Well, Joe, I personally have wrangled with such questions in life. It's nearly a philosophical question. I used to ask my dad, "If you push the gas all the way, and the brakes all the way, which one will win?". To which, he used to laugh, and say, well, it all depends on the condition of the repair, of the engine, or brakes at any given time! It was an old '57 Ford Panel truck....
So, I have played with the above equation, and have developed some ideas.... nothing for sure, but some ideas.
In super challenging places, generally, I think RTK is MORE reliable. But, there have to be exceptions.
So, I have thought about it. Why not use a total station, (Based on long PPK solutions) to get the "real coordinate", and then sit on it all day, and then ppk it, and then look at all the data.....
This is what I sort of think.....
USE the rtk shots alone, and AVG them. And, it will give you one position.
USE PPK alone, and AVG them, and it will give you another.
I think the 2 above observations, (avg derived from RTK, and AVG derived from PPK) that there will be LARGER coordinate piles from PPK, than from RTK.
Meaning this. LARGER scatter, from PPK, than from RTK.
For instance, I did 3 PPK shots some months ago. 2 agreed real well, and another was some 0.2' away. RTK was NOT available there.
So, here is my condensed thoughts.
PPK requires approximately 1.3 to 1.5x time (Time = data) for the same quality of solution, as RTK.
So, IF you allow extra time, average BOTH solutions (RTK, and PPK) into their own piles, they will eventually become the same coord, position, (+ - 0.015')
Averaging RTK solutions, will give you screen shots, (how big the pile is), but, PPK does not give this...
So, IF I had 5 RTK shots, that took 4 hrs, and piggy backed onto this, 5 ppk shots, over the same time period, I'd feel that the PPK shots were weaker, by some magnitude of 1.33 for a multiplier.
OR you could say it this way. IF a RTK shot takes 15 minutes, to get a shot, that looks pretty good, then it would take a 20 minute PPK shot, to get the same quality.
This is based upon my thoroughly non scientific, experience.
Having said that... I have wished for a mechanism to slightly weight the RTK shots, with a PPK leaning.... But, I am not sure how this would work out.
Thanks for bringing this discussion up. It would be fun to have MORE data to analyze this question. But, it is on my mind....
Hey, ain't it great to be fussing about a few hunnerts? This whole conversation could not occur, with any other species of GPS....
N
PS, I'm NOT an expert... I am a man who suffers from curiosity...