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Journal of Applied Science and Technology

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Low earth orbit satellite (LEOsat) for information exchange and retrieval in remote locations in Ghana

AM Muhammadu, A Ayensu

Abstract




A low earth orbit satellite (LEOsat) for global electronic information exchanges between Accra (National Capital) and remote locations in Wa (Upper West Region) and Manga (Upper East Region) was setup for integrated rural development in Ghana. The functions of the communication networks were to facilitate disaster management, humanitarian relief, distance education and training, health care delivery, governance; and to over-come geographic isolation and reliance on obsolete communication systems. The POSAT satellite was equipp-ed with facility for store-and-forward communication by radio between participating ground stations in Africa and Europe. A high-gain directional antenna scanned the earth's surface at frequency, power and dwell time controlled to correct Doppler effect. The satellite positioned at 100 minute polar orbit was visible at least 4 times per day for an average of 13 minutes for information exchange of up to 50 kb to be up-loaded or 100 kb to be down-loaded per pass. On board were computers for digital communication systems based on packet radio protocols employing 9.6 kbps uplink and 38.4 kbps downlink data rates; and trans-receivers with two uplink frequency channels of 148.515 and 148.260 MHz and downlink frequency of 429.985 MHz. The Internet access of the radio-based trans-receiver system provided unlimited source of information of worldwide coverage as an orbiting mailbox. The only drawback with the LEOsat was that real time data was not offered as provided in batch mode communication.

Journal of Applied Science and Technology Vol. 13 (1 & 2) 2008: pp. 92-98



http://dx.doi.org/10.4314/jast.v13i1.17501
AJOL African Journals Online