Garmin GPS 18x Series Technical Specifications

Also see for GPS 18x LVC: Declaration of conformity

Contents

Garmin GPS 18x Series Technical Specifications Manual pdf 29 page image

190-00879-08 GPS 18x Technical Specifications Rev. BPage 25Satellite Data RecordThe satellite data has a record ID of 0x72 with 84 (0x54) data bytes. The data bytes contain data for 12 satellites asdescribed below.typedef struct{uint8 svid; //space vehicle identification (1–32 and 33–64 for WAAS)uint16 snr; //signal-to-noise ratiouint8 elev; //satellite elevation in degreesuint16 azmth; //satellite azimuth in degreesuint8 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 RS-232 Packet for the Satellite Record looks like:- 0x10 (DLE is first byte)- 0x72 (Record ID – single byte)- 0x54 (Number of data bytes – single byte)- 12 cpo_sat_data records- 0x## (2’s complement of the arithmetic sum of the bytes between the delimiters)- 0x10 (DLE)- 0x03 (ETX is last byte)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