Cold front blew through this morning while topoing fill. Strong cold wind swept over the project so much that while trying to hold the rod upright also ?ÿhad to keep one hand on my cap to keep it from blowing away. When I got situated I looked down at the tsc3 screen to see that my error estimates had changed from a 0.03'-0.04'H ?ÿ& 0.06'-0.07'V had changed to a 0.20'H ?ÿ& 0.30'V. ?ÿWide open area and horizon at the site. ?ÿIt corrected itself within about ten minutes, but I had never seen this before and wondered if there was an explanation for this.
I could guess that either; I had two separate atmospheres at the time - sort of like a thermocline - or, the antenna hardware took a minute to adjust to the temperature change. ?ÿNo clue here
The weather change most likely included, pressure, temperature and humidity changes all of which affect the speed of light. The pressure change also would indicate changes in the depth of the atmosphere. Those 4 factors in changing the speed of light and the distance through which that speed change was relevant would require your receiver to recalculate the differences between the L1 and L2 signals.
Consider the math 0.30' vertical divided by the 20,000,000 meters traveled by a signal from a satellite directly overhead is only 1 part in 2,000,000,000.
In reality the change occurred over the time the atmosphere changed from a 30?ø mask from West to East, typical weather movement.
Paul in PA
What Paul said.?ÿ You don't want to try to do precise work between the times a front passes the base and the rover, or shortly thereafter.