APRS Help Document

All APRS documentation is in the form of individual text files in the APRSREADME directory. For an index, just use the DOS DIR command.

There are a few special versions of APRS which were derived from APRS74:

APRSdr.exe Has a dead reckoning path following mode. See DR.HTM
APRSmin.exe A minimized version 316K vice 373K (without DX & WX)
APRtrak.exe A version for SPACE donated to AMSAT. See SPACE.HTM
APRSair.exe A version that will plot airlines. See AIRCRAFT.HTM
APRSlink.exe Can crosslink POSITS between 2 TNC's on 2 freqs or between the PACSAT downlink and normal APRS nets
APRS PACKET PROTOCOL: APRS captures 4 types of packets used in real-time tactical communications for display on its various screens as listed below: For more detail see PROTOCOL.HTM

POSITS Position reports (both STATION and OBJECTS, WX, etc)
MESSAGES Includes messages and Bulletins
STATUS Status packets (any packet not a Posit, or Msg, or Spcl
SPECIAL Acks, Queries, Pings, etc...
STARTUP: APRS prompts new users for most important setup information. But there are two additional commands necessary. These are INPUT-MY-POSIT and INPUT-MY-STATUS. See the INPUTS section further in this text.

APRS COMMANDS: Most APRS commands are single keys which are active from all display pages. The first Help page (F1-HELP), defines all command characters. Many keys bring up additional command sub-menu's on the bottom of the screen. Just hit the first letter of any command listed in the prompt. In most prompts, the ENTER key will select the default choice or complete the prompt with no action. If a mouse driver is loaded, the mouse can be used to move the cursor.

The following section summarizes all of the TOP-LEVEL APRS command keys. the F1-HELP key will give you an on-screen summary or you can print the KEYS.HTM file for a nice one page reference. First are the twelve major display screens accessed by their first letter:

L-LATEST STATUS Latest STATUS beacon from each station
B-BULLETINS Bulletins posted by other stations
P-POSITIONS Position packets from all stations and objects
H-HEARD LOG Number of packets per hour per station
R-READ MSGS Displays your incomming and outgoing messages
T-TRAFFIC Last 23 lines of traffic heard between other stations
D-DIGIs USED Digi paths used by all stations (or DX message list)
A-ALL BCNS Chronological log of all beacons, messages (or DX spots)
V-VIEW Scrolling screen of all live packets
alt-T TELEMETRY screen for the MIM module (see TELEMTRY.HTM)
SPACE BAR Displays the MAP of all stations and objects
Y-Yaxis A quasi-3D view of the map

F1-HELP HELP Menu with several screens
C-CONTROLS For switching on/off many APRS control functions
F-FILES MENU For loading, saving, PRINTing and/or replaying files
I-INPUT MENU For inputing your POSIT, OBJECTS and DF bearings
M-MAP MENU For most MAP functinos
O-OPERATIONS Various commands involved in communications and keyboard ops
W-WEATHER All commands dealing with entering and displaying weather

R-READ MSGS - Displays all incomming and outgoing messages
E-ERASE (TO) - Erase outgoing messages TO other stations
K-KILL (FROM)- Kill incomming lines FROM other stations
S-SEND - Send a message line
T-TRAFFIC - Display the latest 23 lines monitored between other stations
F2-REPLY - Reply to the last incoming message

G-GOTO ME/TRK- Moves cursor immediately to your stn or to the TRACKED stn
J-JUST ONE - Will display Just one type of station
N-NEXT WX - Will move cursor to the next WX stn and display condx
Q-QUIT - Quit APRS. Your POSIT will remain in your TNC BText
U-UNPROTO - Used to set your UNPROTO path
X-XMT PKTS - Transmits all or some of your outstanding packets

SPACE bar - Redraws current map
Arrows - Moves cursor. SHIFT Arrows (white) moves 5 times faster
Home - Homes the screen to the cursor location
PgDn/Up - ZOOMs the display in/out. CTRL-PgUp/Dn zooms by 8
End - Moves map to your default location
1,3,5,7,9 - 1 gets default map. 3-9 reload maps saved in 3-9 keys
ENTER or +/- - Hook/Unhook (select) a station. +/- cycle through all stns Use < and > to cycle through only the stations on the screen (actually, use the "," and"." keys to avoid holding SHIFT.)
TAB - Displays status of most CONTROLS and SETUP items
F1 - Help Menu with several screens
F2 - Reply to message. Pre-loads CALL from last message received
F3/4- More or Fewer Lables on maps. Also works with MAPS-BORDERS
F5 - Mark a FADE point during the Fade-circle DF technique
F6 - ZERO out your SPEED, so when you QRT, others will not DR you.
F7 - Toggle between 25 and 43 line text mode
F8 - In GPS/HSP mode will get and plot an immediate fix
F9 - Center map and scale to show ALL stations
F10 - DOZ mode. Disables all screen writes so works better in WINDOWS

alt-S - SETUP menu and configuration save commands
alt-T - Telemetry screen. See TELEMTRY.HTM
MOUSE: Only moves the cursor on the MAP and L/Plists. See MOUSE.HTM.

FURTHER DETAILS ABOUT DISPLAYS: Each display can have up to 6 pages (96 stations) with new stations added on the last page. Beyond 96, old stations get bumped off the top of page 1. If you occassionally use the FILES-ORDER command to sort the order of the stations, then the oldest will always be at the beginning and the most recent on the higher pages. PgUp and PgDn keys cycle through multiple pages. Move the cursor and hit ENTER to select a single station and get a prompt for a variety of actions. Here are more detail descriptions:

shows the latest STATUS packet from each station. This screen is like a one-line broadcast message display. In DX mode, this screen lists the latest command from all stations on your local cluster.
shows the latest 22 BULLETINS. See SEND command.
shows the latest POSITION packet from each station. Stations using the !FIXED station format will only show on the PList and no other pages once the other pages get full(5 pages). You may disable this FIXED station filter with the CONTROLS-FILTERS!FIXED command. You may select (HOOK) any station or object in this list for additional commands shown below. See the section on OBJects. Also the JUST ONE command will display, print or save JUST one type of station at a time.
Uplink Uplink or quit uplinking that object
Move Move it anywhere else on the map
HOME Center the map on the object
Delete Deletes the object from your list
Follow Forces an OBJ to follow a purple path (APRSdr.exe only)
Kill Kills your uplinked object on EVERYONE's screens!
Track Will keep the map centered on the TRACKED station
Alarm Will cause alarms if the marked station moves
Special Marks the station for isolated display using JUST-SPECIAL
shows the number of packets per station per hour.

screen shows the last 23 messages heard between other stns. In DX mode, also collects TALK messages between DX cluster users.

shows the raw packet headers including the digi- peaters of stations on your LATEST list. Proper use of digis is very important for minimizing QRM on APRS nets. A * in the left column show stations heard DIRECT (maybe only once). In DX mode, the D screen accumulates the list of all ACTIVE DXcluster MESSAGES.

display shows a chronological history of all packets including your own incoming and outgoing message lines. Since messages do not have a time of receipt appended to them, this display is useful for seeing approximately when a message line was received. In DX mode, this screen accumulates all DX/WX/WWV spots and announcements.

gives a menu of several different pages of HELP including reading any of the README files. Other HELP screens:

DIGIS one screen on how to use APRS DIGIPEATERS
FILES Read the README files on line (lots of them!)
HELP List of all APRS Commands
INFO Additional helpful info
NEW New-user simplified help screen
SYMBOLS Shows all APRS symbols
VALID How to validate your copy of APRS

OBJECTS: APRS displays two types of symbols on its maps. The station ICON of each APRS station or TNC and any OBJECTS placed on the map by any station using the INPUT-ADD command. Once on the screen, the object is listed in the P-list with a (+) symbol. This means it will be transmitted by your station. You can stop UPLINKING each object by hooking it on the P-list and toggle the U key. Un-validated users are limited to uplinking only one object. If you delete the object from your screen, or toggled off the UPLINK, it still remains on all screens in the network until each individual operator deletes it. Or you may select to delete from all screens which means your station will continue to transmit the object, but with a special KILL mark on it. It will disappear from all maps, but it will REMAIN in everyone's PList. If an object has not been updated in over two hours, it fades to a dark gray color.

MAP SYMBOL COLORS: Several colors are used to differentiate the status of each station or object on the MAP display:

WHITE Active APRS stations on line
GRAY TNC-only posit with no APRS message capability
YELLOW Objects that you are reporting (uplinking)
VIOLET Objects uplinked by other stations
BLACK Positions older than 2 hours
GREEN WIDE-RELAY digipeaters
BLUE Weather stations
CYAN Dead Reckoned positions
DARK BLUE Old POSIT or track history

MAP COMMANDS AND FUNCTIONS: These are display commands but there is a complete MAPS menu of additional display options.

Re-displays the current map and resets all display defaults.
Selects subsets of symbols to be displayed. JUST SPECIAL displays only the objects marked special on the P-list. JUST CALLS displays all objects but only the calls of those marked SPECIAL. Just PRINT will print all of a selected subset of objects to the printer.
Escapes the cursor from never-never land to the screen center
Map memories for saving particular maps of interest to you. Use the MAP-SAVE command and one of these keys to recall any saved map. The 1 key always has the USA map. Save a CONFIG file to make these permanent.
CENTER ALL CONTACTS. Chooses a map to display ALL objects.
Hook is a Navy term for selecting an object on a radar screen. Use ENTER to hook an object at the cursor. To step through all stations, use the +/- keys. Move the hooked station by moving the cursor to the new location and hitting the INSERT key or it can be removed using the DELETE key. To prevent inadvertent movement of objects, a second ENTER key UNHOOKS. Use the <> keys to cycle through all stations on the current map. (you dont even need to hold down the shift key for these).
Relocates a HOOKED object on the screen.
DEAD RECKONING: For moving stations, APRS draws a small gray anchor circle at the last posit, and then dead-reckons the light blue symbol ahead to the estimated position. Defeat this with CONTROLS-DR. To hook a dead reckoned station, hook the anchor circle, not the symbol itself. There is also a separate program called APRSdr.exe which can dead reckon objects around a known course. This is very useful for tracking known events such as runners in a marathon. See DR.HTM. If DR'ing is messing up, then your PC clock is not sync'ed to GPS time. Hit alt-S-GPS-TIME command and your PC MINUTES will be sync'ed to the next raw GPS posit that comes in...

MAP MENU COMMANDS: The following commands pertain to special functions regarding the map display.

C - CONFIGURATION. Has several sub commands:

Changes Background color. Used to be TINT command.

This is the most important map command for a new user. It allows you to chose the MAPLIST.xxx for your area. APRS uses this list to select each map based on your cursor location. Currently APRS is distributed as EASt, SEast, MIDwest, CENtral,WESt NEAngland and EURopean versions. The default MAPLIST.USA only points to major US and regional maps. NOTE: When you use this command, the cursor will move to the center of the selected MAPLIST.xxx area. If you want to return the cursor to your current map screen, use the ESC key which always returns the cursor to the center of the current display.

Lists all the MAPLISTS in your MAPLISTS dir

Allows you to offset your map a little to match your known GPS position with the datum used in your maps.

Shows all of the APRS distributions that you have loaded in your MAPS directory by listing the .TXT files.

F - Features
Toggle Features on/off such as Boundaries, Headings, Roads, Calls, Waterways, etc. ALL features can also be turned on/off at once. Useful for very slow PCs where turning off all features still shows packet stations but without taking 20 seconds to re-draw map features.
H - Hierarchy:
This is an improvement on the BORDERS command since it colors in the maps in the same sequence as they are listed in the MAPLIST.xxx file. The overlapping colors show the effect of the sequence of this list. Look carefully and you can figure out overlap and out-of-order problems.

L - Lock
Locks the current map to defeat the normal APRS auto-map selection. Useful to avoid interrupting your current map if your cursor gets over on another map during a special event.

O - OVERLAYS Overlays many data files over the current map:
DIGIS Overlays allAPRS digis and their ranges.
GATES Overlays all known HF gates
FREQS Overlays all known APRS frequencies in use
NWS Overlays the locations of all National WX sites.
PREVIOUS Overlays previous (larger) map
OTHER Overlays any other file in the XXXX.POS format

P - PLOTS. Select from a number of different plots:

Borders -
Shows borders of all MAPS in the MAPLIST.xxx file. You must use F3/F4 to select the size maps to display. If a map border appears, but the map does not come up as you zoom in, then the MAP file is listed too early in the MAPLIST and a later map overlaps its area. If the map is missing, APRS will BEEP. If the Map file exists but its border does not show up, then the file is not listed in the MAPLIST.xxx file.

CAPgrid -
Overlays Civil Air Patrol search-and-rescue grids
Displays Maidenhead grid squares

Displays range rings around stations showing an estimate of their radio horizon based on their transmitter power, height above average terrain, antenna gain and favored direction. Defaults for non reporting stations are 10 watts, 20 feet, and 3dB gain, omni.

Displays Range Rings at 1, 3/4, 1/2 and 1/4 of the given range scale. The great circle range and bearing from the center to the position of the cursor is also shown.

Draws lines on the map between all stations sending msgs

DFmenu -
Selects from the following DF displays:
OMNI - Displays Signal strength rings around stations reporting sig-strength on a fox/jammer. Stronger sigs are brighter red and null reports are black circles.

HEARD - Displays only DF stations reporting signal strength on a hidden transmitter. See NOT-HEARD

NOT-HEARD- Displays DF stations reporting NO signal on the fox. These HEARD & NOT-HEARD commands are needed on B/W displays where color cannot distinguish the DF plots.

MESSAGES: There are three types of messages in APRS. The first is simply your one-line STATUS beacon. New STATUS packets are highlighted in green at the bottom of all screens to show a change in status and are added to the ALL and LATEST lists. These STATUS beacons are perfect for alerting the net to your current status. Secondly, APRS implements a one line message capability between operators. Each line is ACKed when received by the other station. Multiple lines can be buffered up for eventual delivery. Finally, any station can send important multi-line BULLETINs to all stations. See BULLETINS page and the SEND command.


B - Bulletins
Displays current Bulletins. To erase old bulletins, use alt-E. Active bulletins will re-appear if a station is still sending them.

Displays the status of your incoming and outgoing messages. Automatically appears when anything changes.
Kills incoming message lines. K key kills one line at a time.

Erase one outgoing line at a time. Erases *ACKed* messages first, then begins prompting you for the line number.
Displays the last 23 lines of message traffic monitored between other stations.

Pre-loads the call of the last station you sent to. Enter a new call for a new station. To abort, just hit ENTER. If you have hooked a station, then that stations CALL will be pre-loaded. You may send a message to any other APRS callsign. But there are three special reserved calls as follows:
BLN# Sends a temporary Bulletin where # is the line number 0-9. The retransmission period will decay for 20 mins and stop. BLN@ - Sends a permanent Bltn where @ is the letters A-Z. The retransmission period will decay to 20 minutes and stay.
LOG Is not transmitted, but is recorded on the ALL and LOG
MSG Is not transmitted. Used to pre-store canned messages for single finger replying. See COPY below.
REPLY Is not transmitted until someone sends you a message.

F2- For REPLYING. F2 pre-loads the callsign of the last msg received.
This command will draw lines between stations on the map who are exchanging messages.

For single key ops while mobile, you may copy a previous message to a new station by entering a single digit line number instead of message text. The nth outgoing message will be copied to the SEND line. You may add additional text or hit ENTER. You can pre-load "canned" messages addressed to MSG which will NOT be transmitted, but are available for copying to new messages. This makes it easy to reply to messages while mobile with only 3 key strokes; F2, then the message number, then ENTER...

You can separately route a message via a different digi path than your normal APRS UNPROTO path by placing a /XX on the end of the TO call. APRS will then attempt to use that two letter DIGIpath for that message line. See OPS-DIGI command. This alt-path will get your message out, but remember that any incomming messages TO YOU will only get ACKS via your normal UNPROTO default path. See TROUBLE.HTM under NO-ACKS.

NOTE: The channel effeciency of APRS TALK messages are no better than normal connected packets since they also require ACK's. Intense real-time rag-chews on a busy APRS frequency should be done without digipeaters or with only the exact path specified; See the OPS-DIGI command below, for a shortcut for rapidly changing your digi path. The more effecient way to keyboard is to just use the OPS-COMM command and use your TNC to connect to the other station using normal packet over the most direct path. The other operator MUST be at his keyboard, though, because APRS will time-out, erase his screen, and dump him back into APRS after 3 minutes of inactivity.

When your MSG is acknowledged, the word *ACK* will be over printed on the outgoing MSG line. Unlike normal packet, APRS does not compute the return path for an ACK. Each station must set his outgoing VIA path so that his packets (including ACKs) get back to all stations in the net. On the 2nd DUPE of an incoming message, APRS will warn you that the other station is probably not getting your ACKS! APRS will then wait 30 seconds and repeat the latest ACK once to provide a better throughput on poor (HF and multi-digipeater) paths.

FILES MENU: This menu has all commands dealing with files.

This will permit you to load a BACKUP file without losing all the stations that are already in your P and L lists. If the same calls are in the appended file as are already in memory, there will be numerous dupes that should be manually deleted. Also, APPEND does not append any LOG or WHEN-HEARD data.

D - DOS Shell
You must be in the APRS directory before you EXIT back.

Loads a backup file. The file named BACKUP which is saved every time you quit APRS, can be reloaded with just the initial B. I save a different file for each packet frequency that I monitor.

SORT THE L and P LISTs - Moves older stations towards page 1 of each list, and the most recent stations to the end. This is useful when the lists begin to fill, so that older stations will be scrolled off to make room for new stations at the end.

Gives you a menu of items to route to the printer. The following categories may be specfied: MSGS, BLNS, POSITS, STATUS WX and ALL. These are printed without dupes.

Savesthe current situation in a file. If any filename other than the BACKUP default is entered, then APRS will also automatically save a LOG and Track HIStory file. If you select NONE (or N) as a file name, then nothing will be saved. This keeps you from writing a new BACKUP file over an older one if needed.

Allows you to replay track history files of past events or any of the automatically saved track histories after they have been saved from memory. See details under TRACK HISTOREIS in this file, or in the overall APRS.DOC file. ALthough only .HST files are shown, you can also replay .BK files from the BAKS directory by just adding the .BK extension.


This commmand allows you to disable APRS and talk straight through to your TNC or GPS/WX/DF COMM port. Use it to establish a direct CONNECTION. This is useful for connecting to another APRS station's internal TNC mailbox to leave a message if he is not on line with APRS. Do NOT use this for sending traffic, because if there is no operator present at the receiving station, it will time out in 3 minutes, and all the packets that you sent him will disappear as APRS re-takes control. Also permits you to monitor your other COM port hooked up to GPS or WX. The F8 key will toggle your HSP switch for looking at the output of your GPS.

Save up to 12 different paths for rapid recall using only the two letter path abbreviation. There are four other single letter comands:
MESSAGES:. When you are in QSO with one station in particular, that is not in your normal path, send the message /XX to force your message packets along that route only. Use this feature cautiously, since APRS must allow at least 5 seconds to change the path each time it transmits... and your ACKS to the same station will NOT go that route.

This command allows you to find a callsign or a gridsquare. If you enter the first character as a [, then APRS will asume the entry is for a grid square. This command works on the MAP, and P and L lists.

This command allows you to Query the net. A general query asks all stations to respond with all of their STATUS, POSITS, OBJECTS, and MESSAGES sometime in the next 2 minutes. This command is AUTOMATICALLY sent when a NEWUSER starts APRS but it is not sent for registered users with a CONFIG file to cut down QRM. You may use your cursor to indicate the location and specify a range radius for your Query. You can Query individual packets from another station and even ask who he hears direct and what his heard log looks like for another station.

Sends out a ping packet. If the packet is digipeated by your selected VIA path, you will see it monitored on the bottom line of your display. This lets you know that your station is transmitting and that the digipeater in your selected VIA path responded.

S - SetRadar
This sets a collision avoidance range. If any station penetrates that range, then an alarm will sound. Clear the alarm by either hooking the station on the MAP or on the P-List.

Used to set up your outgoing digipeater path. (IMPORTANT!) If you have not selected a digipeater that covers your APRS net, then your packets and acks will never get to the other stations on freq even though you see them fine. YOU MUST SET YOUR VIA PATH TO COVER your intended APRS AREA by selecting an appropriate digipeater path! APRS will warn you if another station does not appear to be getting your message ACKs. Use the OPS-DIGI command to save favorite, frequently used paths.

INPUTS MENU: Lets you enter your own POSITION and STATUS as well as to ADD objects to the map. In some of these commands, you are prompted for the LAT/LONG of the object. APRS pre-loads this prompt with the LAT/LONG of the cursor. If that position is correct, just hit ENTER. TO change these values, just type in a new value using as few characters as are needed to give the resolution you need. But you MUST always type the required LEADING ZEROS in longitudes below 100 deg.

Adds a new object to the screen at the current cursor location. You are prompted for all pertinent information. There are over 50 symbols that can be used to display the object. Use the F1-SYMBOLS command to see the symbols available.

This command allows you to enter a beam heading or a signal strength report for your own station during direction finding events. A zero (0) bearing indicates a signal strength report. Use 360 degrees for North.

M - MYdata:
This command lets you enter three items:
POSIT: Selects the current cursor position for your location.
STATUS: THis is your current status
HEADING: Updates your current heading (useful when stopped)

Used to enter your transmitter power, height above average terain, antenna gain, and directivity for plotting your radio range.
This command saves a copy of your present posit as an OBJect. This is useful for marking special locations while you drive such as DF fixes.

Identical to the SAVE command, but the object is marked for uplinking to the net.

CONTROLS: The C command (and TAB key) displays the control panel at the bottom of the screen. This two line panel shows the status of both the SETUP and the CONTROLS. The CONTROLS functions toggle on/off various functions, and show your validation status and your VIA path. Items in lower case are OFF and upper case are ON. Use the TAB key to get this display:

 VAL | TNC | Scrnsvr | 15 | GFL| JUNK | 30/600 |dgps| RELAY |XX50| USA |BEEP|
 XMT | LOG | UP | DR | cw | PFL| BCNS |  VHF   |FADE| VIA DIGI-1,DIGI-2        |

Select HF, VHF or 2-port for KAM's. In 2 port mode, the VHF or HF is still the primary band, but a duplicate of all transmissions is made on the other band. For non-dual port TNC's, this command still sets up the proper HF or VHF unproto paths and timing. For KAM's the MYAlias is set to ECHO/RELAY
C - CW
If CW is on, then ALL NEW STATUS beacons will be sounded in CW. In DX mode, CW is always on, although it can be silenced with the CONTROLS-CW commands. If FREQS is turned on, then the operating frequency as well as the callsign will be sounded out in DX mode. The CW speed defaults to 15 WPM. Other CW functions:

E-Enable D-Disable F-FREQs on S-Speed T-Test

D - Dead Reckoning ON/OFF

Toggle on/off various filters on the data:
BCNS Normaly APRS only monitors UI BEACONS
DX Selects frequency bands for DXcluster mode
OTHER With OTHER set on, then APRS looks at ALL packets
FADE on/off the fade-to-gray for contacts over 2 hours old. When reloading backup files of past events, FADE is turned OFF, but after 2 hours, FADE will automatically come back on.
!FIXED Default ON. Filters !formatted FIXED station packets to only the P-LIST. These stations have no STATUS anyway.
GDinTO Parses all packets for possible GridSq in the TO address This filter is always set in MScat, SPACE and GdSq modes
HF Ignores all packets from HF with GATE in their unproto path
JUNK Will not display any packet on the 25th line that has embedded control characters. THis keeps the map from scrolling on junk from BBS's and NODES. But it slows processging, since every single character must be checked.
POSITIONS This filter is normally ON to ignore the random 100 yd error introduced by GPS. Any posit within +/- of .04 minutes is NOT saved to the log file. If the filter is OFF, then all new posits are logged except for EXACT dupes.
toggles on and off the automatic logging of track histories to file. Default is OFF to keep from filling up your LOGS directory. When ON, and after 150 position reports, a file is automatically saved and memory is cleared for further accumulation. If off, the 150 reports are retained in memory until you QUIT.

This command toggles between METRIC display of speeds in KPH and temperature in CENTIGRADE.
When on, your objects marked for uplinking, will be uplinked to all stations in the net.

disables routine transmitting from your station. Useful for stations not actively participating in an event. Even if XMT is off, however, you can still send packets with the X command and your station will still ACK incoming messages.


The SETUP menu (alt-S) has several commands plus four major sub-menus, GPS, MODES, FORMATS and OTHER. The status of many of the SETUP options are displayed as the top line of the CONTROLS panel:

 VAL | TNC | Scrnsvr | 15 | GFL| JUNK | 30/600 |dgps| MYA RELAY  | APR |BEEP|
 XMT | LOG | UP | DR | cw | PFL| BCNS |  VHF   |FADE| VIA DIGI-1,DIGI-2        |

P - POSrate
This command is used to set both the on-screen and on-air periodicity for WX, DF and GPS reports. The Refresh rate sets how often the interface is sampled just to update the data on your screen, and the POSrate value determines how often it is transmitted.

Saves your total configuration including the present map display. You will be prompted for your Validation number the first time only. If you have chosen any of the GPS, DF or WX options, you will also be prompted for your auxilliary registration number as well. You can save each CFIG file with an optional 3 character file extension so that you can call them up quickly for different applications at the DOS prompt. You invoke the optional files with a /XXX switch when start APRS from dos. IE: C:> APRS79/MOB would load the CFIG79.MOB file which you saved when you operated MOBile. etc

T - TNCsetup
sends out TNC commands to setup the TNC for APRS. Usually initialized when you start, but can be done at any time, if your TNC loses power, or needs to be reset to APRS defaults. These commands may be customized for your TNC in the InitTAPR.TNC or InitAEA.TNC SYSTEM files. When you QUIT APRS, it restores any custom commands that you might list in RESTORE.TNC file.


Configures HSP or SPM mode for ARNAV aircraft data format or for receiving ARNAV reports over the air.
Single Port Mode (See GPS.HTM)
Hardware single port mode (see GPS.HTM)
Sets up APRS to work with STREETS-ON-DISK (Klynas Engineering)
Toggles on the saving of all NMEA data to a LOGSNMEAxxx file
Used to toggle off SPM or HSP without having to restart APRS.
Shows an AZ-EL plot of GPS satellites and signal strength
Uploads POSITS via COM2 to your GPS display as waypoints
Sync's PC clock to the next GPS report received. This command only sync's to the MINUTE. Hours are not matched. Be careful, since many stand-alone trackers will continue to report old GPS posits if the GPS loses lock or becomes inoperative, (car parked under a tree).


B - BEEPS Toggles nuisance BEEPS (and CW in DX mode) on and off.
L - LOCK Prevents un authorized keyboard access to SEND, ERASE, KILL, INPUT-ADD and WX-ENTER commands
S - SCREENSAVER toggles on/off
Z - ZONE allows you to change your timezone offset
G - GAME mode For playing chess. Modifies APRS as follows:

Toggles on and off the DF single port mode
J - dfJR mode.
Configures APRS to look for both DFjr data and GPS data on the single serial port.
M - MAGnetic Variation.
Set for your area if you will be using magnetic DF bearings or headings.

N - alt-NET mode.
Allows a special function net to operate on the APRS frequency with other stations, but WITHOUT their packets cluttering up everyone elses screens. Anyone can monitor an ALTNET by selecting this mode, OR by using the CONTROLS-FILTERS-OTHER command to enable monitoring of all packets on frequency. The alt- NET command modifies APRS as follows:
D - DX mode
Sets up APRS to display information for DX cluster users. See DX.HTM.

S - Special.
Sets up a special event net on a common APRS frequency so that the special event members only see each other without being bothered by other traffic on the channel. All other APRS users, however, DO see all traffic of the special event. This mode modifies APRS as follows:
Sets up your PC to NO LONGER ignore its OWN packets. This is needed if several other PC's (SLAVES using the same call) are all hooked up to the same TNC. A very powerful tool for use in a multi-PC environment. See OPS.HTM.

V - slaVe.
Sets up your PC for slave mode so that multiple slave PCs can share a single TNC and radio such as in an EOC. See OPS.HTM

Sets up for receiving AMTOR formated APRS reports (not fully implemented for transmit yet)
Same as used in SPACS and MScatter modes. Useful for shortening packet on HF.
Sets up for sending and recording minimum length GdSq position reports via SAREX. See SPACE.HTM

M - Meteor scatter.
Sets up for sending minimum length GdSq reports at a MAXIMUM transmit duty cycle. See METEOR.HTM

N - Normal APRS.
Prompts you for a new Status beacon.

WEATHER COMMANDS: APRS displays weather stations as blue circles with a white line showing the wind speed and direction. APRS uses 360 degs for North and 000 means no direction information is available. N is a main APRS WX hot key and the other WX commands are in WEATHER MENU:

N - NEXT WX hot key.
Highlights the next WX station in turn with a circle and shows the WX conditions at the top of the screen. These conditions will be updated on new incoming reports.
Set alarm values on Wind, High and Low temps and rain. If a WX report exceeds these values within the range of your station, the station is marked on the map in RED and the screen is re-centered to that location. An alarm BEEPS and the station is also marked with an ALARM on the P-list. To silence the alarm, either hook/un-hook the reporting station on the map (ENTER-ENTER), or use the WX-ALARM- CLEAR command. If your own station has the automatic WX interface, and your conditions exceed your alarm limits, then your WX reporting period is reset to the minimum POSrate value, for more frequent reporting.

Allows you to select TEMPS, WIND, RAIN or BARO pressure to show up on the maps instead of the station CALLSIGN. ALso lets you select JUST-WX-ALWAYS to lock in ONLY WX stations displays. NWS allows you to toggle many of the APRS symbols between the original APRS graphics and the formal NWS symbols.

E - Enter
Enter a manual weather report. (Will be transmitted for only 30 mins)

L - LOG WX data.
Will cause all WX data to be saved in the TRACK HIST

NATIONAL WEATHER SERVICE SITES - Use the MAPS-PLOTS-OVERLAYS-NWS command to overlay the map with all of the nearby NWS sites. You may either make this temporary or add them to the P-LIST.
Loads data from a designated file for NWS hourly weather advisories for each NWS station listed in both the data file and already in your P-list.

Same as QUERY, but only weather stations respond.

TRACKING and TRACK HISTORIES - All position reports are saved to memory and eventually to file for subsequent replay. Each new position report is checked against the last position from that unit and the current values. If the POSITION filter is ON (default) then a new position will not be saved to track history unless movement is more than about 80 yards. This is to reduce the number of track points for non-moving stations saved in the file. The 80 yard circle allows for most of the randomness of GPS Selective Availability so that parked vehicles do not generate a lot of packets. If the filter is OFF, then only a single digit change in a position will generate a new position report. ALso, when the filter is off, all DF reports are saved to file. This makes it possible to save a DF event, or to keep historical WX data. There are several commands related to station tracking:

a subcommand on the P-list display which allows you to designate a station for tracking. If TRACK is on, then the map will always re-center on the selected station whenever it approaches a map edge. This re-centering anticipates the station's movements and recenter's the map to give the best next view.

a subcommand on the P-list which allows you to set an alarm on a station. If that station moves, APRS will beep and re-center the map to track that station. The same filter as used on the P-list is also used here so that the randomness of Selective Availability does not unnecessarily trigger this alarm. You can silence the beeping by UNHOOKING the station, or by deselecting the ALARM function. This alarm is also used as a marker on any WX station reporting conditions exceeding your preset alarm values. But since the WX station does not move, the Alarm will not go off again, unless the WX station moves!

A subcommand on the P list for moving a station. Similar to just hooking it with the ENTER key, but is the only way to move an object or station with 00000/00000 for LAT/LONG.

On the FILES MENU, this command forces a save of a BACKUP a BLxxxxxx,LOG and a TKxxxxxx.HST file. If you are in the field, and may possibly lose power, do a SAVE now and then, to be sure you save all track histories. After the event, you can use a DOS text editor to append all the track history files together for the one event. When you Quit APRS, ONLY a Backup file is saved, the LOG and TRACK data are LOST! If, however, you give the BACKUP file any OTHER name, then a LOG and TK.HST file ARE saved when you quit.

Found in both the FILES and OPERATIONS MENUS. Track histories are retained in memory for instant replay up to 150 points. When memory is full, a file is automatically saved and memory cleared for more points. If less than 150 points are in memory, you MUST MANUALLY force a save BEFORE exiting the program or the track history points in memory will be lost! During Replay several commands are useful to center the screen on the moving object, change the speed of replay and zoom in or out, etc. The map will AUTOTRACK a moving station if only one station is indicated in the user response to the TRACK-which-station prompt.

DIRECTION FINDING: APRS can instantly traingulate fixes from many reporting packet stations, and even show overlapping signal strength contours from stations with OMNI antennas. This new OMNI feature is a tremendous advantage, since it permits EVERYONE even without any DF equipment to participate in FOX hunts. APRS has serial interfaces for the Agrelo DFjr, the N7LUE Roanoak, or the DSI Doppler unit, or it can accept manual bearings from other stations. Even voice reported beam headings can be placed on the map by anyone using the INPUT-ADD command and selecting the DF station symbol. Note that APRS uses 360 degrees as North and assumes 000 means no direction information is available. A quality of 8 indicates an excellent fix. The main DF command is in the INPUTS menu. For more info, see DF.HTM.

Entering 0 as a beam heading (APRS uses 360 for north), will indicate that the report is a signal strength report and will prompt you for your antenna height above average terrain and antenna gain. To see the signal strength contours on the map, use the MAP- PLOTS-DF command. APRS will plot colored circles around each DF report with a brightness and a radius proportional to signal strength. Note that you MUST UNDERSTAND what HEIGHT-ABOVE-AVERAGE-TERRAIN means, for this to be useful. If you are getting voice reports, be sure the person is giving a true assessment of his HAAT in the general area. Or at least in the general direction where the FOX is suspected.

If you enter any other bearing, APRS will prompt you for the quality of the fix, and then will plot the bearing from your station. heading for your station. If you are running the WX station option, it will be dissabled while the DF report is operative. You may also specify a Quality factor 1-8. The more dotted the line is, the less its quality.

This is a technique used by search and rescue pilots. It assumes that for a given receiver, there is a unique circle around the transmitter where the signal fades out. If the receiver can fly to several points where the signal just fades in or out, then these points define a circle with the transmitter at the center! APRS implements this technique with single keystroke operations. Each time you press F5, a Fade point is entered on the map.

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