U-blox, the Swiss wireless component manufacturer, in the ending of last year introduced their new GNSS modules: NEO-M8U and EVA-M8E, which are dedicated for independent (without any CAN signals) inertial navigation in vehicles. These modules allow, with sufficient accuracy, to determine the location of the vehicle in areas without any GNSS signal, such as tunnels and underground parking lots. Now we had the opportunity to test the NEO-M8U module in the long Prague tunnels.

NEO-M8U module is equipped with the Bosch BMI160 - a combination of accelerometer and  gyroscope, and it does not require any connection to the vehicle's systems, which was needed in earlier versions of such devices - to determine the speed. This greatly simplifies the installation of the unit, which now can be done without the need for professional service, required previously to plug into the CAN bus.
The EVA-M8E module offers the same functionality, but the BMI160 sensor must be connected externally. Again the module does not require any intervention into the vehicle. 

THE ROADTEST:
We have tested the NEO-M8U module with the EVK-M8U evaluation kit fixed in the car and the u-blox ANN-MS antenna on the rooftop. Our testing area was the Blanka tunnel complex (~5.5 km) in Prague. Of course we had to calibrate the sensors beforehand, which we did for about 20 km. As seen on the map below, the module has determined the position - with high accuracy - across the more than five kilometers distance of the complex and also in the following two kilometers of the Strahov tunnel. The map is showing only a one-way route for clarity (the part without sky view is marked in red). The full recording of both directions, including the data from the sensors, can be downloaded here. It can be played with the u-center software, which is available free of charge on the manufacturers website.

More information and resources are available on the manufacturers webpage: u-blox

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