by JOSEPH V.R.PAIVA, PH.D., P.S., P.E.
Wireless technologies are becoming so ubiquitous in our everyday world that we sometimes forget that they are there working for us. While not quite ubiquitous in geomatics applications, it is possible to foresee it. Last month I discussed the radio link between the base station and the rover to enable real time kinematic (RTK) GPS or differential GPS used by surveyors and mapping professionals. Radios also are used to facilitate total stations in "robotic" mode. Although the total station can follow a prism, a radio link is required to trigger the measurement and then to pass the measured data to the data collector at the prism pole end, if the surveyor desires to operate the total station with no additional person at the instrument and with the ability to review the data that has been collected and to display it in tabular or graphical form.
Bluetooth has improved functionality of field systems by making them smaller, lighter, more streamlined, more reliable, and of course, much less frustrating by eliminating the birds nest of cables that some field systems previously required. For example, the power cable connecting a GPS receiver to its power supply has been eliminated by reducing the power requirements of the receiver so that a lightweight battery can be integrated into the receiver. And the antenna cable is eliminated by integrating the antenna with the receiver. The integrated package is so light that it can be perched at the top of a range pole without serious issues of balance and stability.
The next wireless technology trend in GPS is the use of cell phones or cell phone modems that can either send or receive data files. This replaces the cable that connects one computing device to another distant one. Or even better, it makes all the components that need to connect to each other IP addresses so that matters of accessing databases and downloading or uploading files containing text, graphics, still images, video, and sound are as easily done using some type of browser.
While the early cell phone connections used first analog and then digital connections that were designed for voice services, the recent (and ongoing) modernization of the wireless phone network in the United States has seen plummeting "air time" rates per megabyte for data transfer using GPRS and GSM technology.
While only considered as the last resort to enable RTK GPS, these newer technologies are gradually picking up even the everyday user. This is particularly true in congested areas, where narrow band solutions for RTK GPS telemetry add to the already overloaded available channels, and in networked RTK base station configurations where the distance from the base station far exceeds the distances commonly seen with user-setup or maintained base stations.
If GPRS and GSM is used only temporarily or occasionally, it is not uncommon for surveyors to use their own cell phone's ability to access the internet and, using Bluetooth, to link that connection directly to a GPS rover, total station, data collector, or field computer.
In the case of construction, machine automation systems facilitate faster and more efficient earthmoving by using RTK GPS or robotic total station technology to guide the cutting edge of the construction machine by referring to the on-board digital terrain model for the design and existing ground surfaces. While the early machines required a person to load data individually into each machine by physically connecting a computer and transferring the file to the machine, or by installing a pre-loaded PC card in the machine, radio systems are being developed, usually in a network fashion, to send data to each machine from a central (and possibly remote) location. In some cases, this same system can be used to send the GPS receiver on board each machine.
Not to be overlooked are the wi-fi networks and hot spots that are being installed on outdoor sites, similar to the way entire buildings, neighborhoods and towns are being made inter-accessible through wireless technology. While most people are familiar with such wireless connectivity in an office, home, or public building such as an airport, it is also possible to configure these systems to provide an information transfer infrastructure that enables distributed sensing and computing so that a "master" station or the entire system can be configured to "know" the status of various parts of the system. Data and information transfers between the people and machines, coupled with the appropriate systems to provide a response—even in real-time, when needed—are interesting more managers of large projects.
The day is not very far off when several teams at a site using various types of sensors—RTK GPS, static GPS, robotic and non-robotic total stations, digital levels, airborne and groundbased laser scanners, digital photography, and other remotely sensed information—can all contribute to the common database.
When reliable information technology is developed that can use this site-wide communications backbone, it will also be possible to assess work on projects; compare it with schedule, budget, and resource use; and make adjustments to how the work is being done.
Joseph V.R. Paiva, Ph.D., P.S., P.E., is a geomatics consultant. He can be reached at firstname.lastname@example.org.