One Dual Freq+Four Single Freq=OPUS+5 Single Freq?
Posted By John Burr on 6/8/2002 at 3:27 PM

So if get a single Dual Frequency rec like a z-EXTREME and use it to observe on a site basepoint, later to be processed by OPUS. That rec would still be processable, (not sure if that's a real word), inside AS2.5 as one of say 5 L1 recievers?

Way cool if I understand it right. For a morning session, (here in Central Florida), I would typically occupy a central control site with the dual freq for entire morning and just move the other 4 units around to the various section corners I need tied, three moves and I have everything tied into our County Control and the OPUS point.

How can I expect the OPUS stuff to hit with our NAD83 pre 89 County Control Monuments.


Re: One Dual Freq+Four Single Freq=OPUS+5 Single Freq?
Posted By Phil athome on 6/8/2002 at 5:12 PM

That sounds like an excellent science project to me. To get an idea find a NGS data sheet for a point that has the superceded coordinates. Do a conversion with NADCON, Corpscon, or some commercial software and compare the results with the data sheet.

The good news is that the conversions between NAD83(1986) and NAD83(CORS) are a closer approximation of the truth than those conversions to NAD27.

Maybe it's time to push the county toward a new survey and adjustment to the latest iteration of NAD83.

Perhaps you could show them how effectively you could contract with them to do the work.

One other suggestion is to put new coordinates on enough of the old points so that you can come up with your own conversion. That way any time you use OPUS you just do a move, rotate, and scale to make your project match the old county control. At the same time you have information that will let you take the same project into the future when the county is ready to go there.



Re: One Dual Freq+Four Single Freq=OPUS+5 Single Freq?
Posted By John Burr on 6/8/2002 at 9:39 PM

I like it, I don't have to count on the County's work, I can get it right and just tell them where I found their monuments. What a concept.

As usual Phil, you have the insight and the foresight.

Thanks for the info.


University of HK
Posted By Phil athome on 6/9/2002 at 8:07 AM

It mostly comes from banging my toe and stubbing my head.

If you do things wrong enough times you start looking for ways to avoid that hot wire fence.

Just remember to keep making those check ties to the survey monuments. OPUS is a great tool. It is not the only tool.