Response 55h, RETSVDATA (Satellite information reports)
Report Packet 55h is sent in response to Command Packet 54h. The report includes either the ephemeris or almanac information for a specific satellite, or UTC/ION data, the Enabled/Disabled state and Heed/Ignore health state of all satellites, or the condition of satellite status flags for one satellite or all satellites.
All data in the packet flows from the receiver to the data collector.
|
Byte |
Item |
Type |
Value |
Meaning |
|---|---|---|---|---|
|
0 |
STX |
1 (Char) |
02h |
Start Transmission |
|
1 |
STATUS |
1 (Char) |
??h (see below) |
Receiver Status Code |
|
2 |
PACKET TYPE |
1 (Char) |
55h |
Response Packet Type |
|
3 |
LENGTH |
1 (Char) |
??h |
Bytes of data after this byte (excluding checksum and ETX) |
|
4 |
Subtype |
1 byte |
Refer subtype values below |
Each subtype data field shown in the following tables will be output based on the 54h command sent, as shown above. |
|
----- DATA RECORDS 0 to 27 ----- |
||||
|
Data from one of the records that are encoded in Type 55h records, as indicated by byte #4 subtype. 0: SV flags report indicating tracking, ephemeris, almanac, and enabled status (Deprecated. Use subtype 20.) 4: Disable Satellite (Deprecated. Use subtype 20.) 5: Enable Satellite (Deprecated. Use subtype 20.) 7: Extended GPS almanac report (includes clock parameters) 20: SV flags report |
||||
|
Last subtype byte + 1 |
CHECKSUM |
Char |
??h |
Checksum Value |
|
Last subtype byte + 2 |
ETX |
Char |
03h |
End Transmission |
Only the satellite information, requested by Command Packet 54h, is sent in the report packet. As a result, several forms of the Report Packet 55h can be requested.
Returns a NAK if the GETSVDATA request meets one of the following criteria:
-
SV PRN is out of range (except for SV flags)
-
Data Switch is out of range
-
Data is not available for the requested SV