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Design of Store and Forward Data Collection Low-cost NanoSatellite -…
Design of Store and Forward Data Collection Low-cost NanoSatellite
A. Addaim, A. Kherras, B. Zantou, Centre for Space Research and Studies, Mohammadia School of Engineers B.P 765, Rabat, Morocco,
addaim@emi.ac.ma
,
kherras@emi.ac.ma
,
zantou@crers.gov.ma
References
[4]
https://www.tapr.org/pdf/AX25.2.2.pdf
Satellite Mission Description
provide various APRS
services
mobile localization of ships
data collection from autonomous weather stations in inaccessible sites
uses the AX.25 [4] packet radio protocol
1200 bit/s for APRS payload
4800 bit/s for Telemetry/Telecommand (TM/TC) operations
modes
Store-and-Forward APRS mode
terminals use the slotted aloha multiple access to send messages to nanosatellite
Beacon mode
sends periodically basic telemetry
telemetry is encoded in an APRS telemetry format
Command mode
CGS sends telecommand to OBDH
Hardware Architecture
APRS OBDH Unit
controls the whole operations of the payload
built around a 16 bits DSP TMS320C542
Advantage
minimizing the dimensions of the logic board
eliminating the need for external modem hardware needed by other systems
implement AFSK and GMSK modems as software
satellite bus
VHF transceiver
NANOSATELLITE SUBSYSTEMS DESIGN
The Store-and-Forward APRS Payload Design
The store-and-forward APRS payload provides digital
communication facilities between a number of terminals