OVERLAY EXTENSION to APRS SYMBOL SET 9 April 2007 ---------------------------------------------------------------------- References: APRS Symbols: http://www.ew.usna.edu/~bruninga/aprs/symbols.html As of 2007, fewer than about 10 unassigned APRS symbol codes are still available. Yet, APRS continues to grow in depth and scope and needs a vast expansion of symbol characters while still remaining backwards compatible to existing implementations. It is therefore proposed that the OVERLAY character which was defined back in 1996 be useable on all symbol types, not just the original designated few. In fact, the original APRSdos concept was that ALL characters would be overlayable from the beginning, but this was met with resistance from Windows applications that were limited to only a fixed set of ICONS and each overlay character had to be handled as a separate case. We need to no longer be bound by this implementation restriction. By allowing the 36 overlay characters on any symbol, we can in effect expand the existing code base from about 188 symbols to over 3400 combinations. By carefully applying some of the remaining undefined symbols to be "blocks" of symbols, then we can define at least 360 new symbols (10 new symbol blocks, each with a possbile 1 of 36 overlay characters). Implementation stages: Baseline Overlays: Means software will display all of the original symbols plus all of the overlay characters on those selected special overlayable symbols. CARS, BOATS, TRUCKS, CIRCLES, SQUARES, TRIANGLES, STARS, NWS, AIRCRAFT, WX, ARRL, CIVIL DEFENSE, BOXES, VANS, SHELTERS. Backwards compatibility: Means software will receive new overlay characters on any symbol and this packet will be processed as before though the overlay character might be ignored, but the packet parsing is not broken. Overlay Transparency: Means that software will receive new overlay characters on any symbol and this overlay character will be displayed somehow so that it is acccessible to the viewer on every symbol. For example, an S overlay on a house might mean Solar powered. Or W for wind or E for emergency power, or O for off-grid, etc... Full Overlay Capability: Means that software will receive and display all overlay characters and will map any new combinations into any new symbol sets that may be defined. NEW HOME STATION SYMBOL: It is proposed that the HOME symbol shall accept Overlays. Currently the primary HOUSE symbol is a house with a vertical antenna. The basic secondary symbol is a HOUSE with a wire dipole. By allowing OVERLAYS, the house symbol will be a generic house with an overlay character superimposed. Possible overlay definitions are: B = Battery E = Emergency G = Generator S = Solar W = Wind POSSIBLE FUTURE BLOCK ASSIGNMENTS: (these are only suggestions for the sake of showing how these extensions can be used. Any definition of these extensinos would have to be agreed by all parties: ARRL - Already defined. So far only ARES and WINLINK have been used CIVIL - Already defined. So far, only RACES and CERTS have been used SHLTERS - Already defined. FIRENET - Possible Expansion block. This could give them 36 new codes SKYWARN - Possible Expansion block. This could give them 36 new codes EMRGNCY - Possible Expansion block. This could give them 36 new codes ACTION: 1) We need assurence from all authors that their existing code is Baseline Capabile and is Backwards Compatible such that new overlay characters will not break any existing parsing of existing packets. 2) We need concurrence fom all authors that they will support this overlay extension to APRS in the future. For what it is worth, an assessment of the condition of symbols in most APRS clones is attached... Bob Bruninga, WB4APR Addendum: ASSESSSMENT OF SYMBOL SETS IN APRS CLONES (by an un-named APRS expert):: The problem is that WinAPRS, APRSplus and UI-View are orphaned products that are effectively no longer under development. * WinAPRS hasn't seen any significant development in many years... It's symbol set hasn't been updated in 10 years. WinAPRS's symbol set is embedded INSIDE the compiled .EXE file, making it impossible for an outside agent to update. The main people I see still using WinAPRS are the weather buffs because of it's better-than-average support of NWS warning zones and overlays. * APRSplus was effectively orphaned when Delorme radically changed the format of Street Atlas USA that APRSplus depends on for it's maps. Street Atlas Ver 9.0 (the last version that works with APRSplus) was discontinued in 2002. The developer essentially abandoned the program since no newbies could get the maps it requires. An indicator of this is that he dropped the registration fee to zero about 4 years ago. By default, APRSplus doesn't plot standard symbols (it uses a tiny black diamond with the callsign to the upper right), although it does display them in the text lists of stations heard, tracked, etc. * UIview, of course has the problem that it's author is deceased as well as the source code. Fortunately, it DOES properly support the overlay process. Further, the symbol set is in accessible external files, so they can be replaced with updated ones. Unfortunately, the overlay routines are in the "sealed black box" of the unchangeable main program .EXE file, thus preventing the addition of some sort of offset overlay scheme. The closest one could get would be to restyle the symbols to be larger and to take into account readable overlays in their design. * UIview has available a plug in called UI-Point that allows UIview posits to be displayed on Microsoft MapPoint (either the North American or the European versions). UIpoint uses symbols stored in a pair of accessible external .BMP files (so I can update them) but it doesn't support overlays in ANY MANNER WHATSOEVER. * APRSpoint, an APRS client that is itself actually a plugin for MS MapPoint, doesn't use APRS symbols (or overlays) at all. Instead it only uses generic Microsoft "push pins" that are standard with MS MapPoint and MS Streets&Trips. Bottom line: NONE of the current Windows programs are EVER likely to be updated to support either offset overlays or vector-based symbols because they are ALL dead or dying projects that are frozen in time. Probably the only way you will EVER see a compliant Windows client is to stop flailing the dead DOS horse, and develop a modern Windows client yourself...