Top 3 Mistakes When Gathering GPS

It will save you a lot of time and money if the surveyors are well trained as compared to re-gather the points. Surveyors are usually interested in this technology and willing to learn. Thus, better to supply information as much as possible while the attentions are still there. Take note to use simple terms when explaining how the GPS works.

Top 3 mistakes that are common in gathering GPS because the instructor misses to orient surveyors about these details:

1. Stand to close to the property / unit of interest.

During the field gathering, surveyors tend to find shadow to avoid hot sunlight. They will stand close to the property to get shadow. The surveyors forget that by standing too close to the property, most satellite signals are also blocked from one direction. Thus, the GPS coordinates obtained are not as accurate as needed because the satellites detected is coming only from other side of direction (one sided). Standing back a little bit can greatly improve the accuracy.

2. Ignoring PDOP Value.

Some data gathering application is only showing number of satellites to warn surveyor if they have enough satellite to gather correct GPS. As a rule of thumb, the device needs more than 4 satellites to gather accurate GPS. However, number of satellites alone is not enough! There are many satellites out there giving a weak signal, thus, deceiving the device in giving correct GPS coordinates. Another measure to warn surveyors to gather accurate GPS is by displaying PDOP in your application.

What is PDOP?

3. Not Paying Attention on Stuck Application!

Even if the data gathering application have been displaying PDOP, you can never avoid that the application is stuck due to some reasons. Usually this happens because of application problem or communication problem between GPS port and the application. This means that the application keeps on displaying the same PDOP and GPS coordinates even tough the surveyors have moved. The solution is simple. Just restart the application or GPS port. However, this detail is commonly missed by surveyors because they did not pay attention whether the long digits GPS coordinates is moved. One solution to handle this is by placing a map in your application. This way, surveyor will notice it easily if the point is not moved from the map. However, if this complicates your application, simple create a simple algorithm to measure the distance of previously saved points to the current point. The surveyor can notice if the distance showing is still 0. It means that the application is stuck.

PDOP definition is obtained from "EPA publication GIS Technical Memorandum 3: Global Positioning Systems Technology and its Applications in Environmental Programs (EPA/600/R-92/036, February 1992), GPS: A Guide to the Next Utility by Jeff Hurn(1989), and CGRER staff."