We provide two types of smartphone GPS solutions. The first solution utilizes GPS raw measurements collected by an Android phone. Raw data collection was unavailable until 2017, but it is accessible now.
The second solution is about our external GPS devices that can be connected to a phone. With this approach, you are able to maintain nice mobility and prevent bad signal qualities from the phone-embedded antenna from deteriorating positioning accuracy.
Smartphone GPS
GPS Raw Data Processing by Smartphones
Old Android smartphones did not allow one to access the “raw” GPS signal and just output the coordinates computed by a GPS chip inside the phone. The position information was in NMEA (National Marine Electronics Association) format and it does not contain raw measurements such as pseudoranges or carrier phases. From 2017, Android allows you to access the raw GPS data with the launch of Nougat OS. With that, everyone can now produce pseudoranges, carrier phases, Doppler, and SNR measurements and then apply his/her own GPS signal processing engine to get better accuracies.
One example of our solution is shown in the figure on the right. With LTE/Wi-Fi connections either to the VRS or DGPS server, it receives correction messages and applies corresponding positioning algorithms. One thing to note is that it cannot do dual-frequency positioning because no smartphone GPS chip is capable of dual-frequency signal processing yet.
RTAP-MINI: External GPS Device
Even though one can now take raw measurements from a smartphone, the GPS antenna with metal-bezel structure in a phone is not good enough for precise positioning. To compensate for that de-gradation, an external device with connectivity to smartphone was devised by PP-Solution. In this case, the smartphone performs data processing functions, and more accurate coordinates can be calculated. This type of external GPS device is called RTAP-E for Real-Time Absolute Positioning – External.
The pictures on the right show three different kinds of prototypes we made. The device on the very left does not have an internal antenna while the two on the right have tiny antennas inside the unit.