APRStt User Guide rev 2.3 08 Aug 2013 -------------------------------------------------------------------- 08 Aug 13 Reversed order from XXXYYY to YYYXXX in DTMF formats 16 Feb 13 Minor word tweaking to make compatible with coding24.txt 30 Jan 10 Initial revision 2.3 This text file tells the DTMF user how to set up his callsign in DTMF memory and how to prepare for other data entry applications. APRStt KEYPAD: APRStt uses the same keypad as telephones and other APRS radios. See differences on www.aprs.org/aprstt/radios.txt +------------------+ The standard TouchTone Key pad has letter | 1 2 3 A | definitions for each key that we use for | ABC DEF --> | APRStt. For callsigns, we use the two-key | 4 5 6 B | method where you first press the key associated |GHI JKL MNO <-- | with the letter, and then press the A, B, C | 7 8 9 C | or D key depending on whether the letter is |PQRS TUV WXYZ del | listed first, second, third or forth on that | * 0 # D | key. A key alone is the actual digit. The * | space OK! | key is often used as a delimiter (,./) and # +------------------+ ends a string. APRStt DATA FIELDS: All APRStt DTMF data strings begin with a type key to indicate the type of APRS data that follows. They are: "A" - CALLSIGN (FCC calls, callsign suffixes, or tactical calls) "B" - POSITIONS (pre-loaded or manually entered) "C" - COMMENT (comments or local voice freq you are monitoring "D" - MESSAGES (commonly used text messages for you or your family The simplest use of APRStt is to simply send your pre-stored callsign. By hearing only a DTMF callsign, an APRStt node sends a position report into the APRS system containing all of the following: 1) Identifies the station by call, and date and time 2) Plots the station on the global APRS map near that gateway 3) The packet shows the FREQUENCY and TONE he is using 4) The packet contains other info such as Echolink or IRLP node# CALLSIGN LAST: For additional flexibility, other manual or pre- loaded DTMF strings will let you do most of your local routine operating. These additional fields are transmitted first and then followed by your DTMF memoery callsign. This assures that all data is associated with a callsign. Any data, not followed by a callsign will be ignored if no callsign follows in 2 seconds. ADDITIONAL INFORMATION FIELDS: As a minimum, routine DTMF users should consider saving these typical local formats in DTMF memory. 1) AcccccccccccVVK# Your full callsign and Overlay byte 2) AcccVK# Abbreviated callsign suffix 3) Byyxx* Position of HOME 4) Byyxx* Position of work or other hangout etc 5) CFFFFFF* Voice Monitoring Frequency FFF.FFF MHz 6) CFFFFFF* Another favorite frequency... 7) CE123456* ... Echolink node... (6 dgitis starts with "E") 8) CI12345* ... IRLP Repeater ID etc... 9) Dxxxxxxxxxx* Message text. CALLME or PHONE xxxxxxxxxxx etc Once you send at least your callsign on the APRStt channel, then anyone in the local area, or anywhere in the world on APRS can see the information in real time. The Frequency or IRLP/Echolink info is very handy since it can be used to contact you from anywhere. After sending at least a DTMF callsign a user should be able to see himself appear on the APRS Internet system (APRS-IS). For example use this URL with your MYCALL to see how APRS sees you: http://map.findu.com/MYCALL* or http://aprs.fi/MYCALL APRStt CALLSIGN: The callsign is permanently set into a DTMF memory along with a symbol overlay character. A checksum is also added to assure reliability. The format is as follows: AcccccccccccVK# Where A begins the callsign field Where cccccccc is the callsign using two-key text encoding Where V or VV is an overlay digit or two-key letter Where K is a checksum to minimize errors Where # signals the end of the string CALLSIGN-12: By default, an APRStt callsign will appear on APRS with an SSID of -12 so that these callsigns are easily destinguished from other callsigns from the same station on the air. They also all use a square black symbol with the overlay character selected by the APRStt user. Here is an example of how my WB4APR-9 callsign looks in DTMF: A9A2B42A7A7C91# A The leading A key indicates it is an APRS Callsign 9A decodes as W 2B decodes as B 4 decodes as 4 (because another digit follows it) 2A decodes as A 7A decodes as P 7C decodes as R 9 decodes as 9 for the overlay digit on the APRStt symbol 3 Is the checksum (10+9+10+2+11+4+2+10+7+10+7+12+9=103 ) # signals the end of the burst CALLSIGN SUFFIX: Once APRStt has heard a full callsign, it can identify your data in subsequent DTMF bursts using only your callsign suffix. That is, the right 3 characters of your call that are further simplified to only the Digit keys used for those 3 characters. So for WB4APR overlay 9, it would be "APR" and that would short cut to 277, and adding a "9" overlay would result as: A27795# (checksum 35 = 5) Basically, this station is "2779" APRStt will match this abbreviation to your full callsign (previously transmitted). If there is no match APRStt will request the full callsign. New full callsigns are always accepted. This is why any use of a suffix has to be scanned through all active calls recently heard and are only accepted if their callsign association is unique and do not conflict with any other existing call. Users may resolve any conflicts by negotiating different overlay digits to distinguish them. Being a shorter string, you can now store not only your callsign but also a frequent POSITION or a COMMENT string such as your favorite repeater frequency in the same DTMF memory. For example B1234*AcccVK# contains call and an X/Y position of 12/34 C146940*AcccVK# contains call and 146.940 MHz When gated by APRStt to APRS, the "MHz" will be added so that the packet is fully compatible with the APRS frequency field. Frequencies must always be exactly 6 digits long so for HF, leading zeros are required. APRStt COMMENTS: The several APRS Mic-E comment definitions, can also be transmited using the code Cn* where n is as follows: 0 Off duty 3 Returning 6 Priority 9 Custom 2 1 Enroute 4 Committed 7 EMERGENCY 2 In Service 5 Special 8 Custom 1 Simply send the "Cx*" followed by your callsign or suffix digits from your DTMF memory. The full text will be expanded when gated to APRS. APRStt POSITION FORMATS: Positions always begin with the "B" key and end with a * to indicate that your callsign will follow. One of the easiest formats is simply X/Y offsets from a given origin such as the local APRStt gateway. In the example used at Dayton, the simple one-digit "B1yx*" format used a 10x10 grid which could locate anyone to the nearest 150 feet at the hamvention with only one X and Y digit. See www.aprs.org/aprstt/DaytonTTmap.GIF. This same 4 key method can also be used for up to 99 pre-defined locations for other events with special event maps such as the mile marks in a marathon, etc. A two-digit format "B2yyxx*" can place anyone anywhere in a 10 mile area to the nearest tenth of a mile if xx and yy are interpreted as x.x and y.y minutes of LAT/LONG. A three digit format "B3dmm# can locate stations in direction (N,NE,E,SE,S,SW,W,NW (1-8)) and mm is in miles. These position formats can be locally defined for each local area or application. Other POSITION formats are possible, such as 2 digit milemarks in a marathon, or 4 digit flea market spaces at Dayton. A simple table system translates these to exact lat/longs for display on APRS. In all cases, a handout for the club or event will indicate what specific formats are used and what map is used for manual entry. DTMF STATUS TEXT: For the nimble fingered station, you can actually spell out any text you want using normal text-messaging technique. For example: ...C4A3B8A0A6A3B0A2A8A0A3*... Spells out "GET ME AT 3" and can be used by a kid to signal Dad's taxi for a pickup. Kids have no problems using these text-messaging techniques. With these simple formats, you can join the world of APRS! Bob, WB4APR