AFRS (Automatic Frequency Reporting System)                   1 Dec 2008
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                                                                  WB4APR
Previous version: 8 Oct 2005

Ham radio's biggest advantage of thousands of frequencies is also its 
biggest stumbling block at rapidly and efficiently establishing 
communications under emergent or immediate need.  We simply need a way 
to determine the listening frequency of the other stations around us
or to communicate to a distant user, a desired contact frequency.

Fortunately, over the last decade, APRS, the Automatic Position 
Reporting System, provides such a single resource for displaying not 
only the position and other valuable resource information on each 
station but it has the potential to display frequency information as 
well.  Over 30,000 stations worldwide 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.oaprs.net


PRESENT RADIO COMPATIBILITY:  Already there are 5 radios than can send 
and receive frequency information.  They are the TH-D7, TM-D700 and 
D710 APRS radios, plus the YAESY VX8R and the TS-2000 with built-in 
internal TNC could be upgraded with firmware to make it also transmit 
its frequency information.

FUTURE RADIO COMPATIBILITY:  We are encouraging all manufacturers to 
consider adding AFRS capability to their transceivers to also transmit 
their frequency of operation.

BACKWARDS COMPATIBILITY:  The best news is that all existing 
microprocessor controlled radios could be outfitted with simple (under 
$99) PIC processor devices that can interrogate the radios via their 
serial command ports and can then beacon on the national APRS frequency 
their AFRS beacon.  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 query an attached radio for its operating frequency 
and then include that information into its beacon as well.  A good 
example is the pocket tracker which includes its own 1/4W transmitter 
already tuned to the national APRS frequency.

PRESENT NATIONAL VOICE ALERT FREQUENCY:  APRS operators have also 
noted the immediate need to contact by voice a nearby mobile without 
aprior-knowledge of this operating frequency.  For this reason, APRS 
has established what it calls  VOICE ALERT.  This system is usually 
for mobiles.  It simple means that instead of turning their national 
APRS channel speaker OFF (to avoid the packet noise) that instead 
they simply set CTCSS 100 and leave the volume up.  This means that 
they operate APRS normally, but at the same time are ALWAYS monitoring 
the national APRS channel for a voice call with PL 100 too.  This makes 
it possible to contact such an operator at any time because you will 
always know his voice monitoring frequency.  Read about it on: 
http://www.aprs.org/VoiceAlert3.html


OTHER SYSTEMS:  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 
systems.  This way, mobiles monitoring the national APRS frequency 
can be aware of the position and frequency of all amateur radio 
assets around them anywhere in the world.


APRS FREQUENCY FORMATS:
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The remainder of this file has been removed because it is duplicative
of the Frequency information in the APRS frequency spec.  Please 
refer to the details in this file:

www.aprs.org/info/freqspec.txt

de WB4APR
Bob Bruninga