[OZAPRS] New APRS toy...

Richter, Mike W Michael.Richter at team.telstra.com
Thu Nov 14 09:42:42 EST 2002


Darryl

Sounds like a great idea.

What does the GPWPL protocol enable when received by a GPS ?

The main limitation seems to be that you can only use maps available for
Garmin GPS - for Australia that's a serious limitation !

Mike Richter VK2BMM

-----Original Message-----
From: Darryl Smith [mailto:Darryl at radio-active.net.au]
Sent: Thursday, 14 November 2002 09:09 am
To: ozaprs at careless.net; 'VK2-APRS'
Subject: [OZAPRS] New APRS toy...


People...

I have just finished the beta of a new aprs toy... Think Kenwood D7
without the display... For those public service events where you want
some people (race organisers etc) to see what you are tracking, but
don't want to give them a full tracker... 

What most people have concentrated on is Trackers, which transmit the
positions from a GPS reciever to the world. I have developed almost
exactly the oposite - a device the recieves APRS packets and uploads
them to a GPS receiever without the need to a transmitting radio.
Basically think of this as being like a D7 radio, without the radio or
display.

The reason I have done it this way is that there are times in public
service events (or my consulting work) where we need to distribute APRS
information out into the field - but where it is not appropriate to have
transmitting stations, or laptops. So I have developed a device that
will go between a scanner and a GPS reciever to do that.

At the moment I am decoding AX-25 in an 16F84 IC, and feeding the serial
stream into a 16F628. I am working on getting rid of the 16F84 but this
might take a little time. I also have a MAX232 in there, but depending
on the voltage I choose that might change model, or I might get rid of
it all together. [I am pretty sure that 3V will not work for RS-232 high
:-) ]. I am looking at doing a PCB, but that might take some time... [I
also want to do a surface mount version whe I get the bugs out...]

The night before last I was informed that Garmin ETREX GPS recievers
(but higher models are) are not compatible with this [Feel free to email
GARMIN to complain that the ETREX does not have NMEA/NMEA interface mode
- I was really annoyed when I found out]. I am going to have a look at
doing a PIC to allow this unit to work with the GARMIN binary protocol.
It does not look TOO hard, but you can never tell. I have got an upload
to work to the GPS12, so a ETREX should not be hard. The hard part will
be converting the position from degrees (with decimal minutes) into
semicircles....

Anyway some photos are available on
http://radio-active.net.au/web/tracking/antitracker.html

Darryl

---------
Darryl Smith, VK2TDS   POBox 169 Ingleburn NSW 2565 Australia
Mobile Number 0412 929 634 [+61 4 12 929 634 International] 
Darryl at radio-active.net.au | www.radio-active.net.au  


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