Garmin 010-11018-00 GPS 20x Technical Specifications - Page 18

Satellite Data Record The satellite data has a record ID of 0x72 with 84 (0x54) data bytes. The data bytes contain data for 12 satellites as described below. typedef struct { uint8 svid; //space vehicle identification (1-32 and 33-64 for WAAS) uint16 snr; //signal-to-noise ratio uint8 elev; //satellite elevation in degrees uint16 azmth; //satellite azimuth in degrees uint8 status; //status bit-field } cpo_sat_data; The status bit field represents a set of booleans described below: Bit Meaning when bit is one (1) 0 The unit has ephemeris data for the specified satellite. 1 The unit has a differential correction for the specified satellite. 2 The unit is using this satellite in the solution. This pattern is repeated for 12 satellites for a total of 12 X 7 bytes = 84 (0x54) bytes. The USB Packet for the Satellite Record looks like: - 0x14 0x00 0x00 0x00 (USB Transport ID, 1 byte unsigned, 4 bytes reserved) - 0x72 0x00 0x00 0x00 (Record ID, 2 bytes unsigned, 4 bytes reserved) - 0x54 0x00 0x00 0x00 (Number of data bytes, 4 bytes unsigned) - 12 cpo_sat_data records 190-00880-00 GPS 20x Technical Specifications Page 15 Rev. A