Starting from scratch with GPS. How?

GPS. It's where Flat earth land surveying meets a round planet.

Sure, you could get a low grade unit. But, Why not get a survey grade unit? You can do more with it. And, if you are going to bite the bullet, and get in, well, pay a little more, learn a little more, and enjoy a little more.

N

I only have extensive experience with Leica equipment. Might want to look into the Zeno 10 or 15. It is fully upgradable to survey grade. If you plan to use rtk you might want to check and see what networks are available or else you may find yourself needing a base unit which would add to the cost. I'm fairly sure other brands of equipment can be upgraded in a similar way.

> ...I'd like to have GNSS capability without spending for survey grade equipment. I'm thinking 10-50cm accuracy would be more than enough for most of my needs, even a meter (horizontally) would be good most of the time....
You should talk to your friendly neighborhood equipment dealer about GIS equipment for that sort of error limit. Post processed against CORS will yield that.

Who Is Buying?

I would suggest get a pair of used Ashtech ProMark 2s. Single frequency and probably less expensive than mapping grade GIS, Using COR you can meet your reasonable precision but process it from project point to project point and you can match your total station precision.

Paul in PA

> Any recommendations? Suggestions?

It sounds to me as if I'd want 1-L1/L2 receiver and one other receiver, either L1-only or L1/L2 with stop-and-go capabililty.

With the L1/L2 receiver, you have access to NAD83 via OPUS. With the other receiver, you can survey short (<6 miles) vectors while the base is ginning away. If in fact you only need sub-meter positions, those are easily gotten via multiple options.

You need post-processing software and, most importantly, you need Star*Net.

Star*Net is the sort of general all-purpose utility software that can be used to combine conventional survey measurements with GPS vectors as well as just to compute coordinates from the GPS vectors, if that's all you really want.

>With the other receiver, you can survey short (<6 miles) vectors while the base is ginning away.

Can I ask in your experience why you limit the L1 receiver to 6 miles? Do you think it is capable of longer baselines up to 20km?

I did an L1 observation for 30 miles. All night. It had high residuals, and I think I wound up feeling that I got it within 0.25'. It fails to model the atmospheric conditions.

Think of a tape between all the sats, and the 2 receivers, at the same time, and think of a different weather, at both sites, and thus think of crooked tapes to one, that do not exist at the other.

N

> Can I ask in your experience why you limit the L1 receiver to 6 miles? Do you think it is capable of longer baselines up to 20km?

The 6-mile limit wouldn't apply to submeter mapping-grade solutions, but in my experience, a surveyor can expect much higher quality survey-grade L1 solutions if vector length is below 6 miles. If a surveyor has an L1/L2 receiver to connect to NAD83 via OPUS, it works much better to just move the base to shorten vector lengths.

The alternate scheme would be to have two or more L1 receivers, one that can be parked to log a long session on some control point more than 6 miles from the L1/L2 base and used as a secondary base for surveying shorter vectors from it. That works also.

It seems most of the replies you have received are pushing what you weren't asking for. GIS grade makes sense but the software generally is very poorly suited to survey tasks. You asked for 10-50 cm accuracy. Post process dual frequency is a poor choice for the task. But you should by all means listen to those who know what you really need (sarcasm).

I would suggest that you call my good friend Mark Silver at iGage and ask about the ashtech promark 120 with either Carlson Fast software or survey pro (whichever you are more comfortable). This way you get the accuracy you desire in real time with software written for a surveyor.

Since no one read your email thoroughly, I'd suggest a Trimble Geo7X or Pro6H for your needs.

The Geo7X is an all-in-one (controller, receiver/antenna, camera, range finder) handheld solution with sub-meter accuracy. You can get an external antenna to mount on a rod to get survey grade results as needed through post-processing.
http://www.trimble.com/mappingGIS/geo-7-series.aspx

The Pro6H is a receiver that mounts on a pole or back pack, but requires a discrete controller.
http://www.trimble.com/mappingGIS/pro6.aspx

Feel free to shoot me an email (under my profile) and I can walk you through this. I've helped many GNSS newbies in the past.

I'm new to this site, but I have 7 promark 2s that I would let loose of. Sounds like they might fit the bill if your looking for a low entry cost. Just tell me the best way to get in touch with you through this site to talk money.

If you don't want survey grade...use your smart phone. Other day was searching for a control monument, was called out as being on CL of a levee but didn't know where along levee. Had lat/long, typed numbers into search bar of iphone map app and asked for walking directions. Mon was right there where phone said, I was impressed.

> If you don't want survey grade...use your smart phone. Other day was searching for a control monument, was called out as being on CL of a levee but didn't know where along levee. Had lat/long, typed numbers into search bar of iphone map app and asked for walking directions. Mon was right there where phone said, I was impressed.

you're fortunate.