THE Orbcomm 'Little LEO' satellite datamessaging system completed its initial space segment on 23 September with the successful launch of eight satellites aboard a Pegasus air-launch vehicle dropped from a L-1011 TriStar aircraft. The satellites and launcher were developed and built by Orbital Sciences Corp of Hemdon, Virginia, which also owns the aircraft. This launch, plus another similar one on 2 August, brings the Orbcomm constellation up to its initial full capacity of 28 satellites. 'This will give real-time global coverage in 95-97 per cent of all communications," said Alan Parker, président of Orbcomm Global Development. "We are not yet quite there yet in terms of 100 per cent availability in equatorial regions. Another eight satellites will be in place by next summer. Orbcomm does have an FCC licence for 48 satellites; the last 12 will probably be used as in-orbit spares." Following the dropping out of the French-initiated Starsys project, Orbcomm, jointly owned by Orbital Sciences Corp (OSC), Teleglobe of Canada and cellular telephone operator Technology Resources Industries Bhd of Malaysia, is the only truly global Little.

LEO constellation anywhere near operational readiness. In Europe, the Orbcomm licensee is MCS Europe, an Amsterdam-based joint venture comprising Telecom Italia company Telespazio (63 per cent), plus German small-satellite specialist OHB System (9 per cent), Swedish Space Corp (9 per cent), INSA of Spain (4 per cent) and UK-based Satcom International (13 per cent), which specialises in the marketing of conununications products requiring regulatory approval. MSC, headed by CEO Bartolo Mignosa, operates through a Gateway Earth Station in Matera with a Gateway Control Centre at Lario. By late September, country représentatives had been signed-up 18 European countries. Another five countries were the topic of "very advanced negotiations. A second gateway will be installed, most likely in Morocco. It is Orbcomm/MCS policy to place the customer interface as closely as possible to the actual end-user. For this reason it is setting up a dense network of distributors and resellers.

Orbcomm customers fall into three main classes: manned mobile platform operators (largely truck fleets, also other land vehicles and sea-going vessels); unmanned mobile platforrns (autonomous tracking and theft-detection transponders incorporated in containers and high-value loads); and stationary unmanned terminals. The latter usually consist of SCADA monitoring installations on pipelines, dams, buoys at sea, etc. The global market breakdown given by Orbcomm is Mobile Asset Tracking. 13 million terminals or 10 per cent of the market; Messaging: 39 million teminals, 25 per cent; Fixed Asset Monitoring: 60 million terminale, 35 per cent; Other: 51 million terminals, 30 per cent.The positioning function is provided by an associate GPS receiver, or GPS chipset incorporated in the Orbcomm terminal. Orbcomm operates in the VHF band (148.0-149.9MHz subscriber uplink, 137.187-137.818MHz downlink), and in view of die crowding of this frequency band, employs an ingenious "hunting" system to locate an available frequency within the designated bandwidth.. The current data rate is 2.4kBit/s inbound and 4.8 kBit/s outbound, later planned to double.

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