Lefty's Blog: Navigation

Moving On Up to the MTK3339 GPS Chip (9/17/2014)
The Garmin GPS-12 was great in its day, but when I found out I could get a much more powerful receiver for only $40.00, I realized that it was time for a hardware upgrade. You can buy the MTK3339 gps chip already mounted on a breakout board from Adafruit.

Here is my newly arrived ultimate GPS breakout mounted on a bread broad and temporarily wired up to test and see if it works. We tap into the Arduino board for power and borrow the serial interface pins for the USB interface so we can view the GPS output on the computer. Before attempting this, I watched a nice little video on youtube by Paul McWhorter that illustrates how to hook up the board and test it. The video is rather long; about 49 minutes, but it has a lot of good information, if you are willing to sit through it. The message formats are NMEA sentences, just like the Garmin GPS-12, however, the latitude and longitude outputs are given to a resolution of .0001 minutes or arc instead of .001, which means a ten fold increase of precision, if not accuracy. $GPGGA,155858.000,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,60 $GPGGA,155858.200,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,62 $GPGGA,155858.400,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,64 $GPGGA,155858.600,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,66 $GPGGA,155858.800,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,68 $GPGGA,155859.000,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,60 $GPGGA,155859.200,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,62 $GPGGA,155859.400,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,64 $GPGGA,155859.600,2930.1254,N,09456.4954,W,1,06,2.18,77.4,M,-23.9,M,,*69 At a baud rate of 115200 I was able to read messages at 5 Hertz. The MTK3339 requires no external antenna, and it was able to acquire seven satellites in an interior room of my home. The old Garmin GPS-12 only works out of doors, which is a bit unhandy for bench testing. You can connect and external antenna to the MTK3339 for additional performance. Sparkfun and Adafruit sell a convenient antenna unit mounted on a magnet that you can stick on your car. A five meter coaxial cable is included. Thanks for visiting my web-site -- Cary Semar (9/4/2014) Return to Index

Moving On Up to the MTK3339 GPS Chip (9/17/2014)

The Garmin GPS-12 was great in its day, but when I found out I could get a much more powerful receiver for only $40.00, I realized that it was time for a hardware upgrade. You can buy the MTK3339 gps chip already mounted on a breakout board from Adafruit.

Here is my newly arrived ultimate GPS breakout mounted on a bread broad and temporarily wired up to test and see if it works. We tap into the Arduino board for power and borrow the serial interface pins for the USB interface so we can view the GPS output on the computer. Before attempting this, I watched a nice little video on youtube by Paul McWhorter that illustrates how to hook up the board and test it. The video is rather long; about 49 minutes, but it has a lot of good information, if you are willing to sit through it.

The message formats are NMEA sentences, just like the Garmin GPS-12, however, the latitude and longitude outputs are given to a resolution of .0001 minutes or arc instead of .001, which means a ten fold increase of precision, if not accuracy.

$GPGGA,155858.000,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,*60 
$GPGGA,155858.200,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,*62 
$GPGGA,155858.400,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,*64 
$GPGGA,155858.600,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,*66 
$GPGGA,155858.800,2930.1254,N,09456.4954,W,1,06,1.72,77.5,M,-23.9,M,,*68 
$GPGGA,155859.000,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,*60 
$GPGGA,155859.200,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,*62 
$GPGGA,155859.400,2930.1254,N,09456.4954,W,1,06,1.72,77.4,M,-23.9,M,,*64 
$GPGGA,155859.600,2930.1254,N,09456.4954,W,1,06,2.18,77.4,M,-23.9,M,,*69

At a baud rate of 115200 I was able to read messages at 5 Hertz.

The MTK3339 requires no external antenna, and it was able to acquire seven satellites in an interior room of my home. The old Garmin GPS-12 only works out of doors, which is a bit unhandy for bench testing. You can connect and external antenna to the MTK3339 for additional performance. Sparkfun and Adafruit sell a convenient antenna unit mounted on a magnet that you can stick on your car. A five meter coaxial cable is included.

Thanks for visiting my web-site -- Cary Semar (9/4/2014)

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