We see that certain periods of the year at certain times of the day have low satellites. Usually this is a temporary condition and corrects after 10-20 minutes. There needs to be at least five satellites used in the vertical solution to achieve good accuracy. Other conditions known to affect GPS accuracy are related to space weather, high solar flare activity, bad base correction, hardware failures, or untrained users. Typically, RTK GPS is still better than lasers for minimizing drainage down time. We also like to see that the RTK Base is located within two miles of the RTK GPS Rover. This assures better quality data.