Novatel OM-20000041 用户手册

4

Message Formats

MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1

47

NovAtel header and terminates with a checksum.

This message was designed so that 

RTCA

 data can be intermixed with other NovAtel ASCII data over a common

communications port. The log is not in pure 

RTCA

 format. The header (

$RTCA

) and terminator (*xx) must be

stripped off at the receiving end, then the data will need to be converted from hexadecimal to binary before the

RTCA

 information is retrieved.

The 

RTCAA

 log can be directly decoded by other NovAtel GPSCard receivers operating as remote stations. They

will recognize the $

RTCA

 header as a special data input command and the differential corrections data will be

directly applied. The GPSCard remote station receiving this log must have the 

ACCEPT

 command set to "

ACCEPT

port 

COMMANDS

".

$RTCA,990000000447520607BE7C92FA0B82423E9FE507DF5F3FC9FD071AFC7FA0
D207D090808C0E045BACC055E9075271FFB0200413F43FF810049C9DFF8FFD074F
CF3C940504052DFB*20[CR][LF]

The 

RTCAB

 log contains the 

SCAT

-

I

 differential corrections message with the standard NovAtel binary log preamble

(header) added. The 

RTCAB

 log will be accepted by the GPSCard over a 

COM

 port after an "

ACCEPT

 port 

RTCA

"

command is issued.

Format:

Message ID = 38

Message byte count = 12 + (11+(6*obs)): 95 bytes maximum

The Radio Technical Commission for Maritime Services (

RTCM

) was established to facilitate the establishment of

various radio navigation standards, which includes recommended 

GPS

 differential standard formats.

$RTCA

data

*xx

[CR][LF]

1

$RTCA

Log header

$RTCA

2

data

SCAT-I type 1 differential 
corrections

990000000447520607BE7C92FA0B82423E9FE507DF5F3FC9
FD071AFC7FA0D207D090808C0E045BACC055E9075271FFB
0200413F43FF810049C9DFF8FFD074FCF3C940504052DFB

3

*x x

Checksum

*20

4

[CR][LF]

[CR][LF]

1

Sync

3

char

0

(header)

Checksum

1

char

3

Message ID

4

integer

4

Message byte count

4

integer

8

2

–

Message block identifier

–

Reference station ID

–

Message type

–

Message length

6

12

3

–

Modified z-count

–

Acceleration error bound

2

18

4

–

Satellite ID

–

Pseudorange correction

–

Issue of data

–

Range rate correction

–

UDRE

6

20

5

Next PRN offset = 26 + (6*obs) where obs varies from 0 to (obs-1)

6

CRC

3