APRSNET.TXT APRSnet Document version: 8.4.3 1 Nov 1999 (Introduced in Nov 97) Author(s): Bob Bruninga, WB4APR The APRSNET concept uses a local channel to serve a continuous global APRS stream from the internet so local stations can monitor while not having their own Internet Access. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THis version of APRSdos is obsolete. It cannot keep up with the current 27,000 global stations (as of JUne 2004)... APRSnet was based on the pioneering work of Steve Dimse, K4HG, who wrote APRServ as a system for linking together APRS internet IGATES so that APRS traffic nationwide could be distributed among such sites via the very high bandwidth of the internet. APRSnet means three things: 1) APRSnet.exe was APRSdos streamlined for use on the internet 2) APRSnet was a whole new concept for nationwide connectivity. 3) APRStel lets APRSdos users dial in via MODEM to see the APRServe activity. See APRStel.txt This new APRSnet concept is an extension of Steve's original plan, to not only provide nationwide connectivity between APRS internet users, but to also provide on-the-air nationwide connectivity to mobiles and other stations without direct internet access. This also provdes the mechanism for extending the APRSnet into disaster areas or areas that have lost internet connectivity! APRSnet is completely compatible with the existing nationwide APRS tracking network on two meters and just provides for the long haul of data nation/worldwide. APRSnet.EXE was a version of APRSdos modified for the greater tracking capacity (up to 500) and some hot-keys were added to facilitate opening a telnet connection to the APRServe site. When I wrote APRSnet in Nov 97 there were only a few permanent nodes, and dozens of temporary dial in nodes all over the country. Most of this had been going on for about a year using MacAPRS which had always had TcpIp built in. Once WinAPRS and APRSplus added TcpIp, then everyone logged on now can feed every packet heard on VHF/HF/Satellite to each other. APRSNET CONCEPT FOR 2 METER LANS: The APRSnet concept extends this worldwide internet connectivity to local users on dedicated local APRSnet channels. Whereas Steve's APRServe software serves all of the internet sites, APRSnet PC's take this data and STREAM it on a local APRSnet channel for local listeners. DEFINITIONS: NATIONWIDE APRS CHANNEL: This is the single nationwide tracking channel currently endoresed by the ARRL and AMSAT as 144.39 where available. All mobiles report their positions and status on this nationwide APRS frequency in their local area. As more and more APRSnet sites come on line, mobiles and fixed stations need only a minimum path length to cover their local area and make sure their packets at least get to a nearby APRSnet site. APRSnet Channel: This is an optional local channel fed by an APRSnet PC that is logged onto APRServe. This APRSnet channel is preferably different in each area, needing a clear channel coordination. It transmits a near continuous stream of 9600 baud packets of everything heard via the internet. This is similar to the PACSAT protocol that assumes that everyone is listening and will collect what he needs just by monitoring the channel. This continuous distribution of packets is called streaming. Any user desiring to see the national APRS picture, tunes into this channel. IGATE: An IGATE serves as a local user terminal logged onto APRServe, and as gateway for feeding locally monitored VHF packets into APRServe and lastly as gateway for internet traffic back over the air to local VHF linked users. APRServe: This is the software written by K4HG to do the internet packet serving to everyone connected to his site. APRSnet.EXE: My simple DOS program to do the IGATE functions. It has several capabilities. as follows: INTERNET PORT: Use this comm port to telnet to www.aprs.net TNC PORT: Your TNC can either stay on 144.39 or be a server FEEDING: In this mode, everything heard by your TNC is feed into APRServe via the telnet connection. STREAMING: This streams all of your stations heard on the P and L -lists to your community on your APRSnet channel USER: This is standard APRS mode with only the TNC port active. You use APRSnet.exe since it has more rooom for the hundreds of stations than normal APRSdos. CAUTION!!! You must not activate STREAMING if your TNC is listening on the same channel it is serving. Otherwise you will form an infinite loop of packets! TALKBACK CHANNEL: To allow for increased capacity IN THE FUTURE and to avoid cluttering the National APRS channel with keyboard messages between FIXED stations, each APRSnet node can add a "talkback" channel where it listens for incomming traffic. In many instances, it may be advantageous to use +/- 600 KHz offsets so that normal offset transceivers can be used. These talkback channels are again, only a local coordination issue. For now, user talkback is simply transmitted on 144.39 and the IGATE picks it up there... ZIP-LAN: This is not related to the internet, but the protocols added to APRS to handle the IGATES and APRSnet concepts also permits multiple PC's to be interconnected with nothing but 2 conductor zip cord. This is advantageous in the field where many APRS consoles may be connected to a single TNC and radio in an emergency operations center. See ZIP- LAN.txt MESSAGING: Since APRSmessages are by nature, point-to-point, they are already permitted to go both ways through a validated IGATE. This means that a user on the internet may send a message via an IGATE to a nearby station within VHF range of that station. The local IGATE will transmit it and will FEED the ack back via APRServe to the originator. To fit within the FCC rules, only licensed HAMS are permitted to use this capability. A validation protocol exists between the various versions of APRS and the APRServer to authenticate licensed users. APRSNET DIFFERENCES AND COMMANDS: To facilitate the specific application of APRSnet.exe, many features were eliminated from APRSdos, such as DX, Mscatter, DF, and SPACE modes. The D page is truncated to 40 bytes and several new commands have been added: F1-TELNET - Help pages about APRSnet OPS-COM-INTERNET - Use this dumb terminal mode to access your TELNET alt-S-NET-FEED - Activates feeding packets from your TNC port to TELNET -SERVE - Activates serving status/posits out your TNC port -TRANS - Sets the transmit cycle time on your server channel -IGNORE - Toggles IGNORE filter on/off. When ON, only posits on the current screen will be saved. This is so you can zoom into an area, and your PLIST will only fill with local packets to that area. -DIAL - Save a DIAL string for your modem access.* Invoke it on the OPS-COM-INET screen with alt-D -LOGGON - Save your LOGGON string.* Invoke it on the OPS-COM- INET screen with alt-L. -CONNCT - Save your CONNECT string (open www.aprs.net:10151).* Invoket it on the OPS-COM-INET screen with alt-C. * Note, these strings are viewable with OPS-DIGI-LIST CONTROLS-XMT - Toggles ON/OFF your TNC transmit JUST-TELNET - Displays a list of other TELNET stations that are in your P-list. CAPACITY CONSIDERATIONS: Even with 1200 stations showing on APRServe, the overall througput is still only about 2400 baud average with peaks to about 4800 for a few seconds now and then. THus the entire worldwide stream can still be transmitted on a single 9600 baud RF channel even with a digipeter! But even if we grow by a factor of 10 or more, just like with the cellular phone industry, there is no limit to the capacity of the system. As more and more users come on board, the APRSnet "cells" just get smaller and more focused. Or we can spread out the data. One channel for Weather, another may be the EAST coast channel, another may be the WEST coast channel or another may become the special event channel.... With the demise of packet BBS systems, there should be plenty of bandwidth available and APRSnet channels are in fixed areas and don't need to be used for cross linking so coordination is a local issue only. Travelers or visitiors would be alerted to the local APRSnet channels by clicking on any IGATE symbols he sees on his APRS map. USER SOFTWARE: There is no distinction at the user end in APRSnet traffic or conventional traffic. Home stations simply monitor the APRSnet channel if they want to watch nationwide activity. They still transmit their traffic on the normal APRS national channel, or later, on an alternate APRSnet talkback channel. Mobiles will also operate as normal on the national channel, and will be able to see all local activity. Stations with internet access will join the network that way, thus freeing up valuable RF spectrum for the mobiles and users without internet access. OPERATIONS: When you start APRSnet.EXE you will see several pages of description. You may return to these later with the F1-TELNET command. Next you log on to APRS and give the COM port (1 or 2) of your TELNET connection and TNC. Next you alt-S-SAVE your config file so you wont have to do all that again. Finally, you go to OPS-COM-INTERNET screen which is nothing more than a DUMB TERMINAL SCREEN and do what ever you have to do to open a TELNET session to www.aprs.net. If you use a dial up line, you will need to tell your modem to dial the phone. This is simply the command: ATDT ######### (AuTo Dial, Tone ) (Save this string and others using the alt-S-NET-DIAL, etc commands.) Once you are logged in, you will need to open a TELNET connection. Of the three systems where I work, there are three different formats! THey are OPEN www.aprs.net C www.aprs.net @23 www.aprs.net 23 Here the 23 is the port number on APRServe for live data. If you open to port 10151, you will get a fast dump of the mroe than 1000 stations heard in the last 24 hours before the live feed kicks in. APRSdos cannot really handle this high speed dump. Once you are logged on, still on the dumb terminal screen, you will hit the usual ESC to escape back into APRSnet. There is a packet counter displayed during the initial dump. I am seeing 1200 to 2600 packets in the 12 hour buffer. APRSnet only keeps the last 500 for now.. Once you are back into APRSnet you should be able to do everything you normally do. THere is ONE new command, JUST-TELNET on the DIGIpath page which will display a list of only the other APRServe and APRSnet users. If you do an OPS-QUERY 4096 miles, then all other APRServe stations should respond within a few minutes. SPEED DIALING: Once you figure out your modem dial string and your required LOGGON and CONNECT string, you may use the alt-S-NET-DIAL, LOGGON and CONNECT commands to save these strings (alt-S-SAVE). Then when you are on the OPS-COM-INTERNET screen, you can just do alt-D to dial, alt-L to loggon, and alt-C to connect... INITIAL TRIALS FOR SERVING AN APRSNET CHANNEL: You can transmit at a 50% duty cycle on channel A and then have the outlying DIGIS all digipeat those packets back onto channel A. Crude, and people that can hear 2 digis will have problems and if APRSnet catches on, your 50% duty cycle may not handle the load. DUAL FREQUENCY: Same as above, but have each of the other digis listen on A but transmit on their own channels. Still 50%, but everyone gets a clear channel. Also harder to find 4 channels. OR, if you can get enough frequency separation, all of these digis and your site can operate 100%, just tell the digis to operate full duplex. DUAL BAND: THis is probably the best. Transmit on BAND A and then have the outlying digis transmit on band B (multiple freqs) 9600 BAUD: Do all this at 9600 baud! Remember, 5 watt 9600 baud data radios are less than $150... FREQUENCY PLANNING: APRSnet requires a new locally coordinated 9600 baud channel, since it is for a fixed site application for fixed users. As activity grows, an additional talkback channel may be required. Careful planning early on could arrange for the talkback channel to be +/- 600 KHz from the streaming channel so that normal T/R offsets can be used. For example, if 145.63 is the APRSnet channel in an area, then 145.03 could possibly be used as the low duty cycle "talkback" channel to APRSnet. In a pinch, you can use plain ole APRSdos to logont APRServe. Just go to the dumb terminal screen and logon to yoru TELNET account and then ESC back into APRS. It will capture and plot like APRSnet.exe, but will be limited to only the last 150 stations heard. But still, you can zoom into an area and still see EVERYONE pop up on your map, although only the last 150 seen will be on your P-LIST. de WB4APR