Cadastral Expert Improves Business with Low-Cost GPS

Alessandro Prudenzi, an architect by training, Prudenzi performs appraisals and verifications of local real estate property and technical consulting to the Court of Brescia. Because land survey is just one aspect of his multi-faceted practice, and since GPS has been cost prohibitive, Prudenzi had until recently relied solely on a total station for land survey work, He knows, though, that there's no one tool for every job; in difficult terrain, GPS would be a better solution.  

He carefully researching available information and spoke with many people before he found Giorgio Viaggi, of Guido Veronesi SRL, who came up with an excellent solution for his needs.

Viaggi recommended that Prudenzi test a new high performance single-frequency RTK receiver, the L1, ProMark 3 RTK. He conducted many tests in his backyard on different days and found the unit consistently outperformed the manufacturers own published accuracy standards. For example, he says, "In static mode using a free reference local network, Leica SpiderNET, with its reference stations from 90km to 130km distant, the same points showed a variation from 0.02 to 0.04 m, against a predictable and acceptable published datum of 0.095 to 0.125 m (0.005m + 1ppm).  The true values are decidedly better than those expected."

Prudenzi also likes that he is able to simultaneously collect raw data during RTK sessions.  When I'm in RTK mode, I now always collect for 15 seconds on every point to gather the raw data that later allows me to easily reduce my error down to 0.001 to 0.003m. In this way, I get a level of accuracy the equal of instruments costing more than twice as much." He adds, "It is very simple to both record data in RTK mode together with raw data. The raw data is then easily used in the GNSS solutions software to achieve millimeter level accuracy.

Prudenzi notes that many surveyor, to hold costs down, will purchase only a rover and use differential corrections broadcast from nets in their area. The problem is that in too many areas differential corrections are not available and even when they are, the virtual reference station will sometimes be some distance away.  A virtual station 4 km distant, he points out, will have an error of almost 4 mm.  But with the ProMark3 RTK, which includes a base station and rover, I collect in RTK using the base station and simultaneously collect raw data.  In this way I can achieve a precision up to ten times better than the rover only with differential corrections."

Business performance

Alessandro always uses his GPS in difficult physical conditions.  In these conditions a job that would take two days with a total station takes but a couple of hours with the ProMark3 RTK.  Even though the ProMark3 RTK is half the cost of competitive brands offering similar results, its accuracy is so impressive that Prudenzi now uses the unit for almost half his land survey jobs.