u-blox 8 / u-blox M8 Receiver Description - Manual
7.6 Degraded Navigation................................................................................................................. 20
7.6.1 2D Navigation...................................................................................................................... 20
7.7 Geodetic Coordinate Systems and Ellipsoids ............................................................................ 21
8 Clocks and Time................................................................................................................................. 21
8.1 Receiver Local Time.................................................................................................................... 21
8.2 Navigation Epochs...................................................................................................................... 22
8.3 iTOW Timestamps ...................................................................................................................... 23
8.4 GNSS Times ................................................................................................................................. 23
8.5 Time Validity............................................................................................................................... 23
8.6 UTC Representation ................................................................................................................... 24
8.7 Leap Seconds .............................................................................................................................. 24
8.8 Real Time Clock .......................................................................................................................... 24
8.9 Date............................................................................................................................................. 25
8.9.1 GPS-only Date Resolution................................................................................................... 25
9 Broadcast Navigation Data............................................................................................................... 25
9.1 Parsing Navigation Data Subframes ......................................................................................... 26
9.2 GPS .............................................................................................................................................. 26
9.3 GLONASS..................................................................................................................................... 26
9.4 BeiDou ........................................................................................................................................ 27
9.5 Galileo......................................................................................................................................... 27
9.6 SBAS ............................................................................................................................................ 28
9.7 QZSS ............................................................................................................................................ 29
9.8 IMES ............................................................................................................................................ 29
9.9 Summary..................................................................................................................................... 29
10 Serial Communication Ports Description....................................................................................... 30
10.1 TX-ready indication.................................................................................................................. 30
10.2 Extended TX timeout............................................................................................................... 31
10.3 UART Ports................................................................................................................................ 31
10.4 USB Port.................................................................................................................................... 31
10.5 DDC Port ................................................................................................................................... 32
10.5.1 Read Access........................................................................................................................ 32
10.5.2 Write Access....................................................................................................................... 34
10.6 SPI Port...................................................................................................................................... 35
10.6.1 Maximum SPI clock speed................................................................................................. 35
10.6.2 Read Access........................................................................................................................ 35
10.6.3 Back-To-Back Read and Write Access............................................................................... 35
10.7 How to change between protocols......................................................................................... 36
11 Multiple GNSS Assistance (MGA)................................................................................................... 36
11.1 Introduction.............................................................................................................................. 36
11.2 Assistance Data......................................................................................................................... 36
11.3 AssistNow Online ..................................................................................................................... 37
11.3.1 Host Software.................................................................................................................... 38
11.3.2 AssistNow Online Sequence ............................................................................................. 39
UBX-13003221 - R10 Early Production Information Page v
