Data Structure
The messages obey RTCM3.3 standards, and Unicore defines the filed Variable Length Data Message.
See the following tables for the format of the extended RTCM messages defined by Unicore.
Description of Binary Format
| ID | Structure | Description |
|---|---|---|
| 1 | Header | See Table Description of Header |
| 2 | Data | Data field, the length is variable according to different messages. Please see the specific messages for more information |
| 3 | CRC | CRC24Q check |
Description of Header
| Field | Bits | Unit | Range | Description |
|---|---|---|---|---|
| Preamble | 8 | — | — | Constant 11010011 |
| Reserved | 6 | — | — | Reserved; set to 000000 |
| Data Field Length | 10 | — | — | Data Field length in bytes |
| Message Type | 12 | — | — | UINT; Unicore message type = 4074 |
| Sub Message Type | 12 | — | — | UINT 0x00B: GYOACC 0x00C: SNRSTAT 0x00D: NAVATT 0x00E: IMURAW 0x00F: INSPVA 0x010: IMUVEH 0x0FF: Receiver information 0x0FE: Signal information 0x0FB: Ionosphere information 0x0FD: TGD/ISC information |
The messages use CRC24Q check, and the following is an example in C programming language.
U32 Crc24Q_U8(U8 *src, int len)
{
int i;
U32 crc = 0;
for (i = 0; i < len; i++)
crc = (crc << 8) ^ CRC24Q_Table[src[i] ^ (U8)(crc >> 16)];
return crc & 0xFFFFFF;
}