How to achieve sub-metre location accuracy on IOS or Android Devices
Following recent projects that required high accuracy (sub-metre) recording of spatial data we have invested in a device that provides sub-metre location data to your phone or tablet.
At WSI we have been using apple iPhones and iPads in the field for recording ecological data over the past five years. We have found these devices to be excellent as a means of recording field data. The user friendly interface, ease with which text can be inputted, stability of the software, and the security and easy transfer of data are the key advantages we have found with using these devices. The internal GPS of these devices are good and typically provide location data to an accuracy of 5m. This level of accuracy is perfectly adequate for the majority of ecological surveys we have undertaken (particularly when combined with high resolution aerial imagery). However, there are instances where it can be beneficial to acquire a higher level of accuracy, for example rare plant surveys or quadrat monitoring surveys.
There are now a range of options available that enable you to acquire high accuracy (consistently within 1 metre) location data on your phone or tablet. Although the cost of the devices remains high, it is more affordable than purchasing a standalone device with such capability that runs on its own operating system. In our experience these devices are a lot less user friendly than your IOS or Android device.
Following considerable product research and reading online reviews (see links below) we settled on the EOS Arrow 100. This is a small and portable GPS receivers that connect to your phone or tablet via Bluetooth. The device automatically override the internal GPS of the phone and provides real time sub-metre location data. The apparent advantages of this product over others included a removable battery, competitive price, reportedly higher degree of accuracy (even under tree canopy), stable software, and excellent bluetooth connectivity.
We tested the new device during a week surveying remote blanket bog areas in the west of Ireland and are impressed with how it performed. The device itself is rugged and waterproof. It straps to your belt and has an external antenna that can be attached to your backpack or within a pouch of a specially designed funky baseball cap (see above)! While using ESRI Collector on an iPhone we were consistently getting accuracy of between 0.2m and 0.7m. It was rare that the reported accuracy exceeded 1m. The Bluetooth connection is excellent and the device battery still had plenty of charge at the end of the day. Overall we are very happy with the operation of the device, though the cost was significant.
There are a range of products available that provide similar capability and we found the following reviews particularly informative:
http://www.fulcrumapp.com/blog/bluetooth-gps-comparison/
http://anatumfieldsolutions.com/20160314submeter-gnss-field-tested-compared/