Add Bob WB4APR's SSID document

2026-10-20 04:23:07 +02:00
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 APRS SSID Recommendations                                  6 Feb 2012
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 Updated 6 Feb  2012 to clarify the title of this document to be
                    SSID RECOMMENDATIONS not to imply any kind of 
                    decoding "standard".  That original NMEA
                    decodign standard is covered in the original spec
 Updated 9 June 2010 for more flexibility using 1,2,3,4 and 15
 Revised 2 June 2004 to add -10, -11, 12 and -15
 SSID's have seen two different uses in APRS.  Initially as an ICON
 indicator back in the early 1990's.  But that is obsolete for over
 a decade.  Now SSID's are used as an informal way of indicating one 
 of several different typical APRS applications.
 Since many small displays for the handheld and mobile operator show
 nearby APRS station callsigns that flash up on the screen, it is nice
 to have some idea of what type of station or activity might be 
 involved simply from the callsign SSID without having to push 
 buttons, search lists, or look at maps to find out more about them.  
 SSID RECOMMENDATIONS:  It is very convenient to other mobile 
 operators or others looking at callsigns flashing by, to be able to 
 recognize some common applications at a glance.  Here are the 
 recommendations for the 16 possible SSID's (the limit of 16 comes 
 from the 4 bits available in the AX.25 protocol.  Note, The SSID of 
 zero is dropped by most display applications.  So a callsign with no 
 SSID has an SSID of 0.
 -0 Your primary station usually fixed and message capable
 -1 generic additional station, digi, mobile, wx, etc
 -2 generic additional station, digi, mobile, wx, etc
 -3 generic additional station, digi, mobile, wx, etc
 -4 generic additional station, digi, mobile, wx, etc
 -5 Other networks (Dstar, Iphones, Androids, Blackberry's etc)
 -6 Special activity, Satellite ops, camping or 6 meters, etc
 -7 walkie talkies, HT's or other human portable
 -8 boats, sailboats, RV's or second main mobile
 -9 Primary Mobile (usually message capable)
 -10 internet, Igates, echolink, winlink, AVRS, APRN, etc
 -11 balloons, aircraft, spacecraft, etc
 -12 APRStt, DTMF, RFID, devices, one-way trackers*, etc
 -13 Weather stations
 -14 Truckers or generally full time drivers
 -15 generic additional station, digi, mobile, wx, etc
 * One-way trackers should best use the -12 one-way SSID indicator
 because the -9's usually mean a ham in full APRS communication
 both message and voice.  The -9's can be contacted by APRS message
 or by Voice on his frequency included in his beacon, or on Voice
 Alert if he is in simplex range.  The -12's are just moving Icons
 on the map and since they have no 2 way communication for ham radio
 they are not generally of routine interest to other operators.
 OBJECTS or INTERNET:  In addition, Objects or internet generated 
 stations can have any SSID, not just the original 16, since 
 Objects are not constrained by the AX.25 header and can have a 
 9 byte name.  Here are some common OBJECT/Internet SSID's:
 -63 for PSK63 HF stations
 -tt for APRS TouchTone users (DTMF)
 -ID for RFID
 -A through -Z for Dstar
 SSID BACKGROUND:  Originally, in 1992, we had to use the SSID as 
 a way of indicating the type of station that transmitted a raw 
 NMEA-0183 GPS sting.  But in the mid 1990's we began indicating 
 any of the nearly 200 APRS symbols by the setting of the AX.25 
 TOCALL of "GPSxyz".  The "xyz" characters define the symbol from 
 the standard APRS symbol table www.aprs.org/symbols.html.
 The GPSxyz concept worked so well, the original SSID associations 
 are no longer a required part of the spec.  But the conventions
 that evolved from those early SSID's are still encouraged as 
 noted above, for easy recognition of station type or activity by 
 when only the callsign is seen.
 The -1, -2, -3, -4 and -15 are kept generic so that anyone with
 as many as 6 digipeaters, or 6 trackers or 6 weather stations or
 6 vehicles can still have unique SSID's for each of his stations.
 Beyond 6, people will just have to use any SSID that suits their
 fancy.  In some areas there might be 15 digipeaters all under
 one guy's call!
 SSID USAGE:  The SSID's also might give a hint as to how someone 
 is getting into APRS whether via satellite, a one-way tracker, a 
 mobile, an HT or even via DTMF or an RFID device or whether he is 
 doing something special.
 For example, if you are doing something special, change your 
 SSID to -6 to alert others to your excitement, or to make the
 track-history begin and end on site, and not be tied to all 
 your other -9 travels.  Or use -6 SSID for a packet sent 
 via the ISS or APRS satellite or for a 6 meter test so the
 successful packet is preserved and not overwritten by the same
 radio the next time you use it not via the ISS on the 144.39 
 national channel.  By using separate SSID's the WEB data bases 
 will keep statistics and data separate from when you are working 
 normally on other bands with other SSID's.
 So stick to the suggestions above for the obvious applications 
 where you can.  Of course these are not rigid.  If you have 
 more than 6 digipeaters, use any SSID you want.  These are only 
 guidelines to hint at a station's possible application when all  
 you can see easily is the callsign on a screen or in a list....
 de WB4APR, Bob