AIRCRAFT.TXT NOTES ABOUT AIRCRAFT, ACARS, BALLOONS CIVIL AIR PATROL Document version: 8.4.6 20 July 99 Author(s): Bob Bruninga, WB4APR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Special Commands: MAPS-PLOTS-CAP: APRSdos has a subgrid for CAP down to 1/4 mi for foot SAR's MAPS-PLOTS-DIM: has a subtle feature to change the color of REPLAYED objects so that PRINT-SCREEN on a printer will display darker. MAPS-OVERLAY-WRECKS: Can overlay all of the known aircraft crash sites for SAR missions. Be sure to get the WRECKS.POS file for your area. ALTITUDE IN THE KENWOOD THD7: You can manually enter an altitude into the STATUS text by inserting the format xxx}.... at the start of the text. Since XXX must be in base-91 compressed format, here is a handy table of some useful altitudes: "88} = 1000' "VV} = 10,000' "BB} = 4000' "ff} = 15,000' "EZ} = 5000' "vv} = 20,000' "II} = 6000' #00} = 25,000' "LL} = 7000' #AA} = 30,000' "OO} = 8000' #PP} = 35,000' APRSair.exe: Can parse and display ACARS data and posits if you have the DSP-12 TNC. ACARS is the internaltional Airline Packet Data system operated on 131.55 MHz. See ACARS.txt. IMPORTANT!!! OPERATING APRS FROM AIRCRAFT AND BALLOONS: This is UNLIKE any other APRS, since you will hear hundreds of stations and hundreds of stations will hear you. It is imperative that you understand the following: IF OPERATING ON 145.39 or OTHER STANDARD APRS FREQUENCY: * UNPROTO PATH Since everyone will hear you direct, you do not need any digipeaters. But using WIDE2-2 does not hurt since under the New-N paradigm, all digis will only digipeat the packet once no matter how many times it hears it. Recommendation: UNPROTO APRS VIA WIDE2-2 * FULLDUPLEX - If you plan on operating airborne on 145.39 or the main APRS freq in your area, your TNC will hear hundreds of stations, keeping the channel always busy. Thus your TNC may never transmit. To avoid this, set the TNC to FULLDUPLEX ON so that it will ignore the DCD circuitry. Do this with due consideration to others on the channel since you will now NOT be listening before you transmit. The TH-D7G has a DCD Menu option of IGNORE. IF OPERATING ON A DEDICATED NON-APRS CHANNEL: Use UNPROTO APRS VIA GATE,WIDE2-1. This allows the packets to be GATED by dual-port TNCs to a different channel if needed. APRS 3D ALTITUDE DISPLAY: The Y-AXIS command displays a 3D perspective with the horizon infinity at the screen center. The 2D map center appears near the bottom 1/3rd of the screen in 3D and Altitude is displayed along the right screen edge. Altitude is obtained from the string "/A=XXXXXX" appearing in any POSIT. ALtitude is automatically extracted from the standard NMEA GGA sentence or from the special $PGRMZ and $PMGLB sentences, and or it can be manually entered. Note that the field MUST be exactly 6 characters with leading zeros. The ALTITUDE scale along the right side of the 3D screen is calibrated to the original 2D center of the map. This means that the scale will always be correct, but the true 3D visual perspective my be awkward or confusing for stations that are near or far to the south or north of the 2D map centerline. REPLAY the BALLOON and AIRCRAFT.hst files to see the effects. Notice that as the aircraft flies to the south (toward you), it will always stay at the 5000 foot altitude regardless of perspective. At some ZOOM ranges, as it departs the airport or returns, it will actually appear in perspective to have a negative altitude because the SYMBOL is always going to be displayed at the CORRECT altitude according to the scale rather than in perspective. HOW TO MAKE AN AIRCRAFT SYMBOL: For stand-alone-trackers, you must indicate the aircraft symbol character in either of two ways: 1) Set the TNC SSID to -7. i.e. W3ADO-7 OR 2) Make the UNPROTO be: UNPROTO GPSxyz where xyz= GPSBH - small aircraft GPSOH - crash site GPSLG - glider GPSHV - jet aircraft GPSDV - big aircraft GPSDV# - Numbered aircraft 0-9 or A-J GPSSN# - Numbered Triangle (nice for many gliders) ARNAV FORMAT: **** ARNAV is nolonger supprted in APRSdos after version 8.00 ************ The ARNAV data begins with an STX, has lots of data lines, and then ends with an ETX. Each line of data has a single leading character that indicates what the remaining data on the line represents. AN dd mmhh (North Latitude in degrees and minutes to the hundredths BW ddd mmhh (West Longitude in degrees and minutes to the hundredths Cccc (Course) Dsss (Speed) ..... (other fields for E,G,I,J,K,L,M,Q,d,e, and v are given Wxxxxx N dd mmhh W ddd mmhh +aaaa (Waypoint where: xxxxx is its name ) LAT LONG as shown aaaa is altitude in ft) CIVIL AIR PATROL and APRS FOR DETAILS, CONTACT THE ARIZONA WING OF THE CAP. SAR GRIDS: APRS can overlay the 15x15 minute Search & Rescue (SAR) grids used by the CAP. The four quadrants of these grids correlates exactly with the readily available USGS 7.5 minute maps. These grid squares have a standard numbering system within each sectional chart. Where ever there is an overlap, the western most map takes precedence. APRS accomplishes this ordering by the sequence of maps in CAPGRID.DAT. Also, ALBUQUERQUE must be first. Except for the overlaps, most charts are listed alphabetically. A finer grid system was added in APRS815 down to 1/4 mile. If the cursor is in an overlap area, the proper grid numbers will be seen. If you are just to the side of the overlap area, then APRS will use the numbering scheme that applies to the exact grid found at the cursor. This may place the "wrong" numbers in the adjacent overlap area temporarily. If you are unsure, zoom out to see where the overlaps are, or move your cursor to the WEST of the area of interest to force the correct sequence. TO DISPLAY CAP GRIDS, USE THE MAPS-PLOTS-CAP COMMAND. TO DISPLAY CAP CRASH SITES, use the MAPS-OVERLAYS-CRASHES command. The CAP Crashes data is now distributred in all of the 5 standard USA APRS Map distributions as a file CRASHES.XXX where XXX is the MAPLIST.XXX extension. TRACK HISTORIES: Back at the SAR headquarters, track histories can be processed offline by periodically doing a FILES-SAVE to save the latest track history to file and to a floppy for analysis. APRS will automatically do a save whenever 199 positions have been received. After each save, memory is cleared except for the last position of all stations.