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GPS internals: Difference between revisions
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(Created page with 'GPS internals ==Introduction== Although the code is named 'GPS', it is intended to be used to support a wide range of related devices, such as INS or FMS systems. A generic nam…') |
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===Active waypoints=== | ===Active waypoints=== | ||
The active waypoint is available as gps/wp/wp[1], for historical reasons. Various interesting values are computed for the active waypoint, such as distance, bearing and so on. | The active waypoint is available as <tt>gps/wp/wp[1]</tt>, for historical reasons. Various interesting values are computed for the active waypoint, such as distance, bearing and so on. | ||
gps/wp/wp[0] contains another waypoint, which varies depending on mode. For DTO and OBS modes, it is the position at the point the mode was entered; for LEG mode it is the previous waypoint in the route. Again this exists for compatibility reasons, and SHOULD NOT be used by aircraft or instruments. | <tt>gps/wp/wp[0]</tt> contains another waypoint, which varies depending on mode. For DTO and OBS modes, it is the position at the point the mode was entered; for LEG mode it is the previous waypoint in the route. Again this exists for compatibility reasons, and SHOULD NOT be used by aircraft or instruments. | ||
==Commands and the scratch=== | ===Commands and the scratch=== | ||
The GPS has a simple command system - it expects the properties under gps/scratch to be populated with some parameters, and then a command property to be set. Information is also returned via the gps/scratch properties. For example, to go direct to a waypoint, it must be loaded into the scratch, and a 'direct' command executed. To find the nearest VOR, set scratch/type to 'vor' and execute a 'nearest' command. The scratch will be updated with information about the result (if one was found) - and then a 'direct' or 'obs' command can be executed to use the waypoint. | The GPS has a simple command system - it expects the properties under <tt>gps/scratch</tt> to be populated with some parameters, and then a command property to be set. Information is also returned via the <tt>gps/scratch</tt> properties. For example, to go direct to a waypoint, it must be loaded into the scratch, and a 'direct' command executed. To find the nearest VOR, set scratch/type to 'vor' and execute a 'nearest' command. The scratch will be updated with information about the result (if one was found) - and then a 'direct' or 'obs' command can be executed to use the waypoint. | ||
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: Enter DTO mode. The active waypoint is loaded from the scratch, and a course calculated. | : Enter DTO mode. The active waypoint is loaded from the scratch, and a course calculated. | ||
;nearest | |||
: load the nearest waypoint (of a type) into the scratch. The following parameters are supported: | |||
:# max-results - maximum number of nearby waypoints to load. Default is 1. | |||
:# type - a type string. 'any', 'all' or an empty value mean all types | |||
;search, | |||
: load waypoints by matching ident or name. The following parameters are supported: | |||
:# type - as for 'nearest' | |||
:# ident - the string to search on | |||
order-by-range - a flag indicating if matches should be returned sorted by distance (the default) or alphabetically | order-by-range - a flag indicating if matches should be returned sorted by distance (the default) or alphabetically | ||
exact - a flag indicated if matches must be exact (true) or partial (false). In | exact - a flag indicated if matches must be exact (true) or partial (false). In | ||
;next | |||
: load the next result (for nearest/search/load-route-wpt) | |||
;previous | |||
: load the previous search result | |||
;define-user-waypoint | |||
: create a user waypoint based on the current scratch. | |||
==Configuration== | ==Configuration== | ||