I have a 3 Locus Receiver System and my survey usually cover several square miles in open, and level country, with few obstructions. My method of static control usually rotates around a primary control point with 20-30 mins on lines <5k with 10 sec recording interval. (Normally the first green light flashing) Secondary points or Corner ties are leaped frogged with the other 2 units most of the time secondary lines between these point 10min of data pass the quality test. This yields a new point every 20 to 25 mins. and a braced figure with good reduncy. Is this a good method of operation for a single operator? Also I try to tie to a class "B" station at a near by airport. Please let me know if you have had simular experiences.

Stan,

When I have the "luxury" of using 3 receivers here is what I do most times.
Set up 2 receivers as the "bases" and move 1 around. Now, first off I will observe the vector between the bases, then shut one down, change the heighth and start again. After seeing it is going to lock, I then jump in Subaru and hit the other points with the 3rd receiver. Usually I will hit these twice just like changing the heighth of the 1 base.
After hitting them all for the day, I then go back and change the heighth of the 1 base that I did not change, and observe the base-base vector as a single one.
Now, in the processing, they all get processed, BUT, I exclude the vector between the bases while I was off roaming about with the 3rd one. (admittedly, I have fallen for the "trivial vector" argument)
But what I wind up with is 3 repeat vectors between the bases, and 2 vectors from each base to the other points that were blessed by my presence (and the Subaru).
Then say on another day you can use the pair of receivers to fill in between the points you roamed to. Additionally, I work in SPC and tie many horizontal and vertical control points in the network. Then you have a data base to work from.

Dave

I see what you said, But many times we try to finish in one day and can not go back to measure between the rovered points the next day. Since the two rovers are running at the same time I get a line between each rover (approximate 10 min) 10 min to move rover and 10 min to next rover site. This has increase my productivity to approximate 2 new point per hour with good PDOP. What have i sacrificed ?

Stan,

The argument goes that for example,in a 3 receiver session where the data is from the same satellite geometry/time frame, that 2 of the vectors will be "independent" and the third, doesn't matter which of the 3 vectors, will be "dependent" on the other 2. In other words, what the believers of the "trivial vector gang" are saying is that the third vector is merely an inverse.
At first I had a hard time understanding this. Seems like all the vectors would be "independent". As an example, I proposed to the State NGS advisor that it would be like using a total station to perform a traverse, then not closing it but rather using the inverse for the last leg. Of course we now this doesn't work in conventional surveying.
But then again the NGS has their guidelines and some may make the remark that they can "afford to do it that way". But in the end they are the ones that are providing us with the control and that and small airports are worth my tax dollars!
I've only been using Locus for about 15 months now, as my first GPS experience. I make it a point to attend seminars and learn everything I can. Probably if I had any remark to make about the quality control it would include redundency, at least 4 vertical control points and at least 3 horizontal control points; a constrained adjustment that passes the chi square test and no vectors failing the tau test.
For what it is worth, my observation times are on the order of the "next" green light past the vector length + 2 minutes. Any kind of tight spots or tree limbs nearby and I go full solid + 5 minutes.
I've got another firm that uses the yellow brand RTK calling me and asking "what have you got for XXXXX" on a routine basis. They have been performing RTK stuff for about the past 4 years or so and until just the other day the word "multipath" was not in their vocabulary. THAT is scary!
Thanks to Bill Martin and Ashtech for the support and use of this board. A "ziggi zokki ziggi zokki hoy hoy hoy" to you guys.

Dave thanks for the reply. I am going to consider your reply and do some testing. Have some other quiestions reguarding GPS I will post the later. Again Thank you for your input and good luck to you! Stan

I have question on trivial baselines. How do you determine which line is the trivial baseline. If its the longest line, I believe that I have hear that at one time. If so, If you use 2 base units, dont you have to watch your geometical structure to remove the base to base line as the long/triavial baseline, so that the base to rover lines can be used in the solution.

Stan,

Redundency is the key word. We can measure it once no problem, but like I tell the RTK guys "can you hit the same point twice?"
When I use the 2 base setup and rove with the third, I usually solve the base-base vector first as a single one. Then it gets solved again, with many many epochs of data as I rove with the third. When I am done with the roving, one of the base units gets shut down and the heighth changed, and the base-base vector is measured again.
Now, after the all get processed I toss one of the vectors out. I have redundency between the bases in the order of 3 repeat vectors. 2 with minimal data and one with lots of data. I can exclude the base-base vector that had a lot of data while I was roving and take the two vectors, 1 from each point to the roved position(s). Since I hit each roved point twice with a different heigth setup, I have redundency there. I could leave in the long base-base session, and exclude one of the base-rover vectors per session.
I have also heard mention of excluding the longest vector, but have not seen that as a "rule". I don't think it really matters which one you exclude, just as long as you do it.
We discussed the "trivial vector" practice a few months ago here, I don't know if you can go back that far and see what the general concensus of others were. But it is a topic that comes up frequently and I hope others will join in and give us some more insight.
Best Regards,
Dave