[aprssig] GPS/PC/D7A

Stephen H. Smith wa8lmf2 at aol.com
Wed Feb 21 23:15:23 CST 2007

jdv at iglou.com wrote:
> I can only get this setup to work using UI-View with the D7a in 
> non-KISS Packet mode.(GPS connected D7 gps port, D7 pc port connected 
> to laptop.)
> Street Atlas v.6 doesn't see the GPS at all in this configuration.
> Anyone know if you need to send a command to the D7a in packet mode
> in order to enable GPS pass-through?
> '

The GPS  data  IS being passed through, but not in standard NMEA 
format.  The D700/TH-D7 attach a proprietary header to the NMEA data as 
it passes it through.  An APRS program, such as APRSpoint, UIview, 
APRSplus, etc running on the PC knows how to strip the proprietary 
header off the passed-through GPS data strings.  Street Atlas (or any 
other "civilian" program expecting standard NMEA) won't recognize the 

However, there is a workaround.   Run UIview on the PC which will accept 
the data sent from the D700.   In turn, UIview has a feature to 
re-transmit the received GPS data, reformatted back to standard NMEA 
format, out a virtual COM port for use by a second program.    In turn, 
you can use a software bridge driver to connect this virtual port to any 
NMEA-using application such as Street Atlas, MapPoint, Precision Mapping 

[ If you REALLY want to get hard-core about this, UIview can also 
transmit the reconstituted NMEA data via TCP/IP.  You can then use a 
WiFi ad-hoc LAN to share the GPS data with other laptops in/near your car ]

The net result is that you will have TWO mapping applications running at 
once -- the map display inside UIview showing APRS activity, and an 
external program doing the usual moving-map you-are-here display.    The 
most efficient use of your hard disk space in this scenario is to use 
Undertow Software's Precision Mapping with UIview.  UIview actually only 
uses the Precision Mappng database, not the program, to produce a 
continuously scrollable zoomable street-level display of all of the US 
and Canada inside UIview.    

You can run the normal Precision Mapping program at the same time 
independently of UIview, and have it tap the same road database 
simultaneously.    This gives you tremendous flexibility to view APRS 
activity zoomed to a regional view inside of UIview, and plan 
routes/watch your own course at street level in the external Precision 
Mapping program at the same time with identical-looking maps in both. 


Stephen H. Smith    wa8lmf (at) aol.com
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