APRS Freq Spec - AFRS (Automatic Frequency Reporting System) 9 Apr 2008 ------------------------------------------------------------------------ WB4APR Updated 15 Jun 08 to eliminate leading space in FREQ object Updated 21 Feb 08 to add WIDE/NARROW and TONE/CTCSS Updated 13 Dec 07 to updte IRLP beacon info Updated 30 Sep 07 to include Mic-E Echolink format for D710 radio Updated 16 Aug 07 to finalize format of leading SPACE character Updated 1 Aug 07 to merge in IRLP & EchoLink nodes (was on AVRS pages) Updated 21 May 07 to include unique ID's for repeater frequency objects Original 8 Oct 05 Ham radio's biggest advantage of thousands of frequencies is also its biggest stumbling block at rapidly and efficiently establishing com- munications under emergent or immediate need or just to chat on a long trip across country. Ham radio needs a way to determine the operating frequency of the other stations and applications around us. This initiative came out of the Hurricane Katrina lessons learned. APRS, the Automatic Position/Packet Reporting System, provides such a single resource for displaying not only the position and other valuable resource information on each station but frequency information as well. Over 30,000 stations world wide are currently in the system and their live position/status reports can be seen on the air on the single national APRS frequency and on the internet. Simply view any area or station via any APRS client program or via any number of APRS web pages such as the following: http://www.jfindu.net OR http://map.findu.com/callsign* ... and then select "stations near". http://www.APRSworld.net There are MANY applications of FREQUENCY that we want to also show up on APRS that are listed below. They should be transmitted as part of the POSITION TEXT, STATUS TEXT or the OBJECT TEXT or OBJECT NAME so that not only their frequency, but also their location, Tone, nominal Range and other info show up well on the mobile displays. These objects should be routine (direct and local) in every local area: Every mobile's (or fixed station's) operating frequency The locally recommended voice frequency for visitors The local IRLP or EchoLink node and current node status The local WinLink node and current node status Any other local ham radio asset or net of interest to APRS mobiles For local frequency OBJECTS, these should ONLY be transmitted in the local RF area where they can be immediately used. Transmitting them any farther than DIRECT or one hop will just be QRM to areas that cannot use them. The sources of these frequencies are as follows: * Mobiles typically put their operating frequency in their STATUS text * The local Voice Repeater object is TX'ed in the local DIGI's BText * IRLP, EchLink and WinLink objects are generated by their own software and injected into the APRS-IS. From there, each LOCAL IGATE SYSOP decides which IRLP and which Echlink and which WinLINK object is in his immediate area, and he then adds these specific individual objects to his pass-to-RF list via no more than a ONE-HOP-PATH... RECOMMENDED TRAVELERS VOICE REPEATERS: Every digi has a coverage area. It is the responsiblity of that digi to transmit an object showing the best receommended travelers voice repeater in its coverage area, DIRECT, once-every-10-minutes. These packets are transmitted direct (no digipeats) so that they are only received in the vicinity where they are usable. Also, by originating at the Digipeater's high site, there is no impact on the channel load, because the digi will not transmit until the channel is clear. See: http://www.ew.usna.edu/~bruninga/localinfo.html These initiatives are working in parallel with the interest of the post-Katrina ARRL Initiative to provide operating frequency contact information in support of emergency response. Since the APRS-IS exists worldwide and already supplies information on all APRS stations, it can also accept data from WOTA, DX clusters and Logging programs to serve as a single resource for finding the likely operating frequency of interest for any station. ADDING FREQUENCY TO APRS: Already, APRS encodes the following information into typical user position packets. CALL, LAT, LONG, COURSE, SPEED (Grid is calculated) Station type (one of over 200 symbols) Antenna Height above average terrain Antenna Gain Comment (37 bytes max) (usually where stations have their frequency) Software version FREQUENCY has been added in a backwards compatible manner, by simply adding it as a fixed formatted field in the first 10 bytes of the existing free-field position comment text or STATUS field. In addition to these 10 fixed format bytes,(if used) are additional optional format bytes to include additional amplifying information about tone, range, net and meeting times. A typical entry might be: "FFF.FFFMHz Tnnn RXXm". The Tone and Range (XX miles or km) are optional or can be "Dnnn" for DCS. This format shows up well on the 10 byte displays of the D7, D700's and the HAMHUD. Collectively, if we can get all stations to include their frequency of interest in their position texts, then we will have a resource that can be used to help locate operations on the air. We call this initiative AFRS for Automatic Frequency Reporting System. This document specifies a common FORMAT for frequency entry so that all client programs can unambiguously parse for frequency information in any packet. FUTURE RADIO COMPATIBILITY: If we can get everyone to use these standard formats, then we can encourage all manufacturers to consider adding AFRS capability to their transceivers to also transmit their frequency of operation. The Kenwood D710 will already automatically insert its frequency into its position text and on receipt, can parse it and automatically tune to that frequency with a single press of the TUNE button. BACKWARDS COMPATIBILITY: It is also possible that some existing micro- processor controlled radios could be outfitted with simple external PIC processor device that can interrogate the radios via their serial command ports and can then insert their frequency information into their position beacon on the national APRS frequency. This hardware currently exists in a number of small devices called APRS TRACKRES which were originally designed to parse the GPS data and transmit position info. These same PIC processor devices could just as easily be programmed to query an attached radio for its operating frequency and then include that information into its beacon as well. PRESENT NATIONAL VOICE ALERT FREQUENCY: APRS operators have also noted the immediate need to contact by voice a nearby mobile without apriori-knowledge of his operating frequency. For this reason, APRS has established what is called VOICE ALERT. This system is usually for mobiles. It simple means that instead of turning the national APRS packet channel speaker OFF (to avoid the packet noise) that instead the radio is simply set to CTCSS 100 with the volume up. This continues normal APRS operation, with a silent speaker, but at the same time the speaker is ALWAYS monitoring the national APRS channel for a Voice Alert call using PL 100 too. Voice Alert makes it possible to contact such an operator at any time because his voice monitoring frequency is the national APRS channel. The TM-D700 and TH-D7's can both do this as is. Any APRS mobile packet system can also do this if the TNC is attached to the discriminator prior to the CTCSS squelch circuit. OTHER VOICE SYSTEMS: It should also be noted that already, the other three global internet amateur radio linked systems, IRLP, EchoLink and Winlink also include provisions for beaconing their POSIITON and FREQUENCY data onto the national APRS channel using the FFF.FFFMHz format. This way, mobiles monitoring the national APRS frequency anywhere in the country can be aware of the position and frequency of all amateur radio assets around them. APRS FREQUENCY FORMATS: ----------------------- This addition to the APRS spec adds Frequency to the parameters included in an APRS position report. This recognizes that APRS is not an end in itself, but augments other Ham Radio activities operating on other frequencies. Thus, in addition to a position, course, speed or PHG, all stations have another frequency associated with their station and this should be optionally included in APRS protocols. Also, by having a parseable calling frequency associated with APRS stations, voice and other application communications are greatly facilitated. Automatic QSY can be implemented and this, combined with APRS messaging and IRLP or EchoLink networks can lead to fully automatic end-to-end voice connectivity between APRS users anywhere on the planet with only the knowledge of a callsign. All it takes is a little software. This FFF.FFFMHz frequency addition is backwards compatible to all existing software because it is added into the free-field position comment text. The first 10 bytes and optionally a space and an additional 9 bytes are available for this purpose. Specific 10-byte formats are required for unambiguous parsing and consistent presentation on receipt as well as pleasant display on the 10 byte Wide LCD displays of the APRS radios and HAMHUD's. Here are the standard 10-byte formats. Please note that spaces are required where shown. In some cases a "_" may be shown for clarity in this document, but in the actual format, a SPACE should be used: 1st 10-BYTES Frequency Description ---------- ----------------------------------------------------- FFF.FF MHz Freq to nearest 10 KHz FFF.FFFMHz Freq to nearest 1 KHz Examples: 146.52 MHz Enroute Alabama 147.105MHz AARC Radio Club 146.82 MHz T107 AARC Repeater (Tone of 107.2) 146.835MHz C107 R25m AARC (CTCSS of 107.3 and range of 25 mi) 146.805MHz D256 R25m Repeater (DCS code and range of 25 miles) 145.50 MHz t077 Simplex (Tone of 77.X Hz and NARROW band) 2nd 10-BYTES Optional Application Descriptions ---------- ----------------------------------------------------- _Txxx RXXm Optional PL tone and nominal range in miles _Cxxx RXXm Optional CTCSS tone and range in miles _Dxxx RXXk Optional DCS code and nominal range in kilometers _1750 RXXk Optional 1725 tone burst and range in kilometers _Toff RXXk Optional NO-PL, No DCS, no Tone, etc. _Exxm Wxxm East range and West range if different (N,S,E,W) _txxx RXXm Lower case first letter means NARROW modulation 2nd 10-BYTES Optional Frequency Description for added Freq info ---------- ----------------------------------------------------- _FFF.FFFrx Alternate receiver Frequency if not standard offset _FFF.FFF + Alternate Frequency and standard shift The 1st 10 bytes must be frequency and "MHz" in mixed case is required. Notice that the second 10 byte fields begin with a SPACE shown above as "_" (9 useable bytes) for better reading of the packet on normal text displays as shown in the examples below. Do not include the "_" but put a SPACE there in your actual packet. Here is the raw packet format for the comments: FFF.FFFMHz comment... one frequency FFF.FF MHz FFF.FFFrx comment... for separate TX and RX FFF.FF MHz T107 R25m comment... for TX, tone and range The 10x10x8 byte format has been defined so that it shows up well on the TH-D7, TM-D700 and Hamhud displays. Examples are as follows: +------------+ +------------+ | >WB4APR-11 | | >WB4APR-11 | | FFF.FF MHz | | FFF.FFFMHz | | FFF.FFF M | | T107 R17m | +------------+ +------------+ NMEA or OTHER TRACKERS: All of APRS was intended to be a two-way comunications system between human operators. For this reason, tracking devices that do not receive and display APRS should at least include their monitoring voice frequency in their packet information so that they can be contacted. The format is the same. Simply put the frequency in the position text. If the the tracker does not have that flexibility (such as a NMEA tracker), then put the frequency into the STATUS or BEACON text as follows: BText >FFF.FFFMHz Tnnn etc...... Where the leading ">" makes this packet an APRS STATUS packet and the "etc..." can be any additional free text (or TXXX tone) as needed. On recepit, most APRS programs should combine this info with the station data to make the frequency parseable as needed. RECOMMENDED VOICE REPEATER FREQUENCY OBJECTS: --------------------------------------------- Please see: http://www.ew.usna.edu/~bruninga/localinfo.html There are two more parseable locations for frequency in the APRS protocol, one is for Object names and the other is the DX Format. OBJECT NAMES: Every New-N Paradigm APRS digipeater is supposed to periodically transmit an OBJECT showing the locally recommended voice repeater frequency for travelers visiting the digi's own coverage area. APRS software should be able to locate these frequencies as well. The format for these frequency object names is as follows: OBJECTNAME ---------- FFF.FFF-z 5KHz repeaters with up to 62 unique (z) ID's FFF.FFFyz 5KHz repeaters with up to 2700 unique (yz) ID's FFF.FF-yz 10kHz repeaters with over 3600 unique (yz) ID's FFF.FFxyz 10kHz using three xyz unique characters... The frequency can include the standard offset (+/-) or not. But please note that FINDU.COM and other sites will not display an object name with a "+" in it unless you wildcard it. SO we have eliminated the "+" since it is not required, since most repeater offsets are standard anyway. The rest of the OBJECT format contains the TONE and RANGE and any specific information on regular net times and meeting dates. The format for these objects is: ;FFF.FFFxy*111111zDDMM.hhN/DDDMM.hhWrT079 R25m NETxxxxxx MTGxxxxx... (15 Jun 08 change. Eliminated the leading space before the T079) Where T079 is a tone of 79.7 Hz Where R25m is a Range of 25 miles Where NETxxxxxx is something like "Net Tu9PM" or "Net Tu730" Where MTGxxxxx is something like "Mg3rdTu" and must be 8 bytes Where ... 9 more bytes are possible but won't show on mobiles This exact spacing fits nicely on the 10x10x8 displays of the D7, D700 and HAMHUD. TONES and DCS: We force the tone to 3 bytes always for simplicity of display, since all tones are standardized anyway, they do not neet to include the tenths of a Hertz. So T088, C067, T156 and DXXX are all valid entries. Lower case implies NARROW modulation as in t088, c067, t156 etc. OBJECT NAME PERMANANCE: Notice that an object name needs to be unique since there are dozens of 146.94 repeaters in the country, and so these objects choose characters for the optional z, yz and xyz characters above to make them unique. Since these can be upper and lower case and or numbers, this gives 62 unique identifiers for the 5 KHz repeaters and over 3600 for 10 KHz repeaters. If there are still conflicts, then other delimiters such as "_=!^@, etc" can be used in place of the - separator. To see what freqeuncies are already in use, simply do a wildcard (*) link to FINDU.COM. For example, http://map.findu.com/146.94* will provide a list of all 146.94 repeaters currently showing on APRS and their "xyz" modifiers in use! Further, these objects are transmitted with the pseudo permanent date/time stamp of 111111z. This unique time stamp declares this object to be permanent. This means that it should not be replaced by any other similarly named object unless that object is transmitted by the same originating station. This lets the originator of a permanent object update or move his object, but it then prevents his object from being replaced by anyone else's similar object. DX CLUSTER FORMAT: APRS also decodes the DX CLUSTER format, and this format includes a frequency field too. All APRS software should decode and capture this frequency information also. EchoLink OBJECT FORMATS: ------------------------ EchoLink object names have the format of EL-123456 so that the node number can be easily seen on the station list of the mobile. This is important, since the mobile user has to have the node number to activate a link. Not the callsign of the node. The rest of the object uses the previous formats above to convey operating frequency and tone, and range. Here is an example OBJECT for EchoLink nodes. ;EL-123456*111111zDDMM.--NEDDDMM.--W0FFF.FFFMHz Tnnn RXXm STATUS CALL In this case, the TWO digits of precise position are usually entered as SPACE bytes so that the object's precise position is not transmitted, but is transmitted as a one-mile ambiguity object. Replace the two "--" bytes above with SPACES for it to work. The E between LAT/LONG makes APRS display the EchoLink symbol. It is hoped that a single central EchoLink server will generate these objects so that the only thing needed to get them on the air in a local area is to have the local IGate sysop to activate the local object by name for pass-to-RF. ECHOLINK FORMAT USING MIC-E: This format is for the Kenwood D710 radio which reports its position in Mic-E format. This format will appear on the air as: MYCALL>LLLLLL,DIGI:'GGGCSD0E]FFF.FFFMHz Tnnn RXXm Ecolink node= The LLLLLL is the latitude bytes, GGGCSD are the longitude and course speed bytes. The "0E" are the ECHOLINK Symbol bytes. And the "]" byte indicates this is a D700 series Mic-E and the "=" on the end indicates it is the D710 version. The "FFF.FFFMHz Tnnn RXXm" is the frequency and range format. And "Ecolink node" is intentionally misspelled to fit nicely on the display of a D700. IRLP OBJECT FORMATS: -------------------- See the Scrip to add this to your IRLP node: http://irlp.kc6hur.net/irlp_scripts.php IRLP object names are similar and have the format of IRLP-1234 or IRLP12345 if they ever go to 5 digits. This format is so that the node number can be easily seen on the station list of the mobile. The rest of the object uses the previous formats above to convey operating frequency and tone, and range. Here is an example OBJECT for IRLP: ;IRLP-1234*111111zDDMM.--NIDDDMM.--W0FFF.FFFMHz Tnnn RXXm STATUS CALL In this case, the TWO digits of precise position are usually entered as SPACE bytes so that the object's preceise position is not transmitted, but is transmitted as a one-mile ambiguity object. Replace the two "--" bytes above with SPACES for it to work. The I between LAT/LONG makes APRS display the IRLP symbol. It is hoped that a central server will be written for these objects as well so thta they can be consistently generated into the APRS-IS and then only gated back to RF locally. The STATUS can be something like these: (IDLE, OFFLINE, STN1234/REF9876, BUSY). For more info, contact Mark Herson n2mh@n2mh.net WINLINK OBJECT FORMATS: ----------------------- WinLINK Telpac gateway object names have the format of W?-CALLSIGN (where W? can be WL or W1, W2,... W9 for multiple stations) so that the node callsign can be easily seen on the station list of the mobile. The rest of the object uses the previous formats above to convey operating frequency and range. The baud rate, "bbbb" for packet is inserted in place of the TONE, Txxx for voice. Here is an example OBJECT for injection into the APRS-IS: ;WL-AB9XYZ*111111zDDMM.--NWDDDMM.--WaFFF.FFFMHz 1200 RXXm comments In this case, the TWO digits of precise position are usually entered as SPACE bytes so that the object's preceise position is not transmitted, but is transmitted as a one-mile ambiguity object. Replace the two "--" bytes above with SPACES for it to work. The W between LAT/LONG and "a" symbol makes APRS display the WinLink symbol. MICROWAVES: Of course FFF.FFFMHz only works to 999.999 MHz, and so we need to come up with some letter designations above that. There are two methods. One, is to simply use GHz as in XXX.XXXGHz. But this is limited to wideband modes to the nearest MHz. Example is __1.296GHz for 1296 MHz. To retain one KHz resolution, we use this table of alphabetical extensions: A96.000MHz would be 1296 MHz B20.000MHz would be 2320 MHz C01.000MHz would be 2401 MHz D01.000MHz would be 3401 MHz E51.000MHz would be 5651 MHz F60.000MHz would be 5760 MHz G30.000MHz would be 5830 MHz H01.000MHz would be 10,101 MHz I01.000MHz would be 10,201 MHz J68.000MHz would be 10,368 MHz K01.000MHz would be 10,401 MHz L01.000MHz would be 10,501 MHz M48.000MHz would be 24,048 MHz N01.000MHz would be 24,101 MHz O01.000MHz would be 24,201 MHz CONCLUSION: Examples of frequency use in APRS are obvious: 1) Advertising the voice frequency you are monitoring 2) Voice repeater and other local frequency Objects 3) Mobile GPS map display of surrounding frequency assets 4) IRLP and EchoLink nodes 5) WinLINK Packet nodes 6) EOC operations 7) Long distance travelers 8) ATV repeaters and links, etc... Since the object of APRS is to facilitate local communications and situational awareness of all surrounding ham radio assets, everyone is encouraged to include their operating frequency in their position packets to make their availability known. de WB4APR Bob Bruninga