I have been going crazy trying to determine which GPS unit is best for my needs and pocket book. I do mainly boundary work and topo, and create tracts and lots, which I can do with a TS and data collector from control points established with the PM3's. Have pretty much narrowed it down to ProMark 3. Can't afford RTK right now and believe the PM3's are the best units for the buck, and can be upgraded at a later date. Do you PM3 users agree or disagree with my opinion? Also, are the PM3's good for location work in stop and go Kinematic situations, like centerline of road, lakes, ponds, etc? Thanks for all input.....forgot to mention, I am totally solo....
Modified By ron berry on 2/1/2008 at 1:51 PM

I own a pair of PM3's, a single PM2 and a pair of HiPer XT's with L1/L2 RTK UHF radios and cell modem.

The PM3's are good start. But to tell you the truth, after having RTK and Dual freq. I rarley use my PM3's. Unless you decide to upgrade the PM3's to short range RTK, then you'd be better off finding a pair of used PM2's for much less than what you'll pay for PM3's.

I use mine only for large control networks when clients like NYSDOT requires network closures. Otherwise I can get acceptable results with RTK in much less time. The PM's don't NOT work well near any canopy. It requires constant open sky. I'm not sure how much open sky is in Kentucky. Best thing to do is consult with a neighboring survey with GPS on one of your projects. Have the dealer give you a demo, and even rent it.
Modified By Lee Green on 2/1/2008 at 2:44 PM

PM3 is exccelent under canopy, but you have to follow the procedures.
Do not need a dual frecuency for a shorter distances. L1/L2 is cost x 3, heavy units and in a short distances does not help too much.

Ron,

You have not described your pocket book.

If it is truly minimal look at acquiring used PM2s.

Better if you can afford it is a pair of PM3s, maybe adding a used PM2 or two. You can do static work with 2 receivers. but 3 or more receivers is much more effective. Having experience with these simple L1 receivers you can decide on your next step down the road. 1/ Upgrade the PM3s to RTK

2/ Buy a low priced L2 receiver for OPUS OPUS-RS control points continuing with L1 static with your L2 as an extra receiver

3/ Buy that L2 base as well as upgrade the PM3s to RTK.

4/ Wait till next week when the details and price of the newest Magellan L2 unit is available and the advice may be different

So then, what budget are we working with?

I own 3 PM2s and 3 older Z-12 L2 units. Most of my work can be done with a mix of 3 units. I will join up with another surveyor who has 4 PM2s and hit two of his projects hard in one day next week.

Paul in PA

Marcos said

"PM3 is exccelent under canopy, but you have to follow the procedures."

I beg to differ. PM3's give float and partial solutions under canopy. Nothing I can hang my hat on or use for surveying. L1/L2 will yield fix every time with 1 to 2 occupations under deciduous canopy.

Lee
Modified By Lee Green on 2/1/2008 at 3:52 PM

Thanks for the input...Budget is loooowwwwwwww, unless work picks up,can always get a business loan or equity loan, also thought of leasing from Hayes...have also looked at PM2's and even Epoch 10 (SpectraPrecision). A lot of my work is in wooded and hilly terrain, but there is always a clear spot or two for GPS control, also being licensed and from Florida, I could end up back there in the flat lands....

I have used the PM3's in questionable areas(not a "true" canopy), with good, verifiable(verified), results.

I never trusted the results well enough not to verify the results, so I never really gained much benefit from doing it . . . but, it was fun.

I am probably going to give up my pm2's and they will work static, kinematic, stop and go, same as a basic pm3, then you can add one pm3 as budjet allows and get the map stuff also. You can get near thin sticks and get solutions, but if they're thick at all or have leaves on them (only good times are from very late fall to early spring) the solutions are not reliable, even with some higher powered stuff - near the trees may work - in the trees only works on very rare occasions, and you can't tell when.

Even if you go another route, pm2's are a giant leap ahead of none at all.

Ken

I got my PM2s from Hayes. They have a good training vid that comes with them. You might consider posting on the main board for any one that has used ones for sale. You might even be able to set up a payment deal. There's a lot of them just setting on shelves.
Great in the wide open. Gamble with a tree around.