F1 use of GPS based reference lap

At Silverstone's Qualifying there was variable wet weather for the three qualifying sessions. After qualifying a few drivers were unhappy that they did not have a valid reference time for the conditions that prevalent during the 3rd, final session. It was much wetter in the last session than the first session where/when the fastest times were set.

For me it is interesting that the use of GPS based reference lap times and deltas is important enough for F1 drivers to talk/complain about. I assume they are using a system that updates the delta anywhere or any time during during a given lap.

Brian