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'True GPS' (TGPS) is what comes out of our CyberJacket's 'virtual location sensor' (VLS). Our VLS is actually two different location sensors rolled into one: GPS (satellite signal receivers) and 'Pingers' (small, short-range wireless beacon receivers). GPS provides information outside that is supplemented by Pingers that will mark indoor locations.
TGPS comprises both absolute location information and, where available, logical (place name) information. A TGPS absolute location will comprise a reference to a domain specifying the location type, followed one or more numbers giving the location value (/location/absolute/lattitude/52'00'00). A TGPS logical location will comprise a reference to domain representing a named place (/location/name/UK/Bristol'). In addition, the VLS offers a library of functions that operate on specific TGPS domains. This library can be used to compare to TGPS domains and test them for equality, inclusion or distance.
Test on equality :: [ Domains ] -> [ Domains ] ->
Test on inclusion :: [ Domains ] -> [ Domains ] -> Boolean
distance :: [ Domains ] -> [ Domains ] -> Integer
Where Domain is defined in the project on the Note server. The test on equality specifies whether two domains are equal. It can be used when we walk past a pinger, and the note server needs to select a note for that pinger. The test on inclusion test whether the first position is included in the second one. For example, a pinger in a museum is in a museum. This allows one to load all notes related to the museum. The distance measure tells us how far two TGPS data points are from each other. This takes the topology of the world into account. In first instance, a couple of values will suffice (equal, near, far away)
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Last updated: January 14, 2000.
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