Garmin 15 H Series, Технические характеристики

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APPENDIX B: GARMIN BINARY OUTPUT FORMAT
In binary output mode, the GPS 15xH/15xL will transmit packets once per second. The record
contains primarily post-process information such as position and velocity information. The default
serial port settings in binary output mode is 4800 baud, 8 data bits, 1 start bit, 1 stop bit and no
parity. Of those settings, only the baud rate may be changed. Please see Appendix C for details
on changing the baud rate in binary output mode.
To enable the binary output mode as a power-on default (powers up with this mode enabled), use
the $PGRMC1 NMEA 0183 sentence as described in Section 4.1.4 . (You must currently be
operating in NMEA 0183 mode in order for NMEA 0183 configuration sentences to have any
effect.) If you wish to enable the binary output mode and you do not wish to alter the setting for
which mode (NMEA 0183 or binary output) is enabled at power on, use the $PGRMO NMEA
0183 sentence as described in Section 4.1.5 . Refer to the Garmin Device Interface Specification
found in the Garmin Device Interface SDK for details on how to form and parse Garmin packets,
available at https://www8.garmin.com/support/commProtocol.html .
Note that the satellite data information is also enabled when the position record is enabled.
Records sent over RS232 begin with a delimiter byte (10 hex). The second byte identifies the
record type (33 hex for a position record and 72 hex for a satellite data record). The third byte
indicates the size of the data. The fourth byte is the first byte of data. The data is then followed by
a checksum byte, a delimiter byte (10 hex), and an end-of-transmission character (03 hex).
Additionally, any DLEs (0x10) that appear between the delimeters are escaped with a second
DLE. There is sample code at the end of this section that will strip off the DLEs and ETXs.
RS232 Packet:
- 0x10
(DLE is first byte)
- 0x## (Record ID – single byte)
- 0x## (Number of data bytes – single byte)
- data bytes (See descriptions below)
- 0x## (2’s complement of the arithmetic sum of the bytes between the
delimiters)
- 0x10
(DLE)
- 0x03 (ETX is last byte)
The data bytes of each packet contain the record specified by the record ID. A description of each
record follows.
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.