Android apps typically access GNSS chipsets through a filter, which improves the GNSS location output for the majority of use cases. Filters use additional sensors, such as motion sensors, to improve the end user experience. However, filtering isn't appropriate for some applications used by professionals such as researchers and Original Equipment Manufacturer (OEM) developers. The Android Framework provides access to raw GNSS measurements on some Android devices.
This article lists Android devices that support raw GNSS measurements as well as tools that help you log and analyze GNSS data. You can find the tools in the GPS Measurement Tools repo on GitHub, which includes the GNSS Logger APK and the GNSS Analysis app for Linux, Windows, and macOS.
Android devices that support raw GNSS measurements
Before you can get any raw GNSS output, you need to make sure that you have a device that can capture such data. Most devices manufactured in 2016 or later and shipped with Android 7.0 or higher provide raw GNSS data.
Depending on the device, raw GNSS measurements can include all or some of the following data:
- Pseudorange and pseudorange rate.
- Navigation messages.
- Accumulated delta range or carrier.
- Hardware (HW) clock.
The table below lists devices that support raw GNSS measurements and the data they provide. This isn't a comprehensive list, you should contact the manufacturer to make sure that a specific device supports raw GNSS measurements.
|Model||Android version||Pseudorange data||Navigation messages||Accumulated delta range||HW clock||Global systems|
|Huawei Honor 9||7.0||yes||yes||yes||yes||GPS
|Samsung S8 (Exynos)1||7.0||yes||yes||yes||yes||GPS
|Samsung S8 (QCOM)2||7.0||yes||no||no||yes||GPS|
|Huawei P10 Lite||7.0||yes||no||no||yes||GPS|
|Huawei Honor 8||7.0||yes||yes||yes||yes||GPS
|Huawei Mate 9||7.0||yes||yes||yes||yes||GPS
|Nexus 9 (non cellular version)4||7.1||yes||yes||yes||yes||GPS
|Pixel 2 XL5||8.0||yes||no||no||yes||GPS
1 Exynos, EMEA devices, Models: G950F or G955F
2 QCOM, USA devices, Models: G950U or G955U
3 Raw measurements are provided only when a GPS position is available.
4 No duty cycling. Works only on the non cellular version of Nexus 9.
5 Automatic gain control supported.
For more information about the data provided by a device, see Global Navigation Satellite Systems.
Logging raw measurements
You can use Android Studio to build an app that captures raw GNSS measurements and logs them to a file. The GPS Measurement Tools project includes GNSS Logger, a sample app that shows how to log data related to Android location, including raw GNSS measurements.
Download the GNSS Logger APK to install the sample app in your device.
To get GNSS output with the sample app, your device must support raw GNSS measurements. For more information, see Android devices that support raw GNSS measurements.
Once you have captured the GNSS log using the GNSS Logger, you can copy the log files from the device to your computer for further analysis. From within the GNSS Logger you can send the files to yourself via email or save them to Google Drive. Alternatively, you can save the files using the file management app on the device, or you can use the Android Debug Bridge (ADB) as explained in Copy files to/from a device.
Analyzing raw measurements
The GNSS Analysis app reads the GPS/GNSS raw measurements collected by the GNSS Logger and uses them to analyze the GNSS receiver behavior, as shown in figure 1.
The GNSS Analysis app is built on MATLAB, but you don't need MATLAB to run it. The app is compiled into an executable that installs a copy of the MATLAB runtime if needed.
GNSS Analysis Control Panel
The GNSS Analysis control panel, shown in figure 2, lets you manage app features, such as:
- Select which satellites are displayed.
- Control the reference position, velocity, and time (PVT) used for calculating measurement errors.
- Generate analysis reports.
- Define a window in the data between start and end times.
GNSS Analysis interactive plots
The GNSS Analysis app provides interactive plots organized in radio frequency (RF), clocks, and measurements columns, as shown in figure 3.
The RF column shows the following data:
- For each constellation, the four satellites with the strongest signals.
- For each satellite, the time plot of carrier to noise density (C/No).
- The skyplot of satellite positions.
The clock column shows the following data:
- The pseudoranges.
- The offset frequency of the receiver clock, which is computed using one of the following reference positions:
- Automatically computed mean position.
- Latitude, longitude, and altitude entered by the user.
National Marine Electronics Association (NMEA) file with truth reference PVT.
The offset of the standby clock that keeps time when the receiver resets the duty cycle of the primary oscillator.
The measurements column shows the following data:
- The weighted least squares position results obtained from the raw pseudoranges. The weighting is done using the reported uncertainty of each measurement, which is part of the raw measurement API spec.
- The errors of each pseudorange for each measurement.
The errors of each pseudorange rate for each measurement.
GNSS Analysis test report
GNSS Analysis can generate a test report, as shown in figure 4, that evaluates the API implementation, received signal, clock behavior, and measurement accuracy. For each case, the app reports whether the receiver passed or failed the test based on the performance measured against known benchmarks. The test report is useful for device manufacturers, who can use it as they iterate through the design and implementation of new devices. To generate the test report, click Make Report.
The Compare tab provides a side-by-side comparison, shown in figure 5, of C/No from several GNSS log files, which is useful when comparing the RF performance of several devices.
- Read data captured with the GNSS Logger sample app.
- Compute and visualize pseudoranges.
- Compute weighted least squares position and velocity.
- View and analyze carrier phase.
We want to improve the support for GNSS on Android. Let us know about any issues with GNSS support on Android by using the GNSS issue tracker.
If you have other questions or a request for support, see Developer Support Resources.