We are providing smartphone GPS solutions in dual categories. In the first product category, GPS raw measurements collected by an Android phone is used. The raw data collection has been impossible until 2017. Another smartphone solution is to make external GPS devices which 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.
GPS Raw Data Collection and Processing on 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 above. With LTE/Wi-Fi connections either to the VRS or DGPS server, it receives correction messages and apply 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: 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 a 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 below show three different kinds of prototypes we made. The leftmost one does not have an internal antenna while the two on the right have tiny antennas inside the unit.