ashtech DG14, Справочное руководство

Страница: 269 / 390

NMEA Commands 249
NMEA Commands
SBAS satellites numbers are actually 120 to 138, but are represented in the NMEA messages with
numbers 33 to 64. The offset from NMEA SBAS satellite ID to SBAS satellite ID is 87. Add 87 to the
satellite ID fields in the NMEA messages to derive the actual SBAS PRN number.
Typical GSV message:
$GPGSV,2,2,8,08,43,294,47,07,19,062,42,05,49,314,49,02,03,120,2
9 *45
Table 8.21 outlines the response message.
f15 Signal to noise ration (dbHz) 30 to 60
d16 Satellite PRN number 1 to 32 for GPS
33 to 64 for SBAS
d17 Elevation (degrees) 0° to 90°
d18 Azimuth (degrees) 0° to 359°
f19 Signal to noise ration (dbHz) 30 to 60
*hh Checksum 2-character hex
Table 8.21. Typical GSV Message
Field Description
$GPGSV Header
2 Indicates that two GSV messages will output
2 Indicates that this is the second message
8 Indicates that eight satellites are visible
08 Indicates PRN 8 is visible
43 Elevation of PRN 8
294 Azimuth of PRN 8
47 Signal to noise ration of PRN 8
07 Indicates PRN 7 is visible
19 Elevation of PRN 7
062 Azimuth of PRN 7
42 Signal to noise ratio of PRN 7
05 Indicates PRN 5 is visible
49 Elevation of PRN 5
Table 8.20. $GPGSV Message Format (Continued)
Parameter Description Range