[aprssig] Android can do analog APRS on 144.39

Stephen H. Smith wa8lmf2 at aol.com
Thu Mar 28 13:10:42 EDT 2013

On 3/28/2013 12:50 PM, Georg Lukas wrote:
> Hey Tom,
> * Tom Hayward <esarfl at gmail.com> [2013-03-28 17:14]:
>> The D72 has two data ports:
>> - The USB device port enumerates as a serial port and offers memory
>> programming, CAT, and raw TNC access.
>> - The 2.5mm COM port offers NMEA GPS input and waypoint output.
> I was not aware of the two separate ports, as I do not have a D72.

Actually, the port arrangement is nearly identical to the TH-D7; i.e. one 
serial port for the TNC to communicate with the PC, and a second serial port 
for the GPS to communicate with the radio's built-in TNC.

The only major difference is that the  radio<-->PC  interface has been 
converted to USB inside the D72 to accommodate modern "legacy free" PCs that 
lack serial ports, but that do have USB.    This is done with the same sort of 
chip that is used in stand-alone serial<-->USB cable dongles.

Annoyingly, Kenwood opted NOT to use the common Prolific or FTDI serial<-->USB 
chips, whose drivers are very likely already on most systems.   Instead Kenwood 
used the far less common Silicon Labs CP210x "USB to UART Bridge" chip. 
Details here:


As with external   serial<-->USB  dongles, you have to install a driver on the 
PC that recreates a virtual serial port that then communicates with standard 
serial-port-oriented APRS programs.   (Ironically, even Kenwood's own memory 
management program for the D72 still expects a SERIAL port, either virtual or 
real, rather than natively using the D72's USB interface.)

When under the control of a PC, the GPS data sent into the (real) GPS serial 
port on the D72 is echoed out the (virtual) serial port to the PC, just as on 
the earlier TH-D7.  When you use an EXTERNAL GPS on the D72 (but not it's 
built-in one), the (real) GPS serial port can echo received posits from the TNC 
as NMEA waypoints back to the GPS for display if it has one.  I.e. you can use 
both the GPS and the map in an AVmap, Street Pilot, Nuvi 350, etc.



Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

  Long-Range APRS on 30 Meters HF

High Performance Sound Systems for Soundcard Apps

"APRS 101"  Explanation of APRS Path Selection & Digipeating

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