GPS module test and evaluation

A project log for GPS Receiver for Nikon D3100 Cameras

An inexpensive and more accurate GPS receiver accessory for Nikon D3100 (and compatible) cameras.

Kevin 10/02/2015 at 06:020 Comments

A couple of days ago I received the other two GPS receiver modules (NEO-7M and NEO-M8N) I had ordered. Today I took some time to do some initial tests of the two modules and check their performance. I also wanted to look at my original GPS module (NEO-6M) as it hasn't been able to get a satellite lock for several weeks.

I wanted to use the u-center software from Ublox to test the modules but I needed a USB to serial adapter. I finally remembered I had a USB to serial console adapter cable for my Raspberry Pi. It uses a Prolific chip and it was exactly what I needed. The u-center software is Windows only and the only machine I have running Windows is my laptop. It was recently upgraded to Windows 10 and the Prolific driver would often report driver error on each boot. I took some time to research the driver problem and eventually sorted it out with the download of an older driver for my Prolific based device.

Using the u-center software I was able to fix the configuration of my NEO-6M and it was able to get a lock on the satellites. I'm getting more comfortable with using the u-center software. It doesn't have much built-in documentation so it takes a bit of experimenting with it to make sense of its user interface. I started some preliminary tests on the 7M and M8N modules. Both came with a power indicator LED that is on all the time. I'll have to disable that it to avoid wasting power to light an LED that won't be seen in normal use.

I performed some initial checks on the position data from the 7M and 8MN modules. Both units show variations in the position with the M8N typically showing less variation. It also was tracking 12 satellites where the other modules I have were only tracking 6. It will take a few days for me to run further tests and evaluations of the three modules I have. I will be looking at the amount of variation in position reports, checking how one of the configuration options affects the amount of variation, and also checking on the amount of current needed to power these modules. I will also be spending some time reading the hardware integration manual and the protocol specification for these GPS receiver modules.