Kenwood TM-255A User Manual

TM-D710A/E

3

APRS was developed beginning back in the 1980s by Bob Bruninga, WB4APR, as a real-time 
local tactical communications system for rapidly exchanging digital data of immediate value to 
local operations.  This really took off when GPS became available and MAPS were integrated into 
the system for tactical situational awareness of everything in the net.  Unfortunately, in the 13 
years since GPS became readily available to most operators and was added to APRS to facilitate 
the display of the local network, too many follow-on applications have focused too heavily on the 
vehicle tracking function at the expense of many of the more valuable functions of APRS for 
human-to-human ham radio information exchange in real time.
As a result, too many operators appear to misunderstand some of the basic tenets of APRS.  
APRS is not a vehicle tracking system.  The Automatic Packet Reporting system is simply a local 
data channel designed to share everything that is going on in ham radio in real time.  This channel 
was designed to support rapid, reliable exchange of information for local, tactical real-time 
information, events or nets.  The concept, which dates back to the mid 1980s, was to provide a 
single information resource channel where everything happening could be beaconed and where 
anyone could monitor to find out what was going on across all aspects of ham radio interests.

A fundamental principal was that all relevant information is transmitted immediately to everyone in 
the net and every station captures that information for consistent and standard display to all 
participants.  Information was refreshed redundantly but at a decaying rate so that new information 
was rapidly disseminated but old information was updated less frequently than new info.  Since the 
primary objective is consistent exchange of information between everyone, APRS established 
standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and 
QUERIES, it also establishes guidelines for display so that users of different systems would still 
see the same consistent information displayed in a consistent manner (independent of the 
particular display or mapping system in use). 
To emphasize the freshness and importance of local information over the sometimes interference 
of older and more distant data, the new TM-D710A/E implements both the decay algorithm and 
also the new proportional pathing algorithms.