Specifications

APPENDIX

P-13

GBS - GNSS satellite fault detection

This message is used to support receiver autonomous integrity monitoring (RAIM). Given

that a GPS receiver is tracking enough satellites to perform integrity checks of the

positioning quality of the position solution, a message is needed to report the output of this

process to other systems to advise the system user. With the RAIM in the GPS receiver,

the receiver can isolate faults to individual satellites and not use them in its position and

velocity calculations. Also, the GPS receiver can still track the satellite and easily judge

when it is back within tolerance.

This message shall be used for reporting this RAIM information. To perform these integrity

functions, six channels of satellite tracking are a minimum while all-in-view tracking is

most desirable.

$--GBS,hhmmss.ss,x.x,x.x,x.x,xx,x.x,x.x,x.x*hh<CR><LF>

| | | | | | | | |

| | | | | | | | +--------- 9

| | | | | | | +------------ 8

| | | | | | +---------------- 7

| | | | | +-------------------- 6

| | | | +----------------------- 5

| | | +--------------------------- 4

| | +------------------------------- 3

| +----------------------------------- 2

+------------------------------------------- 1

1. UTC time of the GGA or GNS fix associated with this sentence

2. Expected error in latitude

3. Expected error in longitude

4. Expected error in altitude

5. ID number of most likely failed satellite

6. Probability of missed detection for most likely failed satellite

7. Estimate of bias on most likely failed satellite

8. Standard deviation of bias estimate

9. Checksum