I bet you think that just because you have GLONASS you will ALWAYS be able to survey.
Not so fast! Check out this constellation from Salt Lake City at 1:35 pm 22 Jan 2014:
Yes, that is 3 US SV’s above 30 degrees and
4 GLONASS SV’s above 30 degrees.
Surprisingly the HDOP = 0.68, VDOP = 1.38 and GDOP 1.93. Without tracking GLONASS, I don’t know how much RTK work we could get done right now.
I guess the take-away is “Don’t think you never need to mission plan, even if you have GLONASS. I can’t fix in the parking lot with a 2-meter pole, but with a 15′ pole: