DFM-06 Modification to GPS-Mouse

Graw DFM-06
The DFM-06 is a series of small single-board Radiosonde's developed by Graw to carry out meteo soundings.
Inside houses a GPS Jupiter Telit JN3.
If the job is done, they are useless..
But they can be recycled to GPS Mouse.

Hardware Details

DFM-06 Details: https://www.gruan.org/instruments/radiosondes/sonde-models/graw-dfm-06/
Telit JN3 Reference Design                          

Telit Jupiter JN3 Details: https://www.telit.com/m2m-iot-products/positioning-timing-modules/positioning-gps-jupiter-n

GPS chips are often used on Radiosonde's to get a accurate position.
The JN3 uses SIRF at 9600Baud.

Needed stuff

USB-TTL converter.
Some wires.
Soldering tools.

DFM-06 JN3 Modification

Remove the Batteries.
Desolder 4 legs and remove tuner print and Sensor arm.

Wire pin 20 TX and pin 21 RX on JN3 GPS Module.

Wire on brown condesator above, left +3.3V and right -GND.

And solder TTL-USB converter on 4 tiny pins bottom right from JN3 GPS module:

Build together ->


Windows Sirf/NMEA Mode JN3

Connect with USB cable to computer.                                                      

Download and start SirfDemo select COM Port (most probaly Prolific driver is needed on Windows) and use 9600 Baud to connect.


JN3 starts itself in Binary Sirf mode.


From action menu choose Switch to NMEA Protocol.

Choose a desired Baudrate.


DFM-06 works in NMEA 4800 Baud mode.


Can use any GPS Application know.

vis gps

But remember to follow whole procedure again when disconnecting the GPS Mouse, it will start again in Binairy Sirf Mode..

A batch file can be made for auto startup GPS mouse in NMEA Mode .

Example Com:1 4800 Baud:

@echo off

echo Switching DFM to GPS mouse.

mode com1 baud=9600 parity=n data=8 stop=1

copy sirfbinary2nmea.txt com1:

echo  4800 baud.

Linux NMEA/Sirf

In Linux no drivers are needed to install.

For Sifrmode on the 9600 JN3 Short Version a script can be made:


Make dfm.sh


dmesg | grep ttyUSB0

echo "Switch DFM06 from binary 2 NMEA mode..."

cd /home/gps

sudo stty -F /dev/ttyUSB0 speed 9600

echo "Insert sirfbinary2nmea..."

cat sirfbinary2nmea.txt > /dev/ttyUSB0

echo "Switch to 4800 Baud..."

sudo stty -F /dev/ttyUSB0 speed 4800

echo "Done DFM on 4800 Baud"

Before make some sudo chown -R <username:username> /dev/ttyUSB0

You can use GPSD with some build in apps or use FoxtrotGPS/Viking.


gpsd /dev/ttyUSB0

NMEA Mode:
dmesg | grep ttyUSB

xgps /dev/ttyUSB0

cgps -s

gpsmon /dev/ttyUSB0

Make it work in Wine


Some tutorials floating arround the net show a DFM with batteries connected,

So it can store NMEA mode in memory, for continous usage its not safe due the +3.3V, they can explode...