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2 HOW YOU ENJOY APRS WITH TH-D72A/E (WRITTEN BY BOB BRUNINGA, WB4APR)
TH-D72A/E CONTENTS 13
Contribution by Kenwood to APRS
Kenwood has developed its series of radios, TH-D7A/E, TM-D700A/E, TM-D710A/E, and now the
new TH-D72A/E to best support the original objectives of APRS. The display of APRS information on
the front panel of these radios gives the mobile operator instantaneous access to all local information
being provided on the APRS channel about all surrounding ham radio activities.
There are many APRS clients and programs that have been written that sometimes have
concentrated too much on the display of maps and vehicle positions while leaving out much of the
original fundamentals of APRS and the efficiency of the APRS network The Kenwood radios avoid
such an over-simplistic approach to APRS by implementing a rich and diverse function set. The
function set includes almost all of the original functions of APRS that are meant to reinforce the
concept of distributing local information. The Kenwood radios are not just Vehicle Tracking Systems,
but are designed to be real-time information distribution systems for mobile operators with these
features:
• Position Entry
TH-D72A/E with its built in GPS solves the hassle of external connections and setup and always
accurately knows your position. For times indoors the radio has 5 position memories for pre-
stored frequently-used positions.
• Map Displays on attached GPS
Although the radio has a built-in GPS, it still has the special waypoint output for putting all other
APRS positions info on an attached external GPS. When connected to the AvMap G5 series and
later, these position objects will show as any of the nearly 200 special APRS symbols.
• APRS Network Fundamentals
Kenwood fully implemented the more subtle aspects of the APRS fundamentals that assure
optimum network efficiency and channel sharing among all users. New TH-D72A/E supports the
decay algorithm, proportional pathing and SmartBeaconing. These techniques provide good
refresh rates for new and local information while minimizing the network impact of old and distant
data.
•Objects
The Kenwood transceivers fully appreciate the value of APRS objects and display them
prominently. The object location is shown just like other stations either on the attached map
display or on the front panel with distance and range. TH-D72A/E also includes filters for easy
sorting of these objects in the list. These objects are what give APRS the local information value
to local users.
• Two-Way Messaging
Unlike passive one-way tracking devices, the Kenwood radios provide the mobile user with full
two-way messaging and display. This real-time human-to-human communications is what makes
APRS so valuable in support of special events and emergencies.