January 29, 2015
By David Basil
The world of GPS receivers is incredibly complicated and overflowing with acronyms, but in the end you probably just have an accuracy level requirement that you need to meet.
First, do you even need a 3rd party receiver? In clear skies, iPhone, iPad, and Android devices with GPS's can usually reach 5m accuracy.
For engineers, surveyors, and other professionals, you may need accuracy beyond that.
Third party receivers tend to fall in three major categories:
1. 1 meter accuracy - These devices, made by companies such as Bad Elf, are as cheap as $100-300. They usually have no external antenna, and run on a limited number of bands. Post processing is usually not possible on them either. However, for the price, improving from 5m to 1m accuracy on mobile devices is a great solution.
2. Sub-meter accuracy - From our initial questionaries, these devices have enough acuracy for around 75% of the market. Cost depends mostly on how much accuracy you are looking for, and which bands you want to support. Typically, you see a few major bands and networks you can connect to: US based GPS satellites which often provide the most data, GLONASS satellites, and SBAS bands like WAAS that provide additional accuracy with ground based stations and a few extra satellites. Post-processing can be performed afterwards to improve accuracy, and additional RTK (real-time kinetic, where a user will provide a base station) can be optionally added. These devices usually range from $2000-$5000.
3. Centimeter accuracy - For the most demanding customers who need precision measurements, centimeter grade GPS receivers can provide accuracy from the 20-60cm range all the way down to sub-centimeter. These devices usually use the multiple bands as mentioned above, and then add supplemental bands for accuracy. These include RTK L1 (entry-level) and L2 (standard, but much more expensive) bands for maximum accuracy, and often perform post-processing right on the device. Prices here can run from $10,000 to $50,000, depending on requirements.
What does this mean for me?
The market has a plethora of 3rd party GPS units to suit your needs. When choosing a platform, you should evaluate the overall cost of proprietary hardware, including expensive up front equipment costs, post-processing, and any other middleware.
A high-accuracy requirement no longer means being tied to legacy hardware and user interfaces that are painful to use. TerraGo Edge is a customizable, intuitive solution that feels like a consumer app and is easily learned by your users. You already have smart mobile devices in your pocket with the power to run data collection software. Why buy expensive, additional hardware instead of just adding a GPS?