Terminology Used
Acronyms
| Acronym | Acronym Description |
|---|---|
| BTFC | Broadcast Time Frame Count |
| CN0 | Carrier To Noise Density Ratio |
| ECEF | Earth Centered Earth Fixed |
| ENU | East North Up |
| GNSS | Global Navigation Satellite Systems |
| MSL | Mean Sea Level |
| NMEA | National Marine Electronics Association |
| PFOM | Position Figure of Merit |
| PVT | Position, Velocity & Time |
| Rx | Receiver |
| SV | Space Vehicle |
| TFOM | Time Figure of Merit |
| TOA | Time Of Arrival |
| TOV | Time of Validity |
Talker and System IDs
| Common Talker IDs | Descriptions | System IDs |
|---|---|---|
| BD | BeiDou | 4 |
| GA | Galileo | 3 |
| GB | BeiDou | 4 |
| GI | NavIC | 6 |
| GL | GLONASS | 2 |
| GN | Combination of Satellite Systems | |
| GP | Global Positioning System | 1 |
| GQ | QZSS | 5 |
| PXXX | Proprietary (Vendor Specific) |
Common Terminology
GPS Epoch
The system outputs “GPS time” format, of which references the GPS epoch. Said epoch is defined as:
00:00:00, January 6th, 1980, UTC
All “GPS Epoch” references contained within this guide indicate the whole second difference from this timestamp.
GPS Timestamp Format
This field represents a concatenated string of both whole integer seconds since GPS Epoch and the fractional second value with at least 8 digits of precision. If 8 digits are not provided, it is assumed that the fractional values are equal to zero.
Warning: be careful when recasting timestamp string into doubles to avoid precision loss.