I spent some time today working with my new Geosteer on my tractor, and just happened to be looking at the GPS diagnostics screen when it dropped down to 4 available satellites and the PDOP shot to 50! For those of you that aren’t familiar with these numbers, we try to have no less than 5 satellites for steering, and would like to see the PDOP (Positional Dilution of Precision) at or below 5. Our team here at HTS Ag also started taking several calls at the same time with customers having problems with their systems not getting signal. This got me thinking about what I could do to make the system perform better, and Glonass came to mind. I started looking at some planning software to see how much of a difference it would make to add Glonass (for those that don’t know, this is the Russian satellite system) and was quite surprised at the difference of adding the Glonass satellites. Below are some graphs of with and without the Russian satellites, I’ll let you decide.
Here is the available GPS satellites for today in Council Bluffs, IA.
Here is the same location and time, but with adding the Glonass satellites
Keep in mind both of these graphs are assuming good visibility. In my case, my tractor was in the house yard today with some trees around, so it made things even worse.
Here is a graph of the DOPS from today as well, with GPS only.
And here is the graph of DOPS with adding Glonass. Notice the scale on the left side is different.
So, by adding Glonass to a receiver today, you would have kept your DOP below 4 the entire day. Without it, it would have jumped above 10 more than once this afternoon, which means you wouldn’t have very good accuracy, if your auto steer even works!
Several of the new receivers can be unlocked to receive Glonass without any hardware upgrades – it is usually as simple as adding an unlock code. Given the late planting season and limited window to operate in, this seems like a very good investment to me.