Some people eat, sleep and chew gum, I do genealogy and write...

Thursday, February 3, 2011

Genealogist's View -- The ABCs of GPS Part One

One of the miracles of modern electronic technology is the Global Positioning System (GPS). This serendipitous product of the space program, first fully deployed in 1993, enables anyone to accurately determine their exact position on the surface of the earth to within a few feet. Originally designed to serve the Military, the GPS uses from 24 to 32 active satellites that can send signals to an earth based receiver. Using, at least, three satellites, the GPS software in the receiver calculates the receiver's position by comparing the discrete travel times of the signals sent by the different satellites.  However, with the present configuration of satellites, about eight satellites are visible from any point on the earth at any one time. This technology has advanced to the extent that the receivers can be incorporated into a cell phone. I discussed some of the uses of GPS technology in a previous post called "Finding your way -- GPS for genealogists."

Besides the obvious uses of GPS devices for route finding and locating services, genealogists can use the technology for other useful purposes. These include geocoding or geotagging, mapping, identifying landmarks and related functions. GPS receivers either are sold for outdoor off-road use or for use in the city on roads. If you are interested in buying one, you have to decide if you are going to use the device for city street driving or out in the countryside. If you think you need both functions, you may have to purchase two different receivers.

Before we go much further, let me cover some of the basic terminology. First of all, the GPS receiver.

GPS receivers come in an ever increasing variety of shapes and sizes. The receiver is usually a small device with a screen and some buttons. The more expensive devices have touch screens, so there may be only an on/off button externally. As I already mentioned, they can also be integrated into other devices like cell phones or cars, boats, airplanes, cameras and any other movable object. Commonly, there are essentially three types of GPS receivers that you would normally find for sale online or at a local store. They are:

Basic GPS Systems: These basic units are sold primarily for hikers, hunters, farmers and others who need directions in the outdoors. These inexpensive units do not come with maps and will simply give you your location in latitude and longitude coordinates and will record your trip log with speed, heading and bearing information. Depending on the model (and the cost) these units may or may not transfer your trip information to a computer.

Map Enabled GPS Systems: These units can be loaded or come preloaded with topographical maps. They have the same primary outdoor uses as the basic systems, but are usually more expensive. Some of the higher end receivers have lifetime map upgrades. These units commonly have either a computer software component or an online connection or both. Some of the programs that are available will plot your data directly from the hand held receiver to a computer based map.

Vehicle Based GPS Systems: These receivers are designed for use in a vehicle. They usually come pre-loaded with street maps as opposed to topographical maps and have many of the functions of a computer. Some of the more expensive models will connect to the Internet and display current traffic conditions and the location and identity of surrounding businesses. Some of the more expensive vehicle based receivers will also work out of the vehicle. Once again, these units may or may not interface with your desktop computer depending on the model and the software and allow you to save your locations and maps.

If you look at  the product specifications for GPS receivers, you will see a lot of technical terms. However, most of the manufacturers are adding features that really have nothing to do with maps and route finding such as Bluetooth wireless, a way to connect with cell phones and other devices. For example, one manufacturer advertises that you can use your GPS as a wireless cellphone speaker. The manufacturers are even advertising their devices to play video movies and to interact with the Internet and contain hunting and fishing calendars.

Route finding and locating buildings or cemeteries is a common activity and also something you may have to do as a genealogist. But some of the functions of GPS devices are more suited to research trips than others. For example, one of the most useful functions of a GPS unit is to accurate locate cemeteries and grave markers. In the past, you might have to consult topographical maps of the area and rely on map navigation, a skill that requires a great deal of training and experience. GPS units have highly simplified this process.

There are many ways the GPS units can assist in locating a gravemarker. If you happen to have directions or an approximate location, you can use the GPS to guide you to your destination. On the other hand, if you have only a general idea that a grave is located in any particular area, you may have to use your other finding skills to locate the grave, but can then take a reading from your GPS device to record the exact location, so that you or others who are trying to find the gravemarker in the future can do so without having to go through the same process.

I can remember one instance of grave hunting before we had GPS technology, where the trees and brush were so thick that we could not see more than a few feet ahead. We made several attempts to push our way through the undergrowth without finding anything that looked like a cemetery or gravemarkers. We finally asked people in the area and were able to spot a sign marker on a tree and located the graves, but with a GPS our task would have been much simpler and more direct (assuming someone had the correct location).

Once you get to the location, you can take pictures. Some cameras have built-in GPS capabilities. The iPhone camera will automatically attach the location information to a photo in the form of the latitude and longitude. Some genealogy programs like Legacy Family Tree and RootsMagic provide a way to attach the location information directly to an event or photograph.

Watch for Part Two of this series.


  1. After my GPS tried to send me on some primitive roads in rural PA I decided the next best thing was a road map published by AAA. My daughter told me to keep going, and I said "If the road is made of dirt it is best to turn around and reevaluate."
    Besides. I love maps.

  2. I have GPS connected to Google maps built into my phone, so I can see a satellite photo of where I am. Using this, I have been able to photograph several tracts of land pioneered by my ancestors.