Did some stop and go shots on stakes set for B/C last week. Reshot today using same control point for base and there is 0.2 difference.....I now wonder if I can need to ditch the PM-2's and use conventional for this project. Don't intend to buy any concrete as this is a donation to our church job...not for pay...

Is this 0.20 to be expected or should I be getting closer data???

Hey Frank,
Depending, I'd say 0.2' is about the worst I'd expect, but it is a possibility. I'd expect more in the range of 0.10'-0.12' vertical (horizontal at about 0.03-0.07). I don't know what you're looking at doing for your church, but if you need much tighter than a 0.10', S&G probably isn't for the job.

jsb

Just as a side, static is a lot closer, but S&G gets a little more rough.

Will be putting them back on the shelf. THey just cost me a bunch of time.

So much for accuracy and repeatability.
SOmewhere I read that htey were better than
this.

I can't handle 1-1/2" variations.

Can do it much faster conventionally than static...

Have to re do nearly a 10 points to make sure everything is right....this donation just got very expensive....thanks PM-2's....
Modified By Frank Morski on 5/30/2006 at 7:17 AM

I have often got slightly better verticals than horizontals on the PM2's in S&G.

0.2 feet off is more than I've ever had.

That being said, I've been somewhat dis-satisfied with GPS in the afternoon lately(about 2 or 3pm to 7pm).

The afternoon would be a little nicer with PRN 25 turned back on. But if you cannot live with a 7 satellite minimum you are spoiled. What I see from Mission Planning is that it is a good idea to quit working at 5PM and go have dinner. The PDOP spike, 1 hour, is not unbearable and if I had work to be done and was still in the field I would just work through it. That is what mission planning is all about. It is not a great time for S&G but there is also static work to be done. If you go out in the field and don't know when to plan longer sessions you are cheating yourself.

Frank?

I don't recall a lot of comments on vertical results with S&G, but static L1 is 0.02', every day.

BTW L1 S&G is for design work. L2 RTK is needed for stakeout. If I had L2 RTK I would still use conventional stakeout, plus steel tape and a level for checks.

Paul in PA

No LPL seven(as in "7"), would've been great.

No . . . realistically, I think there were 7 sats, but they had terrible locations for my needs of that particuular day.

In the past, running after 4 or 5, I used to get 8-10(full compliment). With a full compliment, all I have to worry about is getting the best sky for the best PDOP.

In the open field(aways away from EVERYTHING), I did get 7. BUT, I expected more for a late afternoon sky.

I just got on-line, just now, to download the latest almanac. I guess I won't be complacent for a while.

BTW LPL, I was on site for 3 hours.

PRN is unusable until further notice. Down about 2 weeks now. It has been down for previous short stints. It is probably getting ready to die. They leave them rest as long as possible until the Air Force may really need it. Then they turn it on for some final glory. I wouldn't count on it for any future work. It does not help PDOP much anymore so I would assume some reopsitioning has filled in the gap.

Start earlier in the day. By August 15 the PDOP spike will be at noon, but a lot more little spikes to PDOP 3 are occurring all afternoon. For static work I see no problem in a 3.

WHOOPS, worst than I thought. I haven't used planning lately, I had downloaded a new almanac but I forgot to check my other settings. My cutoff angle was at 10 not my usual 15. Sad looking sky, 2 PDOP 5+ peaks during a normal working day plus a 4+ for that 5-6PM time.



Paul in PA
Modified By Lawrence Paul Lopresti on 5/30/2006 at 11:23 AM

Ran a level loop and compared to S & G. Most were within 0.01 to 0.03. Had two that were within 5 feet of each other and 0.01 differnece in true elevation bt PM-2's said they were 0.19 in difference.
Occupied each for 30 sec. with pole tripoded.
That is what caused me to not trust the entire session.

Turns out the remianing 40 shots were very close.

Bad part is that you have no way of knowing if something like this happens. Keeps my distrust level up.

Don't have any trouble with horizontal...Can get very good results constantly. High repeatability...only error is bubble on pole...

I can't stand working after 2pm or so. by then I'm ready to go home, download and process. even then I'm doing office work until 5 or 6 pm.

We start very early especially in summer, cooler, quieter, less cars on the road, so on and so forth.

I like to finish by 10:30 to noon if I can.

working that late would get in the way of my afternoon Murphy's draught :-)
Modified By David Karoly on 5/30/2006 at 2:34 PM