Fulcrum records location data with each parent record, child record, and media attachment, ensuring high location accuracy. The collected data relies on the configured location provider in your mobile device’s operating system. Typically, this provider is the onboard GPS sensor, which sometimes works in conjunction with other sensors and radios in the device.
In this post we’ll quickly review how each mobile OS calculates your location and then dive into Android-specific setup for utilizing the Trimble Catalyst antenna with the software-defined receiver to enable you to gather sub-meter location data on your Android phone or tablet.
Platform Specifics
Android
By default, Fulcrum is using Google’s Fused Location API. This means that the OS is controlling data from sensors available and filtering the data from each to provide the “best” available location to any apps — in our case, Fulcrum. One potential issue with this API is that it is currently limited to reporting at best 3 meters of accuracy, even if the accuracy is actually better than 3 meters.
iOS
On iOS devices, Fulcrum is using the Apple Core Location API. Much like the Android Fused Location API, Core Location is controlling and filtering data streams from many sensors on the device providing the “best” location available to any apps that utilize this API.
A little background
Both frameworks use all available onboard hardware to gather data about the device’s location. This approach simplifies the process for mobile developers to integrate the best location source into an app. Currently, most consumer GPS radios achieve a maximum location accuracy of around 3 meters. This level of accuracy usually meets the needs of most Fulcrum users and their data collection tasks.
However, tasks like engineering-grade surveys or delineating wetlands require sub-meter location accuracy. To achieve this, you can add an external GPS device to your data collection toolbox. This setup provides accuracy down to less than 10 centimeters while still capturing all attribute and media data in Fulcrum.
One such solution recently tested with Fulcrum is made by Trimble, and is using a software-defined receiver in an application that you can download to your Android device that is hooked up to an external antenna via the USB port on your phone. After connecting the antenna and configuring the Catalyst software as a mock location provider, Fulcrum will use the external GNSS antenna. Other location-based apps on your device will also use this antenna as the data source.
If you’re curious about what a software-defined receiver is, follow this link to a quick, high-level overview of an open source software GNSS-SDR. It’s definitely over my head, but it’s helpful to think of it as: “the radio hardware has been replaced with software.”
Also check out our comprehensive guide to Bluetooth GPS devices for comparison of different products available.
Android & Trimble Catalyst setup
The Trimble Catalyst only works with Android at this time. This is an example of a simple real-world application of gathering centimeter-level accuracy points using Fulcrum and the Catalyst receiver. These points were taken by placing the antenna at the center point of some ground control point markers made out of tent stakes and square pieces from a styrofoam cooler laid out on the ground. Using a DJI Mavic Pro drone, we flew a photo mission of about 50% of the town and post-processed the data utilizing OpenDroneMap’s new beta Lighting Network. (Here’s a post from our own @colemanm further discussing OpenDroneMap.)
The Setup
Things you’ll need:
ItemCostAndroid DeviceVariesCatalyst Reciever~$300Catalyst Subscription~$50-400/month
The cost of the Catalyst subscription varies depending on the location accuracy you require. The good part is you can rent this on a monthly basis as needed for projects and pay for just the level you need.
Setting up your Android device with the Trimble Catalyst is fairly simple. It does require digging into the Android settings and enabling Developer Mode. You need to do this so that you can select a mock locations app (here are instructions from the Trimble Catalyst website). A mock locations app overrides the internal location provider.
Once you have set up the Android OS settings, you can open up Fulcrum and dive into the settings to check that you are indeed capturing location data based on the data stream from the Trimble Catalyst device.
You can now start capturing sub-meter accurate data in Fulcrum!
Pro-tip: Here is a link to an example Data Event that will display your location and accuracy inside a form.
Fulcrum is a data collection platform that helps businesses reduce costs, access real-time data, and improve decision-making. Using Fulcrum, you can create custom apps with a simple drag-and-drop builder. This feature lets you convert paper documents into digital forms that field teams can quickly complete on mobile devices.