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Chapter 4
3. The CRC is a 32-bit cyclic redundancy check performed on all data including the header. See
Section 4.4.2.5 on Page 44 for the CRC algorithm.
4. The header is in the format shown in Table 7 on Page 40.
Field
Field
Field
Name
Type
1
sync
Char
2
sync
Char
3
sync
Char
header
4
UChar
length
message
ID
5
UShort
message
6
Char
type
port
7
Char
address
message
8
UShort
length
9
sequence
UShort
10
idle time
Char
11
time status Enum
12
week
UShort
milli-
13
GPSec
seconds
receiver
14
ULong
status
15
UShort
Reserved
16
UShort
a. This ENUM is not 4 bytes long but, as indicated in the table, is only 1 byte.
b. These time fields are ignored if Field #11, Time Status, is invalid. In this case the current receiver time is used. The
recommended values for the three time fields are 0, 0, 0.
40
Byte
First
Second
Third
Table 7: Binary Message Header Structure
Description
Hexadecimal 0xAA
Hexadecimal 0x44
Hexadecimal 0x12
Length of the header
Message ID. The message IDs for logs are given in
Table 32 on Page 73.
Message type indicator, as explained in Section
4.2.1 on Page 37.
The port from which the log was generated.
See Table 10 on Page 42.
The length in bytes of the body of the message. This
does not include the header nor the CRC.
For multiple related logs. A number that counts
down from N-1 to 0 where N is the number of
related logs and 0 means it is the last one of the set.
Most logs only come out one at a time in which case
this number is 0.
The percentage of time that the processor is idle in
the last second. Take the time (0-200) and divide by
two to give the percentage of time (0-100%).
The quality of the GPS time, as described in Section
4.4.2.4 on Page 43
GPS week number
Milliseconds from the beginning of the GPS week
32 bits representing the status of various hardware
and firmware components of the receiver. This
number is described in Table 45 on Page 95.
Reserved for internal use
Hex
Decimal
AA
170
44
68
12
18
EuroPak-15ab Receiver User Manual Rev 1
Using Commands and Logs
Binary
Binary
Ignored
Bytes
Offset
on Input
1
0
N
1
1
N
1
2
N
1
3
N
2
4
N
1
6
N
1
7
N
2
8
N
2
10
N
1
12
Y
a
b
13
1
N
b
2
14
N
b
4
16
N
4
20
Y
2
24
Y
2
26
Y
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