadcast transmission activated by the MCC trigger command,
are scheduled during the D-SAT available visibility windows
(agreements on non-interference regulated by no. 4.4 of the ITU
Radio Regulations). For each user on ground, three or four visibility windows of about 480 s per day (depending on the specific
day) are provided. Figure 7 shows the satellite footprint on ground
(yellow circle).

D-SAT MISSION RESULTS
IN-LAB TESTS RESULTS
After the D-SAT Qualification Model has successfully passed the
tests campaign which was based on the Launch Service Provider
(LSP) requirements, including mechanical (Sine and Random Vibration, Shock and Acceleration Test) and thermal-vacuum test,
MAY - JUNE 2018

the D-SAT Flight Model (FM) integration and acceptance test
campaign was completed. In April 2017, the D-SAT FM satellite
delivered to the LSP, integrated within the P-POD deployer [30],
and shipped to the PSLV's launch site in India.
An extended test campaign of Sat Alert operating functions
(MAMES Message generation and on-board processing) has been
performed with good results: the end-to-end communication between the Alert Issuer and Portable SDR user terminal was experimented in D-Orbit facility with all the real equipment, also emulating the path-loss attenuation using power attenuators in receiving
chain.

IN-ORBIT RESULTS
D-SAT FM satellite was successfully launched on 23rd of June
2017 from the Satish Dhawan Space Centre, India, on-board the
PSLV C-38 mission. Immediately since the first visibility window, the team was able to acquire the signal and receive the first
telemetry. Launch and Early Operations Phase was completed
within the first month of Mission and the functional tests proved
that all satellite subsystems, including redundancies, are working
properly. Focusing on the results of the alert messaging system,
the satellite has successfully completed the SatAlert experiment.
The whole chain from the alert message issue to the alert reception has been successfully tested and validated, demonstrating the
proper functioning of the proposed system. All the building blocks
have worked according to the specifications. In detail:
C

MAMES message generation. Different types of MAMES
messages have been generated (ALERT, CANCEL, UltraShort) and tested. The set of WS developed to let the main
entities to interface one to each other and to automatically

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